[RS4GC] Use an value handle to help isolate errors quickly

[oota-llvm.git] / lib / Transforms / Scalar / RewriteStatepointsForGC.cpp

diff --git a/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index a5fbbf92d9bcffbfcd436dbef090546b4cb9eeb0..d72133287f5656a2d7250118760c692915e78590 100644 (file)
--- a/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -115,7 +115,8 @@ struct RewriteStatepointsForGC : public ModulePass {
   /// heap.  stripNonValidAttributes (conservatively) restores correctness
   /// by erasing all attributes in the module that externally imply
   /// dereferenceability.
-  ///
+  /// Similar reasoning also applies to the noalias attributes. gc.statepoint
+  /// can touch the entire heap including noalias objects.
   void stripNonValidAttributes(Module &M);
 
   // Helpers for stripNonValidAttributes
@@ -252,9 +253,8 @@ static bool containsGCPtrType(Type *Ty) {
   if (ArrayType *AT = dyn_cast<ArrayType>(Ty))
     return containsGCPtrType(AT->getElementType());
   if (StructType *ST = dyn_cast<StructType>(Ty))
-    return std::any_of(
-        ST->subtypes().begin(), ST->subtypes().end(),
-        [](Type *SubType) { return containsGCPtrType(SubType); });
+    return std::any_of(ST->subtypes().begin(), ST->subtypes().end(),
+                       containsGCPtrType);
   return false;
 }
 
@@ -641,7 +641,7 @@ public:
 
 private:
   Status status;
-  Value *base; // non null only if status == base
+  AssertingVH<Value> base; // non null only if status == base
 };
 }
 
@@ -1098,10 +1098,10 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
     NewInsts.erase(BaseI);
     ReverseMap.erase(BaseI);
     BaseI->replaceAllUsesWith(Replacement);
-    BaseI->eraseFromParent();
     assert(States.count(BDV));
     assert(States[BDV].isConflict() && States[BDV].getBase() == BaseI);
     States[BDV] = BDVState(BDVState::Conflict, Replacement);
+    BaseI->eraseFromParent();
   };
   const DataLayout &DL = cast<Instruction>(def)->getModule()->getDataLayout();
   while (!Worklist.empty()) {
@@ -1226,7 +1226,7 @@ static void recomputeLiveInValues(GCPtrLivenessData &RevisedLivenessData,
                                   PartiallyConstructedSafepointRecord &result);
 
 static void recomputeLiveInValues(
-    Function &F, DominatorTree &DT, Pass *P, ArrayRef<CallSite> toUpdate,
+    Function &F, DominatorTree &DT, ArrayRef<CallSite> toUpdate,
     MutableArrayRef<struct PartiallyConstructedSafepointRecord> records) {
   // TODO-PERF: reuse the original liveness, then simply run the dataflow
   // again.  The old values are still live and will help it stabilize quickly.
@@ -1917,7 +1917,7 @@ static void insertUseHolderAfter(CallSite &CS, const ArrayRef<Value *> Values,
     // No values to hold live, might as well not insert the empty holder
     return;
 
-  Module *M = CS.getInstruction()->getParent()->getParent()->getParent();
+  Module *M = CS.getInstruction()->getModule();
   // Use a dummy vararg function to actually hold the values live
   Function *Func = cast<Function>(M->getOrInsertFunction(
       "__tmp_use", FunctionType::get(Type::getVoidTy(M->getContext()), true)));
@@ -1937,7 +1937,7 @@ static void insertUseHolderAfter(CallSite &CS, const ArrayRef<Value *> Values,
 }
 
 static void findLiveReferences(
-    Function &F, DominatorTree &DT, Pass *P, ArrayRef<CallSite> toUpdate,
+    Function &F, DominatorTree &DT, ArrayRef<CallSite> toUpdate,
     MutableArrayRef<struct PartiallyConstructedSafepointRecord> records) {
   GCPtrLivenessData OriginalLivenessData;
   computeLiveInValues(DT, F, OriginalLivenessData);
@@ -2276,7 +2276,8 @@ static void rematerializeLiveValues(CallSite CS,
   }
 }
 
-static bool insertParsePoints(Function &F, DominatorTree &DT, Pass *P,
+static bool insertParsePoints(Function &F, DominatorTree &DT,
+                              TargetTransformInfo &TTI,
                               SmallVectorImpl<CallSite> &ToUpdate) {
 #ifndef NDEBUG
   // sanity check the input
@@ -2333,7 +2334,7 @@ static bool insertParsePoints(Function &F, DominatorTree &DT, Pass *P,
 
   // A) Identify all gc pointers which are statically live at the given call
   // site.
-  findLiveReferences(F, DT, P, ToUpdate, Records);
+  findLiveReferences(F, DT, ToUpdate, Records);
 
   // B) Find the base pointers for each live pointer
   /* scope for caching */ {
@@ -2375,7 +2376,7 @@ static bool insertParsePoints(Function &F, DominatorTree &DT, Pass *P,
   // By selecting base pointers, we've effectively inserted new uses. Thus, we
   // need to rerun liveness.  We may *also* have inserted new defs, but that's
   // not the key issue.
-  recomputeLiveInValues(F, DT, P, ToUpdate, Records);
+  recomputeLiveInValues(F, DT, ToUpdate, Records);
 
   if (PrintBasePointers) {
     for (auto &Info : Records) {
@@ -2406,9 +2407,6 @@ static bool insertParsePoints(Function &F, DominatorTree &DT, Pass *P,
   // In order to reduce live set of statepoint we might choose to rematerialize
   // some values instead of relocating them. This is purely an optimization and
   // does not influence correctness.
-  TargetTransformInfo &TTI =
-    P->getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
-
   for (size_t i = 0; i < Records.size(); i++)
     rematerializeLiveValues(ToUpdate[i], Records[i], TTI);
 
@@ -2501,6 +2499,8 @@ static void RemoveNonValidAttrAtIndex(LLVMContext &Ctx, AttrHolder &AH,
   if (AH.getDereferenceableOrNullBytes(Index))
     R.addAttribute(Attribute::get(Ctx, Attribute::DereferenceableOrNull,
                                   AH.getDereferenceableOrNullBytes(Index)));
+  if (AH.doesNotAlias(Index))
+    R.addAttribute(Attribute::NoAlias);
 
   if (!R.empty())
     AH.setAttributes(AH.getAttributes().removeAttributes(
@@ -2594,6 +2594,8 @@ bool RewriteStatepointsForGC::runOnFunction(Function &F) {
     return false;
 
   DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
+  TargetTransformInfo &TTI =
+      getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
 
   auto NeedsRewrite = [](Instruction &I) {
     if (UseDeoptBundles) {
@@ -2674,7 +2676,7 @@ bool RewriteStatepointsForGC::runOnFunction(Function &F) {
       }
   }
 
-  MadeChange |= insertParsePoints(F, DT, this, ParsePointNeeded);
+  MadeChange |= insertParsePoints(F, DT, TTI, ParsePointNeeded);
   return MadeChange;
 }