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From: Milica Matic <milica.matic@htecgroup.com>
To: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>
Cc: Milica Matic <milica.matic@htecgroup.com>,
	Djordje Todorovic <Djordje.Todorovic@htecgroup.com>,
	Milos Kalicanin <milos.kalicanin@htecgroup.com>,
	"simark@simark.ca" <simark@simark.ca>,
	"cfu@wavecomp.com" <cfu@wavecomp.com>,
	"aburgess@redhat.com" <aburgess@redhat.com>,
	"kevinb@redhat.com" <kevinb@redhat.com>,
	"macro@orcam.me.uk" <macro@orcam.me.uk>
Subject: [PATCH^11] gdb: mips: Add MIPSR6 support
Date: Mon, 10 Feb 2025 17:28:12 +0000	[thread overview]
Message-ID: <20250210172801.43302-1-milica.matic@htecgroup.com> (raw)

Introduce new instruction encodings from Release 6 of the MIPS
architecture [1]. Support breakpoints and single stepping with
compact branches, forbidden slots, new branch instruction and
new atomic load-store instruction encodings.

Changes from v10: Apply suggestions provided by Kevin Buettner.
Additionaly, format mips-tdep.c code as described on links:
https://sourceware.org/gdb/wiki/Internals%20GDB-C-Coding-Standards
https://www.gnu.org/prep/standards/standards.html#Comments

[1] "MIPS64 Architecture for Programmers Volume II-A: The MIPS64
    Instruction Set Reference Manual", Document Number: MD00087,
    Revision 6.06, December 15, 2016, Section 3 "The MIPS64
    Instruction Set", pp. 42-530
https://s3-eu-west-1.amazonaws.com/downloads-mips/documents/MD00087-2B-MIPS64BIS-AFP-6.06.pdf
2025-02-10
Andrew Bennett  <andrew.bennett@imgtec.com>
Matthew Fortune  <matthew.fortune@mips.com>
Faraz Shahbazker  <fshahbazker@wavecomp.com>
---
 gdb/mips-tdep.c                       | 941 ++++++++++++++++++++------
 gdb/testsuite/gdb.arch/mips-64-r6.c   | 916 +++++++++++++++++++++++++
 gdb/testsuite/gdb.arch/mips-64-r6.exp |  76 +++
 3 files changed, 1718 insertions(+), 215 deletions(-)
 create mode 100644 gdb/testsuite/gdb.arch/mips-64-r6.c
 create mode 100644 gdb/testsuite/gdb.arch/mips-64-r6.exp

diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index a28c99d3366..49093640e01 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -1,6 +1,6 @@
 /* Target-dependent code for the MIPS architecture, for GDB, the GNU Debugger.
 
-   Copyright (C) 1988-2024 Free Software Foundation, Inc.
+   Copyright (C) 1988-2025 Free Software Foundation, Inc.
 
    Contributed by Alessandro Forin(af@cs.cmu.edu) at CMU
    and by Per Bothner(bothner@cs.wisc.edu) at U.Wisconsin.
@@ -76,8 +76,12 @@ static int mips16_insn_at_pc_has_delay_slot (struct gdbarch *gdbarch,
 static void mips_print_float_info (struct gdbarch *, struct ui_file *,
 				   const frame_info_ptr &, const char *);
 
-/* A useful bit in the CP0 status register (MIPS_PS_REGNUM).  */
-/* This bit is set if we are emulating 32-bit FPRs on a 64-bit chip.  */
+static void
+mips_read_fp_register_single (const frame_info_ptr &frame, int regno,
+			      gdb::array_view<gdb_byte> rare_buffer);
+
+/* A useful bit in the CP0 status register (MIPS_PS_REGNUM).
+   This bit is set if we are emulating 32-bit FPRs on a 64-bit chip.  */
 #define ST0_FR (1 << 26)
 
 /* The sizes of floating point registers.  */
@@ -220,6 +224,7 @@ static std::string mips_disassembler_options;
    to the ABI we have selected, perhaps via a `set mips abi ...'
    override, rather than ones inferred from the ABI set in the ELF
    headers of the binary file selected for debugging.  */
+
 static const char mips_disassembler_options_o32[] = "gpr-names=32";
 static const char mips_disassembler_options_n32[] = "gpr-names=n32";
 static const char mips_disassembler_options_n64[] = "gpr-names=64";
@@ -325,6 +330,17 @@ mips_abi_regsize (struct gdbarch *gdbarch)
     }
 }
 
+/* Return true if the gdbarch is based on MIPS Release 6.  */
+
+static bool
+is_mipsr6_isa (struct gdbarch *gdbarch)
+{
+  const struct bfd_arch_info *info = gdbarch_bfd_arch_info (gdbarch);
+
+  return (info->mach == bfd_mach_mipsisa32r6
+	  || info->mach == bfd_mach_mipsisa64r6);
+}
+
 /* MIPS16/microMIPS function addresses are odd (bit 0 is set).  Here
    are some functions to handle addresses associated with compressed
    code including but not limited to testing, setting, or clearing
@@ -633,7 +649,6 @@ static const char * const mips_linux_reg_names[NUM_MIPS_PROCESSOR_REGS] = {
   "fsr", "fir"
 };
 
-
 /* Return the name of the register corresponding to REGNO.  */
 static const char *
 mips_register_name (struct gdbarch *gdbarch, int regno)
@@ -657,7 +672,7 @@ mips_register_name (struct gdbarch *gdbarch, int regno)
 
   enum mips_abi abi = mips_abi (gdbarch);
 
-  /* Map [gdbarch_num_regs .. 2*gdbarch_num_regs) onto the raw registers, 
+  /* Map [gdbarch_num_regs .. 2*gdbarch_num_regs) onto the raw registers,
      but then don't make the raw register names visible.  This (upper)
      range of user visible register numbers are the pseudo-registers.
 
@@ -668,6 +683,7 @@ mips_register_name (struct gdbarch *gdbarch, int regno)
      configured to be 32-bits wide.  The registers that the user
      sees - the pseudo registers - match the users expectations
      given the programming model being used.  */
+
   int rawnum = regno % gdbarch_num_regs (gdbarch);
   if (regno < gdbarch_num_regs (gdbarch))
     return "";
@@ -1005,7 +1021,7 @@ mips_value_to_register (const frame_info_ptr &frame, int regnum,
       size_t len = type->length ();
       frame_info_ptr next_frame = get_next_frame_sentinel_okay (frame);
 
-      /* Sign extend values, irrespective of type, that are stored to 
+      /* Sign extend values, irrespective of type, that are stored to
 	 a 64-bit general purpose register.  (32-bit unsigned values
 	 are stored as signed quantities within a 64-bit register.
 	 When performing an operation, in compiled code, that combines
@@ -1074,21 +1090,29 @@ mips_register_type (struct gdbarch *gdbarch, int regnum)
       else if (gdbarch_osabi (gdbarch) != GDB_OSABI_LINUX
 	       && rawnum >= MIPS_FIRST_EMBED_REGNUM
 	       && rawnum <= MIPS_LAST_EMBED_REGNUM)
-	/* The pseudo/cooked view of the embedded registers is always
-	   32-bit.  The raw view is handled below.  */
-	return builtin_type (gdbarch)->builtin_int32;
+	{
+	  /* The pseudo/cooked view of the embedded registers is always
+	     32-bit.  The raw view is handled below.  */
+	  return builtin_type (gdbarch)->builtin_int32;
+	}
       else if (tdep->mips64_transfers_32bit_regs_p)
-	/* The target, while possibly using a 64-bit register buffer,
-	   is only transferring 32-bits of each integer register.
-	   Reflect this in the cooked/pseudo (ABI) register value.  */
-	return builtin_type (gdbarch)->builtin_int32;
+	{
+	  /* The target, while possibly using a 64-bit register buffer,
+	     is only transferring 32-bits of each integer register.
+	     Reflect this in the cooked/pseudo (ABI) register value.  */
+	  return builtin_type (gdbarch)->builtin_int32;
+	}
       else if (mips_abi_regsize (gdbarch) == 4)
-	/* The ABI is restricted to 32-bit registers (the ISA could be
-	   32- or 64-bit).  */
-	return builtin_type (gdbarch)->builtin_int32;
+	{
+	  /* The ABI is restricted to 32-bit registers (the ISA could be
+	     32- or 64-bit).  */
+	  return builtin_type (gdbarch)->builtin_int32;
+	}
       else
-	/* 64-bit ABI.  */
-	return builtin_type (gdbarch)->builtin_int64;
+	{
+	  /* 64-bit ABI.  */
+	  return builtin_type (gdbarch)->builtin_int64;
+	}
     }
 }
 
@@ -1236,6 +1260,7 @@ mips_pc_is_mips16 (struct gdbarch *gdbarch, CORE_ADDR memaddr)
      elfread.c in the high bit of the info field.  Use this to decide
      if the function is MIPS16.  Otherwise if bit 0 of the address is
      set, then ELF file flags will tell if this is a MIPS16 function.  */
+
   bound_minimal_symbol sym
     = lookup_minimal_symbol_by_pc (make_compact_addr (memaddr));
   if (sym.minsym)
@@ -1254,6 +1279,7 @@ mips_pc_is_micromips (struct gdbarch *gdbarch, CORE_ADDR memaddr)
      if the function is microMIPS.  Otherwise if bit 0 of the address
      is set, then ELF file flags will tell if this is a microMIPS
      function.  */
+
   bound_minimal_symbol sym
     = lookup_minimal_symbol_by_pc (make_compact_addr (memaddr));
   if (sym.minsym)
@@ -1273,6 +1299,7 @@ mips_pc_isa (struct gdbarch *gdbarch, CORE_ADDR memaddr)
      this to decide if the function is MIPS16 or microMIPS or normal
      MIPS.  Otherwise if bit 0 of the address is set, then ELF file
      flags will tell if this is a MIPS16 or a microMIPS function.  */
+
   bound_minimal_symbol sym
     = lookup_minimal_symbol_by_pc (make_compact_addr (memaddr));
   if (sym.minsym)
@@ -1541,6 +1568,7 @@ mips_fetch_instruction (struct gdbarch *gdbarch,
 #define b0s11_op(x) ((x) & 0x7ff)
 #define b0s12_imm(x) ((x) & 0xfff)
 #define b0s16_imm(x) ((x) & 0xffff)
+#define b0s21_imm(x) ((x) & 0x1fffff)
 #define b0s26_imm(x) ((x) & 0x3ffffff)
 #define b6s10_ext(x) (((x) >> 6) & 0x3ff)
 #define b11s5_reg(x) (((x) >> 11) & 0x1f)
@@ -1566,7 +1594,7 @@ mips_insn_size (enum mips_isa isa, ULONGEST insn)
       else
 	return MIPS_INSN16_SIZE;
     case ISA_MIPS:
-	return MIPS_INSN32_SIZE;
+      return MIPS_INSN32_SIZE;
     }
   internal_error (_("invalid ISA"));
 }
@@ -1577,6 +1605,24 @@ mips32_relative_offset (ULONGEST inst)
   return ((itype_immediate (inst) ^ 0x8000) - 0x8000) << 2;
 }
 
+/* Calculates pc-relative offset from lower 21 bits of instruction.
+   Used by BEQZC, BNEZC.  */
+
+static LONGEST
+mips32_relative_offset21 (ULONGEST insn)
+{
+  return ((b0s21_imm (insn) ^ 0x100000) - 0x100000) << 2;
+}
+
+/* Calculates pc-relative offset from lower 26 bits of an instruction.
+   Used by BC, BALC.  */
+
+static LONGEST
+mips32_relative_offset26 (ULONGEST insn)
+{
+  return ((b0s26_imm (insn) ^ 0x2000000) - 0x2000000) << 2;
+}
+
 /* Determine the address of the next instruction executed after the INST
    floating condition branch instruction at PC.  COUNT specifies the
    number of the floating condition bits tested by the branch.  */
@@ -1593,8 +1639,10 @@ mips32_bc1_pc (struct gdbarch *gdbarch, struct regcache *regcache,
   int cond;
 
   if (fcsr == -1)
-    /* No way to handle; it'll most likely trap anyway.  */
-    return pc;
+    {
+      /* No way to handle; it'll most likely trap anyway.  */
+      return pc;
+    }
 
   fcs = regcache_raw_get_unsigned (regcache, fcsr);
   cond = ((fcs >> 24) & 0xfe) | ((fcs >> 23) & 0x01);
@@ -1626,15 +1674,86 @@ is_octeon_bbit_op (int op, struct gdbarch *gdbarch)
 {
   if (!is_octeon (gdbarch))
     return 0;
-  /* BBIT0 is encoded as LWC2: 110 010.  */
-  /* BBIT032 is encoded as LDC2: 110 110.  */
-  /* BBIT1 is encoded as SWC2: 111 010.  */
-  /* BBIT132 is encoded as SDC2: 111 110.  */
+  /* BBIT0 is encoded as LWC2: 110 010.
+     BBIT032 is encoded as LDC2: 110 110.
+     BBIT1 is encoded as SWC2: 111 010.
+     BBIT132 is encoded as SDC2: 111 110.  */
   if (op == 50 || op == 54 || op == 58 || op == 62)
     return 1;
   return 0;
 }
 
+/* Detects whether overflow occurs when adding two 32-bit integers.  */
+
+static bool
+is_add32bit_overflow (int32_t a, int32_t b)
+{
+  int32_t r = (uint32_t) a + (uint32_t) b;
+  return (a < 0 && b < 0 && r >= 0) || (a > 0 && b > 0 && r <= 0);
+}
+
+/* Helper function for BOVC and BNVC instructions which are introduced in
+   MIPS Release 6.
+
+   BOVC performs a signed 32-bit addition of two registers.  BOVC discards the
+   sum, but detects signed 32-bit integer overflow of the sum (and the inputs,
+   in MIPS64), and branches if such overflow is detected.
+
+   BNVC does the opposite, i.e. branches if such overflow is not detected.  */
+
+static bool
+is_add64bit_overflow (int64_t a, int64_t b)
+{
+  if (a != (int32_t) a)
+    return true;
+  if (b != (int32_t) b)
+    return true;
+  return is_add32bit_overflow ((int32_t) a, (int32_t) b);
+}
+
+#define DELAY_SLOT_SIZE 4
+
+/* Calculate address of next instruction after BLEZ.  */
+
+static CORE_ADDR
+mips32_blez_pc (struct gdbarch *gdbarch, struct regcache *regcache,
+		ULONGEST inst, CORE_ADDR pc, int invert)
+{
+  int rs = itype_rs (inst);
+  int rt = itype_rt (inst);
+  LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+  LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+  ULONGEST uval_rs = regcache_raw_get_unsigned (regcache, rs);
+  ULONGEST uval_rt = regcache_raw_get_unsigned (regcache, rt);
+  bool taken = false;
+
+  /* BLEZ, BLEZL, BGTZ, BGTZL  */
+  if (rt == 0)
+    taken = (val_rs <= 0);
+  else if (is_mipsr6_isa (gdbarch))
+    {
+      /* BLEZALC, BGTZALC  */
+      if (rs == 0 && rt != 0)
+	taken = (val_rt <= 0);
+      /* BGEZALC, BLTZALC  */
+      else if (rs == rt && rt != 0)
+	taken = (val_rt >= 0);
+      /* BGEUC, BLTUC  */
+      else if (rs != rt && rs != 0 && rt != 0)
+	taken = (uval_rs >= uval_rt);
+    }
+
+  if (invert)
+    taken = !taken;
+
+  /* Calculate branch target.  */
+  if (taken)
+    pc += mips32_relative_offset (inst);
+  else
+    pc += DELAY_SLOT_SIZE;
+
+  return pc;
+}
 
 /* Determine where to set a single step breakpoint while considering
    branch prediction.  */
@@ -1645,14 +1764,18 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
   struct gdbarch *gdbarch = regcache->arch ();
   unsigned long inst;
   int op;
+  bool mips64bitreg = false;
+
+  if (mips_isa_regsize (gdbarch) == 8)
+    mips64bitreg = true;
+
   inst = mips_fetch_instruction (gdbarch, ISA_MIPS, pc, NULL);
   op = itype_op (inst);
-  if ((inst & 0xe0000000) != 0)		/* Not a special, jump or branch
-					   instruction.  */
+  if ((inst & 0xe0000000) != 0) /* Not a special, jump or branch instruction.  */
     {
-      if (op >> 2 == 5)
-	/* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx */
+      if (op >> 2 == 5 && ((op & 0x02) == 0 || itype_rt (inst) == 0))
 	{
+	  /* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx */
 	  switch (op & 0x03)
 	    {
 	    case 0:		/* BEQL */
@@ -1660,7 +1783,7 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	    case 1:		/* BNEL */
 	      goto neq_branch;
 	    case 2:		/* BLEZL */
-	      goto less_branch;
+	      goto lez_branch;
 	    case 3:		/* BGTZL */
 	      goto greater_branch;
 	    default:
@@ -1668,20 +1791,30 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	    }
 	}
       else if (op == 17 && itype_rs (inst) == 8)
-	/* BC1F, BC1FL, BC1T, BC1TL: 010001 01000 */
-	pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 1);
-      else if (op == 17 && itype_rs (inst) == 9
+	{
+	  /* BC1F, BC1FL, BC1T, BC1TL: 010001 01000 */
+	  pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 1);
+	}
+      else if (!is_mipsr6_isa (gdbarch)
+	       && op == 17
+	       && itype_rs (inst) == 9
 	       && (itype_rt (inst) & 2) == 0)
-	/* BC1ANY2F, BC1ANY2T: 010001 01001 xxx0x */
-	pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 2);
-      else if (op == 17 && itype_rs (inst) == 10
+	{
+	  /* BC1ANY2F, BC1ANY2T: 010001 01001 xxx0x */
+	  pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 2);
+	}
+      else if (!is_mipsr6_isa (gdbarch)
+	       && op == 17
+	       && itype_rs (inst) == 10
 	       && (itype_rt (inst) & 2) == 0)
-	/* BC1ANY4F, BC1ANY4T: 010001 01010 xxx0x */
-	pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 4);
-      else if (op == 29)
-	/* JALX: 011101 */
-	/* The new PC will be alternate mode.  */
 	{
+	  /* BC1ANY4F, BC1ANY4T: 010001 01010 xxx0x */
+	  pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 4);
+	}
+      else if (!is_mipsr6_isa (gdbarch) && op == 29)
+	{
+	  /* JALX: 011101
+	     The new PC will be alternate mode.  */
 	  unsigned long reg;
 
 	  reg = jtype_target (inst) << 2;
@@ -1695,28 +1828,174 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	  branch_if = op == 58 || op == 62;
 	  bit = itype_rt (inst);
 
-	  /* Take into account the *32 instructions.  */
 	  if (op == 54 || op == 62)
-	    bit += 32;
+	    {
+	      /* Take into account the *32 instructions.  */
+	      bit += 32;
+	    }
 
 	  if (((regcache_raw_get_signed (regcache,
 					 itype_rs (inst)) >> bit) & 1)
 	      == branch_if)
 	    pc += mips32_relative_offset (inst) + 4;
 	  else
-	    pc += 8;        /* After the delay slot.  */
+	    {
+	      /* After the delay slot.  */
+	      pc += 8;
+	    }
 	}
+      else if (is_mipsr6_isa (gdbarch))
+	{
+	  if (op == 8 || op == 24)
+	    {
+	      /* BOVC, BEQZALC, BEQC and BNVC, BNEZALC, BNEC  */
+	      int rs = rtype_rs (inst);
+	      int rt = rtype_rt (inst);
+	      LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+	      LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+	      bool taken = false;
+	      if (rs >= rt)
+		{
+		  /* BOVC (BNVC)  */
+		  if (mips64bitreg)
+		    taken = is_add64bit_overflow (val_rs, val_rt);
+		  else
+		    taken = is_add32bit_overflow (val_rs, val_rt);
+		}
+	      else if (rs < rt && rs == 0)
+		{
+		  /* BEQZALC (BNEZALC)  */
+		  taken = (val_rt == 0);
+		}
+	      else
+		{
+		  /* BEQC (BNEC)  */
+		  taken = (val_rs == val_rt);
+		}
+
+	      if (op == 24)
+		{
+		  /* BNVC, BNEZALC, BNEC  */
+		  taken = !taken;
+		}
 
+	      if (taken)
+		pc += mips32_relative_offset (inst) + 4;
+	      else
+		{
+		  /* Step through the forbidden slot to avoid repeated
+		     exceptions.
+		     We do not currently have access to the BD bit when hitting
+		     a breakpoint and therefore cannot tell if the breakpoint
+		     hit on the branch or the forbidden slot.  */
+		  pc += 8;
+		}
+	    }
+	  else if (op == 17 && (itype_rs (inst) == 9 || itype_rs (inst) == 13))
+	    {
+	      /* BC1EQZ, BC1NEZ  */
+	      gdb_byte status;
+	      gdb_byte true_val = 0;
+	      unsigned int fp = (gdbarch_num_regs (gdbarch)
+				 + mips_regnum (gdbarch)->fp0
+				 + itype_rt (inst));
+	      struct frame_info_ptr frame = get_current_frame ();
+	      gdb_byte *buf_tmp = (gdb_byte *) alloca (sizeof (gdb_byte) * 4);
+	      gdb::array_view<gdb_byte> raw_buffer = gdb::make_array_view (buf_tmp, sizeof (gdb_byte) * 4);
+	      mips_read_fp_register_single (frame, fp, raw_buffer);
+
+	      if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
+		status = raw_buffer[3];
+	      else
+		status = raw_buffer[0];
+
+	      if (itype_rs (inst) == 13)
+		true_val = 1;
+
+	      if ((status & 0x1) == true_val)
+		pc += mips32_relative_offset (inst) + 4;
+	      else
+		pc += 8;
+	    }
+	  else if (op == 22 || op == 23)
+	    {
+	      /* BLEZC, BGEZC, BGEC, BGTZC, BLTZC, BLTC  */
+	      int rs = rtype_rs (inst);
+	      int rt = rtype_rt (inst);
+	      LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+	      LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+	      bool taken = false;
+	      /* The R5 rt == 0 case is handled above so we treat it as
+		 an unknown instruction here for future ISA usage.  */
+	      if (rs == 0 && rt != 0)
+		taken = (val_rt <= 0);
+	      else if (rs == rt && rt != 0)
+		taken = (val_rt >= 0);
+	      else if (rs != rt && rs != 0 && rt != 0)
+		taken = (val_rs >= val_rt);
+
+	      if (op == 23)
+		taken = !taken;
+
+	      if (taken)
+		 pc += mips32_relative_offset (inst) + 4;
+	      else
+		{
+		  /* Step through the forbidden slot to avoid repeated
+		     exceptions.
+		     We do not currently have access to the BD bit when hitting
+		     a breakpoint and therefore cannot tell if the breakpoint
+		     hit on the branch or the forbidden slot.  */
+		  pc += 8;
+		}
+	    }
+	  else if (op == 50 || op == 58)
+	    {
+	      /* BC, BALC  */
+	      pc += mips32_relative_offset26 (inst) + 4;
+	    }
+	  else if ((op == 54 || op == 62)
+		   && rtype_rs (inst) == 0)
+	    {
+	      /* JIC, JIALC  */
+	      pc = regcache_raw_get_signed (regcache, itype_rt (inst));
+	      pc += (itype_immediate (inst) ^ 0x8000) - 0x8000;
+	    }
+	  else if (op == 54 || op == 62)
+	    {
+	      /* BEQZC, BNEZC  */
+	      int rs = itype_rs (inst);
+	      LONGEST rs_val = regcache_raw_get_signed (regcache, rs);
+	      bool taken = (rs_val == 0);
+	      if (op == 62)
+		taken = !taken;
+	      if (taken)
+		pc += mips32_relative_offset21 (inst) + 4;
+	      else
+		{
+		  /* Step through the forbidden slot to avoid repeated exceptions
+		     we do not currently have access to the BD bit when hitting a
+		     breakpoint and therefore cannot tell if the breakpoint
+		     hit on the branch or the forbidden slot.  */
+		  pc += 8;
+		}
+	    }
+	  else
+	    {
+	      /* Not a branch, next instruction is easy.  */
+	      pc += 4;
+	    }
+	}
       else
 	pc += 4;		/* Not a branch, next instruction is easy.  */
     }
   else
-    {				/* This gets way messy.  */
-
-      /* Further subdivide into SPECIAL, REGIMM and other.  */
+    {
+      /* This gets way messy.
+	 Further subdivide into SPECIAL, REGIMM and other.  */
       switch (op & 0x07)	/* Extract bits 28,27,26.  */
 	{
-	case 0:		/* SPECIAL */
+	case 0:  /* SPECIAL */
 	  op = rtype_funct (inst);
 	  switch (op)
 	    {
@@ -1725,7 +2004,7 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	      /* Set PC to that address.  */
 	      pc = regcache_raw_get_signed (regcache, rtype_rs (inst));
 	      break;
-	    case 12:            /* SYSCALL */
+	    case 12:	    /* SYSCALL */
 	      {
 		mips_gdbarch_tdep *tdep
 		  = gdbarch_tdep<mips_gdbarch_tdep> (gdbarch);
@@ -1740,17 +2019,16 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	      pc += 4;
 	    }
 
-	  break;		/* end SPECIAL */
-	case 1:			/* REGIMM */
+	  break;  /* end SPECIAL */
+	case 1:  /* REGIMM */
 	  {
-	    op = itype_rt (inst);	/* branch condition */
+	    op = itype_rt (inst);  /* branch condition */
 	    switch (op)
 	      {
 	      case 0:		/* BLTZ */
 	      case 2:		/* BLTZL */
 	      case 16:		/* BLTZAL */
 	      case 18:		/* BLTZALL */
-	      less_branch:
 		if (regcache_raw_get_signed (regcache, itype_rs (inst)) < 0)
 		  pc += mips32_relative_offset (inst) + 4;
 		else
@@ -1766,6 +2044,7 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 		  pc += 8;	/* after the delay slot */
 		break;
 	      case 0x1c:	/* BPOSGE32 */
+	      case 0x1d:	/* BPOSGE32C  */
 	      case 0x1e:	/* BPOSGE64 */
 		pc += 4;
 		if (itype_rs (inst) == 0)
@@ -1774,14 +2053,23 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 		    int dspctl = mips_regnum (gdbarch)->dspctl;
 
 		    if (dspctl == -1)
-		      /* No way to handle; it'll most likely trap anyway.  */
-		      break;
+		      {
+			/* No way to handle; it'll most likely trap anyway.  */
+			break;
+		      }
+
+		    /* BPOSGE32C  */
+		    if (op == 0x1d)
+		      {
+			if (!is_mipsr6_isa (gdbarch))
+			  break;
+		      }
 
 		    if ((regcache_raw_get_unsigned (regcache,
 						    dspctl) & 0x7f) >= pos)
 		      pc += mips32_relative_offset (inst);
 		    else
-		      pc += 4;
+		      pc += DELAY_SLOT_SIZE;
 		  }
 		break;
 		/* All of the other instructions in the REGIMM category */
@@ -1789,7 +2077,7 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 		pc += 4;
 	      }
 	  }
-	  break;		/* end REGIMM */
+	  break;  /* end REGIMM */
 	case 2:		/* J */
 	case 3:		/* JAL */
 	  {
@@ -1815,19 +2103,14 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	  else
 	    pc += 8;
 	  break;
-	case 6:		/* BLEZ, BLEZL */
-	  if (regcache_raw_get_signed (regcache, itype_rs (inst)) <= 0)
-	    pc += mips32_relative_offset (inst) + 4;
-	  else
-	    pc += 8;
+	case 6:		/* BLEZ, BLEZL, BLEZALC, BGEZALC, BGEUC  */
+	lez_branch:
+	  pc = mips32_blez_pc (gdbarch, regcache, inst, pc + 4, 0);
 	  break;
 	case 7:
 	default:
-	greater_branch:	/* BGTZ, BGTZL */
-	  if (regcache_raw_get_signed (regcache, itype_rs (inst)) > 0)
-	    pc += mips32_relative_offset (inst) + 4;
-	  else
-	    pc += 8;
+	greater_branch: /* BGTZ, BGTZL, BGTZALC, BLTZALC, BLTUC  */
+	  pc = mips32_blez_pc (gdbarch, regcache, inst, pc + 4, 1);
 	  break;
 	}			/* switch */
     }				/* else */
@@ -1889,8 +2172,10 @@ micromips_bc1_pc (struct gdbarch *gdbarch, struct regcache *regcache,
   int cond;
 
   if (fcsr == -1)
-    /* No way to handle; it'll most likely trap anyway.  */
-    return pc;
+    {
+      /* No way to handle; it'll most likely trap anyway.  */
+      return pc;
+    }
 
   fcs = regcache_raw_get_unsigned (regcache, fcsr);
   cond = ((fcs >> 24) & 0xfe) | ((fcs >> 23) & 0x01);
@@ -2004,8 +2289,10 @@ micromips_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	    case 0x14: /* BC2F: bits 010000 10100 xxx00 */
 	    case 0x15: /* BC2T: bits 010000 10101 xxx00 */
 	      if (((insn >> 16) & 0x3) == 0x0)
-		/* BC2F, BC2T: don't know how to handle these.  */
-		break;
+		{
+		  /* BC2F, BC2T: don't know how to handle these.  */
+		  break;
+		}
 	      break;
 
 	    case 0x1a: /* BPOSGE64: bits 010000 11010 */
@@ -2015,8 +2302,10 @@ micromips_next_pc (struct regcache *regcache, CORE_ADDR pc)
 		int dspctl = mips_regnum (gdbarch)->dspctl;
 
 		if (dspctl == -1)
-		  /* No way to handle; it'll most likely trap anyway.  */
-		  break;
+		  {
+		    /* No way to handle; it'll most likely trap anyway.  */
+		    break;
+		  }
 
 		if ((regcache_raw_get_unsigned (regcache,
 						dspctl) & 0x7f) >= pos)
@@ -2046,27 +2335,27 @@ micromips_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	case 0x1d: /* JALS: bits 011101 */
 	case 0x35: /* J: bits 110101 */
 	case 0x3d: /* JAL: bits 111101 */
-	    pc = ((pc | 0x7fffffe) ^ 0x7fffffe) | (b0s26_imm (insn) << 1);
+	  pc = ((pc | 0x7fffffe) ^ 0x7fffffe) | (b0s26_imm (insn) << 1);
 	  break;
 
 	case 0x25: /* BEQ: bits 100101 */
-	    if (regcache_raw_get_signed (regcache, b0s5_reg (insn >> 16))
+	  if (regcache_raw_get_signed (regcache, b0s5_reg (insn >> 16))
 		== regcache_raw_get_signed (regcache, b5s5_reg (insn >> 16)))
-	      pc += micromips_relative_offset16 (insn);
-	    else
-	      pc += micromips_pc_insn_size (gdbarch, pc);
+	    pc += micromips_relative_offset16 (insn);
+	  else
+	    pc += micromips_pc_insn_size (gdbarch, pc);
 	  break;
 
 	case 0x2d: /* BNE: bits 101101 */
 	  if (regcache_raw_get_signed (regcache, b0s5_reg (insn >> 16))
 		!= regcache_raw_get_signed (regcache, b5s5_reg (insn >> 16)))
-	      pc += micromips_relative_offset16 (insn);
+	    pc += micromips_relative_offset16 (insn);
 	  else
-	      pc += micromips_pc_insn_size (gdbarch, pc);
+	    pc += micromips_pc_insn_size (gdbarch, pc);
 	  break;
 
 	case 0x3c: /* JALX: bits 111100 */
-	    pc = ((pc | 0xfffffff) ^ 0xfffffff) | (b0s26_imm (insn) << 2);
+	  pc = ((pc | 0xfffffff) ^ 0xfffffff) | (b0s26_imm (insn) << 2);
 	  break;
 	}
       break;
@@ -2077,11 +2366,15 @@ micromips_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	{
 	case 0x11: /* POOL16C: bits 010001 */
 	  if ((b5s5_op (insn) & 0x1c) == 0xc)
-	    /* JR16, JRC, JALR16, JALRS16: 010001 011xx */
-	    pc = regcache_raw_get_signed (regcache, b0s5_reg (insn));
+	    {
+	      /* JR16, JRC, JALR16, JALRS16: 010001 011xx */
+	      pc = regcache_raw_get_signed (regcache, b0s5_reg (insn));
+	    }
 	  else if (b5s5_op (insn) == 0x18)
-	    /* JRADDIUSP: bits 010001 11000 */
-	    pc = regcache_raw_get_signed (regcache, MIPS_RA_REGNUM);
+	    {
+	      /* JRADDIUSP: bits 010001 11000 */
+	      pc = regcache_raw_get_signed (regcache, MIPS_RA_REGNUM);
+	    }
 	  break;
 
 	case 0x23: /* BEQZ16: bits 100011 */
@@ -2150,6 +2443,7 @@ enum mips16_inst_fmts
   extRi64type,			/* 20  5,6,5,5,3,3,5 */
   extshift64type		/* 21  5,5,1,1,1,1,1,1,5,1,1,1,3,5 */
 };
+
 /* I am heaping all the fields of the formats into one structure and
    then, only the fields which are involved in instruction extension.  */
 struct upk_mips16
@@ -2159,7 +2453,6 @@ struct upk_mips16
   unsigned int regy;
 };
 
-
 /* The EXT-I, EXT-ri nad EXT-I8 instructions all have the same format
    for the bits which make up the immediate extension.  */
 
@@ -2267,7 +2560,6 @@ unpack_mips16 (struct gdbarch *gdbarch, CORE_ADDR pc,
   upk->regy = regy;
 }
 
-
 /* Calculate the destination of a branch whose 16-bit opcode word is at PC,
    and having a signed 16-bit OFFSET.  */
 
@@ -2395,6 +2687,7 @@ mips16_next_pc (struct regcache *regcache, CORE_ADDR pc)
    It works by decoding the current instruction and predicting where a
    branch will go.  This isn't hard because all the data is available.
    The MIPS32, MIPS16 and microMIPS variants are quite different.  */
+
 static CORE_ADDR
 mips_next_pc (struct regcache *regcache, CORE_ADDR pc)
 {
@@ -2450,6 +2743,63 @@ micromips_instruction_is_compact_branch (unsigned short insn)
     }
 }
 
+/* Return non-zero if the MIPS instruction INSN is a compact branch
+   or jump.  A value of 1 indicates an unconditional compact branch
+   and a value of 2 indicates a conditional compact branch.  */
+
+static int
+mips32_instruction_is_compact_branch (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  switch (itype_op (insn))
+    {
+    case 50: /* BC  */
+    case 58: /* BALC  */
+      if (is_mipsr6_isa (gdbarch))
+	return 1;
+      break;
+    case 8: /* BOVC, BEQZALC, BEQC  */
+    case 24: /* BNVC, BNEZALC, BNEC  */
+      if (is_mipsr6_isa (gdbarch))
+	return 2;
+      break;
+    case 54: /* BEQZC, JIC  */
+    case 62: /* BNEZC, JIALC  */
+      if (is_mipsr6_isa (gdbarch))
+	{
+	  /* JIC, JIALC are unconditional  */
+	  return (itype_rs (insn) == 0) ? 1 : 2;
+	}
+      break;
+    case 22: /* BLEZC, BGEZC, BGEC  */
+    case 23: /* BGTZC, BLTZC, BLTC  */
+    case 6: /* BLEZALC, BGEZALC, BGEUC  */
+    case 7: /* BGTZALC, BLTZALC, BLTUC  */
+      if (is_mipsr6_isa (gdbarch)
+	  && itype_rt (insn) != 0)
+	return 2;
+      break;
+    case 1: /* BPOSGE32C  */
+      if (is_mipsr6_isa (gdbarch)
+	  && itype_rt (insn) == 0x1d && itype_rs (insn) == 0)
+	return 2;
+    }
+  return 0;
+}
+
+/* Return true if a standard MIPS instruction at ADDR has a branch
+   forbidden slot (i.e. it is a conditional compact branch instruction).  */
+
+static bool
+mips32_insn_at_pc_has_forbidden_slot (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  int status;
+  ULONGEST insn = mips_fetch_instruction (gdbarch, ISA_MIPS, addr, &status);
+  if (status)
+    return false;
+
+  return mips32_instruction_is_compact_branch (gdbarch, insn) == 2;
+}
+
 struct mips_frame_cache
 {
   CORE_ADDR base;
@@ -2482,7 +2832,6 @@ set_reg_offset (struct gdbarch *gdbarch, struct mips_frame_cache *this_cache,
     }
 }
 
-
 /* Fetch the immediate value from a MIPS16 instruction.
    If the previous instruction was an EXTEND, use it to extend
    the upper bits of the immediate value.  This is a helper function
@@ -2517,8 +2866,7 @@ mips16_get_imm (unsigned short prev_inst,	/* previous instruction */
     }
 }
 
-
-/* Analyze the function prologue from START_PC to LIMIT_PC. Builds
+/* Analyze the function prologue from START_PC to LIMIT_PC.  Builds
    the associated FRAME_CACHE if not null.
    Return the address of the first instruction past the prologue.  */
 
@@ -2535,8 +2883,8 @@ mips16_scan_prologue (struct gdbarch *gdbarch,
   CORE_ADDR cur_pc;
   CORE_ADDR frame_addr = 0;	/* Value of $r17, used as frame pointer.  */
   CORE_ADDR sp;
-  long frame_offset = 0;        /* Size of stack frame.  */
-  long frame_adjust = 0;        /* Offset of FP from SP.  */
+  long frame_offset = 0;	/* Size of stack frame.  */
+  long frame_adjust = 0;	/* Offset of FP from SP.  */
   int frame_reg = MIPS_SP_REGNUM;
   unsigned short prev_inst = 0;	/* saved copy of previous instruction.  */
   unsigned inst = 0;		/* current instruction */
@@ -2600,10 +2948,12 @@ mips16_scan_prologue (struct gdbarch *gdbarch,
 	  if (offset < 0)	/* Negative stack adjustment?  */
 	    frame_offset -= offset;
 	  else
-	    /* Exit loop if a positive stack adjustment is found, which
-	       usually means that the stack cleanup code in the function
-	       epilogue is reached.  */
-	    break;
+	    {
+	      /* Exit loop if a positive stack adjustment is found, which
+		 usually means that the stack cleanup code in the function
+		 epilogue is reached.  */
+	      break;
+	    }
 	}
       else if ((inst & 0xf800) == 0xd000)	/* sw reg,n($sp) */
 	{
@@ -2888,7 +3238,7 @@ mips_insn16_frame_cache (const frame_info_ptr &this_frame, void **this_cache)
     mips16_scan_prologue (gdbarch, start_addr, pc, this_frame,
 			  (struct mips_frame_cache *) *this_cache);
   }
-  
+
   /* gdbarch_sp_regnum contains the value and not the address.  */
   cache->saved_regs[gdbarch_num_regs (gdbarch)
 		    + MIPS_SP_REGNUM].set_value (cache->base);
@@ -3063,7 +3413,7 @@ micromips_scan_prologue (struct gdbarch *gdbarch,
 		  && dreg == MIPS_SP_REGNUM && sreg == MIPS_SP_REGNUM
 		  && treg == 3)
 				/* (D)SUBU $sp, $v1 */
-		    sp_adj = v1_off;
+		sp_adj = v1_off;
 	      else if (op != 0x150
 				/* ADDU: bits 000000 00101010000 */
 				/* DADDU: bits 010110 00101010000 */
@@ -3273,7 +3623,7 @@ micromips_scan_prologue (struct gdbarch *gdbarch,
 				    gdbarch_num_regs (gdbarch) + frame_reg)
 	 + frame_offset - frame_adjust);
       /* FIXME: brobecker/2004-10-10: Just as in the mips32 case, we should
-	 be able to get rid of the assignment below, evetually. But it's
+	 be able to get rid of the assignment below, evetually.  But it's
 	 still needed for now.  */
       this_cache->saved_regs[gdbarch_num_regs (gdbarch)
 			     + mips_regnum (gdbarch)->pc]
@@ -3292,7 +3642,7 @@ micromips_scan_prologue (struct gdbarch *gdbarch,
 
 /* Heuristic unwinder for procedures using microMIPS instructions.
    Procedures that use the 32-bit instruction set are handled by the
-   mips_insn32 unwinder.  Likewise MIPS16 and the mips_insn16 unwinder. */
+   mips_insn32 unwinder.  Likewise MIPS16 and the mips_insn16 unwinder.  */
 
 static struct mips_frame_cache *
 mips_micro_frame_cache (const frame_info_ptr &this_frame, void **this_cache)
@@ -3425,7 +3775,7 @@ reset_saved_regs (struct gdbarch *gdbarch, struct mips_frame_cache *this_cache)
 }
 
 /* Analyze the function prologue from START_PC to LIMIT_PC.  Builds
-   the associated FRAME_CACHE if not null.  
+   the associated FRAME_CACHE if not null.
    Return the address of the first instruction past the prologue.  */
 
 static CORE_ADDR
@@ -3437,7 +3787,7 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
   int prev_non_prologue_insn;
   int this_non_prologue_insn;
   int non_prologue_insns;
-  CORE_ADDR frame_addr = 0; /* Value of $r30. Used by gcc for
+  CORE_ADDR frame_addr = 0; /* Value of $r30.  Used by gcc for
 			       frame-pointer.  */
   int prev_delay_slot;
   CORE_ADDR prev_pc;
@@ -3493,16 +3843,19 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
       reg = high_word & 0x1f;
 
       if (high_word == 0x27bd		/* addiu $sp,$sp,-i */
-	  || high_word == 0x23bd	/* addi $sp,$sp,-i */
+	  || (high_word == 0x23bd	/* addi $sp,$sp,-i  */
+	      && !is_mipsr6_isa (gdbarch))
 	  || high_word == 0x67bd)	/* daddiu $sp,$sp,-i */
 	{
 	  if (offset < 0)		/* Negative stack adjustment?  */
 	    frame_offset -= offset;
 	  else
-	    /* Exit loop if a positive stack adjustment is found, which
-	       usually means that the stack cleanup code in the function
-	       epilogue is reached.  */
-	    break;
+	    {
+	      /* Exit loop if a positive stack adjustment is found, which
+		 usually means that the stack cleanup code in the function
+		 epilogue is reached.  */
+	      break;
+	    }
 	  seen_sp_adjust = 1;
 	}
       else if (((high_word & 0xFFE0) == 0xafa0) /* sw reg,offset($sp) */
@@ -3576,7 +3929,7 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
 		}
 	    }
 	}
-      else if ((high_word & 0xFFE0) == 0xafc0 	/* sw reg,offset($30) */
+      else if ((high_word & 0xFFE0) == 0xafc0		/* sw reg,offset($30) */
 	       && !regsize_is_64_bits)
 	{
 	  set_reg_offset (gdbarch, this_cache, reg, frame_addr + offset);
@@ -3631,7 +3984,9 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
 
       /* A jump or branch, or enough non-prologue insns seen?  If so,
 	 then we must have reached the end of the prologue by now.  */
-      if (prev_delay_slot || non_prologue_insns > 1)
+      if (prev_delay_slot
+	  || non_prologue_insns > 1
+	  || mips32_instruction_is_compact_branch (gdbarch, inst))
 	break;
 
       prev_non_prologue_insn = this_non_prologue_insn;
@@ -3641,7 +3996,7 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
 
   if (this_cache != NULL)
     {
-      this_cache->base = 
+      this_cache->base =
 	(get_frame_register_signed (this_frame,
 				    gdbarch_num_regs (gdbarch) + frame_reg)
 	 + frame_offset);
@@ -3660,7 +4015,7 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
      its address instead.  */
   end_prologue_addr
     = prev_non_prologue_insn || prev_delay_slot ? prev_pc : cur_pc;
-     
+
   /* In a frameless function, we might have incorrectly
      skipped some load immediate instructions.  Undo the skipping
      if the load immediate was not followed by a stack adjustment.  */
@@ -3673,7 +4028,7 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
 /* Heuristic unwinder for procedures using 32-bit instructions (covers
    both 32-bit and 64-bit MIPS ISAs).  Procedures using 16-bit
    instructions (a.k.a. MIPS16) are handled by the mips_insn16
-   unwinder.  Likewise microMIPS and the mips_micro unwinder. */
+   unwinder.  Likewise microMIPS and the mips_micro unwinder.  */
 
 static struct mips_frame_cache *
 mips_insn32_frame_cache (const frame_info_ptr &this_frame, void **this_cache)
@@ -3704,7 +4059,7 @@ mips_insn32_frame_cache (const frame_info_ptr &this_frame, void **this_cache)
     mips32_scan_prologue (gdbarch, start_addr, pc, this_frame,
 			  (struct mips_frame_cache *) *this_cache);
   }
-  
+
   /* gdbarch_sp_regnum contains the value and not the address.  */
   cache->saved_regs[gdbarch_num_regs (gdbarch)
 		    + MIPS_SP_REGNUM].set_value (cache->base);
@@ -3904,30 +4259,31 @@ mips_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr)
   mips_gdbarch_tdep *tdep = gdbarch_tdep<mips_gdbarch_tdep> (gdbarch);
 
   if (mips_mask_address_p (tdep) && (((ULONGEST) addr) >> 32 == 0xffffffffUL))
-    /* This hack is a work-around for existing boards using PMON, the
-       simulator, and any other 64-bit targets that doesn't have true
-       64-bit addressing.  On these targets, the upper 32 bits of
-       addresses are ignored by the hardware.  Thus, the PC or SP are
-       likely to have been sign extended to all 1s by instruction
-       sequences that load 32-bit addresses.  For example, a typical
-       piece of code that loads an address is this:
-
-       lui $r2, <upper 16 bits>
-       ori $r2, <lower 16 bits>
-
-       But the lui sign-extends the value such that the upper 32 bits
-       may be all 1s.  The workaround is simply to mask off these
-       bits.  In the future, gcc may be changed to support true 64-bit
-       addressing, and this masking will have to be disabled.  */
-    return addr &= 0xffffffffUL;
+    {
+      /* This hack is a work-around for existing boards using PMON, the
+	 simulator, and any other 64-bit targets that doesn't have true
+	 64-bit addressing.  On these targets, the upper 32 bits of
+	 addresses are ignored by the hardware.  Thus, the PC or SP are
+	 likely to have been sign extended to all 1s by instruction
+	 sequences that load 32-bit addresses.  For example, a typical
+	 piece of code that loads an address is this:
+
+	 lui $r2, <upper 16 bits>
+	 ori $r2, <lower 16 bits>
+
+	 But the lui sign-extends the value such that the upper 32 bits
+	 may be all 1s.  The workaround is simply to mask off these
+	 bits.  In the future, gcc may be changed to support true 64-bit
+	 addressing, and this masking will have to be disabled.  */
+      return addr &= 0xffffffffUL;
+    }
   else
     return addr;
 }
 
-
 /* Checks for an atomic sequence of instructions beginning with a LL/LLD
    instruction and ending with a SC/SCD instruction.  If such a sequence
-   is found, attempt to step through it.  A breakpoint is placed at the end of 
+   is found, attempt to step through it.  A breakpoint is placed at the end of
    the sequence.  */
 
 /* Instructions used during single-stepping of atomic sequences, standard
@@ -3936,6 +4292,70 @@ mips_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr)
 #define LLD_OPCODE 0x34
 #define SC_OPCODE 0x38
 #define SCD_OPCODE 0x3c
+#define LLSC_R6_OPCODE 0x1f
+#define LL_R6_FUNCT 0x36
+#define LLE_FUNCT 0x2e
+#define LLD_R6_FUNCT 0x37
+#define SC_R6_FUNCT 0x26
+#define SCE_FUNCT 0x1e
+#define SCD_R6_FUNCT 0x27
+
+/* Determine whether instruction 'insn' is of 'load linked X' type.
+   LL/SC instructions provide primitives to implement atomic
+   read-modify-write operations for synchronizable memory locations.  */
+
+static bool
+is_ll_insn (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  if (itype_op (insn) == LL_OPCODE
+      || itype_op (insn) == LLD_OPCODE)
+    return true;
+
+  if (rtype_op (insn) == LLSC_R6_OPCODE
+      && rtype_funct (insn) == LLE_FUNCT
+      && (insn & 0x40) == 0)
+    return true;
+
+  /* Handle LL and LLP varieties.  */
+  if (is_mipsr6_isa (gdbarch)
+      && rtype_op (insn) == LLSC_R6_OPCODE
+      && (rtype_funct (insn) == LL_R6_FUNCT
+	  || rtype_funct (insn) == LLD_R6_FUNCT
+	  || rtype_funct (insn) == LLE_FUNCT))
+    return true;
+
+  return false;
+}
+
+/* Determine whether instruction 'insn' is of 'store conditional X' type.
+   SC instructions and varieties perform completion of read-modify-write
+   atomic sequence.  */
+
+static bool
+is_sc_insn (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  if (itype_op (insn) == SC_OPCODE
+      || itype_op (insn) == SCD_OPCODE)
+    return true;
+
+  if (rtype_op (insn) == LLSC_R6_OPCODE
+      && rtype_funct (insn) == SCE_FUNCT
+      && (insn & 0x40) == 0)
+    return true;
+
+  /* Handle SC and SCP varieties.  */
+  if (is_mipsr6_isa (gdbarch)
+      && rtype_op (insn) == LLSC_R6_OPCODE
+      && (rtype_funct (insn) == SC_R6_FUNCT
+	  || rtype_funct (insn) == SCD_R6_FUNCT
+	  || rtype_funct (insn) == SCE_FUNCT))
+    return true;
+
+  return false;
+}
+
+/* Handle mips atomic sequence which starts with LL/LLD and ends with
+   SC/SCD instruction.  */
 
 static std::vector<CORE_ADDR>
 mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
@@ -3946,15 +4366,16 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
   ULONGEST insn;
   int insn_count;
   int index;
-  int last_breakpoint = 0; /* Defaults to 0 (no breakpoints placed).  */  
+  int last_breakpoint = 0; /* Defaults to 0 (no breakpoints placed).  */
   const int atomic_sequence_length = 16; /* Instruction sequence length.  */
+  bool is_mipsr6 = is_mipsr6_isa (gdbarch);
 
   insn = mips_fetch_instruction (gdbarch, ISA_MIPS, loc, NULL);
   /* Assume all atomic sequences start with a ll/lld instruction.  */
-  if (itype_op (insn) != LL_OPCODE && itype_op (insn) != LLD_OPCODE)
+  if (!is_ll_insn (gdbarch, insn))
     return {};
 
-  /* Assume that no atomic sequence is longer than "atomic_sequence_length" 
+  /* Assume that no atomic sequence is longer than "atomic_sequence_length"
      instructions.  */
   for (insn_count = 0; insn_count < atomic_sequence_length; ++insn_count)
     {
@@ -3981,28 +4402,72 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
 	  return {}; /* fallback to the standard single-step code.  */
 	case 4: /* BEQ */
 	case 5: /* BNE */
-	case 6: /* BLEZ */
-	case 7: /* BGTZ */
 	case 20: /* BEQL */
 	case 21: /* BNEL */
-	case 22: /* BLEZL */
-	case 23: /* BGTTL */
+	case 22: /* BLEZL (BLEZC, BGEZC, BGEC)  */
+	case 23: /* BGTZL (BGTZC, BLTZC, BLTC)  */
+	  is_branch = 1;
+	  break;
+	case 6: /* BLEZ (BLEZALC, BGEZALC, BGEUC)  */
+	case 7: /* BGTZ (BGTZALC, BLTZALC, BLTUC)  */
+	  if (is_mipsr6)
+	    {
+	      /* BLEZALC, BGTZALC  */
+	      if (itype_rs (insn) == 0 && itype_rt (insn) != 0)
+		return {}; /* fallback to the standard single-step code.  */
+	      /* BGEZALC, BLTZALC  */
+	      else if (itype_rs (insn) == itype_rt (insn)
+		       && itype_rt (insn) != 0)
+		return {}; /* fallback to the standard single-step code.  */
+	    }
 	  is_branch = 1;
 	  break;
+	case 8: /* BOVC, BEQZALC, BEQC  */
+	case 24: /* BNVC, BNEZALC, BNEC  */
+	  if (is_mipsr6)
+	    is_branch = 1;
+	  break;
+	case 50: /* BC  */
+	case 58: /* BALC  */
+	  if (is_mipsr6)
+	    return {}; /* fallback to the standard single-step code.  */
+	  break;
+	case 54: /* BEQZC, JIC  */
+	case 62: /* BNEZC, JIALC  */
+	  if (is_mipsr6)
+	    {
+	      if (itype_rs (insn) == 0) /* JIC, JIALC  */
+		return {}; /* fallback to the standard single-step code.  */
+	      else
+		is_branch = 2; /* Marker for branches with a 21-bit offset.  */
+	    }
+	  break;
 	case 17: /* COP1 */
-	  is_branch = ((itype_rs (insn) == 9 || itype_rs (insn) == 10)
-		       && (itype_rt (insn) & 0x2) == 0);
-	  if (is_branch) /* BC1ANY2F, BC1ANY2T, BC1ANY4F, BC1ANY4T */
+	  is_branch = ((!is_mipsr6
+		       /* BC1ANY2F, BC1ANY2T, BC1ANY4F, BC1ANY4T  */
+			&& (itype_rs (insn) == 9 || itype_rs (insn) == 10)
+			&& (itype_rt (insn) & 0x2) == 0)
+		       /* BZ.df:  010001 110xx  */
+		       || (itype_rs (insn) & 0x18) == 0x18);
+	  if (is_branch != 0)
 	    break;
 	  [[fallthrough]];
 	case 18: /* COP2 */
 	case 19: /* COP3 */
-	  is_branch = (itype_rs (insn) == 8); /* BCzF, BCzFL, BCzT, BCzTL */
+	  /* BCzF, BCzFL, BCzT, BCzTL, BC*EQZ, BC*NEZ  */
+	  is_branch = ((itype_rs (insn) == 8)
+		       || (is_mipsr6
+			   && (itype_rs (insn) == 9
+			       || itype_rs (insn) == 13)));
 	  break;
 	}
-      if (is_branch)
+      if (is_branch != 0)
 	{
-	  branch_bp = loc + mips32_relative_offset (insn) + 4;
+	  /* Is this a special PC21_S2 branch?  */
+	  if (is_branch == 2)
+	    branch_bp = loc + mips32_relative_offset21 (insn) + 4;
+	  else
+	    branch_bp = loc + mips32_relative_offset (insn) + 4;
 	  if (last_breakpoint >= 1)
 	    return {}; /* More than one branch found, fallback to the
 			  standard single-step code.  */
@@ -4010,12 +4475,12 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
 	  last_breakpoint++;
 	}
 
-      if (itype_op (insn) == SC_OPCODE || itype_op (insn) == SCD_OPCODE)
+      if (is_sc_insn (gdbarch, insn))
 	break;
     }
 
   /* Assume that the atomic sequence ends with a sc/scd instruction.  */
-  if (itype_op (insn) != SC_OPCODE && itype_op (insn) != SCD_OPCODE)
+  if (!is_sc_insn (gdbarch, insn))
     return {};
 
   loc += MIPS_INSN32_SIZE;
@@ -4130,7 +4595,7 @@ micromips_deal_with_atomic_sequence (struct gdbarch *gdbarch,
 	    case 0x35: /* J: bits 110101 */
 	    case 0x3d: /* JAL: bits 111101 */
 	    case 0x3c: /* JALX: bits 111100 */
-	      return {}; /* Fall back to the standard single-step code. */
+	      return {}; /* Fall back to the standard single-step code.  */
 
 	    case 0x18: /* POOL32C: bits 011000 */
 	      if ((b12s4_op (insn) & 0xb) == 0xb)
@@ -4157,14 +4622,14 @@ micromips_deal_with_atomic_sequence (struct gdbarch *gdbarch,
 		  && b5s5_op (insn) != 0x18)
 				/* JRADDIUSP: bits 010001 11000 */
 		break;
-	      return {}; /* Fall back to the standard single-step code. */
+	      return {}; /* Fall back to the standard single-step code.  */
 
 	    case 0x33: /* B16: bits 110011 */
-	      return {}; /* Fall back to the standard single-step code. */
+	      return {}; /* Fall back to the standard single-step code.  */
 	    }
 	  break;
 	}
-      if (is_branch)
+      if (is_branch != 0)
 	{
 	  if (last_breakpoint >= 1)
 	    return {}; /* More than one branch found, fallback to the
@@ -4240,10 +4705,15 @@ mips_about_to_return (struct gdbarch *gdbarch, CORE_ADDR pc)
   gdb_assert (mips_pc_is_mips (pc));
 
   insn = mips_fetch_instruction (gdbarch, ISA_MIPS, pc, NULL);
-  hint = 0x7c0;
-  return (insn & ~hint) == 0x3e00008;			/* jr(.hb) $ra */
-}
+  /* Mask the hint and the jalr/jr bit.  */
+  hint = 0x7c1;
+
+  if (is_mipsr6_isa (gdbarch) && insn == 0xd81f0000) /* jrc $31  */
+    return 1;
 
+  /* jr(.hb) $ra and "jalr(.hb) $ra"  */
+  return ((insn & ~hint) == 0x3e00008);
+}
 
 /* This fencepost looks highly suspicious to me.  Removing it also
    seems suspicious as it could affect remote debugging across serial
@@ -4476,6 +4946,7 @@ mips_type_needs_double_align (struct type *type)
 
 /* Adjust the address downward (direction of stack growth) so that it
    is correctly aligned for a new stack frame.  */
+
 static CORE_ADDR
 mips_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
 {
@@ -4817,7 +5288,7 @@ mips_eabi_return_value (struct gdbarch *gdbarch, struct value *function,
     {
       if (type->code () == TYPE_CODE_FLT)
 	fp_return_type = 1;
-      /* Structs with a single field of float type 
+      /* Structs with a single field of float type
 	 are returned in a floating point register.  */
       if ((type->code () == TYPE_CODE_STRUCT
 	   || type->code () == TYPE_CODE_UNION)
@@ -4830,7 +5301,7 @@ mips_eabi_return_value (struct gdbarch *gdbarch, struct value *function,
 	}
     }
 
-  if (fp_return_type)      
+  if (fp_return_type)
     {
       /* A floating-point value belongs in the least significant part
 	 of FP0/FP1.  */
@@ -4838,7 +5309,7 @@ mips_eabi_return_value (struct gdbarch *gdbarch, struct value *function,
 	gdb_printf (gdb_stderr, "Return float in $fp0\n");
       regnum = mips_regnum (gdbarch)->fp0;
     }
-  else 
+  else
     {
       /* An integer value goes in V0/V1.  */
       if (mips_debug)
@@ -4861,7 +5332,6 @@ mips_eabi_return_value (struct gdbarch *gdbarch, struct value *function,
   return RETURN_VALUE_REGISTER_CONVENTION;
 }
 
-
 /* N32/N64 ABI stuff.  */
 
 /* Search for a naturally aligned double at OFFSET inside a struct
@@ -6525,7 +6995,6 @@ print_fp_register_row (struct ui_file *file, const frame_info_ptr &frame,
   return regnum + 1;
 }
 
-
 /* Print a row's worth of GP (int) registers, with name labels above.  */
 
 static int
@@ -6723,7 +7192,7 @@ mips_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
      that bound, then use an arbitrary large number as the upper bound.  */
   limit_pc = skip_prologue_using_sal (gdbarch, pc);
   if (limit_pc == 0)
-    limit_pc = pc + 100;          /* Magic.  */
+    limit_pc = pc + 100;	  /* Magic.  */
 
   if (mips_pc_is_mips16 (gdbarch, pc))
     return mips16_scan_prologue (gdbarch, pc, limit_pc, NULL, NULL);
@@ -6761,7 +7230,9 @@ mips32_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
 
 	  if (high_word != 0x27bd	/* addiu $sp,$sp,offset */
 	      && high_word != 0x67bd	/* daddiu $sp,$sp,offset */
-	      && inst != 0x03e00008	/* jr $ra */
+	      && (inst & ~0x1) != 0x03e00008 /* jr $31 or jalr $0, $31  */
+	      && (!is_mipsr6_isa (gdbarch)
+		  || inst != 0xd81f0000) /* jrc $31  */
 	      && inst != 0x00000000)	/* nop */
 	    return 0;
 	}
@@ -6964,7 +7435,6 @@ show_mipsfpu_command (const char *args, int from_tty)
       ("The MIPS floating-point coprocessor is assumed to be %s\n", fpu);
 }
 
-
 static void
 set_mipsfpu_single_command (const char *args, int from_tty)
 {
@@ -7140,22 +7610,31 @@ mips32_instruction_has_delay_slot (struct gdbarch *gdbarch, ULONGEST inst)
   int op;
   int rs;
   int rt;
+  bool is_mipsr6 = is_mipsr6_isa (gdbarch);
 
   op = itype_op (inst);
   if ((inst & 0xe0000000) != 0)
     {
       rs = itype_rs (inst);
       rt = itype_rt (inst);
-      return (is_octeon_bbit_op (op, gdbarch) 
-	      || op >> 2 == 5	/* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx  */
-	      || op == 29	/* JALX: bits 011101  */
+      return (is_octeon_bbit_op (op, gdbarch)
+	      || (op >> 1 == 10) /* BEQL, BNEL: bits 01010x  */
+	      || (op >> 1 == 11 && rt == 0) /* BLEZL, BGTZL: bits 01011x  */
+	      || (!is_mipsr6 && op == 29)	/* JALX: bits 011101  */
 	      || (op == 17
 		  && (rs == 8
 				/* BC1F, BC1FL, BC1T, BC1TL: 010001 01000  */
-		      || (rs == 9 && (rt & 0x2) == 0)
+		      || (!is_mipsr6 && rs == 9 && (rt & 0x2) == 0)
 				/* BC1ANY2F, BC1ANY2T: bits 010001 01001  */
-		      || (rs == 10 && (rt & 0x2) == 0))));
+		      || (!is_mipsr6 && rs == 10 && (rt & 0x2) == 0)))
 				/* BC1ANY4F, BC1ANY4T: bits 010001 01010  */
+	      || (is_mipsr6
+		  && ((op == 17
+		       && (rs == 9  /* BC1EQZ: 010001 01001  */
+			   || rs == 13))  /* BC1NEZ: 010001 01101  */
+		      || (op == 18
+			  && (rs == 9  /* BC2EQZ: 010010 01001  */
+			      || rs == 13)))));  /* BC2NEZ: 010010 01101  */
     }
   else
     switch (op & 0x07)		/* extract bits 28,27,26  */
@@ -7174,7 +7653,11 @@ mips32_instruction_has_delay_slot (struct gdbarch *gdbarch, ULONGEST inst)
 		|| ((rt & 0x1e) == 0x1c && rs == 0));
 				/* BPOSGE32, BPOSGE64: bits 1110x  */
 	break;			/* end REGIMM  */
-      default:			/* J, JAL, BEQ, BNE, BLEZ, BGTZ  */
+      case 6:		 /* BLEZ  */
+      case 7:		 /* BGTZ  */
+	return (itype_rt (inst) == 0);
+	break;
+      default:		 /* J, JAL, BEQ, BNE  */
 	return 1;
 	break;
       }
@@ -7386,14 +7869,25 @@ mips_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
 
      So, we'll use the second solution.  To do this we need to know if
      the instruction we're trying to set the breakpoint on is in the
-     branch delay slot.  */
+     branch delay slot.
+
+     A similar problem occurs for breakpoints on forbidden slots where
+     the trap will be reported for the branch with the BD bit set.
+     In this case it would be ideal to recover using solution 1 from
+     above as there is no problem with the branch being skipped
+     (since the forbidden slot only exists on not-taken branches).
+     However, the BD bit is not available in all scenarios currently
+     so instead we move the breakpoint on to the next instruction.
+     This means that it is not possible to stop on an instruction
+     that can be in a forbidden slot even if that instruction is
+     jumped to directly.  */
 
   boundary = mips_segment_boundary (bpaddr);
 
   /* Make sure we don't scan back before the beginning of the current
      function, since we may fetch constant data or insns that look like
      a jump.  Of course we might do that anyway if the compiler has
-     moved constants inline. :-(  */
+     moved constants inline.  :-(  */
   if (find_pc_partial_function (bpaddr, NULL, &func_addr, NULL)
       && func_addr > boundary && func_addr <= bpaddr)
     boundary = func_addr;
@@ -7404,10 +7898,16 @@ mips_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
 	return bpaddr;
 
       /* If the previous instruction has a branch delay slot, we have
-	 to move the breakpoint to the branch instruction. */
+	 to move the breakpoint to the branch instruction.  */
       prev_addr = bpaddr - 4;
       if (mips32_insn_at_pc_has_delay_slot (gdbarch, prev_addr))
 	bpaddr = prev_addr;
+      /* If the previous instruction has a forbidden slot, we have to
+	 move the breakpoint to the following instruction to prevent
+	 breakpoints in forbidden slots being reported as unknown
+	 traps.  */
+      else if (mips32_insn_at_pc_has_forbidden_slot (gdbarch, prev_addr))
+	bpaddr += 4;
     }
   else
     {
@@ -7437,36 +7937,42 @@ mips_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
 	    break;
 	  addr -= MIPS_INSN16_SIZE;
 	  if (i == 1 && insn_at_pc_has_delay_slot (gdbarch, addr, 0))
-	    /* Looks like a JR/JALR at [target-1], but it could be
-	       the second word of a previous JAL/JALX, so record it
-	       and check back one more.  */
-	    jmpaddr = addr;
+	    {
+	      /* Looks like a JR/JALR at [target-1], but it could be
+		 the second word of a previous JAL/JALX, so record it
+		 and check back one more.  */
+	      jmpaddr = addr;
+	    }
 	  else if (i > 1 && insn_at_pc_has_delay_slot (gdbarch, addr, 1))
 	    {
 	      if (i == 2)
-		/* Looks like a JAL/JALX at [target-2], but it could also
-		   be the second word of a previous JAL/JALX, record it,
-		   and check back one more.  */
-		jmpaddr = addr;
+		{
+		  /* Looks like a JAL/JALX at [target-2], but it could also
+		     be the second word of a previous JAL/JALX, record it,
+		     and check back one more.  */
+		  jmpaddr = addr;
+		}
 	      else
-		/* Looks like a JAL/JALX at [target-3], so any previously
-		   recorded JAL/JALX or JR/JALR must be wrong, because:
-
-		   >-3: JAL
-		    -2: JAL-ext (can't be JAL/JALX)
-		    -1: bdslot (can't be JR/JALR)
-		     0: target insn
-
-		   Of course it could be another JAL-ext which looks
-		   like a JAL, but in that case we'd have broken out
-		   of this loop at [target-2]:
-
-		    -4: JAL
-		   >-3: JAL-ext
-		    -2: bdslot (can't be jmp)
-		    -1: JR/JALR
-		     0: target insn  */
-		jmpaddr = 0;
+		{
+		  /* Looks like a JAL/JALX at [target-3], so any previously
+		     recorded JAL/JALX or JR/JALR must be wrong, because:
+
+		       >-3: JAL
+			-2: JAL-ext (can't be JAL/JALX)
+			-1: bdslot (can't be JR/JALR)
+			 0: target insn
+
+		     Of course it could be another JAL-ext which looks
+		     like a JAL, but in that case we'd have broken out
+		     of this loop at [target-2]:
+
+			-4: JAL
+		       >-3: JAL-ext
+			-2: bdslot (can't be jmp)
+			-1: JR/JALR
+			 0: target insn  */
+		  jmpaddr = 0;
+		}
 	    }
 	  else
 	    {
@@ -7733,15 +8239,19 @@ mips_skip_mips16_trampoline_code (const frame_info_ptr &frame, CORE_ADDR pc)
 	       && mips_is_stub_suffix (name + prefixlen + 3, 0))
 	{
 	  if (pc == start_addr)
-	    /* This is the 'call' part of a call stub.  The return
-	       address is in $2.  */
-	    return get_frame_register_signed
+	    {
+	      /* This is the 'call' part of a call stub.  The return
+		 address is in $2.  */
+	      return get_frame_register_signed
 		     (frame, gdbarch_num_regs (gdbarch) + MIPS_V0_REGNUM);
+	    }
 	  else
-	    /* This is the 'return' part of a call stub.  The return
-	       address is in $18.  */
-	    return get_frame_register_signed
+	    {
+	      /* This is the 'return' part of a call stub.  The return
+		 address is in $18.  */
+	      return get_frame_register_signed
 		     (frame, gdbarch_num_regs (gdbarch) + MIPS_S2_REGNUM);
+	    }
 	}
       else
 	return 0;		/* Not a stub.  */
@@ -7753,15 +8263,19 @@ mips_skip_mips16_trampoline_code (const frame_info_ptr &frame, CORE_ADDR pc)
       || startswith (name, mips_str_call_stub))
     {
       if (pc == start_addr)
-	/* This is the 'call' part of a call stub.  Call this helper
-	   to scan through this code for interesting instructions
-	   and determine the final PC.  */
-	return mips_get_mips16_fn_stub_pc (frame, pc);
+	{
+	  /* This is the 'call' part of a call stub.  Call this helper
+	     to scan through this code for interesting instructions
+	     and determine the final PC.  */
+	  return mips_get_mips16_fn_stub_pc (frame, pc);
+	}
       else
-	/* This is the 'return' part of a call stub.  The return address
-	   is in $18.  */
-	return get_frame_register_signed
+	{
+	  /* This is the 'return' part of a call stub.  The return address
+	     is in $18.  */
+	  return get_frame_register_signed
 		 (frame, gdbarch_num_regs (gdbarch) + MIPS_S2_REGNUM);
+	}
     }
 
   return 0;			/* Not a stub.  */
@@ -7922,7 +8436,6 @@ mips_stab_reg_to_regnum (struct gdbarch *gdbarch, int num)
   return gdbarch_num_regs (gdbarch) + regnum;
 }
 
-
 /* Convert a dwarf, dwarf2, or ecoff register number to a GDB [1 *
    gdbarch_num_regs .. 2 * gdbarch_num_regs) REGNUM.  */
 
@@ -7960,7 +8473,6 @@ mips_register_sim_regno (struct gdbarch *gdbarch, int regnum)
     return LEGACY_SIM_REGNO_IGNORE;
 }
 
-
 /* Convert an integer into an address.  Extracting the value signed
    guarantees a correctly sign extended address.  */
 
@@ -8361,7 +8873,6 @@ mips_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 	valid_p &= tdesc_numbered_register (feature, tdesc_data.get (), i,
 					    mips_gprs[i]);
 
-
       valid_p &= tdesc_numbered_register (feature, tdesc_data.get (),
 					  mips_regnum.lo, "lo");
       valid_p &= tdesc_numbered_register (feature, tdesc_data.get (),
@@ -8832,7 +9343,7 @@ mips_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 
   for (i = 0; i < ARRAY_SIZE (mips_numeric_register_aliases); i++)
     user_reg_add (gdbarch, mips_numeric_register_aliases[i].name,
-		  value_of_mips_user_reg, 
+		  value_of_mips_user_reg,
 		  &mips_numeric_register_aliases[i].regnum);
 
   return gdbarch;
@@ -8860,7 +9371,7 @@ show_mips_abi (struct ui_file *file,
   if (gdbarch_bfd_arch_info (current_inferior ()->arch  ())->arch
       != bfd_arch_mips)
     gdb_printf
-      (file, 
+      (file,
        "The MIPS ABI is unknown because the current architecture "
        "is not MIPS.\n");
   else
@@ -8871,7 +9382,7 @@ show_mips_abi (struct ui_file *file,
 
       if (global_abi == MIPS_ABI_UNKNOWN)
 	gdb_printf
-	  (file, 
+	  (file,
 	   "The MIPS ABI is set automatically (currently \"%s\").\n",
 	   actual_abi_str);
       else if (global_abi == actual_abi)
diff --git a/gdb/testsuite/gdb.arch/mips-64-r6.c b/gdb/testsuite/gdb.arch/mips-64-r6.c
new file mode 100644
index 00000000000..e1a1dd041cc
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/mips-64-r6.c
@@ -0,0 +1,916 @@
+/*
+   Copyright 2023-2025 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#define xstr(s) str(s)
+#define str(s) #s
+
+/* ============ macros from sim/testutils/mips/utils-r6.inc ============= */
+
+/* 58 is local label to exit with errcode != 0, indicating error.  */
+#define fp_assert(a, b) "beq " xstr (a) ", " xstr (b) ", 1f \n\t" \
+  "nop \n\t" \
+  "b 58f \n\t" \
+  "nop \n\t" \
+  "1: \n\t"
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1r(inst, a, ret) \
+  "li $4, " xstr (a) "    \n\t" \
+  "li $6, " xstr (ret) "  \n\t" \
+  xstr (inst) " $7, $4    \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1dr(inst, a, ret) \
+  "ld $4, " xstr (a) "   \n\t" \
+  "ld $6, " xstr (ret) " \n\t" \
+  xstr (inst) " $7, $4   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2r(inst, a, b, ret) \
+  "li $4, " xstr (a) "   \n\t" \
+  "li $5, " xstr (b) "   \n\t" \
+  "li $6, " xstr (ret) " \n\t" \
+  xstr (inst) " $7, $4, $5   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2dr(inst, a, b, ret) \
+  "ld $4, " xstr (a) "    \n\t" \
+  "ld $5, " xstr (b) "    \n\t" \
+  "ld $6, " xstr (ret) "  \n\t" \
+  xstr (inst) " $7, $4, $5  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2dr1i(inst, a, b, imm, ret) \
+  "ld $4, " xstr (a) "      \n\t" \
+  "ld $5, " xstr (b) "      \n\t" \
+  "ld $6, " xstr (ret) "    \n\t" \
+  xstr (inst) " $7, $4, $5, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1r1i(inst, a, imm, ret) \
+  "li $4, " xstr (a) "      \n\t" \
+  "li $6, " xstr (ret) "    \n\t" \
+  xstr (inst) " $7, $4, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1dr1i(inst, a, imm, ret) \
+  "ld $4, " xstr (a) "     \n\t" \
+  "ld $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $7, $4, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6.  */
+#define r6ck_0dr1i(inst, a, imm, ret) \
+  "ld $4, " xstr (a) "     \n\t" \
+  "ld $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $4, $4, " xstr (imm) "   \n\t" \
+  fp_assert ($6, $4)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2r1i(inst, a, b, imm, ret) \
+  "li $4, " xstr (a) "     \n\t" \
+  "li $5, " xstr (b) "     \n\t" \
+  "li $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $7, $4, $5, " xstr (imm) "   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7,$8,$f2,$f4,$f6.  */
+#define r6ck_3s(inst, a, b, c, ret) \
+  "li $4, " xstr (a) "     \n\t" \
+  "li $5, " xstr (b) "     \n\t" \
+  "li $6, " xstr (c) "     \n\t" \
+  "li $7, " xstr (ret) "   \n\t" \
+  "mtc1 $4, $f2           \n\t" \
+  "mtc1 $5, $f4           \n\t" \
+  "mtc1 $6, $f6           \n\t" \
+  xstr (inst) " $f2, $f4, $f6       \n\t" \
+  "mfc1 $8, $f2           \n\t" \
+  fp_assert ($7, $8)
+
+/* Clobbers: $4,$5,$6,$7,$f2,$f4.  */
+#define r6ck_2s(inst, a, b, ret) \
+  "li $4, " xstr (a) "       \n\t" \
+  "li $5, " xstr (b) "       \n\t" \
+  "li $6, " xstr (ret) "     \n\t" \
+  "mtc1 $4, $f2             \n\t" \
+  "mtc1 $5, $f4             \n\t" \
+  xstr (inst) " $f2, $f4     \n\t" \
+  "mfc1 $7, $f2             \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7,$8,$9,$10,$f2,$f4.  */
+#define r6ck_2d(inst, a, b, ret) \
+  ".data                  \n\t" \
+  "1: .dword " xstr (a) "    \n\t" \
+  "2: .dword " xstr (b) "    \n\t" \
+  "3: .dword " xstr (ret) "  \n\t" \
+  ".text                   \n\t" \
+  "dla $4, 1b              \n\t" \
+  "dla $5, 2b              \n\t" \
+  "dla $6, 3b              \n\t" \
+  "ldc1 $f2, 0($4)        \n\t" \
+  "ldc1 $f4, 0($5)        \n\t" \
+  "lw $7, 0($6)           \n\t" \
+  "lw $8, 4($6)           \n\t" \
+  xstr (inst) " $f2, $f4   \n\t" \
+  "mfhc1 $9, $f2          \n\t" \
+  "mfc1 $10, $f2          \n\t" \
+  fp_assert ($7, $9) \
+  fp_assert ($8, $10)
+
+/* Clobbers: $2,$4,$5,$6,$7,$8,$9,$10,$f2,$f4,$f6.  */
+#define r6ck_3d(inst, a, b, c, ret) \
+  ".data                                \n\t" \
+  "1: .dword " xstr (a) "                  \n\t" \
+  "2: .dword " xstr (b) "                  \n\t" \
+  "3: .dword " xstr (c) "                  \n\t" \
+  "4: .dword " xstr (ret) "                \n\t" \
+  ".text                                \n\t" \
+  "dla $4, 1b                            \n\t" \
+  "dla $5, 2b                            \n\t" \
+  "dla $6, 3b                            \n\t" \
+  "dla $2, 4b                            \n\t" \
+  "ldc1 $f2, 0($4)                      \n\t" \
+  "ldc1 $f4, 0($5)                      \n\t" \
+  "ldc1 $f6, 0($6)                      \n\t" \
+  "lw $7, 0($2)                         \n\t" \
+  "lw $8, 4($2)                         \n\t" \
+  xstr (inst) " $f2, $f4, $f6            \n\t" \
+  "mfhc1 $9, $f2                        \n\t" \
+  "mfc1 $10, $f2                        \n\t" \
+  fp_assert ($7, $9) \
+  fp_assert ($8, $10)
+
+/* ============ macros from sim/testutils/mips/testutils.inc ============= */
+
+/* Put value 'val' into register 'reg'.
+   Clobbers: None.  */
+#define load32(reg, val) \
+  "li  " xstr (reg) ", " xstr (val) "     \n\t"
+
+/* Check whether two registers contain the same value.
+   Clobbers: None.  */
+#define checkreg(reg, expreg) \
+  ".set push         \n\t" \
+  ".set noat         \n\t" \
+  ".set noreorder    \n\t" \
+  "beq "  xstr (expreg) ", " xstr (reg) ", 901f    \n\t" \
+  "nop               \n\t" \
+  "b 58f              \n\t" \
+  "nop                \n\t" \
+  "901:                   \n\t" \
+  ".set pop           \n\t"
+
+/* Check if register 'reg' contains value 'val'.
+   Clobbers: $1.  */
+#define check32(reg, val) \
+  ".set push         \n\t" \
+  ".set noat         \n\t" \
+  load32 ($1, val) \
+  checkreg (reg, $1) \
+  ".set pop          \n\t"
+
+/* Checkpair based on endianess
+   Clobbers: $1.  */
+#define checkpair_xendian(lo, hi, base, ec, w) \
+  ".set noat               \n\t" \
+  "lw   $1, " xstr (ec) "   \n\t" \
+  "andi $1, $1, 0x1        \n\t" \
+  "beqz  $1, 2f            \n\t" \
+  ".set at                 \n\t" \
+  "1:                          \n\t" \
+  checkpair_be_##w (lo, hi, base) \
+  "b 3f                    \n\t" \
+  "nop                     \n\t" \
+  "2:                          \n\t" \
+  checkpair_le_##w (lo, hi, base) \
+  "3:                          \n\t"
+
+/* Check hi-lo register pair against data stored at base+o1 and base+o2.
+   Clobbers: $1 - $5.  */
+#define  checkpair(lo, hi, base, w, o1, o2) \
+  "move  $2, " xstr (lo) "   \n\t" \
+  "move  $3, " xstr (hi) "   \n\t" \
+  ".set noat                \n\t" \
+  "dla   $1, " xstr (base) "  \n\t" \
+  "l" xstr (w) " $4, " xstr (o1) "($1)  \n\t" \
+  "l" xstr (w)  " $5, " xstr (o2) "($1)  \n\t" \
+  ".set at                  \n\t" \
+  checkreg ($2, $4) \
+  checkreg ($3, $5)
+
+#define checkpair_le_d(lo, hi, base) \
+  checkpair (lo, hi, base, w, 0, 4)
+
+#define checkpair_be_d(lo, hi, base) \
+  checkpair (lo, hi, base, w, 4, 0)
+
+#define checkpair_le_q(lo, hi, base) \
+  checkpair (lo, hi, base, d, 0, 8)
+
+#define checkpair_be_q(lo, hi, base) \
+  checkpair (lo, hi, base, d, 8, 0)
+
+#define checkpair_qword(lo, hi, base, oe) \
+  checkpair_xendian (lo, hi, base, oe, q)
+
+#define checkpair_dword(lo, hi, base, oe) \
+  checkpair_xendian (lo, hi, base, oe, d)
+
+void
+abort (void);
+
+/* Tests branch instructions.  */
+
+int
+test_r6_branch (void)
+{
+/* Using volatile to prevent certain optimizations which could cause
+   instruction deletion.
+   'err' identifies instruction which (eventually) caused error.
+   (err == 0) ==> all instructions executed successfully.  */
+
+  volatile int err = -1;
+  volatile int a14 = 0xffffffff;
+  volatile int a13 = 0x123;
+  volatile int a12 = 0x45;
+  volatile int a7 = 0x45;
+  volatile int a8 = 0xfffffffe;
+  volatile int a9 = 2147483647;
+  volatile int a11 = 0;
+  volatile int a10 = 0;
+
+  asm (
+  ".set push             \n\t" /* Create new scope for asm configuration.  */
+  ".set noreorder        \n\t" /* Don't allow reordering of instructions.  */
+  "li %[err], 1                  \n\t"
+  "bovc %[a12], %[a13], Lfail    \n\t" /* BOVC */
+  "nop                           \n\t"
+  "bovc %[a9], %[a13], L2        \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L2:                           \n\t"
+  "li %[err], 2                  \n\t"
+  "bnvc %[a9], %[a13], Lfail     \n\t" /* BNVC */
+  "nop                           \n\t"
+  "bnvc %[a12], %[a13], L3       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L3:                           \n\t"
+  "li %[err], 3                  \n\t"
+  "beqc %[a12], %[a13], Lfail    \n\t" /* BEQC */
+  "nop                           \n\t"
+  "beqc %[a12], %[a7], L4        \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L4:                           \n\t"
+  "li %[err], 4                  \n\t"
+  "bnec %[a12], %[a7], Lfail     \n\t" /* BNEC */
+  "nop                           \n\t"
+  "bnec %[a12], %[a13], L5       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L5:                           \n\t"
+  "li %[err], 5                  \n\t"
+  "bltc %[a13], %[a12], Lfail    \n\t" /* BLTC */
+  "nop                           \n\t"
+  "bltc %[a12], %[a13], L6       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L6:                           \n\t"
+  "L7:                           \n\t"
+  "li %[err], 7                  \n\t"
+  "bgec %[a12], %[a13], Lfail    \n\t" /* BGEC */
+  "nop                           \n\t"
+  "bgec %[a13], %[a12], L8       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L8:                           \n\t"
+  "L9:                           \n\t"
+  "li %[err], 9                  \n\t"
+  "bltuc %[a14], %[a13], Lfail   \n\t" /* BLTUC */
+  "nop                           \n\t"
+  "bltuc %[a8], %[a14], L10      \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L10:                          \n\t"
+  "L11:                          \n\t"
+  "li %[err], 11                 \n\t"
+  "bgeuc %[a13], %[a14], Lfail   \n\t" /* BGEUC */
+  "nop                           \n\t"
+  "bgeuc %[a14], %[a8], L12      \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L12:                          \n\t"
+  "L13:                          \n\t"
+  "li %[err], 13                 \n\t"
+  "bltzc %[a13], Lfail           \n\t" /* BLTZC */
+  "nop                           \n\t"
+  "bltzc %[a11], Lfail           \n\t"
+  "nop                           \n\t"
+  "bltzc %[a14], L14             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L14:                          \n\t"
+  "li %[err], 14                 \n\t"
+  "blezc %[a13], Lfail           \n\t" /* BLEZC */
+  "nop                           \n\t"
+  "blezc %[a11], L145            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L145:                         \n\t"
+  "blezc %[a14], L15             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L15:                          \n\t"
+  "li %[err], 15                 \n\t"
+  "bgezc %[a8], Lfail            \n\t" /* BGEZC */
+  "nop                           \n\t"
+  "bgezc %[a11], L155            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L155:                         \n\t"
+  "bgezc %[a13], L16             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L16:                          \n\t"
+  "li %[err], 16                 \n\t"
+  "bgtzc %[a8], Lfail            \n\t" /* BGTZC */
+  "nop                           \n\t"
+  "bgtzc %[a11], Lfail           \n\t"
+  "nop                           \n\t"
+  "bgtzc %[a13], L17             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "li %[a10], 0                  \n\t"
+  "L17:                          \n\t"
+  "li %[err], 17                 \n\t"
+  "blezalc %[a12], Lfail         \n\t" /* BLEZALC */
+  "nop                           \n\t"
+  "blezalc %[a11], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L175            \n\t" /* BEQZC */
+  "nop                           \n\t"
+  "li %[err], 8531               \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L175:                         \n\t"
+  "li %[err], 23531              \n\t"
+  "blezalc %[a14], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L18             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L18:                          \n\t"
+  "li %[err], 18                 \n\t"
+  "bgezalc %[a14], Lfail         \n\t" /* BGEZALC */
+  "nop                           \n\t"
+  "bgezalc %[a11], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L185            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L185:                         \n\t"
+  "bgezalc %[a12], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L19             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L19:                          \n\t"
+  "li %[err], 19                 \n\t"
+  "bgtzalc %[a14], Lfail         \n\t" /* BGTZALC */
+  "nop                           \n\t"
+  "bgtzalc %[a11], Lfail         \n\t"
+  "nop                           \n\t"
+  "bgtzalc %[a12], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L20             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L20:                          \n\t"
+  "li %[err], 20                 \n\t"
+  "bltzalc %[a12], Lfail         \n\t" /* BLTZALC */
+  "nop                           \n\t"
+  "bltzalc %[a11], Lfail         \n\t"
+  "nop                           \n\t"
+  "bltzalc %[a14], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L21             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L21:                          \n\t"
+  "li %[err], 21                 \n\t"
+  "bc L22                        \n\t" /* BC */
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L22:                          \n\t"
+  "li %[err], 22                 \n\t"
+  "balc Lret                     \n\t" /* BALC */
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L23             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L23:                          \n\t"
+  "li %[err], 23                 \n\t"
+  "jal GetPC                     \n\t" /* JAL */
+  "nop                           \n\t"
+  "jic $6, 4                     \n\t" /* JIC */
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L24:                          \n\t"
+  "li %[err], 24                 \n\t"
+  "li %[a10], 1                  \n\t"
+  "jal GetPC                     \n\t"
+  "nop                           \n\t"
+  "jialc $6, 20                  \n\t" /* JIALC */
+  "nop                           \n\t"
+  "beqzc %[a10], L25             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "LJIALCRET:                    \n\t"
+  "li %[a10], 0                  \n\t"
+  "jr $31                        \n\t" /* JR */
+  "nop                           \n\t"
+  "L25:                          \n\t"
+  "li %[err], 25                 \n\t"
+  "jal GetPC                     \n\t"
+  "nop                           \n\t"
+  "move %[a11], $6               \n\t"
+  "nal                           \n\t"
+  "nop                           \n\t"
+  "addiu %[a11], 12              \n\t" /* ADDIU */
+  "beqc %[a11], $31, L26         \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L26:                          \n\t"
+  "li %[err], 26                 \n\t"
+  "balc Lret                     \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], Lend            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "Lret:                         \n\t"
+  "li %[a10], 0                  \n\t"
+  "daddiu $31, 4                 \n\t" /* DADDIU */
+  "jrc $31                       \n\t" /* JRC */
+  "nop                           \n\t"
+  "GetPC:                        \n\t"
+  "move $6, $31                  \n\t"
+  "jr $31                        \n\t"
+  "Lend:                         \n\t"
+  "li %[err], 0                  \n\t"
+  "Lfail:                        \n\t"
+  ".set pop                      \n\t" /* Restore previous config */
+  : [err] "+r"(err), [a14] "+r"(a14), [a13] "+r"(a13), [a12] "+r"(a12),
+    [a7] "+r"(a7), [a8] "+r"(a8), [a9] "+r"(a9), [a10] "+r"(a10),
+    [a11] "+r"(a11)
+  : /* inputs */
+  : "$31", "$6" /* clobbers */
+  );
+
+  return err;
+}
+
+/* Tests forbidden slot branching i.e. conditional compact branch
+   instructions.  */
+
+int
+test_r6_forbidden (void)
+{
+  volatile int err = -1;
+  volatile int a4 = 0;
+  volatile int a2 = 0;
+  volatile int a1 = 0;
+
+  asm (
+  ".set push                         \n\t"
+  ".set noreorder                    \n\t"
+/* Test if FS is ignored when branch is taken */
+  "li %[err], 1                      \n\t"
+  "li %[a4], 0                       \n\t"
+  "beqzalc %[a4], L41                \n\t"
+  "li %[err], -85                    \n\t"
+  "L42:                              \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "L41:                              \n\t"
+  "blez %[err], Lfail2               \n\t"
+/* Test if FS is used when branch is not taken */
+  "li %[err], 2                      \n\t"
+  "li %[a4], 1                       \n\t"
+  "blezc %[a4], L43                  \n\t"
+  "addiu %[a4], %[a4], 1             \n\t"
+  "li %[a2], 2                       \n\t"
+  "beq %[a4], %[a2], L44             \n\t"
+  "nop                               \n\t"
+  "L43:                              \n\t"
+  "nop                               \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "L44:                              \n\t"
+  "li %[err], 3                      \n\t"
+  "li %[a4], 3                       \n\t"
+  "beqzalc %[a4], Lfail2             \n\t"
+/* Note: 'bc L45' instead nop would cause SegFault: Illegal instruction:
+   Forbidden slot causes an error when it contains a branch.  */
+  "nop                               \n\t"
+  "b Lend2                           \n\t"
+  "nop                               \n\t"
+  "L45:                              \n\t"
+  "nop                               \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "Lend2:                            \n\t"
+  "li %[err], 0                      \n\t"
+  "Lfail2:                           \n\t"
+  "nop                               \n\t"
+  ".set pop                          \n\t"
+  : [err] "+r" (err), [a4] "+r"(a4), [a2] "+r"(a2), [a1] "+r"(a1) /* outputs */
+  : /* inputs */
+  : "$31" /* clobbers */
+  );
+
+  return err;
+}
+
+int
+test_r6_64 (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                   \n\t"
+  ".set noreorder                              \n\t"
+  ".data                                       \n\t"
+  "dval: .dword 0xaa55bb66cc77dd88             \n\t"
+  "d1:   .dword 0xaaaabbbbccccdddd             \n\t"
+  "d5:   .dword 0x00000000000000dd             \n\t"
+  "d7:   .dword 0xeeeeffff00001111             \n\t"
+  "d8:   .dword 0xbbccccddddeeeeff             \n\t"
+  "d9:   .dword 0x000000ddaaaabbbb             \n\t"
+  "dval1: .word 0x1234abcd                     \n\t"
+  "dval2: .word 0xffee0000                     \n\t"
+  "dval3: .dword 0xffffffffffffffff            \n\t"
+  "  .fill 240,1,0                             \n\t"
+  "dval4: .dword 0x5555555555555555            \n\t"
+  "  .fill  264,1,0                            \n\t"
+
+/* Register $11 stores instruction currently being tested and hence
+ * identifies error if it occurs.  */
+  ".text                                       \n\t"
+
+  "li $11, 1                                   \n\t" /* Test DALIGN */
+  r6ck_2dr1i (dalign, d7, d1, 3, d8)
+  r6ck_2dr1i (dalign, d1, d5, 4, d9)
+
+  "li $11, 2                                   \n\t" /* Test LDPC */
+  "ld $5, dval                                 \n\t"
+  "nop                                         \n\t"
+  "ldpc $4, dval                               \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 3                                   \n\t" /* Test LWUPC */
+  "lwu $5, dval1                               \n\t"
+  "lwupc $4, dval1                             \n\t"
+  fp_assert ($4, $5)
+  "lwu $5, dval2                               \n\t"
+  "lwupc $4, dval2                             \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 4                                   \n\t" /* Test LLD */
+  "ld $5, dval3                                \n\t"
+  "dla $3, dval4                               \n\t"
+  "lld $4, -248($3)                            \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 5                                   \n\t" /* Test SCD */
+  "lld $4, -248($3)                            \n\t"
+  "dli $4, 0xafaf                              \n\t"
+  "scd $4, -248($3)                            \n\t"
+  "ld $5, dval3                                \n\t"
+  "dli $4, 0xafaf                              \n\t"
+  fp_assert ($4, $5)
+
+  "Lend3:                                      \n\t"
+  "li $11, 0                                   \n\t"
+  "58:                                         \n\t"
+  "move %[err], $11                            \n\t"
+  ".set pop                                    \n\t"
+   : [err] "+r" (err) /* outputs */
+   :                  /* inputs */
+   : "$3", "$4", "$5", "$6", "$7", "$11" /* clobbers */
+  );
+
+  return err;
+}
+
+int
+test_r6 (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                                   \n\t"
+  ".set noreorder                                              \n\t"
+  ".data                                                       \n\t"
+  "dval_1:  .word 0xabcd1234                                   \n\t"
+  "dval_2: .word 0x1234eeff                                    \n\t"
+  ".fill 248,1,0                                               \n\t"
+  "dval_3: .word 0x55555555                                    \n\t"
+  ".fill  260,1,0                                              \n\t"
+  "dval_4: .word 0xaaaaaaaa                                    \n\t"
+  ".text                                                       \n\t"
+  "li $11, 1            \n\t" /* ADDIUPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 8                                           \n\t"
+  "addiupc $5, 4                                             \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 2            \n\t" /* AUIPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 8                                           \n\t"
+  "aui $4, $4, 8                                             \n\t"
+  "auipc $5, 8                                               \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 3            \n\t" /* ALUIPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 16                                          \n\t"
+  "aui $4, $4, 8                                             \n\t"
+  "li $7, 0xffff0000                                         \n\t"
+  "and $4, $4, $7                                            \n\t"
+  "aluipc $5, 8                                              \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 4            \n\t" /* LWPC */
+  "lw $5, dval_1                                             \n\t"
+  "lwpc $4, dval_1                                           \n\t"
+  fp_assert ($4, $5)
+  "lw $5, dval_2                                             \n\t"
+  "lwpc $4, dval_2                                           \n\t"
+  fp_assert ($4, $5)
+
+/* Testing LL follows.
+ * NOTE: May be redundant because SC already contains LL in its test.  */
+  "li $11, 5                                                \n\t"
+  "lw $5, dval_2                                             \n\t"
+  "dla $3, dval_3                                            \n\t"
+  "ll $4, -252($3)                                           \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 6        \n\t"    /* LL-SC sequence */
+  "ll $4, -252($3)                                           \n\t"
+  "li $4, 0xafaf                                             \n\t"
+  "sc $4, -252($3)                                           \n\t"
+  "lw $5, dval_2                                             \n\t"
+  "li $4, 0xafaf                                             \n\t"
+  fp_assert ($4, $5)
+  "b Lend4                                                   \n\t"
+  "nop                                                       \n\t"
+  "GetPC_2:                                                  \n\t"
+  "move $6, $31                                              \n\t"
+  "jr $31                                                    \n\t"
+  "Lend4:                                                    \n\t"
+  "li $11, 0                                                 \n\t"
+  "58:                                                       \n\t"
+  "move %[err], $11                                          \n\t"
+  ".set pop                                                  \n\t"
+  : [err] "+r"(err)  /* outputs */
+  : /* inputs */
+  : "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10",
+    "$11", "$31" /* clobbers */
+  );
+
+  return err;
+}
+
+/* For fpu-branching testing, bc1eq/eqz are enough.  */
+
+int
+test_r6_fpu (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                               \n\t"
+  ".set noreorder                          \n\t"
+/* Test qNaN format is 754-2008 */
+  "li $11, 1                               \n\t"
+  "li $4, 0x0                              \n\t"
+  "li $5, 0x0                              \n\t"
+  "li $6, 0x7fc00000                       \n\t"
+  "mtc1 $4, $f2                            \n\t"
+  "mtc1 $5, $f4                            \n\t"
+  "div.s $f6, $f2, $f4                     \n\t"
+  "mfc1 $8, $f6                            \n\t"
+  fp_assert ($6, $8)
+
+  "li $11, 2                                \n\t"  /* bc1eqz */
+  "li $10, 0x01                             \n\t"
+  "mtc1 $10, $f2                            \n\t"
+  "mtc1 $0, $f4                             \n\t"
+  "bc1eqz $f2, 58f                          \n\t"
+  "nop                                      \n\t"
+  "bc1eqz $f4, L62                          \n\t"
+  "nop                                      \n\t"
+  "b 58f                                    \n\t"
+  "nop                                      \n\t"
+"L62:                                       \n\t"
+  "li $11, 3                                \n\t"  /* bc1nez */
+  "bc1nez $f4, 58f                          \n\t"
+  "nop                                      \n\t"
+  "bc1nez $f2, Lend8                        \n\t"
+  "nop                                      \n\t"
+  "b 58f                                    \n\t"
+  "nop                                      \n\t"
+"Lend8:                                     \n\t"
+  "li $11, 0                                \n\t"
+  "58:                                      \n\t"
+  "move %[err], $11                         \n\t"
+  ".set pop                                 \n\t"
+  : [err] "+r"(err)  /* outputs */
+  :                  /* inputs */
+  : "$4", "$5", "$6", "$8", "$10", "$11", "$31",
+    "$f2", "$f4", "$f6" /* clobbers */
+  );
+
+  return err;
+}
+
+/* R6 specific tests for mips64 (64-bit).  */
+
+int
+test_r6_llsc_dp (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                            \n\t"
+  ".set noreorder                                       \n\t"
+  ".data                                                \n\t"
+  ".align 16                                            \n\t"
+  "test_data:                                           \n\t"
+  ".word 0xaaaaaaaa                                     \n\t"
+  ".word 0xbbbbbbbb                                     \n\t"
+  ".word 0xcccccccc                                     \n\t"
+  ".word 0xdddddddd                                     \n\t"
+  ".align 16                                            \n\t"
+  "end_check:                                           \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0x1                                            \n\t"
+  ".text                                                \n\t"
+  "li $11, 1                                            \n\t" /* LLWP */
+  "llwp $2, $3, test_data                               \n\t"
+  checkpair_dword ($2, $3, test_data, end_check)
+  "sll $2, $2, 1                                        \n\t"
+  "srl $3, $3, 1                                        \n\t"
+  "move  $s0, $2                                        \n\t"
+  "scwp $2, $3, test_data                               \n\t"
+  check32 ($2, 1)
+  checkpair_dword ($s0, $3, test_data, end_check)
+  /* Test SCWP, done */
+  "li $11, 2                                            \n\t"
+  "li $11, 3                                            \n\t" /* LLDP */
+  "lldp $2, $3, test_data                               \n\t"
+  checkpair_qword ($2, $3, test_data, end_check)
+  "dsll $2, $2, 1                                       \n\t"
+  "dsrl $3, $3, 1                                       \n\t"
+  "move $s0, $2                                         \n\t"
+  "scdp $2, $3, test_data                               \n\t"
+  check32 ($2, 1)
+  checkpair_qword ($s0, $3, test_data, end_check)
+  "li $11, 4                                            \n\t" /* SCDP done */
+  "Lend5:                                               \n\t"
+  "li $11, 0                                            \n\t"
+  "58:                                                  \n\t"
+  "move %[err], $11                                     \n\t"
+  ".set pop                                             \n\t"
+  : [err] "+r"(err) /* outputs */
+  : /* inputs */
+  : "$2", "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10", "$11",
+    "$31", "$s0"  /* clobbers */
+  );
+
+  return err;
+}
+
+/* R6 specific tests for mips32 (32-bit).  */
+
+int
+test_r6_llsc_wp (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                            \n\t"
+  ".set noreorder                                       \n\t"
+  ".data                                                \n\t"
+  ".align 8                                             \n\t"
+  "test_data_2:                                         \n\t"
+  ".word 0xaaaaaaaa                                     \n\t"
+  ".word 0xbbbbbbbb                                     \n\t"
+  ".align 8                                             \n\t"
+  "end_check_2:                                         \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0x1                                            \n\t"
+  ".text                                                \n\t"
+  "li $11, 1                                            \n\t" /* Test LLWP */
+  "llwp $2, $3, test_data_2                             \n\t"
+  checkpair_dword ($2, $3, test_data_2, end_check_2)
+  "sll $2, $2, 1                                        \n\t"
+  "srl $3, $3, 1                                        \n\t"
+  "move  $s0, $2                                        \n\t"
+  "scwp $2, $3, test_data_2                             \n\t"
+  check32 ($2, 1)
+  checkpair_dword ($s0, $3, test_data_2, end_check_2)
+/* Test SCWP, done.  */
+  "li $11, 2                                            \n\t"
+  "Lend6:                                               \n\t"
+  "li $11, 0                                            \n\t"
+  "58:                                                  \n\t"
+  "move %[err], $11                                     \n\t"
+  ".set pop                                             \n\t"
+  : [err] "+r"(err) /* outputs */
+  : /* inputs */
+  : "$2", "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10",
+    "$11", "$31", "$s0"  /* clobbers */
+  );
+
+  return err;
+}
+
+/* If any test_r6_* function returns non-zero, it's a failure.  */
+#define EXPECT(X) if ((X)) abort ();
+
+int
+main (void)
+{
+  EXPECT (test_r6_branch ());
+
+  EXPECT (test_r6_forbidden ());
+
+  EXPECT (test_r6_64 ());
+
+  EXPECT (test_r6 ());
+
+  EXPECT (test_r6_fpu ());
+
+  EXPECT (test_r6_llsc_dp ());
+
+  EXPECT (test_r6_llsc_wp ());
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/mips-64-r6.exp b/gdb/testsuite/gdb.arch/mips-64-r6.exp
new file mode 100644
index 00000000000..710da94c542
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/mips-64-r6.exp
@@ -0,0 +1,76 @@
+# Copyright (C) 2023-2025 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+################################################################
+################## MIPS Release 6 patch tests ##################
+################################################################
+
+# Send 'si' to gdb until inferior exits.
+proc stepi {} {
+    global gdb_prompt
+    set timeout [get_largest_timeout]
+    set start [timestamp]
+    while { [timestamp] - $start < 3*$timeout } {
+	gdb_test_multiple "stepi" "" {
+	    -re ".*exited normally.*" {
+		pass "success"
+		return
+	    }
+	    -re ".*The program is not being run.*" {
+		fail "failure"
+		return
+	    }
+	    -re ".*Breakpoint.*test_.*$gdb_prompt $" {
+	    }
+	    -re "$gdb_prompt.*" {
+	    }
+	}
+    }
+    fail "test failed"
+    return
+}
+
+require {istarget "*mips*"}
+
+set testfile "mips-64-r6"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+
+if {[prepare_for_testing "failed to prepare" "${binfile}" "${srcfile}" {debug nowarnings}]} {
+    untested "failed to prepare"
+    return
+}
+
+# Native needs run.
+if { ![runto_main] } {
+    untested "couldn't run to main"
+    return
+}
+
+set tests ""
+foreach n [list "r6_branch" "r6_forbidden" "r6_64" "r6" "r6_fpu" "r6_llsc_dp" "r6_llsc_wp"] {
+    lappend tests "test_$n"
+}
+
+# Put breakpoint on each test-function
+foreach func $tests {
+    if {![gdb_breakpoint "$func"]} {
+	untested "couldn't put breakpoint to $func"
+	return
+    }
+}
+
+# Step through the binary
+stepi
-- 
2.34.1

             reply	other threads:[~2025-02-10 17:29 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-10 17:28 Milica Matic [this message]
2025-02-11 20:10 ` Kevin Buettner
2025-02-11 20:45   ` Maciej W. Rozycki
2025-02-19 13:05     ` Milica Matic
2025-02-19 13:14     ` Milica Matic

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