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

This reverts commit 921f871ac438175ca8fcfcafdfcfac4d7ddf3905 because it
causes libc++ code to trigger __warn_memset_zero_len.

See https://reviews.llvm.org/D71082.

(cherry picked from commit 3d210ed3d1880c615776b07d1916edb400c245a6)

1 files changed, 1 insertions, 8 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 8e0604181fb..b23d9df5f4b 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4621,15 +4621,8 @@ RValue CodeGenFunction::EmitSimpleCallExpr(const CallExpr *E,
 }
 
 static CGCallee EmitDirectCallee(CodeGenFunction &CGF, const FunctionDecl *FD) {
-
   if (auto builtinID = FD->getBuiltinID()) {
-    // 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);
+    return CGCallee::forBuiltin(builtinID, FD);
   }
 
   llvm::Constant *calleePtr = EmitFunctionDeclPointer(CGF.CGM, FD);