Tested on x86_64-darwin/linux(cascadelake), pushed to trunk, thanks
Iain
--- 8< ---
Darwin enables the avx512 state in XCR0 lazily which means that a
constructor querying it is unreliable. However, the kernel will
correctly report the availability, so query that.
gcc/ChangeLog:
* common/config/i386/cpuinfo.h (darwin_get_kernel_bool): New.
(get_available_features): Query kernel for avx512 availability
on Darwin.
Signed-off-by: Iain Sandoe <[email protected]>
---
gcc/common/config/i386/cpuinfo.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/gcc/common/config/i386/cpuinfo.h b/gcc/common/config/i386/cpuinfo.h
index a689afabd3d..f433810457b 100644
--- a/gcc/common/config/i386/cpuinfo.h
+++ b/gcc/common/config/i386/cpuinfo.h
@@ -782,6 +782,17 @@ get_zhaoxin_cpu (struct __processor_model *cpu_model,
return cpu;
}
+#ifdef __APPLE__
+#include <sys/sysctl.h>
+/* Will return false if the queried state is either absent or 0. */
+static inline int
+darwin_get_kernel_bool (const char *name)
+{
+ int val = 0; size_t len = sizeof (val);
+ return sysctlbyname (name, &val, &len, NULL, 0) == 0 && val != 0;
+}
+#endif
+
/* ECX and EDX are output of CPUID at level one. */
static inline void
get_available_features (struct __processor_model *cpu_model,
@@ -840,8 +851,14 @@ get_available_features (struct __processor_model
*cpu_model,
if ((xcrlow & XCR_AVX_ENABLED_MASK) == XCR_AVX_ENABLED_MASK)
{
avx_usable = 1;
+#ifdef __APPLE__
+ /* Darwin enables the avx512 XSAVE state lazily, so a constructor
+ that reads XCR0 is not reliable - query the kernel instead. */
+ avx512_usable = darwin_get_kernel_bool ("hw.optional.avx512f");
+#else
avx512_usable = ((xcrlow & XCR_AVX512F_ENABLED_MASK)
== XCR_AVX512F_ENABLED_MASK);
+#endif
}
amx_usable = ((xcrlow & XCR_AMX_ENABLED_MASK)
== XCR_AMX_ENABLED_MASK);
--
2.50.1 (Apple Git-155)
