On Monday 26 January 2015, H.J. Lu wrote: > 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 ();
I guess since they represent the exact same effective ISA, they would have equal priority, so that it would likely chose whatever comes last. `Allan