On Mon, Mar 31, 2025 at 03:12:56PM +0200, Richard Biener wrote:
> The following fixes ix86_handle_option to properly handle -mno-sse4
> which is always handled as -msse4 with value unset. I've verified
> no other OPT_mno_* is left around.
>
> Bootstrap and regtest running on x86_64-unknown-linux-gnu.
>
> This error goes back quite some time, I'm not sure how prevalent
> the use of -mno-sse4 is. In fact I have no idea why we have
> OPT_mno_sse4 at all...
That is because SSE4 is SSE4.1 + SSE4.2.
So for -msse4 we want it to act as -msse4.2 and for -mno-sse4
to act as -mno-sse4.1
> msse4
> Target RejectNegative Mask(ISA_SSE4_2) Var(ix86_isa_flags) Save
> Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1 and SSE4.2 built-in functions
> and code generation.
>
> mno-sse4
> Target RejectNegative InverseMask(ISA_SSE4_1) Var(ix86_isa_flags) Save
> Do not support SSE4.1 and SSE4.2 built-in functions and code generation.
>
> but we end up building
>
> $3 = {opt_index = 2231, warn_message = 0x0, arg = 0x0,
> orig_option_with_args_text = 0x440d108 "-msse4", canonical_option = {
> 0x440d108 "-msse4", 0x0, 0x0, 0x0}, canonical_option_num_elements = 1,
> value = 0, mask = 0, errors = 0}
>
> from -mno-sse4 in target("") via ix86_valid_target_attribute_inner_p.
>
> OK? Any clarification on what the above is about?
>
> Richard.
>
> PR target/119549
> * common/config/i386/i386-common.cc (ix86_handle_option):
> Handle OPT_mno_sse4 via OPT_msse4 and looking at value.
>
> * gcc.target/i386/pr119549.c: New testcase.
> ---
> gcc/common/config/i386/i386-common.cc | 21 ++++++++++++---------
> gcc/testsuite/gcc.target/i386/pr119549.c | 15 +++++++++++++++
> 2 files changed, 27 insertions(+), 9 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr119549.c
>
> diff --git a/gcc/common/config/i386/i386-common.cc
> b/gcc/common/config/i386/i386-common.cc
> index 80aec3244bc..296df3b3230 100644
> --- a/gcc/common/config/i386/i386-common.cc
> +++ b/gcc/common/config/i386/i386-common.cc
> @@ -1519,15 +1519,18 @@ ix86_handle_option (struct gcc_options *opts,
> return true;
>
> case OPT_msse4:
> - opts->x_ix86_isa_flags |= OPTION_MASK_ISA_SSE4_SET;
> - opts->x_ix86_isa_flags_explicit |= OPTION_MASK_ISA_SSE4_SET;
> - return true;
> -
> - case OPT_mno_sse4:
> - opts->x_ix86_isa_flags &= ~OPTION_MASK_ISA_SSE4_UNSET;
> - opts->x_ix86_isa_flags_explicit |= OPTION_MASK_ISA_SSE4_UNSET;
> - opts->x_ix86_isa_flags2 &= ~OPTION_MASK_ISA2_SSE4_UNSET;
> - opts->x_ix86_isa_flags2_explicit |= OPTION_MASK_ISA2_SSE4_UNSET;
> + if (value)
> + {
> + opts->x_ix86_isa_flags |= OPTION_MASK_ISA_SSE4_SET;
> + opts->x_ix86_isa_flags_explicit |= OPTION_MASK_ISA_SSE4_SET;
> + }
> + else
> + {
> + opts->x_ix86_isa_flags &= ~OPTION_MASK_ISA_SSE4_UNSET;
> + opts->x_ix86_isa_flags_explicit |= OPTION_MASK_ISA_SSE4_UNSET;
> + opts->x_ix86_isa_flags2 &= ~OPTION_MASK_ISA2_SSE4_UNSET;
> + opts->x_ix86_isa_flags2_explicit |= OPTION_MASK_ISA2_SSE4_UNSET;
> + }
> return true;
>
> case OPT_msse4a:
For OPT_msse4 that looks reasonable, but I wonder if the old code shouldn't
be kept for OPT_mno_sse4. When I just try to compile something with
-O2 -mavx2 -mno-sse4
previously this would make it like -O2 -mssse3, now it will act as -O2 -mavx2.
E.g. compile
#if __SSSE3__
int i;
#endif
#if __AVX2__
int j;
#endif
I wonder what OPT_mno_sse4 with !value would actually mean though (if it
ever happens).
Jakub
