Fix overconfident assert in ScalarEvolution::isImpliedViaMerge

We can have AddRec with loops having many predecessors.
This changes an assert to an early return.

Differential Revision: https://reviews.llvm.org/D48766

llvm-svn: 335965

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index fce2a0e905f..d52c5b0276a 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9712,8 +9712,9 @@ bool ScalarEvolution::isImpliedViaMerge(ICmpInst::Predicate Pred,
     // AddRec. It means that there is a loop which has both AddRec and Unknown
     // PHIs, for it we can compare incoming values of AddRec from above the loop
     // and latch with their respective incoming values of LPhi.
-    assert(LPhi->getNumIncomingValues() == 2 &&
-           "Phi node standing in loop header does not have exactly 2 inputs?");
+    // TODO: Generalize to handle loops with many inputs in a header.
+    if (LPhi->getNumIncomingValues() != 2) return false;
+
     auto *RLoop = RAR->getLoop();
     auto *Predecessor = RLoop->getLoopPredecessor();
     assert(Predecessor && "Loop with AddRec with no predecessor?");