add compiler macro

Author: Pierre-vh

llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutor.h

@@ -721,7 +721,8 @@ class GIMatchTableExecutor {
   // - Unchecked execution, assumes no error.
   // - Fast common case handling (1 byte values).
   LLVM_ATTRIBUTE_ALWAYS_INLINE static uint64_t
-  fastDecodeULEB128(const uint8_t *MatchTable, uint64_t &CurrentIdx) {
+  fastDecodeULEB128(const uint8_t *LLVM_ATTRIBUTE_RESTRICT MatchTable,
+                    uint64_t &CurrentIdx) {
     uint64_t Value = MatchTable[CurrentIdx++];
     if (LLVM_UNLIKELY(Value >= 128)) {
       Value &= 0x7f;

llvm/include/llvm/Support/Compiler.h

@@ -278,6 +278,14 @@
 #define LLVM_ATTRIBUTE_RETURNS_NONNULL
 #endif
 
+/// LLVM_ATTRIBUTE_RESTRICT- Annotates a pointer to tell the compiler that
+/// it is not aliased in the current scope.
+#if defined(__clang__) || defined(__GNUC__) || defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_RESTRICT __restrict
+#else
+#define LLVM_ATTRIBUTE_RESTRICT
+#endif
+
 /// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a
 /// pointer that does not alias any other valid pointer.
 #ifdef __GNUC__