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[PATCH] powerpc: Expose VSX feature test
- From: Nathan Phillips <waic9e at protonmail dot com>
- To: "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>
- Date: Wed, 28 Mar 2018 04:19:57 -0400
- Subject: [PATCH] powerpc: Expose VSX feature test
- Feedback-id: pIMM7SjgsBkoh1VHiFjtO1aCnt3hdIguBtsk5guUZVvO7OljEshi__TzlKj4CrF76xqm0sJcB-O9Syj4wMI1Lg==:Ext:ProtonMail
- Reply-to: Nathan Phillips <waic9e at protonmail dot com>
Hope it's OK to submit a small change like this. Trying to familiarize myself
with the patch process.
My copyright assignment is underway.
--
Read the HWCAP auxval key to test for VSX support. Expose result through
the cpu_features interface.
Preliminary change to prepare for PowerPC optimized libmvec implementations
[BZ #20123]. Enables selecting optimized version at load time in ifunc
resolver.
* sysdeps/powerpc/cpu-features.h (cpu_features): Add vsx field.
* sysdeps/powerpc/cpu-features.c (init_cpu_features):
Feature test VSX availability.
---
diff --git a/sysdeps/powerpc/cpu-features.c b/sysdeps/powerpc/cpu-features.c
index 955d4778a6..477c7504b9 100644
--- a/sysdeps/powerpc/cpu-features.c
+++ b/sysdeps/powerpc/cpu-features.c
@@ -16,6 +16,8 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <errno.h>
+#include <sys/auxv.h>
#include <stdint.h>
#include <cpu-features.h>
@@ -26,6 +28,9 @@
static inline void
init_cpu_features (struct cpu_features *cpu_features)
{
+ errno = 0;
+ unsigned long int hwcap = getauxval (AT_HWCAP);
+
/* Default is to use aligned memory access on optimized function unless
tunables is enable, since for this case user can explicit disable
unaligned optimizations. */
@@ -36,4 +41,13 @@ init_cpu_features (struct cpu_features *cpu_features)
#else
cpu_features->use_cached_memopt = false;
#endif
+
+ if (errno == ENOENT)
+ {
+ cpu_features->vsx = false;
+ }
+ else
+ {
+ cpu_features->vsx = ((hwcap & PPC_FEATURE_HAS_VSX) != 0);
+ }
}
diff --git a/sysdeps/powerpc/cpu-features.h b/sysdeps/powerpc/cpu-features.h
index e596385b4b..0248862b8a 100644
--- a/sysdeps/powerpc/cpu-features.h
+++ b/sysdeps/powerpc/cpu-features.h
@@ -23,6 +23,7 @@
struct cpu_features
{
bool use_cached_memopt;
+ bool vsx;
};
#endif /* __CPU_FEATURES_H */