On Mon, Jan 26, 2015 at 10:53 AM, Allan Sandfeld Jensen
<carew...@gmail.com> wrote:
>> >> >>
>> >> >> Committed with a bunch of fixes (e.g. missing fold_builtin_cpu part
>> >> >> in gcc/config/i386/i386.c, and mv17.C test didn't compile at all due
>> >> >> to missing parenthesis).
>> >> >
>> >> > ... and now with committed ChangeLog and patch.
>> >> >
>> >> > gcc/ChangeLog:
>> >> > * config/i386/i386.c (get_builtin_code_for_version): Add
>> >> > support for BMI and BMI2 multiversion functions.
>> >> > (fold_builtin_cpu): Add F_BMI and F_BMI2.
>> >> >
>> >> > libgcc/ChangeLog:
>> >> > * config/i386/cpuinfo.c (enum processor_features): Add FEATURE_BMI
>> >> > and FEATURE_BMI2.
>> >> > (get_available_features): Detect FEATURE_BMI and FEATURE_BMI2.
>> >> >
>> >> > testsuite/ChangeLog:
>> >> > * gcc.target/i386/funcspec-5.c: Test new multiversion targets.
>> >> > * g++.dg/ext/mv17.C: Test BMI/BMI2 multiversion dispatcher.
>> >>
>> >> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>> >> index 9ec40cb..441911d 100644
>> >> --- a/gcc/config/i386/i386.c
>> >> +++ b/gcc/config/i386/i386.c
>> >> @@ -34289,15 +34289,18 @@ get_builtin_code_for_version (tree decl, tree
>> >> *predica te_list)
>> >>
>> >> P_PROC_SSE4_A,
>> >> P_SSE4_1,
>> >> P_SSE4_2,
>> >>
>> >> - P_PROC_SSE4_2,
>> >>
>> >> P_POPCNT,
>> >>
>> >> + P_PROC_SSE4_2,
>> >>
>> >> P_AVX,
>> >> P_PROC_AVX,
>> >>
>> >> + P_BMI,
>> >> + P_PROC_BMI,
>> >>
>> >> P_FMA4,
>> >> P_XOP,
>> >> P_PROC_XOP,
>> >> P_FMA,
>> >> P_PROC_FMA,
>> >>
>> >> + P_BMI2,
>> >>
>> >> P_AVX2,
>> >> P_PROC_AVX2,
>> >> P_AVX512F,
>> >>
>> >> This changed the priority of P_POPCNT and caused
>> >>
>> >> FAIL: g++.dg/ext/mv1.C -std=gnu++98 execution test
>> >> FAIL: g++.dg/ext/mv1.C -std=gnu++11 execution test
>> >> FAIL: g++.dg/ext/mv1.C -std=gnu++14 execution test
>> >>
>> >> on Nehalem and Westmere machines:
>> >>
>> >> mv1.exe:
>> >> /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/ext/mv1.C:51:
>> >> int main(): Assertion `val == 5' failed.
>> >>
>> >> since "val" is 6 now.
>> >
>> > Right. I am not sure why popcnt was prioritized below arch=corei7. The
>> > logic is supposed to be that any target that includes an extension is
>> > prioritized
>>
>> I don't understand your question. popcnt feature is separate from -march.
>> Its priority has nothing to do with -march=corei7.
>>
> arch=corei7 implies popcnt. See PTA_NEHALEM in i386.c. The test would probably
> work with -march=core2.
>
> AFAIK The logic of the priorities in multiversioning is that architecture
> specific functions are chosen over feature specific, unless the feature is one
> that isn't required by the architecture.
>
On SSE4.2 machines, we should choose
int __attribute__ ((target("arch=corei7"))) foo ();
over
int __attribute__ ((target("popcnt"))) foo ();
But we shouldn't choose
int __attribute__ ((target("arch=corei7"))) foo ();
over
int __attribute__ ((target("arch=corei7,popcnt"))) foo ();
--
H.J.
