vendor/llvm/llvm-trunk-r321414

1 files changed, 16 insertions, 3 deletions

diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index 6b0377e0ecb3..1476f7850cf0 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -282,7 +282,7 @@ bool JumpThreading::runOnFunction(Function &F) {
   auto AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
   std::unique_ptr<BlockFrequencyInfo> BFI;
   std::unique_ptr<BranchProbabilityInfo> BPI;
-  bool HasProfileData = F.getEntryCount().hasValue();
+  bool HasProfileData = F.hasProfileData();
   if (HasProfileData) {
     LoopInfo LI{DominatorTree(F)};
     BPI.reset(new BranchProbabilityInfo(F, LI, TLI));
@@ -307,8 +307,7 @@ PreservedAnalyses JumpThreadingPass::run(Function &F,
 
   std::unique_ptr<BlockFrequencyInfo> BFI;
   std::unique_ptr<BranchProbabilityInfo> BPI;
-  bool HasProfileData = F.getEntryCount().hasValue();
-  if (HasProfileData) {
+  if (F.hasProfileData()) {
     LoopInfo LI{DominatorTree(F)};
     BPI.reset(new BranchProbabilityInfo(F, LI, &TLI));
     BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
@@ -1333,6 +1332,20 @@ bool JumpThreadingPass::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
   // code size.
   BasicBlock *UnavailablePred = nullptr;
 
+  // If the value is unavailable in one of predecessors, we will end up
+  // inserting a new instruction into them. It is only valid if all the
+  // instructions before LI are guaranteed to pass execution to its successor,
+  // or if LI is safe to speculate.
+  // TODO: If this logic becomes more complex, and we will perform PRE insertion
+  // farther than to a predecessor, we need to reuse the code from GVN's PRE.
+  // It requires domination tree analysis, so for this simple case it is an
+  // overkill.
+  if (PredsScanned.size() != AvailablePreds.size() &&
+      !isSafeToSpeculativelyExecute(LI))
+    for (auto I = LoadBB->begin(); &*I != LI; ++I)
+      if (!isGuaranteedToTransferExecutionToSuccessor(&*I))
+        return false;
+
   // If there is exactly one predecessor where the value is unavailable, the
   // already computed 'OneUnavailablePred' block is it.  If it ends in an
   // unconditional branch, we know that it isn't a critical edge.