* Re: [PATCH/mips] small code reordering...
2004-10-15 7:30 [PATCH/mips] small code reordering Joel Brobecker
@ 2004-10-15 14:04 ` Joel Brobecker
0 siblings, 0 replies; 2+ messages in thread
From: Joel Brobecker @ 2004-10-15 14:04 UTC (permalink / raw)
To: gdb-patches
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[with the patch, this time... Thanks Andrew]
Hello,
The attached patch does a bit of code reordering. The idea was to
get rid of the following FIXME introduced in the previous change
(to avoid bloating the patch with code-moving changes):
/* FIXME: brobecker/2004-10-15: I suspect these two declarations can
be removed by a better ordering of the functions below. But I want
to do that as a separate change later in order to separate real
changes and changes that just move some code around. */
It turns out that I find the new location to be more natural anyway,
so I think the move was more than worthwhile.
Sorry for the obfuscated diff. It's just all cut, move, paste actions.
2004-10-15 Joel Brobecker <brobecker@gnat.com>
* mips-tdep.c (mips32_scan_prologue): Move the implementation up
a bit to avoid the necessity of an advance declaration. Remove
declaration.
(set_reg_offset): Move implemenation up.
(mips16_get_imm): Likewise.
(mips16_scan_prologue): Likewise.
(reset_saved_regs): Likewise.
(mips32_scan_prologue): Likewise.
Comitted.
--
Joel
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Index: mips-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mips-tdep.c,v
retrieving revision 1.334
diff -u -p -r1.334 mips-tdep.c
--- mips-tdep.c 15 Oct 2004 07:09:09 -0000 1.334
+++ mips-tdep.c 15 Oct 2004 07:24:12 -0000
@@ -442,17 +442,6 @@ static struct type *mips_double_register
static struct cmd_list_element *setmipscmdlist = NULL;
static struct cmd_list_element *showmipscmdlist = NULL;
-/* FIXME: brobecker/2004-10-15: I suspect these two declarations can
- be removed by a better ordering of the functions below. But I want
- to do that as a separate change later in order to separate real
- changes and changes that just move some code around. */
-static CORE_ADDR mips32_scan_prologue (CORE_ADDR start_pc, CORE_ADDR limit_pc,
- struct frame_info *next_frame,
- struct mips_frame_cache *this_cache);
-static CORE_ADDR mips16_scan_prologue (CORE_ADDR start_pc, CORE_ADDR limit_pc,
- struct frame_info *next_frame,
- struct mips_frame_cache *this_cache);
-
/* Integer registers 0 thru 31 are handled explicitly by
mips_register_name(). Processor specific registers 32 and above
are listed in the followign tables. */
@@ -1721,961 +1710,961 @@ mips_mdebug_frame_base_sniffer (struct f
return NULL;
}
-/* Heuristic unwinder for 16-bit MIPS instruction set (aka MIPS16).
- Procedures that use the 32-bit instruction set are handled by the
- mips_insn32 unwinder. */
-
-static struct mips_frame_cache *
-mips_insn16_frame_cache (struct frame_info *next_frame, void **this_cache)
-{
- struct mips_frame_cache *cache;
-
- if ((*this_cache) != NULL)
- return (*this_cache);
- cache = FRAME_OBSTACK_ZALLOC (struct mips_frame_cache);
- (*this_cache) = cache;
- cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);
-
- /* Analyze the function prologue. */
- {
- const CORE_ADDR pc = frame_pc_unwind (next_frame);
- CORE_ADDR start_addr;
-
- find_pc_partial_function (pc, NULL, &start_addr, NULL);
- if (start_addr == 0)
- start_addr = heuristic_proc_start (pc);
- /* We can't analyze the prologue if we couldn't find the begining
- of the function. */
- if (start_addr == 0)
- return cache;
-
- mips16_scan_prologue (start_addr, pc, next_frame, *this_cache);
- }
-
- /* SP_REGNUM, contains the value and not the address. */
- trad_frame_set_value (cache->saved_regs, NUM_REGS + MIPS_SP_REGNUM, cache->base);
-
- return (*this_cache);
-}
+/* Set a register's saved stack address in temp_saved_regs. If an
+ address has already been set for this register, do nothing; this
+ way we will only recognize the first save of a given register in a
+ function prologue.
-static void
-mips_insn16_frame_this_id (struct frame_info *next_frame, void **this_cache,
- struct frame_id *this_id)
-{
- struct mips_frame_cache *info = mips_insn16_frame_cache (next_frame,
- this_cache);
- (*this_id) = frame_id_build (info->base, frame_func_unwind (next_frame));
-}
+ For simplicity, save the address in both [0 .. NUM_REGS) and
+ [NUM_REGS .. 2*NUM_REGS). Strictly speaking, only the second range
+ is used as it is only second range (the ABI instead of ISA
+ registers) that comes into play when finding saved registers in a
+ frame. */
static void
-mips_insn16_frame_prev_register (struct frame_info *next_frame,
- void **this_cache,
- int regnum, int *optimizedp,
- enum lval_type *lvalp, CORE_ADDR *addrp,
- int *realnump, void *valuep)
+set_reg_offset (struct mips_frame_cache *this_cache, int regnum,
+ CORE_ADDR offset)
{
- struct mips_frame_cache *info = mips_insn16_frame_cache (next_frame,
- this_cache);
- trad_frame_get_prev_register (next_frame, info->saved_regs, regnum,
- optimizedp, lvalp, addrp, realnump, valuep);
+ if (this_cache != NULL
+ && this_cache->saved_regs[regnum].addr == -1)
+ {
+ this_cache->saved_regs[regnum + 0 * NUM_REGS].addr = offset;
+ this_cache->saved_regs[regnum + 1 * NUM_REGS].addr = offset;
+ }
}
-static const struct frame_unwind mips_insn16_frame_unwind =
-{
- NORMAL_FRAME,
- mips_insn16_frame_this_id,
- mips_insn16_frame_prev_register
-};
-
-static const struct frame_unwind *
-mips_insn16_frame_sniffer (struct frame_info *next_frame)
-{
- CORE_ADDR pc = frame_pc_unwind (next_frame);
- if (pc_is_mips16 (pc))
- return &mips_insn16_frame_unwind;
- return NULL;
-}
-static CORE_ADDR
-mips_insn16_frame_base_address (struct frame_info *next_frame,
- void **this_cache)
-{
- struct mips_frame_cache *info = mips_insn16_frame_cache (next_frame,
- this_cache);
- return info->base;
-}
+/* 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
+ for mips16_scan_prologue. */
-static const struct frame_base mips_insn16_frame_base =
+static int
+mips16_get_imm (unsigned short prev_inst, /* previous instruction */
+ unsigned short inst, /* current instruction */
+ int nbits, /* number of bits in imm field */
+ int scale, /* scale factor to be applied to imm */
+ int is_signed) /* is the imm field signed? */
{
- &mips_insn16_frame_unwind,
- mips_insn16_frame_base_address,
- mips_insn16_frame_base_address,
- mips_insn16_frame_base_address
-};
+ int offset;
-static const struct frame_base *
-mips_insn16_frame_base_sniffer (struct frame_info *next_frame)
-{
- if (mips_insn16_frame_sniffer (next_frame) != NULL)
- return &mips_insn16_frame_base;
+ if ((prev_inst & 0xf800) == 0xf000) /* prev instruction was EXTEND? */
+ {
+ offset = ((prev_inst & 0x1f) << 11) | (prev_inst & 0x7e0);
+ if (offset & 0x8000) /* check for negative extend */
+ offset = 0 - (0x10000 - (offset & 0xffff));
+ return offset | (inst & 0x1f);
+ }
else
- return NULL;
-}
-
-/* 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. */
+ {
+ int max_imm = 1 << nbits;
+ int mask = max_imm - 1;
+ int sign_bit = max_imm >> 1;
-static struct mips_frame_cache *
-mips_insn32_frame_cache (struct frame_info *next_frame, void **this_cache)
-{
- struct mips_frame_cache *cache;
+ offset = inst & mask;
+ if (is_signed && (offset & sign_bit))
+ offset = 0 - (max_imm - offset);
+ return offset * scale;
+ }
+}
- if ((*this_cache) != NULL)
- return (*this_cache);
- cache = FRAME_OBSTACK_ZALLOC (struct mips_frame_cache);
- (*this_cache) = cache;
- cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);
+/* 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. */
- /* Analyze the function prologue. */
- {
- const CORE_ADDR pc = frame_pc_unwind (next_frame);
- CORE_ADDR start_addr;
+static CORE_ADDR
+mips16_scan_prologue (CORE_ADDR start_pc, CORE_ADDR limit_pc,
+ struct frame_info *next_frame,
+ struct mips_frame_cache *this_cache)
+{
+ 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. */
+ int frame_reg = MIPS_SP_REGNUM;
+ unsigned short prev_inst = 0; /* saved copy of previous instruction */
+ unsigned inst = 0; /* current instruction */
+ unsigned entry_inst = 0; /* the entry instruction */
+ int reg, offset;
- find_pc_partial_function (pc, NULL, &start_addr, NULL);
- if (start_addr == 0)
- start_addr = heuristic_proc_start (pc);
- /* We can't analyze the prologue if we couldn't find the begining
- of the function. */
- if (start_addr == 0)
- return cache;
+ int extend_bytes = 0;
+ int prev_extend_bytes;
+ CORE_ADDR end_prologue_addr = 0;
- mips32_scan_prologue (start_addr, pc, next_frame, *this_cache);
- }
-
- /* SP_REGNUM, contains the value and not the address. */
- trad_frame_set_value (cache->saved_regs, NUM_REGS + MIPS_SP_REGNUM, cache->base);
+ /* Can be called when there's no process, and hence when there's no
+ NEXT_FRAME. */
+ if (next_frame != NULL)
+ sp = read_next_frame_reg (next_frame, NUM_REGS + MIPS_SP_REGNUM);
+ else
+ sp = 0;
- return (*this_cache);
-}
+ if (limit_pc > start_pc + 200)
+ limit_pc = start_pc + 200;
-static void
-mips_insn32_frame_this_id (struct frame_info *next_frame, void **this_cache,
- struct frame_id *this_id)
-{
- struct mips_frame_cache *info = mips_insn32_frame_cache (next_frame,
- this_cache);
- (*this_id) = frame_id_build (info->base, frame_func_unwind (next_frame));
-}
+ for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += MIPS16_INSTLEN)
+ {
+ /* Save the previous instruction. If it's an EXTEND, we'll extract
+ the immediate offset extension from it in mips16_get_imm. */
+ prev_inst = inst;
-static void
-mips_insn32_frame_prev_register (struct frame_info *next_frame,
- void **this_cache,
- int regnum, int *optimizedp,
- enum lval_type *lvalp, CORE_ADDR *addrp,
- int *realnump, void *valuep)
-{
- struct mips_frame_cache *info = mips_insn32_frame_cache (next_frame,
- this_cache);
- trad_frame_get_prev_register (next_frame, info->saved_regs, regnum,
- optimizedp, lvalp, addrp, realnump, valuep);
-}
+ /* Fetch and decode the instruction. */
+ inst = (unsigned short) mips_fetch_instruction (cur_pc);
-static const struct frame_unwind mips_insn32_frame_unwind =
-{
- NORMAL_FRAME,
- mips_insn32_frame_this_id,
- mips_insn32_frame_prev_register
-};
+ /* Normally we ignore extend instructions. However, if it is
+ not followed by a valid prologue instruction, then this
+ instruction is not part of the prologue either. We must
+ remember in this case to adjust the end_prologue_addr back
+ over the extend. */
+ if ((inst & 0xf800) == 0xf000) /* extend */
+ {
+ extend_bytes = MIPS16_INSTLEN;
+ continue;
+ }
-static const struct frame_unwind *
-mips_insn32_frame_sniffer (struct frame_info *next_frame)
-{
- CORE_ADDR pc = frame_pc_unwind (next_frame);
- if (! pc_is_mips16 (pc))
- return &mips_insn32_frame_unwind;
- return NULL;
-}
+ prev_extend_bytes = extend_bytes;
+ extend_bytes = 0;
-static CORE_ADDR
-mips_insn32_frame_base_address (struct frame_info *next_frame,
- void **this_cache)
-{
- struct mips_frame_cache *info = mips_insn32_frame_cache (next_frame,
- this_cache);
- return info->base;
-}
+ if ((inst & 0xff00) == 0x6300 /* addiu sp */
+ || (inst & 0xff00) == 0xfb00) /* daddiu sp */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 8, 8, 1);
+ 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;
+ }
+ else if ((inst & 0xf800) == 0xd000) /* sw reg,n($sp) */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 8, 4, 0);
+ reg = mips16_to_32_reg[(inst & 0x700) >> 8];
+ set_reg_offset (this_cache, reg, sp + offset);
+ }
+ else if ((inst & 0xff00) == 0xf900) /* sd reg,n($sp) */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 5, 8, 0);
+ reg = mips16_to_32_reg[(inst & 0xe0) >> 5];
+ set_reg_offset (this_cache, reg, sp + offset);
+ }
+ else if ((inst & 0xff00) == 0x6200) /* sw $ra,n($sp) */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 8, 4, 0);
+ set_reg_offset (this_cache, RA_REGNUM, sp + offset);
+ }
+ else if ((inst & 0xff00) == 0xfa00) /* sd $ra,n($sp) */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 8, 8, 0);
+ set_reg_offset (this_cache, RA_REGNUM, sp + offset);
+ }
+ else if (inst == 0x673d) /* move $s1, $sp */
+ {
+ frame_addr = sp;
+ frame_reg = 17;
+ }
+ else if ((inst & 0xff00) == 0x0100) /* addiu $s1,sp,n */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 8, 4, 0);
+ frame_addr = sp + offset;
+ frame_reg = 17;
+ frame_adjust = offset;
+ }
+ else if ((inst & 0xFF00) == 0xd900) /* sw reg,offset($s1) */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 5, 4, 0);
+ reg = mips16_to_32_reg[(inst & 0xe0) >> 5];
+ set_reg_offset (this_cache, reg, frame_addr + offset);
+ }
+ else if ((inst & 0xFF00) == 0x7900) /* sd reg,offset($s1) */
+ {
+ offset = mips16_get_imm (prev_inst, inst, 5, 8, 0);
+ reg = mips16_to_32_reg[(inst & 0xe0) >> 5];
+ set_reg_offset (this_cache, reg, frame_addr + offset);
+ }
+ else if ((inst & 0xf81f) == 0xe809
+ && (inst & 0x700) != 0x700) /* entry */
+ entry_inst = inst; /* save for later processing */
+ else if ((inst & 0xf800) == 0x1800) /* jal(x) */
+ cur_pc += MIPS16_INSTLEN; /* 32-bit instruction */
+ else if ((inst & 0xff1c) == 0x6704) /* move reg,$a0-$a3 */
+ {
+ /* This instruction is part of the prologue, but we don't
+ need to do anything special to handle it. */
+ }
+ else
+ {
+ /* This instruction is not an instruction typically found
+ in a prologue, so we must have reached the end of the
+ prologue. */
+ if (end_prologue_addr == 0)
+ end_prologue_addr = cur_pc - prev_extend_bytes;
+ }
+ }
-static const struct frame_base mips_insn32_frame_base =
-{
- &mips_insn32_frame_unwind,
- mips_insn32_frame_base_address,
- mips_insn32_frame_base_address,
- mips_insn32_frame_base_address
-};
+ /* The entry instruction is typically the first instruction in a function,
+ and it stores registers at offsets relative to the value of the old SP
+ (before the prologue). But the value of the sp parameter to this
+ function is the new SP (after the prologue has been executed). So we
+ can't calculate those offsets until we've seen the entire prologue,
+ and can calculate what the old SP must have been. */
+ if (entry_inst != 0)
+ {
+ int areg_count = (entry_inst >> 8) & 7;
+ int sreg_count = (entry_inst >> 6) & 3;
-static const struct frame_base *
-mips_insn32_frame_base_sniffer (struct frame_info *next_frame)
-{
- if (mips_insn32_frame_sniffer (next_frame) != NULL)
- return &mips_insn32_frame_base;
- else
- return NULL;
+ /* The entry instruction always subtracts 32 from the SP. */
+ frame_offset += 32;
+
+ /* Now we can calculate what the SP must have been at the
+ start of the function prologue. */
+ sp += frame_offset;
+
+ /* Check if a0-a3 were saved in the caller's argument save area. */
+ for (reg = 4, offset = 0; reg < areg_count + 4; reg++)
+ {
+ set_reg_offset (this_cache, reg, sp + offset);
+ offset += mips_abi_regsize (current_gdbarch);
+ }
+
+ /* Check if the ra register was pushed on the stack. */
+ offset = -4;
+ if (entry_inst & 0x20)
+ {
+ set_reg_offset (this_cache, RA_REGNUM, sp + offset);
+ offset -= mips_abi_regsize (current_gdbarch);
+ }
+
+ /* Check if the s0 and s1 registers were pushed on the stack. */
+ for (reg = 16; reg < sreg_count + 16; reg++)
+ {
+ set_reg_offset (this_cache, reg, sp + offset);
+ offset -= mips_abi_regsize (current_gdbarch);
+ }
+ }
+
+ if (this_cache != NULL)
+ {
+ this_cache->base =
+ (frame_unwind_register_signed (next_frame, NUM_REGS + 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
+ still needed for now. */
+ this_cache->saved_regs[NUM_REGS + mips_regnum (current_gdbarch)->pc]
+ = this_cache->saved_regs[NUM_REGS + RA_REGNUM];
+ }
+
+ /* If we didn't reach the end of the prologue when scanning the function
+ instructions, then set end_prologue_addr to the address of the
+ instruction immediately after the last one we scanned. */
+ if (end_prologue_addr == 0)
+ end_prologue_addr = cur_pc;
+
+ return end_prologue_addr;
}
-static struct trad_frame_cache *
-mips_stub_frame_cache (struct frame_info *next_frame, void **this_cache)
+/* Heuristic unwinder for 16-bit MIPS instruction set (aka MIPS16).
+ Procedures that use the 32-bit instruction set are handled by the
+ mips_insn32 unwinder. */
+
+static struct mips_frame_cache *
+mips_insn16_frame_cache (struct frame_info *next_frame, void **this_cache)
{
- CORE_ADDR pc;
- CORE_ADDR start_addr;
- CORE_ADDR stack_addr;
- struct trad_frame_cache *this_trad_cache;
+ struct mips_frame_cache *cache;
if ((*this_cache) != NULL)
return (*this_cache);
- this_trad_cache = trad_frame_cache_zalloc (next_frame);
- (*this_cache) = this_trad_cache;
+ cache = FRAME_OBSTACK_ZALLOC (struct mips_frame_cache);
+ (*this_cache) = cache;
+ cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);
- /* The return address is in the link register. */
- trad_frame_set_reg_realreg (this_trad_cache, PC_REGNUM, RA_REGNUM);
+ /* Analyze the function prologue. */
+ {
+ const CORE_ADDR pc = frame_pc_unwind (next_frame);
+ CORE_ADDR start_addr;
- /* Frame ID, since it's a frameless / stackless function, no stack
- space is allocated and SP on entry is the current SP. */
- pc = frame_pc_unwind (next_frame);
- find_pc_partial_function (pc, NULL, &start_addr, NULL);
- stack_addr = frame_unwind_register_signed (next_frame, SP_REGNUM);
- trad_frame_set_id (this_trad_cache, frame_id_build (start_addr, stack_addr));
+ find_pc_partial_function (pc, NULL, &start_addr, NULL);
+ if (start_addr == 0)
+ start_addr = heuristic_proc_start (pc);
+ /* We can't analyze the prologue if we couldn't find the begining
+ of the function. */
+ if (start_addr == 0)
+ return cache;
- /* Assume that the frame's base is the same as the
- stack-pointer. */
- trad_frame_set_this_base (this_trad_cache, stack_addr);
+ mips16_scan_prologue (start_addr, pc, next_frame, *this_cache);
+ }
+
+ /* SP_REGNUM, contains the value and not the address. */
+ trad_frame_set_value (cache->saved_regs, NUM_REGS + MIPS_SP_REGNUM, cache->base);
- return this_trad_cache;
+ return (*this_cache);
}
static void
-mips_stub_frame_this_id (struct frame_info *next_frame, void **this_cache,
- struct frame_id *this_id)
+mips_insn16_frame_this_id (struct frame_info *next_frame, void **this_cache,
+ struct frame_id *this_id)
{
- struct trad_frame_cache *this_trad_cache
- = mips_stub_frame_cache (next_frame, this_cache);
- trad_frame_get_id (this_trad_cache, this_id);
+ struct mips_frame_cache *info = mips_insn16_frame_cache (next_frame,
+ this_cache);
+ (*this_id) = frame_id_build (info->base, frame_func_unwind (next_frame));
}
static void
-mips_stub_frame_prev_register (struct frame_info *next_frame,
+mips_insn16_frame_prev_register (struct frame_info *next_frame,
void **this_cache,
int regnum, int *optimizedp,
enum lval_type *lvalp, CORE_ADDR *addrp,
int *realnump, void *valuep)
{
- struct trad_frame_cache *this_trad_cache
- = mips_stub_frame_cache (next_frame, this_cache);
- trad_frame_get_register (this_trad_cache, next_frame, regnum, optimizedp,
- lvalp, addrp, realnump, valuep);
+ struct mips_frame_cache *info = mips_insn16_frame_cache (next_frame,
+ this_cache);
+ trad_frame_get_prev_register (next_frame, info->saved_regs, regnum,
+ optimizedp, lvalp, addrp, realnump, valuep);
}
-static const struct frame_unwind mips_stub_frame_unwind =
+static const struct frame_unwind mips_insn16_frame_unwind =
{
NORMAL_FRAME,
- mips_stub_frame_this_id,
- mips_stub_frame_prev_register
+ mips_insn16_frame_this_id,
+ mips_insn16_frame_prev_register
};
static const struct frame_unwind *
-mips_stub_frame_sniffer (struct frame_info *next_frame)
+mips_insn16_frame_sniffer (struct frame_info *next_frame)
{
CORE_ADDR pc = frame_pc_unwind (next_frame);
- if (in_plt_section (pc, NULL))
- return &mips_stub_frame_unwind;
- else
- return NULL;
+ if (pc_is_mips16 (pc))
+ return &mips_insn16_frame_unwind;
+ return NULL;
}
static CORE_ADDR
-mips_stub_frame_base_address (struct frame_info *next_frame,
- void **this_cache)
+mips_insn16_frame_base_address (struct frame_info *next_frame,
+ void **this_cache)
{
- struct trad_frame_cache *this_trad_cache
- = mips_stub_frame_cache (next_frame, this_cache);
- return trad_frame_get_this_base (this_trad_cache);
+ struct mips_frame_cache *info = mips_insn16_frame_cache (next_frame,
+ this_cache);
+ return info->base;
}
-static const struct frame_base mips_stub_frame_base =
+static const struct frame_base mips_insn16_frame_base =
{
- &mips_stub_frame_unwind,
- mips_stub_frame_base_address,
- mips_stub_frame_base_address,
- mips_stub_frame_base_address
+ &mips_insn16_frame_unwind,
+ mips_insn16_frame_base_address,
+ mips_insn16_frame_base_address,
+ mips_insn16_frame_base_address
};
static const struct frame_base *
-mips_stub_frame_base_sniffer (struct frame_info *next_frame)
+mips_insn16_frame_base_sniffer (struct frame_info *next_frame)
{
- if (mips_stub_frame_sniffer (next_frame) != NULL)
- return &mips_stub_frame_base;
+ if (mips_insn16_frame_sniffer (next_frame) != NULL)
+ return &mips_insn16_frame_base;
else
return NULL;
}
-static CORE_ADDR
-read_next_frame_reg (struct frame_info *fi, int regno)
+/* Mark all the registers as unset in the saved_regs array
+ of THIS_CACHE. Do nothing if THIS_CACHE is null. */
+
+void
+reset_saved_regs (struct mips_frame_cache *this_cache)
{
- /* Always a pseudo. */
- gdb_assert (regno >= NUM_REGS);
- if (fi == NULL)
- {
- LONGEST val;
- regcache_cooked_read_signed (current_regcache, regno, &val);
- return val;
- }
- else
- return frame_unwind_register_signed (fi, regno);
+ if (this_cache == NULL || this_cache->saved_regs == NULL)
+ return;
+
+ {
+ const int num_regs = NUM_REGS;
+ int i;
+ for (i = 0; i < num_regs; i++)
+ {
+ this_cache->saved_regs[i].addr = -1;
+ }
+ }
}
-/* mips_addr_bits_remove - remove useless address bits */
+/* 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. */
static CORE_ADDR
-mips_addr_bits_remove (CORE_ADDR addr)
+mips32_scan_prologue (CORE_ADDR start_pc, CORE_ADDR limit_pc,
+ struct frame_info *next_frame,
+ struct mips_frame_cache *this_cache)
{
- struct gdbarch_tdep *tdep = gdbarch_tdep (current_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:
+ CORE_ADDR cur_pc;
+ CORE_ADDR frame_addr = 0; /* Value of $r30. Used by gcc for frame-pointer */
+ CORE_ADDR sp;
+ long frame_offset;
+ int frame_reg = MIPS_SP_REGNUM;
- lui $r2, <upper 16 bits>
- ori $r2, <lower 16 bits>
+ CORE_ADDR end_prologue_addr = 0;
+ int seen_sp_adjust = 0;
+ int load_immediate_bytes = 0;
- 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;
+ /* Can be called when there's no process, and hence when there's no
+ NEXT_FRAME. */
+ if (next_frame != NULL)
+ sp = read_next_frame_reg (next_frame, NUM_REGS + MIPS_SP_REGNUM);
else
- return addr;
-}
-
-/* mips_software_single_step() is called just before we want to resume
- the inferior, if we want to single-step it but there is no hardware
- or kernel single-step support (MIPS on GNU/Linux for example). We find
- the target of the coming instruction and breakpoint it.
+ sp = 0;
- single_step is also called just after the inferior stops. If we had
- set up a simulated single-step, we undo our damage. */
+ if (limit_pc > start_pc + 200)
+ limit_pc = start_pc + 200;
-void
-mips_software_single_step (enum target_signal sig, int insert_breakpoints_p)
-{
- static CORE_ADDR next_pc;
- typedef char binsn_quantum[BREAKPOINT_MAX];
- static binsn_quantum break_mem;
- CORE_ADDR pc;
+restart:
- if (insert_breakpoints_p)
+ frame_offset = 0;
+ for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += MIPS_INSTLEN)
{
- pc = read_register (mips_regnum (current_gdbarch)->pc);
- next_pc = mips_next_pc (pc);
+ unsigned long inst, high_word, low_word;
+ int reg;
- target_insert_breakpoint (next_pc, break_mem);
- }
- else
- target_remove_breakpoint (next_pc, break_mem);
-}
+ /* Fetch the instruction. */
+ inst = (unsigned long) mips_fetch_instruction (cur_pc);
-static struct mips_extra_func_info temp_proc_desc;
+ /* Save some code by pre-extracting some useful fields. */
+ high_word = (inst >> 16) & 0xffff;
+ low_word = inst & 0xffff;
+ reg = high_word & 0x1f;
-/* Set a register's saved stack address in temp_saved_regs. If an
- address has already been set for this register, do nothing; this
- way we will only recognize the first save of a given register in a
- function prologue.
+ if (high_word == 0x27bd /* addiu $sp,$sp,-i */
+ || high_word == 0x23bd /* addi $sp,$sp,-i */
+ || high_word == 0x67bd) /* daddiu $sp,$sp,-i */
+ {
+ if (low_word & 0x8000) /* negative stack adjustment? */
+ frame_offset += 0x10000 - low_word;
+ 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;
+ seen_sp_adjust = 1;
+ }
+ else if ((high_word & 0xFFE0) == 0xafa0) /* sw reg,offset($sp) */
+ {
+ set_reg_offset (this_cache, reg, sp + low_word);
+ }
+ else if ((high_word & 0xFFE0) == 0xffa0) /* sd reg,offset($sp) */
+ {
+ /* Irix 6.2 N32 ABI uses sd instructions for saving $gp and $ra. */
+ set_reg_offset (this_cache, reg, sp + low_word);
+ }
+ else if (high_word == 0x27be) /* addiu $30,$sp,size */
+ {
+ /* Old gcc frame, r30 is virtual frame pointer. */
+ if ((long) low_word != frame_offset)
+ frame_addr = sp + low_word;
+ else if (frame_reg == MIPS_SP_REGNUM)
+ {
+ unsigned alloca_adjust;
- For simplicity, save the address in both [0 .. NUM_REGS) and
- [NUM_REGS .. 2*NUM_REGS). Strictly speaking, only the second range
- is used as it is only second range (the ABI instead of ISA
- registers) that comes into play when finding saved registers in a
- frame. */
+ frame_reg = 30;
+ frame_addr = read_next_frame_reg (next_frame, NUM_REGS + 30);
+ alloca_adjust = (unsigned) (frame_addr - (sp + low_word));
+ if (alloca_adjust > 0)
+ {
+ /* FP > SP + frame_size. This may be because of
+ an alloca or somethings similar. Fix sp to
+ "pre-alloca" value, and try again. */
+ sp += alloca_adjust;
+ /* Need to reset the status of all registers. Otherwise,
+ we will hit a guard that prevents the new address
+ for each register to be recomputed during the second
+ pass. */
+ reset_saved_regs (this_cache);
+ goto restart;
+ }
+ }
+ }
+ /* move $30,$sp. With different versions of gas this will be either
+ `addu $30,$sp,$zero' or `or $30,$sp,$zero' or `daddu 30,sp,$0'.
+ Accept any one of these. */
+ else if (inst == 0x03A0F021 || inst == 0x03a0f025 || inst == 0x03a0f02d)
+ {
+ /* New gcc frame, virtual frame pointer is at r30 + frame_size. */
+ if (frame_reg == MIPS_SP_REGNUM)
+ {
+ unsigned alloca_adjust;
-static void
-set_reg_offset (struct mips_frame_cache *this_cache, int regnum,
- CORE_ADDR offset)
-{
- if (this_cache != NULL
- && this_cache->saved_regs[regnum].addr == -1)
- {
- this_cache->saved_regs[regnum + 0 * NUM_REGS].addr = offset;
- this_cache->saved_regs[regnum + 1 * NUM_REGS].addr = offset;
+ frame_reg = 30;
+ frame_addr = read_next_frame_reg (next_frame, NUM_REGS + 30);
+ alloca_adjust = (unsigned) (frame_addr - sp);
+ if (alloca_adjust > 0)
+ {
+ /* FP > SP + frame_size. This may be because of
+ an alloca or somethings similar. Fix sp to
+ "pre-alloca" value, and try again. */
+ sp = frame_addr;
+ /* Need to reset the status of all registers. Otherwise,
+ we will hit a guard that prevents the new address
+ for each register to be recomputed during the second
+ pass. */
+ reset_saved_regs (this_cache);
+ goto restart;
+ }
+ }
+ }
+ else if ((high_word & 0xFFE0) == 0xafc0) /* sw reg,offset($30) */
+ {
+ set_reg_offset (this_cache, reg, frame_addr + low_word);
+ }
+ else if ((high_word & 0xFFE0) == 0xE7A0 /* swc1 freg,n($sp) */
+ || (high_word & 0xF3E0) == 0xA3C0 /* sx reg,n($s8) */
+ || (inst & 0xFF9F07FF) == 0x00800021 /* move reg,$a0-$a3 */
+ || high_word == 0x3c1c /* lui $gp,n */
+ || high_word == 0x279c /* addiu $gp,$gp,n */
+ || inst == 0x0399e021 /* addu $gp,$gp,$t9 */
+ || inst == 0x033ce021 /* addu $gp,$t9,$gp */
+ )
+ {
+ /* These instructions are part of the prologue, but we don't
+ need to do anything special to handle them. */
+ }
+ /* The instructions below load $at or $t0 with an immediate
+ value in preparation for a stack adjustment via
+ subu $sp,$sp,[$at,$t0]. These instructions could also
+ initialize a local variable, so we accept them only before
+ a stack adjustment instruction was seen. */
+ else if (!seen_sp_adjust
+ && (high_word == 0x3c01 /* lui $at,n */
+ || high_word == 0x3c08 /* lui $t0,n */
+ || high_word == 0x3421 /* ori $at,$at,n */
+ || high_word == 0x3508 /* ori $t0,$t0,n */
+ || high_word == 0x3401 /* ori $at,$zero,n */
+ || high_word == 0x3408 /* ori $t0,$zero,n */
+ ))
+ {
+ load_immediate_bytes += MIPS_INSTLEN; /* FIXME!! */
+ }
+ else
+ {
+ /* This instruction is not an instruction typically found
+ in a prologue, so we must have reached the end of the
+ prologue. */
+ /* FIXME: brobecker/2004-10-10: Can't we just break out of this
+ loop now? Why would we need to continue scanning the function
+ instructions? */
+ if (end_prologue_addr == 0)
+ end_prologue_addr = cur_pc;
+ }
}
-}
+ if (this_cache != NULL)
+ {
+ this_cache->base =
+ (frame_unwind_register_signed (next_frame, NUM_REGS + frame_reg)
+ + frame_offset);
+ /* FIXME: brobecker/2004-09-15: We should be able to get rid of
+ this assignment below, eventually. But it's still needed
+ for now. */
+ this_cache->saved_regs[NUM_REGS + mips_regnum (current_gdbarch)->pc]
+ = this_cache->saved_regs[NUM_REGS + RA_REGNUM];
+ }
-/* Test whether the PC points to the return instruction at the
- end of a function. */
+ /* If we didn't reach the end of the prologue when scanning the function
+ instructions, then set end_prologue_addr to the address of the
+ instruction immediately after the last one we scanned. */
+ /* brobecker/2004-10-10: I don't think this would ever happen, but
+ we may as well be careful and do our best if we have a null
+ end_prologue_addr. */
+ if (end_prologue_addr == 0)
+ end_prologue_addr = 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. */
+ if (load_immediate_bytes && !seen_sp_adjust)
+ end_prologue_addr -= load_immediate_bytes;
-static int
-mips_about_to_return (CORE_ADDR pc)
-{
- if (pc_is_mips16 (pc))
- /* This mips16 case isn't necessarily reliable. Sometimes the compiler
- generates a "jr $ra"; other times it generates code to load
- the return address from the stack to an accessible register (such
- as $a3), then a "jr" using that register. This second case
- is almost impossible to distinguish from an indirect jump
- used for switch statements, so we don't even try. */
- return mips_fetch_instruction (pc) == 0xe820; /* jr $ra */
- else
- return mips_fetch_instruction (pc) == 0x3e00008; /* jr $ra */
+ return end_prologue_addr;
}
+/* 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. */
-/* This fencepost looks highly suspicious to me. Removing it also
- seems suspicious as it could affect remote debugging across serial
- lines. */
-
-static CORE_ADDR
-heuristic_proc_start (CORE_ADDR pc)
+static struct mips_frame_cache *
+mips_insn32_frame_cache (struct frame_info *next_frame, void **this_cache)
{
- CORE_ADDR start_pc;
- CORE_ADDR fence;
- int instlen;
- int seen_adjsp = 0;
-
- pc = ADDR_BITS_REMOVE (pc);
- start_pc = pc;
- fence = start_pc - heuristic_fence_post;
- if (start_pc == 0)
- return 0;
-
- if (heuristic_fence_post == UINT_MAX || fence < VM_MIN_ADDRESS)
- fence = VM_MIN_ADDRESS;
-
- instlen = pc_is_mips16 (pc) ? MIPS16_INSTLEN : MIPS_INSTLEN;
+ struct mips_frame_cache *cache;
- /* search back for previous return */
- for (start_pc -= instlen;; start_pc -= instlen)
- if (start_pc < fence)
- {
- /* It's not clear to me why we reach this point when
- stop_soon, but with this test, at least we
- don't print out warnings for every child forked (eg, on
- decstation). 22apr93 rich@cygnus.com. */
- if (stop_soon == NO_STOP_QUIETLY)
- {
- static int blurb_printed = 0;
+ if ((*this_cache) != NULL)
+ return (*this_cache);
- warning ("GDB can't find the start of the function at 0x%s.",
- paddr_nz (pc));
+ cache = FRAME_OBSTACK_ZALLOC (struct mips_frame_cache);
+ (*this_cache) = cache;
+ cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);
- if (!blurb_printed)
- {
- /* This actually happens frequently in embedded
- development, when you first connect to a board
- and your stack pointer and pc are nowhere in
- particular. This message needs to give people
- in that situation enough information to
- determine that it's no big deal. */
- printf_filtered ("\n\
- GDB is unable to find the start of the function at 0x%s\n\
-and thus can't determine the size of that function's stack frame.\n\
-This means that GDB may be unable to access that stack frame, or\n\
-the frames below it.\n\
- This problem is most likely caused by an invalid program counter or\n\
-stack pointer.\n\
- However, if you think GDB should simply search farther back\n\
-from 0x%s for code which looks like the beginning of a\n\
-function, you can increase the range of the search using the `set\n\
-heuristic-fence-post' command.\n", paddr_nz (pc), paddr_nz (pc));
- blurb_printed = 1;
- }
- }
+ /* Analyze the function prologue. */
+ {
+ const CORE_ADDR pc = frame_pc_unwind (next_frame);
+ CORE_ADDR start_addr;
- return 0;
- }
- else if (pc_is_mips16 (start_pc))
- {
- unsigned short inst;
+ find_pc_partial_function (pc, NULL, &start_addr, NULL);
+ if (start_addr == 0)
+ start_addr = heuristic_proc_start (pc);
+ /* We can't analyze the prologue if we couldn't find the begining
+ of the function. */
+ if (start_addr == 0)
+ return cache;
- /* On MIPS16, any one of the following is likely to be the
- start of a function:
- entry
- addiu sp,-n
- daddiu sp,-n
- extend -n followed by 'addiu sp,+n' or 'daddiu sp,+n' */
- inst = mips_fetch_instruction (start_pc);
- if (((inst & 0xf81f) == 0xe809 && (inst & 0x700) != 0x700) /* entry */
- || (inst & 0xff80) == 0x6380 /* addiu sp,-n */
- || (inst & 0xff80) == 0xfb80 /* daddiu sp,-n */
- || ((inst & 0xf810) == 0xf010 && seen_adjsp)) /* extend -n */
- break;
- else if ((inst & 0xff00) == 0x6300 /* addiu sp */
- || (inst & 0xff00) == 0xfb00) /* daddiu sp */
- seen_adjsp = 1;
- else
- seen_adjsp = 0;
- }
- else if (mips_about_to_return (start_pc))
- {
- start_pc += 2 * MIPS_INSTLEN; /* skip return, and its delay slot */
- break;
- }
+ mips32_scan_prologue (start_addr, pc, next_frame, *this_cache);
+ }
+
+ /* SP_REGNUM, contains the value and not the address. */
+ trad_frame_set_value (cache->saved_regs, NUM_REGS + MIPS_SP_REGNUM, cache->base);
- return start_pc;
+ return (*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
- for mips16_scan_prologue. */
-
-static int
-mips16_get_imm (unsigned short prev_inst, /* previous instruction */
- unsigned short inst, /* current instruction */
- int nbits, /* number of bits in imm field */
- int scale, /* scale factor to be applied to imm */
- int is_signed) /* is the imm field signed? */
+static void
+mips_insn32_frame_this_id (struct frame_info *next_frame, void **this_cache,
+ struct frame_id *this_id)
{
- int offset;
-
- if ((prev_inst & 0xf800) == 0xf000) /* prev instruction was EXTEND? */
- {
- offset = ((prev_inst & 0x1f) << 11) | (prev_inst & 0x7e0);
- if (offset & 0x8000) /* check for negative extend */
- offset = 0 - (0x10000 - (offset & 0xffff));
- return offset | (inst & 0x1f);
- }
- else
- {
- int max_imm = 1 << nbits;
- int mask = max_imm - 1;
- int sign_bit = max_imm >> 1;
+ struct mips_frame_cache *info = mips_insn32_frame_cache (next_frame,
+ this_cache);
+ (*this_id) = frame_id_build (info->base, frame_func_unwind (next_frame));
+}
- offset = inst & mask;
- if (is_signed && (offset & sign_bit))
- offset = 0 - (max_imm - offset);
- return offset * scale;
- }
+static void
+mips_insn32_frame_prev_register (struct frame_info *next_frame,
+ void **this_cache,
+ int regnum, int *optimizedp,
+ enum lval_type *lvalp, CORE_ADDR *addrp,
+ int *realnump, void *valuep)
+{
+ struct mips_frame_cache *info = mips_insn32_frame_cache (next_frame,
+ this_cache);
+ trad_frame_get_prev_register (next_frame, info->saved_regs, regnum,
+ optimizedp, lvalp, addrp, realnump, valuep);
}
+static const struct frame_unwind mips_insn32_frame_unwind =
+{
+ NORMAL_FRAME,
+ mips_insn32_frame_this_id,
+ mips_insn32_frame_prev_register
+};
-/* 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. */
+static const struct frame_unwind *
+mips_insn32_frame_sniffer (struct frame_info *next_frame)
+{
+ CORE_ADDR pc = frame_pc_unwind (next_frame);
+ if (! pc_is_mips16 (pc))
+ return &mips_insn32_frame_unwind;
+ return NULL;
+}
static CORE_ADDR
-mips16_scan_prologue (CORE_ADDR start_pc, CORE_ADDR limit_pc,
- struct frame_info *next_frame,
- struct mips_frame_cache *this_cache)
+mips_insn32_frame_base_address (struct frame_info *next_frame,
+ void **this_cache)
{
- 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. */
- int frame_reg = MIPS_SP_REGNUM;
- unsigned short prev_inst = 0; /* saved copy of previous instruction */
- unsigned inst = 0; /* current instruction */
- unsigned entry_inst = 0; /* the entry instruction */
- int reg, offset;
+ struct mips_frame_cache *info = mips_insn32_frame_cache (next_frame,
+ this_cache);
+ return info->base;
+}
- int extend_bytes = 0;
- int prev_extend_bytes;
- CORE_ADDR end_prologue_addr = 0;
+static const struct frame_base mips_insn32_frame_base =
+{
+ &mips_insn32_frame_unwind,
+ mips_insn32_frame_base_address,
+ mips_insn32_frame_base_address,
+ mips_insn32_frame_base_address
+};
- /* Can be called when there's no process, and hence when there's no
- NEXT_FRAME. */
- if (next_frame != NULL)
- sp = read_next_frame_reg (next_frame, NUM_REGS + MIPS_SP_REGNUM);
+static const struct frame_base *
+mips_insn32_frame_base_sniffer (struct frame_info *next_frame)
+{
+ if (mips_insn32_frame_sniffer (next_frame) != NULL)
+ return &mips_insn32_frame_base;
else
- sp = 0;
-
- if (limit_pc > start_pc + 200)
- limit_pc = start_pc + 200;
+ return NULL;
+}
- for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += MIPS16_INSTLEN)
- {
- /* Save the previous instruction. If it's an EXTEND, we'll extract
- the immediate offset extension from it in mips16_get_imm. */
- prev_inst = inst;
+static struct trad_frame_cache *
+mips_stub_frame_cache (struct frame_info *next_frame, void **this_cache)
+{
+ CORE_ADDR pc;
+ CORE_ADDR start_addr;
+ CORE_ADDR stack_addr;
+ struct trad_frame_cache *this_trad_cache;
- /* Fetch and decode the instruction. */
- inst = (unsigned short) mips_fetch_instruction (cur_pc);
+ if ((*this_cache) != NULL)
+ return (*this_cache);
+ this_trad_cache = trad_frame_cache_zalloc (next_frame);
+ (*this_cache) = this_trad_cache;
- /* Normally we ignore extend instructions. However, if it is
- not followed by a valid prologue instruction, then this
- instruction is not part of the prologue either. We must
- remember in this case to adjust the end_prologue_addr back
- over the extend. */
- if ((inst & 0xf800) == 0xf000) /* extend */
- {
- extend_bytes = MIPS16_INSTLEN;
- continue;
- }
+ /* The return address is in the link register. */
+ trad_frame_set_reg_realreg (this_trad_cache, PC_REGNUM, RA_REGNUM);
- prev_extend_bytes = extend_bytes;
- extend_bytes = 0;
+ /* Frame ID, since it's a frameless / stackless function, no stack
+ space is allocated and SP on entry is the current SP. */
+ pc = frame_pc_unwind (next_frame);
+ find_pc_partial_function (pc, NULL, &start_addr, NULL);
+ stack_addr = frame_unwind_register_signed (next_frame, SP_REGNUM);
+ trad_frame_set_id (this_trad_cache, frame_id_build (start_addr, stack_addr));
- if ((inst & 0xff00) == 0x6300 /* addiu sp */
- || (inst & 0xff00) == 0xfb00) /* daddiu sp */
- {
- offset = mips16_get_imm (prev_inst, inst, 8, 8, 1);
- 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;
- }
- else if ((inst & 0xf800) == 0xd000) /* sw reg,n($sp) */
- {
- offset = mips16_get_imm (prev_inst, inst, 8, 4, 0);
- reg = mips16_to_32_reg[(inst & 0x700) >> 8];
- set_reg_offset (this_cache, reg, sp + offset);
- }
- else if ((inst & 0xff00) == 0xf900) /* sd reg,n($sp) */
- {
- offset = mips16_get_imm (prev_inst, inst, 5, 8, 0);
- reg = mips16_to_32_reg[(inst & 0xe0) >> 5];
- set_reg_offset (this_cache, reg, sp + offset);
- }
- else if ((inst & 0xff00) == 0x6200) /* sw $ra,n($sp) */
- {
- offset = mips16_get_imm (prev_inst, inst, 8, 4, 0);
- set_reg_offset (this_cache, RA_REGNUM, sp + offset);
- }
- else if ((inst & 0xff00) == 0xfa00) /* sd $ra,n($sp) */
- {
- offset = mips16_get_imm (prev_inst, inst, 8, 8, 0);
- set_reg_offset (this_cache, RA_REGNUM, sp + offset);
- }
- else if (inst == 0x673d) /* move $s1, $sp */
- {
- frame_addr = sp;
- frame_reg = 17;
- }
- else if ((inst & 0xff00) == 0x0100) /* addiu $s1,sp,n */
- {
- offset = mips16_get_imm (prev_inst, inst, 8, 4, 0);
- frame_addr = sp + offset;
- frame_reg = 17;
- frame_adjust = offset;
- }
- else if ((inst & 0xFF00) == 0xd900) /* sw reg,offset($s1) */
- {
- offset = mips16_get_imm (prev_inst, inst, 5, 4, 0);
- reg = mips16_to_32_reg[(inst & 0xe0) >> 5];
- set_reg_offset (this_cache, reg, frame_addr + offset);
- }
- else if ((inst & 0xFF00) == 0x7900) /* sd reg,offset($s1) */
- {
- offset = mips16_get_imm (prev_inst, inst, 5, 8, 0);
- reg = mips16_to_32_reg[(inst & 0xe0) >> 5];
- set_reg_offset (this_cache, reg, frame_addr + offset);
- }
- else if ((inst & 0xf81f) == 0xe809
- && (inst & 0x700) != 0x700) /* entry */
- entry_inst = inst; /* save for later processing */
- else if ((inst & 0xf800) == 0x1800) /* jal(x) */
- cur_pc += MIPS16_INSTLEN; /* 32-bit instruction */
- else if ((inst & 0xff1c) == 0x6704) /* move reg,$a0-$a3 */
- {
- /* This instruction is part of the prologue, but we don't
- need to do anything special to handle it. */
- }
- else
- {
- /* This instruction is not an instruction typically found
- in a prologue, so we must have reached the end of the
- prologue. */
- if (end_prologue_addr == 0)
- end_prologue_addr = cur_pc - prev_extend_bytes;
- }
- }
+ /* Assume that the frame's base is the same as the
+ stack-pointer. */
+ trad_frame_set_this_base (this_trad_cache, stack_addr);
- /* The entry instruction is typically the first instruction in a function,
- and it stores registers at offsets relative to the value of the old SP
- (before the prologue). But the value of the sp parameter to this
- function is the new SP (after the prologue has been executed). So we
- can't calculate those offsets until we've seen the entire prologue,
- and can calculate what the old SP must have been. */
- if (entry_inst != 0)
- {
- int areg_count = (entry_inst >> 8) & 7;
- int sreg_count = (entry_inst >> 6) & 3;
+ return this_trad_cache;
+}
- /* The entry instruction always subtracts 32 from the SP. */
- frame_offset += 32;
+static void
+mips_stub_frame_this_id (struct frame_info *next_frame, void **this_cache,
+ struct frame_id *this_id)
+{
+ struct trad_frame_cache *this_trad_cache
+ = mips_stub_frame_cache (next_frame, this_cache);
+ trad_frame_get_id (this_trad_cache, this_id);
+}
- /* Now we can calculate what the SP must have been at the
- start of the function prologue. */
- sp += frame_offset;
+static void
+mips_stub_frame_prev_register (struct frame_info *next_frame,
+ void **this_cache,
+ int regnum, int *optimizedp,
+ enum lval_type *lvalp, CORE_ADDR *addrp,
+ int *realnump, void *valuep)
+{
+ struct trad_frame_cache *this_trad_cache
+ = mips_stub_frame_cache (next_frame, this_cache);
+ trad_frame_get_register (this_trad_cache, next_frame, regnum, optimizedp,
+ lvalp, addrp, realnump, valuep);
+}
- /* Check if a0-a3 were saved in the caller's argument save area. */
- for (reg = 4, offset = 0; reg < areg_count + 4; reg++)
- {
- set_reg_offset (this_cache, reg, sp + offset);
- offset += mips_abi_regsize (current_gdbarch);
- }
+static const struct frame_unwind mips_stub_frame_unwind =
+{
+ NORMAL_FRAME,
+ mips_stub_frame_this_id,
+ mips_stub_frame_prev_register
+};
- /* Check if the ra register was pushed on the stack. */
- offset = -4;
- if (entry_inst & 0x20)
- {
- set_reg_offset (this_cache, RA_REGNUM, sp + offset);
- offset -= mips_abi_regsize (current_gdbarch);
- }
+static const struct frame_unwind *
+mips_stub_frame_sniffer (struct frame_info *next_frame)
+{
+ CORE_ADDR pc = frame_pc_unwind (next_frame);
+ if (in_plt_section (pc, NULL))
+ return &mips_stub_frame_unwind;
+ else
+ return NULL;
+}
- /* Check if the s0 and s1 registers were pushed on the stack. */
- for (reg = 16; reg < sreg_count + 16; reg++)
- {
- set_reg_offset (this_cache, reg, sp + offset);
- offset -= mips_abi_regsize (current_gdbarch);
- }
- }
+static CORE_ADDR
+mips_stub_frame_base_address (struct frame_info *next_frame,
+ void **this_cache)
+{
+ struct trad_frame_cache *this_trad_cache
+ = mips_stub_frame_cache (next_frame, this_cache);
+ return trad_frame_get_this_base (this_trad_cache);
+}
- if (this_cache != NULL)
+static const struct frame_base mips_stub_frame_base =
+{
+ &mips_stub_frame_unwind,
+ mips_stub_frame_base_address,
+ mips_stub_frame_base_address,
+ mips_stub_frame_base_address
+};
+
+static const struct frame_base *
+mips_stub_frame_base_sniffer (struct frame_info *next_frame)
+{
+ if (mips_stub_frame_sniffer (next_frame) != NULL)
+ return &mips_stub_frame_base;
+ else
+ return NULL;
+}
+
+static CORE_ADDR
+read_next_frame_reg (struct frame_info *fi, int regno)
+{
+ /* Always a pseudo. */
+ gdb_assert (regno >= NUM_REGS);
+ if (fi == NULL)
{
- this_cache->base =
- (frame_unwind_register_signed (next_frame, NUM_REGS + 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
- still needed for now. */
- this_cache->saved_regs[NUM_REGS + mips_regnum (current_gdbarch)->pc]
- = this_cache->saved_regs[NUM_REGS + RA_REGNUM];
+ LONGEST val;
+ regcache_cooked_read_signed (current_regcache, regno, &val);
+ return val;
}
+ else
+ return frame_unwind_register_signed (fi, regno);
- /* If we didn't reach the end of the prologue when scanning the function
- instructions, then set end_prologue_addr to the address of the
- instruction immediately after the last one we scanned. */
- if (end_prologue_addr == 0)
- end_prologue_addr = cur_pc;
-
- return end_prologue_addr;
}
-/* Mark all the registers as unset in the saved_regs array
- of THIS_CACHE. Do nothing if THIS_CACHE is null. */
+/* mips_addr_bits_remove - remove useless address bits */
-void
-reset_saved_regs (struct mips_frame_cache *this_cache)
+static CORE_ADDR
+mips_addr_bits_remove (CORE_ADDR addr)
{
- if (this_cache == NULL || this_cache->saved_regs == NULL)
- return;
+ struct gdbarch_tdep *tdep = gdbarch_tdep (current_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:
- {
- const int num_regs = NUM_REGS;
- int i;
+ lui $r2, <upper 16 bits>
+ ori $r2, <lower 16 bits>
- for (i = 0; i < num_regs; i++)
- {
- this_cache->saved_regs[i].addr = -1;
- }
- }
+ 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;
}
-/* 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. */
+/* mips_software_single_step() is called just before we want to resume
+ the inferior, if we want to single-step it but there is no hardware
+ or kernel single-step support (MIPS on GNU/Linux for example). We find
+ the target of the coming instruction and breakpoint it.
-static CORE_ADDR
-mips32_scan_prologue (CORE_ADDR start_pc, CORE_ADDR limit_pc,
- struct frame_info *next_frame,
- struct mips_frame_cache *this_cache)
+ single_step is also called just after the inferior stops. If we had
+ set up a simulated single-step, we undo our damage. */
+
+void
+mips_software_single_step (enum target_signal sig, int insert_breakpoints_p)
{
- CORE_ADDR cur_pc;
- CORE_ADDR frame_addr = 0; /* Value of $r30. Used by gcc for frame-pointer */
- CORE_ADDR sp;
- long frame_offset;
- int frame_reg = MIPS_SP_REGNUM;
+ static CORE_ADDR next_pc;
+ typedef char binsn_quantum[BREAKPOINT_MAX];
+ static binsn_quantum break_mem;
+ CORE_ADDR pc;
- CORE_ADDR end_prologue_addr = 0;
- int seen_sp_adjust = 0;
- int load_immediate_bytes = 0;
+ if (insert_breakpoints_p)
+ {
+ pc = read_register (mips_regnum (current_gdbarch)->pc);
+ next_pc = mips_next_pc (pc);
- /* Can be called when there's no process, and hence when there's no
- NEXT_FRAME. */
- if (next_frame != NULL)
- sp = read_next_frame_reg (next_frame, NUM_REGS + MIPS_SP_REGNUM);
+ target_insert_breakpoint (next_pc, break_mem);
+ }
else
- sp = 0;
+ target_remove_breakpoint (next_pc, break_mem);
+}
- if (limit_pc > start_pc + 200)
- limit_pc = start_pc + 200;
+static struct mips_extra_func_info temp_proc_desc;
-restart:
+/* Test whether the PC points to the return instruction at the
+ end of a function. */
- frame_offset = 0;
- for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += MIPS_INSTLEN)
- {
- unsigned long inst, high_word, low_word;
- int reg;
+static int
+mips_about_to_return (CORE_ADDR pc)
+{
+ if (pc_is_mips16 (pc))
+ /* This mips16 case isn't necessarily reliable. Sometimes the compiler
+ generates a "jr $ra"; other times it generates code to load
+ the return address from the stack to an accessible register (such
+ as $a3), then a "jr" using that register. This second case
+ is almost impossible to distinguish from an indirect jump
+ used for switch statements, so we don't even try. */
+ return mips_fetch_instruction (pc) == 0xe820; /* jr $ra */
+ else
+ return mips_fetch_instruction (pc) == 0x3e00008; /* jr $ra */
+}
- /* Fetch the instruction. */
- inst = (unsigned long) mips_fetch_instruction (cur_pc);
- /* Save some code by pre-extracting some useful fields. */
- high_word = (inst >> 16) & 0xffff;
- low_word = inst & 0xffff;
- reg = high_word & 0x1f;
+/* This fencepost looks highly suspicious to me. Removing it also
+ seems suspicious as it could affect remote debugging across serial
+ lines. */
- if (high_word == 0x27bd /* addiu $sp,$sp,-i */
- || high_word == 0x23bd /* addi $sp,$sp,-i */
- || high_word == 0x67bd) /* daddiu $sp,$sp,-i */
- {
- if (low_word & 0x8000) /* negative stack adjustment? */
- frame_offset += 0x10000 - low_word;
- 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;
- seen_sp_adjust = 1;
- }
- else if ((high_word & 0xFFE0) == 0xafa0) /* sw reg,offset($sp) */
- {
- set_reg_offset (this_cache, reg, sp + low_word);
- }
- else if ((high_word & 0xFFE0) == 0xffa0) /* sd reg,offset($sp) */
- {
- /* Irix 6.2 N32 ABI uses sd instructions for saving $gp and $ra. */
- set_reg_offset (this_cache, reg, sp + low_word);
- }
- else if (high_word == 0x27be) /* addiu $30,$sp,size */
- {
- /* Old gcc frame, r30 is virtual frame pointer. */
- if ((long) low_word != frame_offset)
- frame_addr = sp + low_word;
- else if (frame_reg == MIPS_SP_REGNUM)
- {
- unsigned alloca_adjust;
+static CORE_ADDR
+heuristic_proc_start (CORE_ADDR pc)
+{
+ CORE_ADDR start_pc;
+ CORE_ADDR fence;
+ int instlen;
+ int seen_adjsp = 0;
- frame_reg = 30;
- frame_addr = read_next_frame_reg (next_frame, NUM_REGS + 30);
- alloca_adjust = (unsigned) (frame_addr - (sp + low_word));
- if (alloca_adjust > 0)
- {
- /* FP > SP + frame_size. This may be because of
- an alloca or somethings similar. Fix sp to
- "pre-alloca" value, and try again. */
- sp += alloca_adjust;
- /* Need to reset the status of all registers. Otherwise,
- we will hit a guard that prevents the new address
- for each register to be recomputed during the second
- pass. */
- reset_saved_regs (this_cache);
- goto restart;
- }
- }
- }
- /* move $30,$sp. With different versions of gas this will be either
- `addu $30,$sp,$zero' or `or $30,$sp,$zero' or `daddu 30,sp,$0'.
- Accept any one of these. */
- else if (inst == 0x03A0F021 || inst == 0x03a0f025 || inst == 0x03a0f02d)
- {
- /* New gcc frame, virtual frame pointer is at r30 + frame_size. */
- if (frame_reg == MIPS_SP_REGNUM)
- {
- unsigned alloca_adjust;
+ pc = ADDR_BITS_REMOVE (pc);
+ start_pc = pc;
+ fence = start_pc - heuristic_fence_post;
+ if (start_pc == 0)
+ return 0;
- frame_reg = 30;
- frame_addr = read_next_frame_reg (next_frame, NUM_REGS + 30);
- alloca_adjust = (unsigned) (frame_addr - sp);
- if (alloca_adjust > 0)
- {
- /* FP > SP + frame_size. This may be because of
- an alloca or somethings similar. Fix sp to
- "pre-alloca" value, and try again. */
- sp = frame_addr;
- /* Need to reset the status of all registers. Otherwise,
- we will hit a guard that prevents the new address
- for each register to be recomputed during the second
- pass. */
- reset_saved_regs (this_cache);
- goto restart;
- }
- }
- }
- else if ((high_word & 0xFFE0) == 0xafc0) /* sw reg,offset($30) */
- {
- set_reg_offset (this_cache, reg, frame_addr + low_word);
- }
- else if ((high_word & 0xFFE0) == 0xE7A0 /* swc1 freg,n($sp) */
- || (high_word & 0xF3E0) == 0xA3C0 /* sx reg,n($s8) */
- || (inst & 0xFF9F07FF) == 0x00800021 /* move reg,$a0-$a3 */
- || high_word == 0x3c1c /* lui $gp,n */
- || high_word == 0x279c /* addiu $gp,$gp,n */
- || inst == 0x0399e021 /* addu $gp,$gp,$t9 */
- || inst == 0x033ce021 /* addu $gp,$t9,$gp */
- )
- {
- /* These instructions are part of the prologue, but we don't
- need to do anything special to handle them. */
- }
- /* The instructions below load $at or $t0 with an immediate
- value in preparation for a stack adjustment via
- subu $sp,$sp,[$at,$t0]. These instructions could also
- initialize a local variable, so we accept them only before
- a stack adjustment instruction was seen. */
- else if (!seen_sp_adjust
- && (high_word == 0x3c01 /* lui $at,n */
- || high_word == 0x3c08 /* lui $t0,n */
- || high_word == 0x3421 /* ori $at,$at,n */
- || high_word == 0x3508 /* ori $t0,$t0,n */
- || high_word == 0x3401 /* ori $at,$zero,n */
- || high_word == 0x3408 /* ori $t0,$zero,n */
- ))
- {
- load_immediate_bytes += MIPS_INSTLEN; /* FIXME!! */
- }
- else
- {
- /* This instruction is not an instruction typically found
- in a prologue, so we must have reached the end of the
- prologue. */
- /* FIXME: brobecker/2004-10-10: Can't we just break out of this
- loop now? Why would we need to continue scanning the function
- instructions? */
- if (end_prologue_addr == 0)
- end_prologue_addr = cur_pc;
- }
- }
+ if (heuristic_fence_post == UINT_MAX || fence < VM_MIN_ADDRESS)
+ fence = VM_MIN_ADDRESS;
- if (this_cache != NULL)
- {
- this_cache->base =
- (frame_unwind_register_signed (next_frame, NUM_REGS + frame_reg)
- + frame_offset);
- /* FIXME: brobecker/2004-09-15: We should be able to get rid of
- this assignment below, eventually. But it's still needed
- for now. */
- this_cache->saved_regs[NUM_REGS + mips_regnum (current_gdbarch)->pc]
- = this_cache->saved_regs[NUM_REGS + RA_REGNUM];
- }
+ instlen = pc_is_mips16 (pc) ? MIPS16_INSTLEN : MIPS_INSTLEN;
- /* If we didn't reach the end of the prologue when scanning the function
- instructions, then set end_prologue_addr to the address of the
- instruction immediately after the last one we scanned. */
- /* brobecker/2004-10-10: I don't think this would ever happen, but
- we may as well be careful and do our best if we have a null
- end_prologue_addr. */
- if (end_prologue_addr == 0)
- end_prologue_addr = 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. */
- if (load_immediate_bytes && !seen_sp_adjust)
- end_prologue_addr -= load_immediate_bytes;
+ /* search back for previous return */
+ for (start_pc -= instlen;; start_pc -= instlen)
+ if (start_pc < fence)
+ {
+ /* It's not clear to me why we reach this point when
+ stop_soon, but with this test, at least we
+ don't print out warnings for every child forked (eg, on
+ decstation). 22apr93 rich@cygnus.com. */
+ if (stop_soon == NO_STOP_QUIETLY)
+ {
+ static int blurb_printed = 0;
- return end_prologue_addr;
+ warning ("GDB can't find the start of the function at 0x%s.",
+ paddr_nz (pc));
+
+ if (!blurb_printed)
+ {
+ /* This actually happens frequently in embedded
+ development, when you first connect to a board
+ and your stack pointer and pc are nowhere in
+ particular. This message needs to give people
+ in that situation enough information to
+ determine that it's no big deal. */
+ printf_filtered ("\n\
+ GDB is unable to find the start of the function at 0x%s\n\
+and thus can't determine the size of that function's stack frame.\n\
+This means that GDB may be unable to access that stack frame, or\n\
+the frames below it.\n\
+ This problem is most likely caused by an invalid program counter or\n\
+stack pointer.\n\
+ However, if you think GDB should simply search farther back\n\
+from 0x%s for code which looks like the beginning of a\n\
+function, you can increase the range of the search using the `set\n\
+heuristic-fence-post' command.\n", paddr_nz (pc), paddr_nz (pc));
+ blurb_printed = 1;
+ }
+ }
+
+ return 0;
+ }
+ else if (pc_is_mips16 (start_pc))
+ {
+ unsigned short inst;
+
+ /* On MIPS16, any one of the following is likely to be the
+ start of a function:
+ entry
+ addiu sp,-n
+ daddiu sp,-n
+ extend -n followed by 'addiu sp,+n' or 'daddiu sp,+n' */
+ inst = mips_fetch_instruction (start_pc);
+ if (((inst & 0xf81f) == 0xe809 && (inst & 0x700) != 0x700) /* entry */
+ || (inst & 0xff80) == 0x6380 /* addiu sp,-n */
+ || (inst & 0xff80) == 0xfb80 /* daddiu sp,-n */
+ || ((inst & 0xf810) == 0xf010 && seen_adjsp)) /* extend -n */
+ break;
+ else if ((inst & 0xff00) == 0x6300 /* addiu sp */
+ || (inst & 0xff00) == 0xfb00) /* daddiu sp */
+ seen_adjsp = 1;
+ else
+ seen_adjsp = 0;
+ }
+ else if (mips_about_to_return (start_pc))
+ {
+ start_pc += 2 * MIPS_INSTLEN; /* skip return, and its delay slot */
+ break;
+ }
+
+ return start_pc;
}
static mips_extra_func_info_t
^ permalink raw reply [flat|nested] 2+ messages in thread