[IR] make -warn-frame-size into a module attr

-Wframe-larger-than= is an interesting warning; we can't know the frame
size until PrologueEpilogueInsertion (PEI); very late in the compilation
pipeline.

-Wframe-larger-than= was propagated through CC1 as an -mllvm flag, then
was a cl::opt in LLVM's PEI pass; this meant it was dropped during LTO
and needed to be re-specified via -plugin-opt.

Instead, make it part of the IR proper as a module level attribute,
similar to D103048. Introduce -fwarn-stack-size CC1 option.

Reviewed By: rsmith, qcolombet

Differential Revision: https://reviews.llvm.org/D103928

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 7efc97c51eda..c3a4b1ba6b3d 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -787,6 +787,8 @@ void CodeGenModule::Release() {
         getCodeGenOpts().StackProtectorGuardOffset);
   if (getCodeGenOpts().StackAlignment)
     getModule().setOverrideStackAlignment(getCodeGenOpts().StackAlignment);
+  if (getCodeGenOpts().WarnStackSize != UINT_MAX)
+    getModule().setWarnStackSize(getCodeGenOpts().WarnStackSize);
 
   getTargetCodeGenInfo().emitTargetMetadata(*this, MangledDeclNames);