Use gnu style builtins in MathExtras.h with clang on Windows

Clang does not provide BitScan* intrinsic implementations yet.

llvm-svn: 187813

diff --git a/llvm/include/llvm/Support/MathExtras.h b/llvm/include/llvm/Support/MathExtras.h
index 7742e32737a677ebcdebcf7400bd7b194702b04c..00c6ad70d4350fb87c5e64975f85b04b70e88863 100644 (file)
--- a/llvm/include/llvm/Support/MathExtras.h
+++ b/llvm/include/llvm/Support/MathExtras.h
@@ -80,7 +80,7 @@ inline std::size_t countTrailingZeros<uint32_t>(uint32_t Val, ZeroBehavior ZB) {
   if (ZB != ZB_Undefined && Val == 0)
     return 32;
 
-#if __GNUC__ >= 4
+#if __has_builtin(__builtin_ctz) || __GNUC_PREREQ(4, 0)
   return __builtin_ctz(Val);
 #elif _MSC_VER
   unsigned long Index;
@@ -95,7 +95,7 @@ inline std::size_t countTrailingZeros<uint64_t>(uint64_t Val, ZeroBehavior ZB) {
   if (ZB != ZB_Undefined && Val == 0)
     return 64;
 
-#if __GNUC__ >= 4
+#if __has_builtin(__builtin_ctzll) || __GNUC_PREREQ(4, 0)
   return __builtin_ctzll(Val);
 #elif _MSC_VER
   unsigned long Index;
@@ -146,7 +146,7 @@ inline std::size_t countLeadingZeros<uint32_t>(uint32_t Val, ZeroBehavior ZB) {
   if (ZB != ZB_Undefined && Val == 0)
     return 32;
 
-#if __GNUC__ >= 4
+#if __has_builtin(__builtin_clz) || __GNUC_PREREQ(4, 0)
   return __builtin_clz(Val);
 #elif _MSC_VER
   unsigned long Index;
@@ -161,7 +161,7 @@ inline std::size_t countLeadingZeros<uint64_t>(uint64_t Val, ZeroBehavior ZB) {
   if (ZB != ZB_Undefined && Val == 0)
     return 64;
 
-#if __GNUC__ >= 4
+#if __has_builtin(__builtin_clzll) || __GNUC_PREREQ(4, 0)
   return __builtin_clzll(Val);
 #elif _MSC_VER
   unsigned long Index;