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MSP430: Fix CFA generation during function epilogues

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There is no CFA information generated for instructions that manipulate the
stack during function epilogues. This means a debugger cannot determine the
position of variables on the stack whilst the epilogue is in progress.

This can cause the debugger to give erroneous information when printing a
backtrace whilst stepping through the epilogue, or cause software watchpoints
set on stack variables to become invalidated after a function epilogue
is executed.

The patch fixes this by marking stack manipulation insns as
frame_related, and adding reg_note RTXs to stack pop instructions in the
epilogue.

gcc/ChangeLog:

	* config/msp430/msp430.c (increment_stack): Mark insns which increment
	the stack as frame_related.
	(msp430_expand_prologue): Add comments.
	(msp430_expand_epilogue): Mark insns which decrement
	the stack as frame_related.
	Add reg_note to stack pop insns describing position of register
	variables on the stack.
This commit is contained in:
Jozef Lawrynowicz 2020-09-18 13:03:13 +01:00
parent 220724c311
commit 685c95ebc4
1 changed files with 59 additions and 13 deletions
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72
gcc/config/msp430/msp430.c
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@ -1695,9 +1695,9 @@ increment_stack (HOST_WIDE_INT amount)
{
inc = GEN_INT (amount);
if (TARGET_LARGE)
emit_insn (gen_addpsi3 (sp, sp, inc));
F (emit_insn (gen_addpsi3 (sp, sp, inc)));
else
emit_insn (gen_addhi3 (sp, sp, inc));
F (emit_insn (gen_addhi3 (sp, sp, inc)));
}
}
@ -2408,6 +2408,8 @@ msp430_expand_prologue (void)
for (i = 15; i >= 4; i--)
if (cfun->machine->need_to_save[i])
{
/* We need to save COUNT sequential registers starting from regnum
I. */
int seq, count;
rtx note;
@ -2422,6 +2424,7 @@ msp430_expand_prologue (void)
p = F (emit_insn (gen_pushm (gen_rtx_REG (Pmode, i),
GEN_INT (count))));
/* Document the stack decrement as a result of PUSHM. */
note = gen_rtx_SEQUENCE (VOIDmode, rtvec_alloc (count + 1));
XVECEXP (note, 0, 0)
@ -2470,8 +2473,10 @@ msp430_expand_prologue (void)
void
msp430_expand_epilogue (int is_eh)
{
int i;
int i, j;
int fs;
rtx sp = stack_pointer_rtx;
rtx p;
int helper_n = 0;
if (is_naked_func ())
@ -2540,19 +2545,27 @@ msp430_expand_epilogue (int is_eh)
for (i = 4; i <= 15; i++)
if (cfun->machine->need_to_save[i])
{
int seq, count;
/* We need to restore COUNT sequential registers starting from regnum
I. */
int seq;
int count = 1;
int helper_used = 0;
rtx note, addr;
for (seq = i + 1; seq <= 15 && cfun->machine->need_to_save[seq]; seq ++)
;
count = seq - i;
if (msp430x)
{
for (seq = i + 1; seq <= 15 && cfun->machine->need_to_save[seq];
seq++)
;
count = seq - i;
}
if (msp430x)
{
/* Note: With TARGET_LARGE we still use
POPM as POPX.A is two bytes bigger. */
emit_insn (gen_popm (stack_pointer_rtx, GEN_INT (seq - 1),
GEN_INT (count)));
i += count - 1;
p = F (emit_insn (gen_popm (stack_pointer_rtx, GEN_INT (seq - 1),
GEN_INT (count))));
}
else if (i == 11 - helper_n
&& ! msp430_is_interrupt_func ()
@ -2564,11 +2577,44 @@ msp430_expand_epilogue (int is_eh)
&& helper_n > 1
&& !is_eh)
{
emit_jump_insn (gen_epilogue_helper (GEN_INT (helper_n)));
return;
p = F (emit_jump_insn (gen_epilogue_helper (GEN_INT (helper_n))));
count = helper_n;
helper_used = 1;
}
else
emit_insn (gen_pop (gen_rtx_REG (Pmode, i)));
p = F (emit_insn (gen_pop (gen_rtx_REG (Pmode, i))));
/* Document the stack increment as a result of POPM. */
note = gen_rtx_SEQUENCE (VOIDmode, rtvec_alloc (count + 1));
addr = gen_rtx_PLUS (Pmode, stack_pointer_rtx,
GEN_INT (count * (TARGET_LARGE ? 4 : 2)));
XVECEXP (note, 0, 0) = F (gen_rtx_SET (stack_pointer_rtx, addr));
/* *sp++ = R[i+j] */
/* sp R4
...
sp+N R10. */
for (j = 0; j < count; j++)
{
int ofs = j * (TARGET_LARGE ? 4 : 2);
if (ofs)
addr = gen_rtx_PLUS (Pmode, sp, GEN_INT (ofs));
else
addr = stack_pointer_rtx;
XVECEXP (note, 0, j + 1)
= F (gen_rtx_SET (gen_rtx_MEM (Pmode, addr),
gen_rtx_REG (Pmode, i + j)));
}
add_reg_note (p, REG_FRAME_RELATED_EXPR, note);
i += count - 1;
if (helper_used)
return;
}
if (is_eh)