[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, 11 insertions, 0 deletions

diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp
index 9b95550..40d3401 100644
--- a/llvm/lib/IR/Module.cpp
+++ b/llvm/lib/IR/Module.cpp
@@ -732,6 +732,17 @@ void Module::setOverrideStackAlignment(unsigned Align) {
   addModuleFlag(ModFlagBehavior::Error, "override-stack-alignment", Align);
 }
 
+unsigned Module::getWarnStackSize() const {
+  Metadata *MD = getModuleFlag("warn-stack-size");
+  if (auto *CI = mdconst::dyn_extract_or_null<ConstantInt>(MD))
+    return CI->getZExtValue();
+  return UINT_MAX;
+}
+
+void Module::setWarnStackSize(unsigned Threshold) {
+  addModuleFlag(ModFlagBehavior::Error, "warn-stack-size", Threshold);
+}
+
 void Module::setSDKVersion(const VersionTuple &V) {
   SmallVector<unsigned, 3> Entries;
   Entries.push_back(V.getMajor());