[LAA] Prevent invalid IR for loop-invariant bound in loop body
Summary:
If LAA expands a bound that is loop invariant, but not hoisted out
of the loop body, it used to use that value anyway, causing a
non-domination error, because the memcheck block is of course not
dominated by the scalar loop body. Detect this situation and expand
the SCEV expression instead.
Fixes PR31251
Reviewers: anemet
Subscribers: mzolotukhin, llvm-commits
Differential Revision: https://reviews.llvm.org/D27397
llvm-svn: 288705
diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index 01a2f46..2f3dca3 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1870,18 +1870,24 @@
Value *Ptr = PtrRtChecking.Pointers[CG->Members[0]].PointerValue;
const SCEV *Sc = SE->getSCEV(Ptr);
+ unsigned AS = Ptr->getType()->getPointerAddressSpace();
+ LLVMContext &Ctx = Loc->getContext();
+
+ // Use this type for pointer arithmetic.
+ Type *PtrArithTy = Type::getInt8PtrTy(Ctx, AS);
+
if (SE->isLoopInvariant(Sc, TheLoop)) {
DEBUG(dbgs() << "LAA: Adding RT check for a loop invariant ptr:" << *Ptr
<< "\n");
- return {Ptr, Ptr};
+ // Ptr could be in the loop body. If so, expand a new one at the correct
+ // location.
+ Instruction *Inst = dyn_cast<Instruction>(Ptr);
+ Value *NewPtr = (Inst && TheLoop->contains(Inst))
+ ? Exp.expandCodeFor(Sc, PtrArithTy, Loc)
+ : Ptr;
+ return {NewPtr, NewPtr};
} else {
- unsigned AS = Ptr->getType()->getPointerAddressSpace();
- LLVMContext &Ctx = Loc->getContext();
-
- // Use this type for pointer arithmetic.
- Type *PtrArithTy = Type::getInt8PtrTy(Ctx, AS);
Value *Start = nullptr, *End = nullptr;
-
DEBUG(dbgs() << "LAA: Adding RT check for range:\n");
Start = Exp.expandCodeFor(CG->Low, PtrArithTy, Loc);
End = Exp.expandCodeFor(CG->High, PtrArithTy, Loc);