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cprop_hardreg: fix ORIGINAL_REGNO/REG_ATTRS/REG_POINTER handling

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Fixes: 6a2e8dcbbd

Propagation for the stack pointer in regcprop was enabled in
6a2e8dcbbd, but set ORIGINAL_REGNO/REG_ATTRS/REG_POINTER for
stack_pointer_rtx which caused regression (e.g., PR 110313, PR 110308).

This fix adds special handling for stack_pointer_rtx in the places
where maybe_mode_change is called. This also adds an check in
maybe_mode_change to return the stack pointer only when the requested
mode matches the mode of stack_pointer_rtx.

	PR debug/110308

gcc/ChangeLog:

	* regcprop.cc (maybe_mode_change): Check stack_pointer_rtx mode.
	(maybe_copy_reg_attrs): New function.
	(find_oldest_value_reg): Use maybe_copy_reg_attrs.
	(copyprop_hardreg_forward_1): Ditto.

gcc/testsuite/ChangeLog:

	* g++.dg/torture/pr110308.C: New test.

Signed-off-by: Manolis Tsamis <manolis.tsamis@vrull.eu>
Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
This commit is contained in:
Manolis Tsamis 2023-06-20 16:23:52 +02:00 • committed by Philipp Tomsich
parent 4bf76b5b6d
commit 893883f2f8
2 changed files with 65 additions and 16 deletions
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52
gcc/regcprop.cc
View file

@ -423,7 +423,7 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
It's unclear if we need to do the same for other special registers. */
if (regno == STACK_POINTER_REGNUM)
{
if (orig_mode == new_mode)
if (orig_mode == new_mode && new_mode == GET_MODE (stack_pointer_rtx))
return stack_pointer_rtx;
else
return NULL_RTX;
@ -451,6 +451,31 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
return NULL_RTX;
}
/* Helper function to copy attributes when replacing OLD_REG with NEW_REG.
If the changes required for NEW_REG are invalid return NULL_RTX, otherwise
return NEW_REG. This is intended to be used with maybe_mode_change. */
static rtx
maybe_copy_reg_attrs (rtx new_reg, rtx old_reg)
{
if (new_reg != stack_pointer_rtx)
{
/* NEW_REG is assumed to be a register copy resulting from
maybe_mode_change. */
ORIGINAL_REGNO (new_reg) = ORIGINAL_REGNO (old_reg);
REG_ATTRS (new_reg) = REG_ATTRS (old_reg);
REG_POINTER (new_reg) = REG_POINTER (old_reg);
}
else if (REG_POINTER (new_reg) != REG_POINTER (old_reg))
{
/* Only a single instance of STACK_POINTER_RTX must exist and we cannot
modify it. Allow propagation if REG_POINTER for OLD_REG matches and
don't touch ORIGINAL_REGNO and REG_ATTRS. */
return NULL_RTX;
}
return new_reg;
}
/* Find the oldest copy of the value contained in REGNO that is in
register class CL and has mode MODE. If found, return an rtx
of that oldest register, otherwise return NULL. */
@ -486,12 +511,7 @@ find_oldest_value_reg (enum reg_class cl, rtx reg, struct value_data *vd)
new_rtx = maybe_mode_change (oldmode, vd->e[regno].mode, mode, i, regno);
if (new_rtx)
{
ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (reg);
REG_ATTRS (new_rtx) = REG_ATTRS (reg);
REG_POINTER (new_rtx) = REG_POINTER (reg);
return new_rtx;
}
return maybe_copy_reg_attrs (new_rtx, reg);
}
return NULL_RTX;
@ -965,15 +985,15 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
if (validate_change (insn, &SET_SRC (set), new_rtx, 0))
{
ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (src);
REG_ATTRS (new_rtx) = REG_ATTRS (src);
REG_POINTER (new_rtx) = REG_POINTER (src);
if (dump_file)
fprintf (dump_file,
"insn %u: replaced reg %u with %u\n",
INSN_UID (insn), regno, REGNO (new_rtx));
changed = true;
goto did_replacement;
if (maybe_copy_reg_attrs (new_rtx, src))
{
if (dump_file)
fprintf (dump_file,
"insn %u: replaced reg %u with %u\n",
INSN_UID (insn), regno, REGNO (new_rtx));
changed = true;
goto did_replacement;
}
}
/* We need to re-extract as validate_change clobbers
recog_data. */

29
gcc/testsuite/g++.dg/torture/pr110308.C Normal file
View file

@ -0,0 +1,29 @@
/* { dg-do compile } */
int channelCount, decodeBlock_outputLength;
struct BlockCodec {
virtual int decodeBlock(const unsigned char *, short *);
};
struct ms_adpcm_state {
char predictorIndex;
int sample1;
ms_adpcm_state();
};
bool decodeBlock_ok;
void encodeBlock() { ms_adpcm_state(); }
struct MSADPCM : BlockCodec {
int decodeBlock(const unsigned char *, short *);
};
void decodeSample(ms_adpcm_state, bool *);
int MSADPCM::decodeBlock(const unsigned char *, short *) {
ms_adpcm_state decoderState[2];
ms_adpcm_state *state[2];
state[0] = &decoderState[0];
if (channelCount == 2)
state[1] = &decoderState[0];
short m_coefficients[state[1]->predictorIndex];
for (int i = 0; i < channelCount; i++)
++state[i]->sample1;
decodeSample(*state[1], &decodeBlock_ok);
return decodeBlock_outputLength;
}