Add InstCombine/InstructionSimplify support for Freeze Instruction
Summary:
- Add llvm::SimplifyFreezeInst
- Add InstCombiner::visitFreeze
- Add llvm tests
Reviewers: majnemer, sanjoy, reames, lebedev.ri, spatel
Reviewed By: reames, lebedev.ri
Subscribers: reames, lebedev.ri, filcab, regehr, trentxintong, llvm-commits
Differential Revision: https://reviews.llvm.org/D29013
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index cc5acf5..b26c629 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4221,6 +4221,20 @@
return llvm::any_of(GuardingBranches, AllUsesGuardedByBranch);
}
+bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V) {
+ // If the value is a freeze instruction, then it can never
+ // be undef or poison.
+ if (isa<FreezeInst>(V))
+ return true;
+ // TODO: Some instructions are guaranteed to return neither undef
+ // nor poison if their arguments are not poison/undef.
+
+ // TODO: Deal with other Constant subclasses.
+ if (isa<ConstantInt>(V) || isa<GlobalVariable>(V))
+ return true;
+
+ return false;
+}
OverflowResult llvm::computeOverflowForSignedAdd(const AddOperator *Add,
const DataLayout &DL,