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

[kongyi]

Summary

8ace12130526 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.

[MaskRay]

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

5

-c -S = -S

5

Prefer %clang_cc1 for codegen tests.

I know the main test doesn't conform. Just ignore that divergence.

8

-c -S = -S

[MaskRay]

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

5

In cc1, the last of -S and -emit-llvm wins. Drop -S. The output is already textual IR.

clang/lib/CodeGen/CodeGenFunction.cpp

#undef SANITIZER
   if (CGM.getCodeGenOpts().PackedStack) {
     if (getContext().getTargetInfo().getTriple().getArch() !=
         llvm::Triple::systemz)
       CGM.getDiags().Report(diag::err_opt_not_valid_on_target)
         << "-mpacked-stack";
     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));
 
   if (RetTy->isVoidType()) {
     // Void type; nothing to return.
     ReturnValue = Address::invalid();
 
     // Count the implicit return.

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

+// 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