From: Uros Bizjak <ubizjak@gmail.com>
Date: Tue, 21 May 2019 15:17:57 +0000 (+0200)
Subject: cpuid.h (__cpuid): For 32bit targets...
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8c365be6e199bcd3e20b36f7907ce5303af105a1;p=gcc.git

cpuid.h (__cpuid): For 32bit targets...

	* config/i386/cpuid.h (__cpuid): For 32bit targets, zero
	%ebx and %ecx bafore calling cpuid with leaf 1 or
	non-constant leaf argument.

From-SVN: r271469
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index eff11afb0d2..38f9046ffc7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-05-21  Uroš Bizjak  <ubizjak@gmail.com>
+
+	* config/i386/cpuid.h (__cpuid): For 32bit targets, zero
+	%ebx and %ecx bafore calling cpuid with leaf 1 or
+	non-constant leaf argument.
+
 2019-05-21  Alan Modra  <amodra@gmail.com>
 
 	PR target/90545
diff --git a/gcc/config/i386/cpuid.h b/gcc/config/i386/cpuid.h
index 8ddd425c8b7..1d6ef335e76 100644
--- a/gcc/config/i386/cpuid.h
+++ b/gcc/config/i386/cpuid.h
@@ -187,10 +187,27 @@
 #define signature_VORTEX_ecx	0x436f5320
 #define signature_VORTEX_edx	0x36387865
 
+#ifndef __x86_64__
+/* At least one cpu (Winchip 2) does not set %ebx and %ecx
+   for cpuid leaf 1. Forcibly zero the two registers before
+   calling cpuid as a precaution.  */
+#define __cpuid(level, a, b, c, d)			\
+  do {							\
+    if (__builtin_constant_p (level) && (level) != 1)	\
+      __asm__ ("cpuid\n\t"				\
+	      : "=a" (a), "=b" (b), "=c" (c), "=d" (d)	\
+	      : "0" (level));				\
+    else						\
+      __asm__ ("cpuid\n\t"				\
+	      : "=a" (a), "=b" (b), "=c" (c), "=d" (d)	\
+	      : "0" (level), "1" (0), "2" (0));		\
+  } while (0)
+#else
 #define __cpuid(level, a, b, c, d)			\
   __asm__ ("cpuid\n\t"					\
 	   : "=a" (a), "=b" (b), "=c" (c), "=d" (d)	\
 	   : "0" (level))
+#endif
 
 #define __cpuid_count(level, count, a, b, c, d)		\
   __asm__ ("cpuid\n\t"					\