Fix SCEVExpander's canonical addrec expansion code to work on loops that
aren't in canonical loop-simplify form, since it doesn't itself depend
on LoopSimplify. This means handling loops without preheaders and loops
with multiple backedges.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82905 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index fd37d7b..02cfed7 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -680,29 +680,22 @@
// Create and insert the PHI node for the induction variable in the
// specified loop.
BasicBlock *Header = L->getHeader();
- BasicBlock *Preheader = L->getLoopPreheader();
PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin());
InsertedValues.insert(PN);
- PN->addIncoming(Constant::getNullValue(Ty), Preheader);
- pred_iterator HPI = pred_begin(Header);
- assert(HPI != pred_end(Header) && "Loop with zero preds???");
- if (!L->contains(*HPI)) ++HPI;
- assert(HPI != pred_end(Header) && L->contains(*HPI) &&
- "No backedge in loop?");
-
- // Insert a unit add instruction right before the terminator corresponding
- // to the back-edge.
Constant *One = ConstantInt::get(Ty, 1);
- Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next",
- (*HPI)->getTerminator());
- InsertedValues.insert(Add);
-
- pred_iterator PI = pred_begin(Header);
- if (*PI == Preheader)
- ++PI;
- PN->addIncoming(Add, *PI);
- return PN;
+ for (pred_iterator HPI = pred_begin(Header), HPE = pred_end(Header);
+ HPI != HPE; ++HPI)
+ if (L->contains(*HPI)) {
+ // Insert a unit add instruction right before the terminator corresponding
+ // to the back-edge.
+ Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next",
+ (*HPI)->getTerminator());
+ InsertedValues.insert(Add);
+ PN->addIncoming(Add, *HPI);
+ } else {
+ PN->addIncoming(Constant::getNullValue(Ty), *HPI);
+ }
}
// {0,+,F} --> {0,+,1} * F