From 9feae9f0de032c66d01d16399a4c5296e38870e3 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Wed, 17 Feb 2010 02:39:31 +0000
Subject: [PATCH] Fix SCEVExpander's existing PHI reuse checking to recognize
 the case where there are loop-invariant instructions somehow left inside the
 loop, and in a position where they won't dominate the IV increment position.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96448 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/ScalarEvolutionExpander.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index ccd6d6b2778..478d04749e2 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -658,6 +658,19 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
             IncV = 0;
             break;
           }
+          // If any of the operands don't dominate the insert position, bail.
+          // Addrec operands are always loop-invariant, so this can only happen
+          // if there are instructions which haven't been hoisted.
+          for (User::op_iterator OI = IncV->op_begin()+1,
+               OE = IncV->op_end(); OI != OE; ++OI)
+            if (Instruction *OInst = dyn_cast<Instruction>(OI))
+              if (!SE.DT->dominates(OInst, IVIncInsertPos)) {
+                IncV = 0;
+                break;
+              }
+          if (!IncV)
+            break;
+          // Advance to the next instruction.
           IncV = dyn_cast<Instruction>(IncV->getOperand(0));
           if (!IncV)
             break;