Re: [PATCH]AArch64: Do not allow SIMD clones with simdlen 1 [PR113552]

[Richard Sandiford <richard.sandiford@arm.com>]

Tamar Christina <tamar.christina@arm.com> writes:
> Hi All,
>
> The AArch64 vector PCS does not allow simd calls with simdlen 1,
> however due to a bug we currently do allow it for num == 0.
>
> This causes us to emit a symbol that doesn't exist and we fail to link.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Ok for master? and for backport to GCC 13,12,11?
>
> Thanks,
> Tamar
>
>
>
> gcc/ChangeLog:
>
> 	PR tree-optimization/113552
> 	* config/aarch64/aarch64.cc
> 	(aarch64_simd_clone_compute_vecsize_and_simdlen): Block simdlen 1.
>
> gcc/testsuite/ChangeLog:
>
> 	PR tree-optimization/113552
> 	* gcc.target/aarch64/pr113552.c: New test.
> 	* gcc.target/aarch64/simd_pcs_attribute-3.c: Remove bogus check.
>
> --- inline copy of patch -- 
> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> index e6bd3fd0bb42c70603d5335402b89c9deeaf48d8..a2fc1a5d9d27e9d837e4d616e3feaf38f7272b4f 100644
> --- a/gcc/config/aarch64/aarch64.cc
> +++ b/gcc/config/aarch64/aarch64.cc
> @@ -28620,7 +28620,8 @@ aarch64_simd_clone_compute_vecsize_and_simdlen (struct cgraph_node *node,
>    if (known_eq (clonei->simdlen, 0U))
>      {
>        simdlen = exact_div (poly_uint64 (64), nds_elt_bits);
> -      simdlens.safe_push (simdlen);
> +      if (known_ne (simdlen, 1U))

maybe_ne (i.e. !known_eq) is more canonical.

> +	simdlens.safe_push (simdlen);
>        simdlens.safe_push (simdlen * 2);
>      }
>    else
> diff --git a/gcc/testsuite/gcc.target/aarch64/pr113552.c b/gcc/testsuite/gcc.target/aarch64/pr113552.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..9c96b061ed2b4fcc57e58925277f74d14f79c51f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/pr113552.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Ofast -march=armv8-a" } */
> +
> +__attribute__ ((__simd__ ("notinbranch"), const))
> +double cos (double);
> +
> +void foo (float *a, double *b)
> +{
> +    for (int i = 0; i < 12; i+=3)
> +      {
> +        b[i] = cos (5.0 * a[i]);
> +        b[i+1] = cos (5.0 * a[i+1]);
> +        b[i+2] = cos (5.0 * a[i+2]);
> +      }
> +}
> +
> +/* { dg-final { scan-assembler-times {bl\t_ZGVnN2v_cos} 6 } } */
> diff --git a/gcc/testsuite/gcc.target/aarch64/simd_pcs_attribute-3.c b/gcc/testsuite/gcc.target/aarch64/simd_pcs_attribute-3.c
> index 95f6a6803e889c02177ef10972962ed62d2095eb..661764b3d4a89e08951a7a3c0495d5b7ba7f0871 100644
> --- a/gcc/testsuite/gcc.target/aarch64/simd_pcs_attribute-3.c
> +++ b/gcc/testsuite/gcc.target/aarch64/simd_pcs_attribute-3.c
> @@ -18,7 +18,5 @@ double foo(double x)
>  }
>  
>  /* { dg-final { scan-assembler-not {\.variant_pcs\tfoo} } } */
> -/* { dg-final { scan-assembler-times {\.variant_pcs\t_ZGVnM1v_foo} 1 } } */
>  /* { dg-final { scan-assembler-times {\.variant_pcs\t_ZGVnM2v_foo} 1 } } */
> -/* { dg-final { scan-assembler-times {\.variant_pcs\t_ZGVnN1v_foo} 1 } } */
>  /* { dg-final { scan-assembler-times {\.variant_pcs\t_ZGVnN2v_foo} 1 } } */

Think it'd be a bit safer to turn these into scan-assembler-nots,
rather than remove them.

OK for trunk and branches with those changes, thanks.

Richard