ValueTracking, InstSimplify: address review

Author: artagnon

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -4343,8 +4343,7 @@ static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
   if (isa<PHINode>(I))
     return nullptr;
 
-  if (Op->getType()->isVectorTy() &&
-      (!I->getType()->isVectorTy() || !isLanewiseOperation(I)))
+  if (Op->getType()->isVectorTy() && !isLanewiseOperation(I))
     // For vector types, the simplification must hold per-lane, so forbid
     // potentially cross-lane operations like shufflevector.
     return nullptr;

llvm/lib/Analysis/ValueTracking.cpp

@@ -6950,6 +6950,7 @@ bool llvm::onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V) {
 bool llvm::isLanewiseOperation(const Instruction *I) {
   if (auto *II = dyn_cast<IntrinsicInst>(I)) {
     switch (II->getIntrinsicID()) {
+    // TODO: expand this list.
     case Intrinsic::ctlz:
     case Intrinsic::cttz:
     case Intrinsic::ctpop:
@@ -6967,8 +6968,8 @@ bool llvm::isLanewiseOperation(const Instruction *I) {
     }
   }
   auto *Shuffle = dyn_cast<ShuffleVectorInst>(I);
-  return (!Shuffle || Shuffle->isIdentity() || Shuffle->isSelect()) &&
-         !isa<CallBase>(I) && !isa<BitCastInst>(I);
+  return (!Shuffle || Shuffle->isSelect()) &&
+         !isa<CallBase, BitCastInst, ExtractElementInst>(I);
 }
 
 bool llvm::isSafeToSpeculativelyExecute(const Instruction *Inst,

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -3629,7 +3629,8 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
   //  * The intrinsic is speculatable.
   //  * The select condition is not a vector, or the intrinsic does not
   //    perform cross-lane operations.
-  if (isLanewiseOperation(II))
+  if (isSafeToSpeculativelyExecuteWithVariableReplaced(&CI) &&
+      isLanewiseOperation(II))
     for (Value *Op : II->args())
       if (auto *Sel = dyn_cast<SelectInst>(Op))
         if (Instruction *R = FoldOpIntoSelect(*II, Sel))