From 326d976eb2b03d1f2b7537d7b90dff264fd84378 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Tue, 15 Feb 2011 05:00:24 +0000
Subject: [PATCH] Fix thinko. Cmp can be the first instruction in a MBB.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125552 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/PeepholeOptimizer.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/CodeGen/PeepholeOptimizer.cpp b/lib/CodeGen/PeepholeOptimizer.cpp
index 3474f755b8e..5d7123caa01 100644
--- a/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/lib/CodeGen/PeepholeOptimizer.cpp
@@ -331,7 +331,8 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
     ImmDefRegs.clear();
     ImmDefMIs.clear();
 
-    MachineBasicBlock::iterator PMII = I->begin();
+    bool First = true;
+    MachineBasicBlock::iterator PMII;
     for (MachineBasicBlock::iterator
            MII = I->begin(), MIE = I->end(); MII != MIE; ) {
       MachineInstr *MI = &*MII;
@@ -348,7 +349,7 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
         if (OptimizeCmpInstr(MI, MBB)) {
           // MI is deleted.
           Changed = true;
-          MII = llvm::next(PMII);
+          MII = First ? I->begin() : llvm::next(PMII);
           continue;
         }
       }
@@ -360,6 +361,8 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
         if (SeenMoveImm)
           Changed |= FoldImmediate(MI, MBB, ImmDefRegs, ImmDefMIs);
       }
+
+      First = false;
       PMII = MII;
       ++MII;
     }
-- 
2.34.1