i386: Enable AVX/AVX512 features only if supported by OSXSAVE

Enable AVX and AVX512 features only if their states are supported by
OSXSAVE.

	Backport from mainline
	PR target/85100
	* config/i386/cpuinfo.c (XCR_XFEATURE_ENABLED_MASK): New.
	(XSTATE_FP): Likewise.
	(XSTATE_SSE): Likewise.
	(XSTATE_YMM): Likewise.
	(XSTATE_OPMASK): Likewise.
	(XSTATE_ZMM): Likewise.
	(XSTATE_HI_ZMM): Likewise.
	(XCR_AVX_ENABLED_MASK): Likewise.
	(XCR_AVX512F_ENABLED_MASK): Likewise.
	(get_available_features): Enable AVX and AVX512 features only
	if their states are supported by OSXSAVE.

From-SVN: r259007

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index f7910111d8182f1721222fc55b75c7b982fc4ca3..df5e7a44659de1c21632255ac79b3943e4853f75 100644 (file)
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,21 @@
+2018-04-02  H.J. Lu  <hongjiu.lu@intel.com>
+
+       Backport from mainline
+       2018-03-29  H.J. Lu  <hongjiu.lu@intel.com>
+
+       PR target/85100
+       * config/i386/cpuinfo.c (XCR_XFEATURE_ENABLED_MASK): New.
+       (XSTATE_FP): Likewise.
+       (XSTATE_SSE): Likewise.
+       (XSTATE_YMM): Likewise.
+       (XSTATE_OPMASK): Likewise.
+       (XSTATE_ZMM): Likewise.
+       (XSTATE_HI_ZMM): Likewise.
+       (XCR_AVX_ENABLED_MASK): Likewise.
+       (XCR_AVX512F_ENABLED_MASK): Likewise.
+       (get_available_features): Enable AVX and AVX512 features only
+       if their states are supported by OSXSAVE.
+
 2018-03-11  John David Anglin  <danglin@gcc.gnu.org>
 
        Backport from mainline

diff --git a/libgcc/config/i386/cpuinfo.c b/libgcc/config/i386/cpuinfo.c
index 8c2248df3d391d70169681ec23d124319988e0cf..0886b836292d616669166175d164d3a97ccbc8c6 100644 (file)
--- a/libgcc/config/i386/cpuinfo.c
+++ b/libgcc/config/i386/cpuinfo.c
@@ -303,6 +303,40 @@ get_available_features (unsigned int ecx, unsigned int edx,
 {
   unsigned int features = 0;
 
+  /* Get XCR_XFEATURE_ENABLED_MASK register with xgetbv.  */
+#define XCR_XFEATURE_ENABLED_MASK      0x0
+#define XSTATE_FP                      0x1
+#define XSTATE_SSE                     0x2
+#define XSTATE_YMM                     0x4
+#define XSTATE_OPMASK                  0x20
+#define XSTATE_ZMM                     0x40
+#define XSTATE_HI_ZMM                  0x80
+
+#define XCR_AVX_ENABLED_MASK \
+  (XSTATE_SSE | XSTATE_YMM)
+#define XCR_AVX512F_ENABLED_MASK \
+  (XSTATE_SSE | XSTATE_YMM | XSTATE_OPMASK | XSTATE_ZMM | XSTATE_HI_ZMM)
+
+  /* Check if AVX and AVX512 are usable.  */
+  int avx_usable = 0;
+  int avx512_usable = 0;
+  if ((ecx & bit_OSXSAVE))
+    {
+      /* Check if XMM, YMM, OPMASK, upper 256 bits of ZMM0-ZMM15 and
+         ZMM16-ZMM31 states are supported by OSXSAVE.  */
+      unsigned int xcrlow;
+      unsigned int xcrhigh;
+      asm (".byte 0x0f, 0x01, 0xd0"
+          : "=a" (xcrlow), "=d" (xcrhigh)
+          : "c" (XCR_XFEATURE_ENABLED_MASK));
+      if ((xcrlow & XCR_AVX_ENABLED_MASK) == XCR_AVX_ENABLED_MASK)
+       {
+         avx_usable = 1;
+         avx512_usable = ((xcrlow & XCR_AVX512F_ENABLED_MASK)
+                          == XCR_AVX512F_ENABLED_MASK);
+       }
+    }
+
   if (edx & bit_CMOV)
     features |= (1 << FEATURE_CMOV);
   if (edx & bit_MMX)
@@ -325,10 +359,13 @@ get_available_features (unsigned int ecx, unsigned int edx,
     features |= (1 << FEATURE_SSE4_1);
   if (ecx & bit_SSE4_2)
     features |= (1 << FEATURE_SSE4_2);
-  if (ecx & bit_AVX)
-    features |= (1 << FEATURE_AVX);
-  if (ecx & bit_FMA)
-    features |= (1 << FEATURE_FMA);
+  if (avx_usable)
+    {
+      if (ecx & bit_AVX)
+       features |= (1 << FEATURE_AVX);
+      if (ecx & bit_FMA)
+       features |= (1 << FEATURE_FMA);
+    }
 
   /* Get Advanced Features at level 7 (eax = 7, ecx = 0). */
   if (max_cpuid_level >= 7)
@@ -337,28 +374,34 @@ get_available_features (unsigned int ecx, unsigned int edx,
       __cpuid_count (7, 0, eax, ebx, ecx, edx);
       if (ebx & bit_BMI)
         features |= (1 << FEATURE_BMI);
-      if (ebx & bit_AVX2)
-       features |= (1 << FEATURE_AVX2);
+      if (avx_usable)
+       {
+         if (ebx & bit_AVX2)
+           features |= (1 << FEATURE_AVX2);
+       }
       if (ebx & bit_BMI2)
         features |= (1 << FEATURE_BMI2);
-      if (ebx & bit_AVX512F)
-       features |= (1 << FEATURE_AVX512F);
-      if (ebx & bit_AVX512VL)
-       features |= (1 << FEATURE_AVX512VL);
-      if (ebx & bit_AVX512BW)
-       features |= (1 << FEATURE_AVX512BW);
-      if (ebx & bit_AVX512DQ)
-       features |= (1 << FEATURE_AVX512DQ);
-      if (ebx & bit_AVX512CD)
-       features |= (1 << FEATURE_AVX512CD);
-      if (ebx & bit_AVX512PF)
-       features |= (1 << FEATURE_AVX512PF);
-      if (ebx & bit_AVX512ER)
-       features |= (1 << FEATURE_AVX512ER);
-      if (ebx & bit_AVX512IFMA)
-       features |= (1 << FEATURE_AVX512IFMA);
-      if (ecx & bit_AVX512VBMI)
-       features |= (1 << FEATURE_AVX512VBMI);
+      if (avx512_usable)
+       {
+         if (ebx & bit_AVX512F)
+           features |= (1 << FEATURE_AVX512F);
+         if (ebx & bit_AVX512VL)
+           features |= (1 << FEATURE_AVX512VL);
+         if (ebx & bit_AVX512BW)
+           features |= (1 << FEATURE_AVX512BW);
+         if (ebx & bit_AVX512DQ)
+           features |= (1 << FEATURE_AVX512DQ);
+         if (ebx & bit_AVX512CD)
+           features |= (1 << FEATURE_AVX512CD);
+         if (ebx & bit_AVX512PF)
+           features |= (1 << FEATURE_AVX512PF);
+         if (ebx & bit_AVX512ER)
+           features |= (1 << FEATURE_AVX512ER);
+         if (ebx & bit_AVX512IFMA)
+           features |= (1 << FEATURE_AVX512IFMA);
+         if (ecx & bit_AVX512VBMI)
+           features |= (1 << FEATURE_AVX512VBMI);
+       }
     }
 
   unsigned int ext_level;
@@ -372,10 +415,13 @@ get_available_features (unsigned int ecx, unsigned int edx,
 
       if (ecx & bit_SSE4a)
        features |= (1 << FEATURE_SSE4_A);
-      if (ecx & bit_FMA4)
-       features |= (1 << FEATURE_FMA4);
-      if (ecx & bit_XOP)
-       features |= (1 << FEATURE_XOP);
+      if (avx_usable)
+       {
+         if (ecx & bit_FMA4)
+           features |= (1 << FEATURE_FMA4);
+         if (ecx & bit_XOP)
+           features |= (1 << FEATURE_XOP);
+       }
     }
     
   __cpu_model.__cpu_features[0] = features;