[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, 3 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index ca57248..e09face1 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -138,11 +138,6 @@ char PEI::ID = 0;
 
 char &llvm::PrologEpilogCodeInserterID = PEI::ID;
 
-static cl::opt<unsigned>
-WarnStackSize("warn-stack-size", cl::Hidden, cl::init((unsigned)-1),
-              cl::desc("Warn for stack size bigger than the given"
-                       " number"));
-
 INITIALIZE_PASS_BEGIN(PEI, DEBUG_TYPE, "Prologue/Epilogue Insertion", false,
                       false)
 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
@@ -278,7 +273,9 @@ bool PEI::runOnMachineFunction(MachineFunction &MF) {
   // Warn on stack size when we exceeds the given limit.
   MachineFrameInfo &MFI = MF.getFrameInfo();
   uint64_t StackSize = MFI.getStackSize();
-  if (WarnStackSize.getNumOccurrences() > 0 && WarnStackSize < StackSize) {
+
+  unsigned Threshold = MF.getFunction().getParent()->getWarnStackSize();
+  if (StackSize > Threshold) {
     DiagnosticInfoStackSize DiagStackSize(F, StackSize);
     F.getContext().diagnose(DiagStackSize);
   }