From: Mark Wielaard <mark@klomp.org>
Date: Fri, 18 Oct 2013 13:11:05 +0000 (+0000)
Subject: Don't report BMI support when AVX support is missing.
X-Git-Tag: svn/VALGRIND_3_9_0~35
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e671b086cf450c2e5a4832a49334f0ac05d3c6ff;p=thirdparty%2Fvalgrind.git

Don't report BMI support when AVX support is missing.

Bug #326113. This is a bit conservative, but it is what the linux kernel
also seems to be doing. If AVX support is missing (because the OS doesn't
save the wide registers), then also don't report supporting BMI.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13656
---

diff --git a/coregrind/m_machine.c b/coregrind/m_machine.c
index 69bd7ac5b2..c4740327cb 100644
--- a/coregrind/m_machine.c
+++ b/coregrind/m_machine.c
@@ -868,13 +868,13 @@ Bool VG_(machine_get_hwcaps)( void )
         have_rdtscp = (edx & (1<<27)) != 0; /* True => have RDTSVCP */
      }
 
-     /* Check for BMI1 and AVX2. */
+     /* Check for BMI1 and AVX2. If we have AVX1 (plus OS support). */
      have_bmi = False;
      have_avx2 = False;
-     if (max_basic >= 7) {
+     if (have_avx && max_basic >= 7) {
         VG_(cpuid)(7, 0, &eax, &ebx, &ecx, &edx);
         have_bmi = (ebx & (1<<3)) != 0; /* True => have BMI1 */
-        have_avx2 = have_avx && ((ebx & (1<<5)) != 0); /* True => have AVX2 */
+        have_avx2 = (ebx & (1<<5)) != 0; /* True => have AVX2 */
      }
 
      va         = VexArchAMD64;