[X86] Add Clang support for intrinsics __rdtsc and __rdtscp.

This patch:
 1. Adds a definition for two new GCCBuiltins in BuiltinsX86.def:
   __builtin_ia32_rdtsc;
   __builtin_ia32_rdtscp;

 2. Replaces the already existing definition of intrinsic __rdtsc in
    ia32intrin.h with a simple call to the new GCC builtin __builtin_ia32_rdtsc.

 3. Adds a definition for the new intrinsic __rdtscp in ia32intrin.h

llvm-svn: 207132

1 files changed, 7 insertions, 3 deletions

diff --git a/clang/lib/Headers/ia32intrin.h b/clang/lib/Headers/ia32intrin.h
index a5985f660bb..55c22473ba7 100644
--- a/clang/lib/Headers/ia32intrin.h
+++ b/clang/lib/Headers/ia32intrin.h
@@ -82,9 +82,13 @@ __writeeflags(unsigned int __f)
 /* __rdtsc */
 static __inline__ unsigned long long __attribute__((__always_inline__, __nodebug__))
 __rdtsc(void) {
-  unsigned int __eax, __edx;
-  __asm__ ("rdtsc" : "=a" (__eax), "=d" (__edx));
-  return ((unsigned long long)__edx << 32) | __eax;
+  return __builtin_ia32_rdtsc();
+}
+
+/* __rdtscp */
+static __inline__ unsigned long long __attribute__((__always_inline__, __nodebug__))
+__rdtscp(unsigned int *__A) {
+  return __builtin_ia32_rdtscp(__A);
 }
 
 #define _rdtsc() __rdtsc()