Add a flag to debug automatic variable initialization

Summary:
Add -ftrivial-auto-var-init-stop-after= to limit the number of times
stack variables are initialized when -ftrivial-auto-var-init= is used to
initialize stack variables to zero or a pattern. This flag can be used
to bisect uninitialized uses of a stack variable exposed by automatic
variable initialization, such as http://crrev.com/c/2020401.

Reviewers: jfb, vitalybuka, kcc, glider, rsmith, rjmccall, pcc, eugenis, vlad.tsyrklevich

Reviewed By: jfb

Subscribers: phosek, hubert.reinterpretcast, srhines, MaskRay, george.burgess.iv, dexonsmith, inglorion, gbiv, llozano, manojgupta, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77168

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 864488c..17d42c5 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -302,6 +302,7 @@ private:
   const HeaderSearchOptions &HeaderSearchOpts; // Only used for debug info.
   const PreprocessorOptions &PreprocessorOpts; // Only used for debug info.
   const CodeGenOptions &CodeGenOpts;
+  unsigned NumAutoVarInit = 0;
   llvm::Module &TheModule;
   DiagnosticsEngine &Diags;
   const TargetInfo &Target;
@@ -1393,6 +1394,7 @@ public:
   CharUnits getNaturalPointeeTypeAlignment(QualType T,
                                            LValueBaseInfo *BaseInfo = nullptr,
                                            TBAAAccessInfo *TBAAInfo = nullptr);
+  bool stopAutoInit();
 
 private:
   llvm::Constant *GetOrCreateLLVMFunction(