[PATCH 1/2] x86: Skip XSAVE state size reset if ISA level requires XSAVE

[Florian Weimer]

If we have to use XSAVE or XSAVEC trampolines, do not adjust the size
information they need.  Technically, it is an operator error to try to
run with -XSAVE,-XSAVEC on such builds, but this change here disables
some unnecessary code with higher ISA levels and simplifies testing.

Related to commit befe2d3c4dec8be2cdd01a47132e47bdb7020922
("x86-64: Don't use SSE resolvers for ISA level 3 or above").
---
 sysdeps/x86/cpu-features.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index 27abaca8b7..06876bff14 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -1161,7 +1161,8 @@ no_cpuid:
 
   bool disable_xsave_features = false;
 
-  if (!CPU_FEATURE_USABLE_P (cpu_features, OSXSAVE))
+  if (MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
+      && !CPU_FEATURE_USABLE_P (cpu_features, OSXSAVE))
     {
       /* These features are usable only if OSXSAVE is usable.  */
       CPU_FEATURE_UNSET (cpu_features, XSAVE);
@@ -1173,9 +1174,10 @@ no_cpuid:
       disable_xsave_features = true;
     }
 
-  if (disable_xsave_features
-      || (!CPU_FEATURE_USABLE_P (cpu_features, XSAVE)
-	  && !CPU_FEATURE_USABLE_P (cpu_features, XSAVEC)))
+  if (MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
+      && (disable_xsave_features
+	  || (!CPU_FEATURE_USABLE_P (cpu_features, XSAVE)
+	      && !CPU_FEATURE_USABLE_P (cpu_features, XSAVEC))))
     {
       /* Clear xsave_state_size if both XSAVE and XSAVEC aren't usable.  */
       cpu_features->xsave_state_size = 0;

base-commit: be61b9493d38032519e596f282f9695667402c8d
-- 
2.48.1