Revert "System: Add SwapByteOrder and update Support/MathExtras.h to use it."

This reverts commit 116234.

It compiled just fine with MSVC and clang...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116242 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 31 insertions, 4 deletions

diff --git a/include/llvm/Support/MathExtras.h b/include/llvm/Support/MathExtras.h
index 3b907808dd..982813f718 100644
--- a/include/llvm/Support/MathExtras.h
+++ b/include/llvm/Support/MathExtras.h
@@ -15,7 +15,6 @@
 #define LLVM_SUPPORT_MATHEXTRAS_H
 
 #include "llvm/System/DataTypes.h"
-#include "llvm/System/SwapByteOrder.h"
 
 namespace llvm {
 
@@ -113,19 +112,47 @@ inline bool isPowerOf2_64(uint64_t Value) {
 /// ByteSwap_16 - This function returns a byte-swapped representation of the
 /// 16-bit argument, Value.
 inline uint16_t ByteSwap_16(uint16_t Value) {
-  return sys::SwapByteOrder(Value);
+#if defined(_MSC_VER) && !defined(_DEBUG)
+  // The DLL version of the runtime lacks these functions (bug!?), but in a
+  // release build they're replaced with BSWAP instructions anyway.
+  return _byteswap_ushort(Value);
+#else
+  uint16_t Hi = Value << 8;
+  uint16_t Lo = Value >> 8;
+  return Hi | Lo;
+#endif
 }
 
 /// ByteSwap_32 - This function returns a byte-swapped representation of the
 /// 32-bit argument, Value.
 inline uint32_t ByteSwap_32(uint32_t Value) {
-  return sys::SwapByteOrder(Value);
+#if defined(__llvm__) || \
+    (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)) && !defined(__ICC)
+  return __builtin_bswap32(Value);
+#elif defined(_MSC_VER) && !defined(_DEBUG)
+  return _byteswap_ulong(Value);
+#else
+  uint32_t Byte0 = Value & 0x000000FF;
+  uint32_t Byte1 = Value & 0x0000FF00;
+  uint32_t Byte2 = Value & 0x00FF0000;
+  uint32_t Byte3 = Value & 0xFF000000;
+  return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
+#endif
 }
 
 /// ByteSwap_64 - This function returns a byte-swapped representation of the
 /// 64-bit argument, Value.
 inline uint64_t ByteSwap_64(uint64_t Value) {
-  return sys::SwapByteOrder(Value);
+#if defined(__llvm__) || \
+    (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)) && !defined(__ICC)
+  return __builtin_bswap64(Value);
+#elif defined(_MSC_VER) && !defined(_DEBUG)
+  return _byteswap_uint64(Value);
+#else
+  uint64_t Hi = ByteSwap_32(uint32_t(Value));
+  uint32_t Lo = ByteSwap_32(uint32_t(Value >> 32));
+  return (Hi << 32) | Lo;
+#endif
 }
 
 /// CountLeadingZeros_32 - this function performs the platform optimal form of