[clang] Don't generate warn-stack-size when the warning is ignored

8ace121 introduced a regression for code that explicitly ignores the
-Wframe-larger-than= warning. Make sure we don't generate the
warn-stack-size attribute for that case.

Differential Revision: https://reviews.llvm.org/D108686

Author: kongy

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -1049,7 +1049,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
     Fn->addFnAttr("packed-stack");
   }
 
-  if (CGM.getCodeGenOpts().WarnStackSize != UINT_MAX)
+  if (CGM.getCodeGenOpts().WarnStackSize != UINT_MAX &&
+      !CGM.getDiags().isIgnored(diag::warn_fe_backend_frame_larger_than, Loc))
     Fn->addFnAttr("warn-stack-size",
                   std::to_string(CGM.getCodeGenOpts().WarnStackSize));
 

clang/test/Misc/backend-stack-frame-diagnostics-attributes.cpp

@@ -0,0 +1,24 @@
+// Test the warn-stack-size function attribute is not generated when -Wframe-larger-than is ignored
+// through pragma.
+
+// RUN: %clang_cc1 -fwarn-stack-size=70 -emit-llvm -o - %s | FileCheck %s
+// CHECK: "warn-stack-size"="70"
+
+// RUN: %clang_cc1 -DIGNORED -fwarn-stack-size=70 -emit-llvm -o - %s | FileCheck %s --check-prefix=IGNORED
+// IGNORED-NOT: "warn-stack-size"="70"
+
+extern void doIt(char *);
+
+#ifdef IGNORED
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wframe-larger-than"
+#endif
+
+void frameSizeAttr() {
+  char buffer[80];
+  doIt(buffer);
+}
+
+#ifdef IGNORED
+#pragma GCC diagnostic pop
+#endif