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Restrict matching add/sub sp, #imm

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Currently, GDB matches both add/sub sp, #imm in prologue and epilogue,
which is not very precise.  On the instruction level, the immediate
number in both instruction can't be negative, so 'sub sp, #imm' only
appears in prologue while 'add sp, #imm' only appears in epilogue.
Note that on assembly level, we can write 'add sp, -8', but gas will
translate to 'sub sp, 8' instruction.

This patch is to only match 'sub sp, #imm' in prologue and match
'add sp, #immm' in epilogue.  It paves the way for the following
patch.

gdb:

2014-07-11  Yao Qi  <yao@codesourcery.com>

	* arm-tdep.c (thumb_analyze_prologue): Don't match instruction
	'add sp, #imm'.
	(thumb_in_function_epilogue_p): Don't match 'sub sp, #imm'.
This commit is contained in:
Yao Qi 2014-07-01 15:36:44 +08:00
parent 3116063bd6
commit 1db01f22f5
2 changed files with 11 additions and 10 deletions
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6
gdb/ChangeLog
View file

@ -1,3 +1,9 @@
2014-07-11 Yao Qi <yao@codesourcery.com>
* arm-tdep.c (thumb_analyze_prologue): Don't match instruction
'add sp, #imm'.
(thumb_in_function_epilogue_p): Don't match 'sub sp, #imm'.
2014-07-11 Gary Benson <gbenson@redhat.com>
* amd64-linux-nat.c (gdbcore.h): Remove include.

15
gdb/arm-tdep.c
View file

@ -737,16 +737,11 @@ thumb_analyze_prologue (struct gdbarch *gdbarch,
pv_area_store (stack, regs[ARM_SP_REGNUM], 4, regs[regno]);
}
}
else if ((insn & 0xff00) == 0xb000) /* add sp, #simm OR
sub sp, #simm */
else if ((insn & 0xff80) == 0xb080) /* sub sp, #imm */
{
offset = (insn & 0x7f) << 2; /* get scaled offset */
if (insn & 0x80) /* Check for SUB. */
regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM],
-offset);
else
regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM],
offset);
regs[ARM_SP_REGNUM] = pv_add_constant (regs[ARM_SP_REGNUM],
-offset);
}
else if ((insn & 0xf800) == 0xa800) /* add Rd, sp, #imm */
regs[bits (insn, 8, 10)] = pv_add_constant (regs[ARM_SP_REGNUM],
@ -3264,7 +3259,7 @@ thumb_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
found_return = 1;
else if (insn == 0x46bd) /* mov sp, r7 */
found_stack_adjust = 1;
else if ((insn & 0xff00) == 0xb000) /* add sp, imm or sub sp, imm */
else if ((insn & 0xff80) == 0xb000) /* add sp, imm */
found_stack_adjust = 1;
else if ((insn & 0xfe00) == 0xbc00) /* pop <registers> */
{
@ -3324,7 +3319,7 @@ thumb_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
if (insn2 == 0x46bd) /* mov sp, r7 */
found_stack_adjust = 1;
else if ((insn2 & 0xff00) == 0xb000) /* add sp, imm or sub sp, imm */
else if ((insn2 & 0xff80) == 0xb000) /* add sp, imm */
found_stack_adjust = 1;
else if ((insn2 & 0xff00) == 0xbc00) /* pop <registers> without PC */
found_stack_adjust = 1;