Tamar Christina <tamar.christ...@arm.com> writes:
> Hi All,
>
> When the input is already a subreg and we try to make a paradoxical
> subreg out of it for copysign this can fail if it violates the sugreg
subreg
> relationship.
>
> Use force_lowpart_subreg instead of lowpart_subreg to then force the
> results to a register instead of ICEing.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Ok for master?
>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> PR target/118892
> * config/aarch64/aarch64.md (copysign<GPF:mode>3): Use
> force_lowpart_subreg instead of lowpart_subreg.
>
> gcc/testsuite/ChangeLog:
>
> PR target/118892
> * gcc.target/aarch64/copysign-pr118892.c: New test.
>
> ---
>
> diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
> index
> cfe730f3732ce45c914b30a908851a4a7dd77c0f..62be9713cf417922b3c06e38f12f401872751fa2
> 100644
> --- a/gcc/config/aarch64/aarch64.md
> +++ b/gcc/config/aarch64/aarch64.md
> @@ -7479,8 +7479,8 @@ (define_expand "copysign<GPF:mode>3"
> && real_isneg (CONST_DOUBLE_REAL_VALUE (op2_elt)))
> {
> emit_insn (gen_ior<vq_int_equiv>3 (
> - lowpart_subreg (<VQ_INT_EQUIV>mode, operands[0], <MODE>mode),
> - lowpart_subreg (<VQ_INT_EQUIV>mode, operands[1], <MODE>mode),
> + force_lowpart_subreg (<VQ_INT_EQUIV>mode, operands[0], <MODE>mode),
> + force_lowpart_subreg (<VQ_INT_EQUIV>mode, operands[1], <MODE>mode),
force_lowpart_subreg conditionally forces the SUBREG_REG into a new temporary
register and then takes the subreg of that. It's therefore only appropriate
for source operands, not destination operands.
It's true that the same problem could in principle occur for the
destination, but that would need to be fixed in a different way.
OK with just the operands[1] change, without the operands[0] change.
Thanks,
Richard
> v_bitmask));
> DONE;
> }
> diff --git a/gcc/testsuite/gcc.target/aarch64/copysign-pr118892.c
> b/gcc/testsuite/gcc.target/aarch64/copysign-pr118892.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..adfa30dc3e2db895af4f2057bdd1011fdb7d4537
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/copysign-pr118892.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Ofast" } */
> +
> +double l();
> +double f()
> +{
> + double t6[2] = {l(), l()};
> + double t7[2];
> + __builtin_memcpy(&t7, &t6, sizeof(t6));
> + return -__builtin_fabs(t7[1]);
> +}
