target.h (htm_available): Determine vendor from __get_cpuid_max return.

	* config/x86/target.h (htm_available): Determine vendor from
	__get_cpuid_max return.  Use signature_INTEL_ebx.  Cleanup.

From-SVN: r244644

libitm/ChangeLog

+2017-01-19  Uros Bizjak  <ubizjak@gmail.com>
+
+	* config/x86/target.h (htm_available): Determine vendor from
+	__get_cpuid_max return.  Use signature_INTEL_ebx.  Cleanup.
+
 2017-01-18  Torvald Riegel  <triegel@redhat.com>
 
 	* config/x86/target.h (htm_available): Add check for some processors

libitm/config/x86/target.h

@@ -75,31 +75,32 @@ static inline bool
 htm_available ()
 {
   const unsigned cpuid_rtm = bit_RTM;
-  if (__get_cpuid_max (0, NULL) >= 7)
+  unsigned vendor;
+
+  if (__get_cpuid_max (0, &vendor) >= 7)
     {
       unsigned a, b, c, d;
-      /* TSX is broken on some processors.  This can be fixed by microcode,
+      unsigned family;
+
+      __cpuid (1, a, b, c, d);
+      family = (a >> 8) & 0x0f;
+      /* TSX is broken on some processors.  TSX can be disabled by microcode,
 	 but we cannot reliably detect whether the microcode has been
 	 updated.  Therefore, do not report availability of TSX on these
 	 processors.  We use the same approach here as in glibc (see
 	 https://sourceware.org/ml/libc-alpha/2016-12/msg00470.html).  */
-      __cpuid (0, a, b, c, d);
-      if (b == 0x756e6547 && c == 0x6c65746e && d == 0x49656e69)
+      if (vendor == signature_INTEL_ebx && family == 0x06)
 	{
-	  __cpuid (1, a, b, c, d);
-	  if (((a >> 8) & 0x0f) == 0x06) // Family.
-	    {
-	      unsigned model = ((a >> 4) & 0x0f) // Model.
-		  + ((a >> 12) & 0xf0); // Extended model.
-	      unsigned stepping = a & 0x0f;
-	      if ((model == 0x3c)
-		  || (model == 0x45)
-		  || (model == 0x46)
-		  /* Xeon E7 v3 has correct TSX if stepping >= 4.  */
-		  || ((model == 0x3f) && (stepping < 4)))
-		return false;
-	    }
+	  unsigned model = ((a >> 4) & 0x0f) + ((a >> 12) & 0xf0);
+	  unsigned stepping = a & 0x0f;
+	  if (model == 0x3c
+	      /* Xeon E7 v3 has correct TSX if stepping >= 4.  */
+	      || (model == 0x3f && stepping < 4)
+	      || model == 0x45
+	      || model == 0x46)
+	    return false;
 	}
+
       __cpuid_count (7, 0, a, b, c, d);
       if (b & cpuid_rtm)
 	return true;