On Thu, Jun 22, 2023 at 4:12 AM Philipp Tomsich
<philipp.toms...@vrull.eu> wrote:
>
> From: Manolis Tsamis <manolis.tsa...@vrull.eu>
>
> Fixes: 6a2e8dcbbd4bab3
>
> Propagation for the stack pointer in regcprop was enabled in
> 6a2e8dcbbd4bab3, 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.
The only comment I have is on the testcase.
>
> PR 110308
>
> gcc/ChangeLog:
>
> * regcprop.cc (maybe_mode_change): Check stack_pointer_rtx mode.
> (find_oldest_value_reg): Special handling of stack_pointer_rtx.
> (copyprop_hardreg_forward_1): Ditto.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/torture/pr110308.C: New test.
>
> Signed-off-by: Manolis Tsamis <manolis.tsa...@vrull.eu>
> Signed-off-by: Philipp Tomsich <philipp.toms...@vrull.eu>
>
> ---
> This addresses both the PRs (110308 and 110313) and was confirmed to
> resolve the AArch64 bootstrap issue reported by Thiago.
>
> OK for trunk?
>
> gcc/regcprop.cc | 43 +++++++++++++++++--------
> gcc/testsuite/g++.dg/torture/pr110308.C | 30 +++++++++++++++++
> 2 files changed, 60 insertions(+), 13 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/torture/pr110308.C
>
> diff --git a/gcc/regcprop.cc b/gcc/regcprop.cc
> index 6cbfadb181f..fe75b7f1fa0 100644
> --- a/gcc/regcprop.cc
> +++ b/gcc/regcprop.cc
> @@ -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;
> @@ -487,9 +487,14 @@ 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);
> + if (new_rtx != stack_pointer_rtx)
> + {
> + ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (reg);
> + REG_ATTRS (new_rtx) = REG_ATTRS (reg);
> + REG_POINTER (new_rtx) = REG_POINTER (reg);
> + }
> + else if (REG_POINTER (new_rtx) != REG_POINTER (reg))
> + return NULL_RTX;
> return new_rtx;
> }
> }
> @@ -965,15 +970,27 @@ 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;
> + bool can_change;
> + if (new_rtx != stack_pointer_rtx)
> + {
> + ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (src);
> + REG_ATTRS (new_rtx) = REG_ATTRS (src);
> + REG_POINTER (new_rtx) = REG_POINTER (src);
> + can_change = true;
> + }
> + else
> + can_change
> + = (REG_POINTER (new_rtx) == REG_POINTER (src));
> +
> + if (can_change)
> + {
> + 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. */
> diff --git a/gcc/testsuite/g++.dg/torture/pr110308.C
> b/gcc/testsuite/g++.dg/torture/pr110308.C
> new file mode 100644
> index 00000000000..ddd30d4fc3f
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/pr110308.C
> @@ -0,0 +1,30 @@
> +/* { dg-do compile } */
> +/* { dg-options "-g2 -O2" } */
Since this is in `g++.dg/torture`, you don't need dg-options as the
DG_TORTURE_OPTIONS includes `-O3 -g` already (note `-g` is the same as
`-g2`).
Thanks,
Andrew
> +
> +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;
> +}
> \ No newline at end of file
> --
> 2.34.1
>
