On 20/03/2025 16:15, Christophe Lyon wrote:
> Depending on if/how the testing flags are overridden, the first value
> we try("") might not do what we want.
>
> For instance, if the whole testsuite is executed with
> (A) -mthumb -march=armv7-m -mtune=cortex-m3 -mfloat-abi=softfp
>
> bf16_neon_ok is first compiled with
> (A) (B)
> where B = -mcpu=unset -march=armv8.2-a+bf16
>
> which is accepted, so a testcase like vld2q_lane_bf16_indices_1.c
> is compiled with:
> (A) (C) (B)
> where C = -mfpu=neon -mfloat-abi=softfp -mcpu=unset -march=armv7-a
> -mfpu=neon-fp16 -mfp16-format=ieee
>
> because advsimd-intrinsics.exp has set additional_flags to (C)
> via arm_neon_fp16_ok
>
> So the testcase is compiled with
> [...] -mfpu=neon-fp16 -mcpu=unset -march=armv8.2-a+bf16
> (thus -mfpu=neon-fp16) and bf16 support is disabled.
>
> The patch replaces "" with -mfpu=auto which matches the intended
> effect of -march=armv8.2-a+bf16 as added by bf16_neon_ok, and the
> testcase is now compiled with
> (A) (C) -mfpu=auto (B)
>
> However, since this effective-target is also used on aarch64 (which
> does not support -mfpu=auto), we do this only on arm.
>
> This patch improves coverage, and makes
> v{ld,st}[234]q_lane_bf16_indices_1.c pass when testsuite flags are
> overridden as described above (e.g. for M-profile).
>
> gcc/testsuite/
> * lib/target-supports.exp
> (check_effective_target_arm_v8_2a_bf16_neon_ok_nocache):
> Conditionally use -mfpu=auto.
> ---
> gcc/testsuite/lib/target-supports.exp | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/testsuite/lib/target-supports.exp
> b/gcc/testsuite/lib/target-supports.exp
> index e2622a445c5..09b16a14024 100644
> --- a/gcc/testsuite/lib/target-supports.exp
> +++ b/gcc/testsuite/lib/target-supports.exp
> @@ -6871,12 +6871,19 @@ proc add_options_for_arm_fp16fml_neon { flags } {
> proc check_effective_target_arm_v8_2a_bf16_neon_ok_nocache { } {
> global et_arm_v8_2a_bf16_neon_flags
> set et_arm_v8_2a_bf16_neon_flags ""
> + set fpu_auto ""
>
> if { ![istarget arm*-*-*] && ![istarget aarch64*-*-*] } {
> return 0;
> }
>
> - foreach flags {"" "-mfloat-abi=softfp -mfpu=neon-fp-armv8"
> "-mfloat-abi=hard -mfpu=neon-fp-armv8" } {
> + if { [istarget arm*-*-*] } {
> + set fpu_auto "-mfpu=auto"
> + }
> +
> + foreach flags [list "$fpu_auto" \
Shouldn't we try first with "", even on Arm? Thus
foreach flags [list "" "$fpu_auto" \
...
> + "-mfloat-abi=softfp -mfpu=neon-fp-armv8" \
> + "-mfloat-abi=hard -mfpu=neon-fp-armv8" ] {
> if { [check_no_compiler_messages_nocache arm_v8_2a_bf16_neon_ok object {
> #include <arm_neon.h>
> #if !defined (__ARM_FEATURE_BF16_VECTOR_ARITHMETIC)
In fact, since aarch64 doesn't support -mfpu at all, only "" is ever going to
work here, so perhaps we can recast all this code, perhaps along the lines of
that in check_effective_target_arm_neon_h_ok_nocache so that we don't need to
actually try to include arm_neon.h at all while figuring out the options.
R.
