Mark function used by asm block as used, otherwise optimizer may not see the...

Mark function used by asm block as used, otherwise optimizer may not see the use and may delete the function.

llvm-svn: 53692

llvm/include/llvm/Support/Compiler.h

@@ -23,6 +23,11 @@
 #define VISIBILITY_HIDDEN
 #endif
 
+#if (__GNUC__ >= 4)
+#define ATTRIBUTE_USED __attribute__((__used__))
+#else
+#define ATTRIBUTE_USED
+#endif
 
 // C++ doesn't support 'extern template' of template specializations.  GCC does,
 // but requires __extension__ before it.  In the header, use this:

llvm/lib/Target/X86/X86JITInfo.cpp

@@ -18,6 +18,7 @@
 #include "llvm/Function.h"
 #include "llvm/CodeGen/MachineCodeEmitter.h"
 #include "llvm/Config/alloca.h"
+#include "llvm/Support/Compiler.h"
 #include <cstdlib>
 #include <cstring>
 using namespace llvm;
@@ -315,7 +316,8 @@ extern "C" {
 /// function stub when we did not know the real target of a call.  This function
 /// must locate the start of the stub or call site and pass it into the JIT
 /// compiler function.
-extern "C" void X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr) {
+extern "C" void ATTRIBUTE_USED
+X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr) {
   intptr_t *RetAddrLoc = &StackPtr[1];
   assert(*RetAddrLoc == RetAddr &&
          "Could not find return address on the stack!");