Re: [patch 1/3] Displaced stepping for 16-bit Thumb instructions

[Yao Qi <yao@codesourcery.com>]

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Patch 1 is about refactoring, without any effect on functionality.

-- 
Yao (齐尧)

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2010-12-25  Yao Qi  <yao@codesourcery.com>

	* gdb/arm-tdep.c (arm_displaced_step_copy_insn): Move code to ...
	(arm_process_displaced_insn): .. here. Remove parameter INSN.
	(thumb_process_displaced_insn): New.
	* gdb/arm-linux-tdep.c (arm_linux_displaced_step_copy_insn): Update
	call to arm_process_displaced_insn.
	* gdb/arm-tdep.h : Update declaration of arm_process_displaced_insn.

diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c
index 4758ded..06f386a 100644
--- a/gdb/arm-linux-tdep.c
+++ b/gdb/arm-linux-tdep.c
@@ -913,18 +913,10 @@ arm_linux_displaced_step_copy_insn (struct gdbarch *gdbarch,
     }
   else
     {
-      enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-      uint32_t insn = read_memory_unsigned_integer (from, 4, byte_order);
-
-      if (debug_displaced)
-	fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx "
-			    "at %.8lx\n", (unsigned long) insn,
-			    (unsigned long) from);
-
       /* Override the default handling of SVC instructions.  */
       dsc->u.svc.copy_svc_os = arm_linux_copy_svc;
 
-      arm_process_displaced_insn (gdbarch, insn, from, to, regs, dsc);
+      arm_process_displaced_insn (gdbarch, from, to, regs, dsc);
     }
 
   arm_displaced_init_closure (gdbarch, from, to, dsc);
diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index d4013c6..64aa500 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -5837,16 +5837,22 @@ decode_svc_copro (struct gdbarch *gdbarch, uint32_t insn, CORE_ADDR to,
   else
     return copy_undef (gdbarch, insn, dsc);  /* Possibly unreachable.  */
 }
+static void
+thumb_process_displaced_insn (struct gdbarch *gdbarch, CORE_ADDR from,
+			      CORE_ADDR to, struct regcache *regs,
+			      struct displaced_step_closure *dsc)
+{
+  error (_("Displaced stepping is only supported in ARM mode"));
+}
 
 void
-arm_process_displaced_insn (struct gdbarch *gdbarch, uint32_t insn,
-			    CORE_ADDR from, CORE_ADDR to, struct regcache *regs,
+arm_process_displaced_insn (struct gdbarch *gdbarch, CORE_ADDR from,
+			    CORE_ADDR to, struct regcache *regs,
 			    struct displaced_step_closure *dsc)
 {
   int err = 0;
-
-  if (!displaced_in_arm_mode (regs))
-    error (_("Displaced stepping is only supported in ARM mode"));
+  enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
+  uint32_t insn;
 
   /* Most displaced instructions use a 1-instruction scratch space, so set this
      here and override below if/when necessary.  */
@@ -5856,6 +5862,15 @@ arm_process_displaced_insn (struct gdbarch *gdbarch, uint32_t insn,
   dsc->cleanup = NULL;
   dsc->wrote_to_pc = 0;
 
+  if (!displaced_in_arm_mode (regs))
+    return thumb_process_displaced_insn (gdbarch, from, to, regs, dsc);
+
+  insn = read_memory_unsigned_integer (from, 4, byte_order_for_code);
+  if (debug_displaced)
+    fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx "
+			"at %.8lx\n", (unsigned long) insn,
+			(unsigned long) from);
+
   if ((insn & 0xf0000000) == 0xf0000000)
     err = decode_unconditional (gdbarch, insn, regs, dsc);
   else switch (((insn & 0x10) >> 4) | ((insn & 0xe000000) >> 24))
@@ -5926,15 +5941,7 @@ arm_displaced_step_copy_insn (struct gdbarch *gdbarch,
 {
   struct displaced_step_closure *dsc
     = xmalloc (sizeof (struct displaced_step_closure));
-  enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch);
-  uint32_t insn = read_memory_unsigned_integer (from, 4, byte_order_for_code);
-
-  if (debug_displaced)
-    fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx "
-			"at %.8lx\n", (unsigned long) insn,
-			(unsigned long) from);
-
-  arm_process_displaced_insn (gdbarch, insn, from, to, regs, dsc);
+  arm_process_displaced_insn (gdbarch, from, to, regs, dsc);
   arm_displaced_init_closure (gdbarch, from, to, dsc);
 
   return dsc;
diff --git a/gdb/arm-tdep.h b/gdb/arm-tdep.h
index 61cdb5d..cfb85ff 100644
--- a/gdb/arm-tdep.h
+++ b/gdb/arm-tdep.h
@@ -284,9 +284,8 @@ enum pc_write_style
 };
 
 extern void
-  arm_process_displaced_insn (struct gdbarch *gdbarch, uint32_t insn,
-			      CORE_ADDR from, CORE_ADDR to,
-			      struct regcache *regs,
+  arm_process_displaced_insn (struct gdbarch *gdbarch, CORE_ADDR from,
+			      CORE_ADDR to, struct regcache *regs,
 			      struct displaced_step_closure *dsc);
 extern void
   arm_displaced_init_closure (struct gdbarch *gdbarch, CORE_ADDR from,