1 files changed, 15 insertions, 2 deletions
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 0309e22..b6dd174 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -1839,7 +1839,8 @@ bool CodeGenPrepare::unfoldPowerOf2Test(CmpInst *Cmp) {
 /// lose; some adjustment may be wanted there.
 ///
 /// Return true if any changes are made.
-static bool sinkCmpExpression(CmpInst *Cmp, const TargetLowering &TLI) {
+static bool sinkCmpExpression(CmpInst *Cmp, const TargetLowering &TLI,
+                              const DataLayout &DL) {
   if (TLI.hasMultipleConditionRegisters(EVT::getEVT(Cmp->getType())))
     return false;
 
@@ -1847,6 +1848,18 @@ static bool sinkCmpExpression(CmpInst *Cmp, const TargetLowering &TLI) {
   if (TLI.useSoftFloat() && isa<FCmpInst>(Cmp))
     return false;
 
+  bool UsedInPhiOrCurrentBlock = any_of(Cmp->users(), [Cmp](User *U) {
+    return isa<PHINode>(U) ||
+           cast<Instruction>(U)->getParent() == Cmp->getParent();
+  });
+
+  // Avoid sinking larger than legal integer comparisons unless its ONLY used in
+  // another BB.
+  if (UsedInPhiOrCurrentBlock && Cmp->getOperand(0)->getType()->isIntegerTy() &&
+      Cmp->getOperand(0)->getType()->getScalarSizeInBits() >
+          DL.getLargestLegalIntTypeSizeInBits())
+    return false;
+
   // Only insert a cmp in each block once.
   DenseMap<BasicBlock *, CmpInst *> InsertedCmps;
 
@@ -2224,7 +2237,7 @@ bool CodeGenPrepare::optimizeURem(Instruction *Rem) {
 }
 
 bool CodeGenPrepare::optimizeCmp(CmpInst *Cmp, ModifyDT &ModifiedDT) {
-  if (sinkCmpExpression(Cmp, *TLI))
+  if (sinkCmpExpression(Cmp, *TLI, *DL))
     return true;
 
   if (combineToUAddWithOverflow(Cmp, ModifiedDT))