Re: Commit 2d63a517e4084ec80403cd9f278690fa8b676cc4

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Mar 13, 2014 at 7:41 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Mar 13, 2014 at 6:57 PM, Paul Pluzhnikov <ppluzhnikov@google.com> wrote:
>> After latest commit:
>>
>> commit 2d63a517e4084ec80403cd9f278690fa8b676cc4
>> Author: Igor Zamyatin <igor.zamyatin@intel.com>
>> Date:   Thu Mar 13 11:10:22 2014 -0700
>>
>>     Save and restore AVX-512 zmm registers to x86-64 ld.so
>> ...
>>
>> "make check" fails like this for me:
>>
>>
>> /tmp/ccJEXrrY.s: Assembler messages:
>> /tmp/ccJEXrrY.s:47: Error: no such instruction: `vmovdqa64 %zmm0,-176(%rbp)'
>> /tmp/ccJEXrrY.s:51: Error: bad register name `%zmm0'
>> /tmp/ccJEXrrY.s:57: Error: no such instruction: `vmovdqa64 %zmm1,-240(%rbp)'
>> /tmp/ccJEXrrY.s:58: Error: no such instruction: `vmovdqa64 %zmm2,-304(%rbp)'
>> /tmp/ccJEXrrY.s:59: Error: no such instruction: `vmovdqa64 %zmm3,-368(%rbp)'
>> /tmp/ccJEXrrY.s:60: Error: no such instruction: `vmovdqa64 %zmm4,-432(%rbp)'
>> /tmp/ccJEXrrY.s:61: Error: no such instruction: `vmovdqa64 %zmm5,-496(%rbp)'
>> /tmp/ccJEXrrY.s:62: Error: no such instruction: `vmovdqa64 %zmm6,-560(%rbp)'
>> /tmp/ccJEXrrY.s:63: Error: no such instruction: `vmovdqa64 %zmm7,-624(%rbp)'
>> /tmp/ccJEXrrY.s:65: Error: no such instruction: `vmovdqa64 %zmm0,-112(%rbp)'
>> /tmp/ccJEXrrY.s:84: Error: bad register name `%zmm0'
>> /tmp/ccJEXrrY.s:90: Error: no such instruction: `vmovdqa64 %zmm0,-112(%rbp)'
>> ...
>> make[2]: *** [/build/elf/tst-auditmod10a.os] Error 1
>>
>>
>> Likely my binutils/as are too old. Should this test be conditional?
>
> You have GCC 4.9 and a very old binutils.  We didn't test this combination.

I am testing this patch.  It checks AVX-512 assembler support first and
sets libc_cv_cc_avx512 to $libc_cv_asm_avx512, instead of yes.  GCC
won't support AVX-512 if assembler doesn't support it.  I will check it
in if all tests pass.  Sorry for the inconvenience.

Thanks.

-- 
H.J.
--
diff --git a/sysdeps/x86_64/configure.ac b/sysdeps/x86_64/configure.ac
index 5e5d61b..d34f9a8 100644
--- a/sysdeps/x86_64/configure.ac
+++ b/sysdeps/x86_64/configure.ac
@@ -23,15 +23,6 @@ if test $libc_cv_cc_avx = yes; then
 fi
 LIBC_CONFIG_VAR([config-cflags-avx], [$libc_cv_cc_avx])

-dnl Check if -mavx512f works.
-AC_CACHE_CHECK(for AVX512 support, libc_cv_cc_avx512, [dnl
-LIBC_TRY_CC_OPTION([-mavx512f], [libc_cv_cc_avx512=yes],
[libc_cv_cc_avx512=no])
-])
-if test $libc_cv_cc_avx512 = yes; then
-  AC_DEFINE(HAVE_AVX512_SUPPORT)
-fi
-LIBC_CONFIG_VAR([config-cflags-avx512], [$libc_cv_cc_avx512])
-
 dnl Check if asm supports AVX512.
 AC_CACHE_CHECK(for AVX512 support in assembler, libc_cv_asm_avx512, [dnl
 cat > conftest.s <<\EOF
@@ -47,6 +38,15 @@ if test $libc_cv_asm_avx512 == yes; then
   AC_DEFINE(HAVE_AVX512_ASM_SUPPORT)
 fi

+dnl Check if -mavx512f works.
+AC_CACHE_CHECK(for AVX512 support, libc_cv_cc_avx512, [dnl
+LIBC_TRY_CC_OPTION([-mavx512f],
[libc_cv_cc_avx512=$libc_cv_asm_avx512], [libc_cv_cc_avx512=no])
+])
+if test $libc_cv_cc_avx512 = yes; then
+  AC_DEFINE(HAVE_AVX512_SUPPORT)
+fi
+LIBC_CONFIG_VAR([config-cflags-avx512], [$libc_cv_cc_avx512])
+
 dnl Check if -msse2avx works.
 AC_CACHE_CHECK(for AVX encoding of SSE instructions, libc_cv_cc_sse2avx, [dnl
 LIBC_TRY_CC_OPTION([-msse2avx],