Revert 9007f06af0e "Revert "Allow system header to provide their own implementation of some builtin""

This should no longer be necessary after
cd4c65f91d5 "Add __warn_memset_zero_len builtin as a workaround for glibc issue"

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index b23d9df5f4b..8e0604181fb 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4621,8 +4621,15 @@ RValue CodeGenFunction::EmitSimpleCallExpr(const CallExpr *E,
 }
 
 static CGCallee EmitDirectCallee(CodeGenFunction &CGF, const FunctionDecl *FD) {
+
   if (auto builtinID = FD->getBuiltinID()) {
-    return CGCallee::forBuiltin(builtinID, FD);
+    // Replaceable builtin provide their own implementation of a builtin. Unless
+    // we are in the builtin implementation itself, don't call the actual
+    // builtin. If we are in the builtin implementation, avoid trivial infinite
+    // recursion.
+    if (!FD->isInlineBuiltinDeclaration() ||
+        CGF.CurFn->getName() == FD->getName())
+      return CGCallee::forBuiltin(builtinID, FD);
   }
 
   llvm::Constant *calleePtr = EmitFunctionDeclPointer(CGF.CGM, FD);