> On 16 May 2025, at 18:54, Richard Sandiford <richard.sandif...@arm.com> wrote:
>
> External email: Use caution opening links or attachments
>
>
> Jennifer Schmitz <jschm...@nvidia.com> writes:
>> [PATCH] [PR120276] regcprop: Return from copy_value for unordered modes
>>
>> The ICE in PR120276 resulted from a comparison of VNx4QI and V8QI using
>> partial_subreg_p in the function copy_value during the RTL pass
>> regcprop, failing the assertion in
>>
>> inline bool
>> partial_subreg_p (machine_mode outermode, machine_mode innermode)
>> {
>> /* Modes involved in a subreg must be ordered. In particular, we must
>> always know at compile time whether the subreg is paradoxical. */
>> poly_int64 outer_prec = GET_MODE_PRECISION (outermode);
>> poly_int64 inner_prec = GET_MODE_PRECISION (innermode);
>> gcc_checking_assert (ordered_p (outer_prec, inner_prec));
>> return maybe_lt (outer_prec, inner_prec);
>> }
>>
>> Returning from the function if the modes are not ordered before reaching
>> the call to partial_subreg_p resolves the ICE and passes bootstrap and
>> testing without regression.
>> OK for mainline?
>>
>> Signed-off-by: Jennifer Schmitz <jschm...@nvidia.com>
>>
>> gcc/
>> PR middle-end/120276
>> * regcprop.cc (copy_value): Return in case of unordered modes.
>>
>> gcc/testsuite/
>> PR middle-end/120276
>> * gcc.dg/torture/pr120276.c: New test.
>
> OK, thanks.
Thanks, committed to trunk: 2ec5082dd24cef5149ba645ee88a9acd8b4c290a
Jennifer
>
> Richard
>
>> ---
>> gcc/regcprop.cc | 4 ++++
>> gcc/testsuite/gcc.dg/torture/pr120276.c | 20 ++++++++++++++++++++
>> 2 files changed, 24 insertions(+)
>> create mode 100644 gcc/testsuite/gcc.dg/torture/pr120276.c
>>
>> diff --git a/gcc/regcprop.cc b/gcc/regcprop.cc
>> index 4fa1305526c..98ab3f77e83 100644
>> --- a/gcc/regcprop.cc
>> +++ b/gcc/regcprop.cc
>> @@ -332,6 +332,10 @@ copy_value (rtx dest, rtx src, struct value_data *vd)
>> if (vd->e[sr].mode == VOIDmode)
>> set_value_regno (sr, vd->e[dr].mode, vd);
>>
>> + else if (!ordered_p (GET_MODE_PRECISION (vd->e[sr].mode),
>> + GET_MODE_PRECISION (GET_MODE (src))))
>> + return;
>> +
>> /* If we are narrowing the input to a smaller number of hard regs,
>> and it is in big endian, we are really extracting a high part.
>> Since we generally associate a low part of a value with the value
>> itself,
>> diff --git a/gcc/testsuite/gcc.dg/torture/pr120276.c
>> b/gcc/testsuite/gcc.dg/torture/pr120276.c
>> new file mode 100644
>> index 00000000000..9717a7103e5
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/torture/pr120276.c
>> @@ -0,0 +1,20 @@
>> +/* { dg-do compile } */
>> +/* { dg-additional-options "-march=armv8.2-a+sve" { target aarch64*-*-* } }
>> */
>> +
>> +int a;
>> +char b[1];
>> +int c[18];
>> +void d(char *);
>> +void e() {
>> + int f;
>> + char *g;
>> + a = 0;
>> + for (; a < 18; a++) {
>> + int h = f = 0;
>> + for (; f < 4; f++) {
>> + g[a * 4 + f] = c[a] >> h;
>> + h += 8;
>> + }
>> + }
>> + d(b);
>> +}
>> \ No newline at end of file
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