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Fix Nios II GDB epilogue detection to handle multiple stack adjustments. 

2014-11-25  Sandra Loosemore  <sandra@codesourcery.com>

	gdb/
	* nios2-tdep.c (nios2_in_epilogue_p): Handle multiple stack
	adjustments.
This commit is contained in:
Sandra Loosemore 2014-11-25 18:37:41 -08:00
parent d53c26c753
commit 7f1659b587
2 changed files with 47 additions and 17 deletions
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5
gdb/ChangeLog
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@ -1,3 +1,8 @@
2014-11-25 Sandra Loosemore <sandra@codesourcery.com>
* nios2-tdep.c (nios2_in_epilogue_p): Handle multiple stack
adjustments.
2014-11-25 Sandra Loosemore <sandra@codesourcery.com>
* nios2-tdep.c (nios2_fetch_insn): Move up in file. Disassemble

59
gdb/nios2-tdep.c
View File

@ -589,26 +589,42 @@ nios2_in_epilogue_p (struct gdbarch *gdbarch,
CORE_ADDR start_pc)
{
unsigned long mach = gdbarch_bfd_arch_info (gdbarch)->mach;
/* Maximum number of possibly-epilogue instructions to check.
Note that this number should not be too large, else we can
potentially end up iterating through unmapped memory. */
int ninsns, max_insns = 5;
unsigned int insn;
const struct nios2_opcode *op = NULL;
unsigned int uimm;
int imm;
int ra, rb, rc;
enum branch_condition cond;
CORE_ADDR pc;
/* There has to be a previous instruction in the function. */
if (current_pc > start_pc)
{
int ok = 0;
if (current_pc <= start_pc)
return 0;
/* Check whether the previous instruction was a stack adjustment.
Possible instructions here include:
/* Find the previous instruction before current_pc.
For the moment we will assume that all instructions are the
same size here. */
pc = current_pc - NIOS2_OPCODE_SIZE;
/* Beginning with the previous instruction we just located, check whether
we are in a sequence of at least one stack adjustment instruction.
Possible instructions here include:
ADDI sp, sp, n
ADD sp, sp, rn
LDW sp, n(sp) */
op = nios2_fetch_insn (gdbarch, current_pc - NIOS2_OPCODE_SIZE, &insn);
for (ninsns = 0; ninsns < max_insns; ninsns++)
{
int ok = 0;
/* Fetch the insn at pc. */
op = nios2_fetch_insn (gdbarch, pc, &insn);
if (op == NULL)
return 0;
pc += op->size;
/* Was it a stack adjustment? */
if (nios2_match_addi (insn, op, mach, &ra, &rb, &imm))
@ -618,18 +634,27 @@ nios2_in_epilogue_p (struct gdbarch *gdbarch,
else if (nios2_match_ldw (insn, op, mach, &ra, &rb, &imm))
ok = (rb == NIOS2_SP_REGNUM);
if (!ok)
return 0;
/* Then check if it's followed by a return or a tail call. */
op = nios2_fetch_insn (gdbarch, current_pc, &insn);
if (op == NULL)
return 0;
if (nios2_match_jmpr (insn, op, mach, &ra)
|| nios2_match_jmpi (insn, op, mach, &uimm)
|| (nios2_match_branch (insn, op, mach, &ra, &rb, &imm, &cond)
&& cond == branch_none))
return 1;
break;
}
/* No stack adjustments found. */
if (ninsns == 0)
return 0;
/* We found more stack adjustments than we expect GCC to be generating.
Since it looks like a stack unwind might be in progress tell GDB to
treat it as such. */
if (ninsns == max_insns)
return 1;
/* The next instruction following the stack adjustments must be a
return, jump, or unconditional branch. */
if (nios2_match_jmpr (insn, op, mach, &ra)
|| nios2_match_jmpi (insn, op, mach, &uimm)
|| (nios2_match_branch (insn, op, mach, &ra, &rb, &imm, &cond)
&& cond == branch_none))
return 1;
return 0;
}