From 1abe64663e0865cf9bdc23de734df49acea2b0d4 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Wed, 22 Apr 2009 22:45:37 +0000
Subject: [PATCH] Avoid deferencing use_begin() if value does not have a use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69836 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/IndVarSimplify.cpp        |  1 +
 .../IndVarSimplify/2009-04-22-IndvarCrash.ll    | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)
 create mode 100644 test/Transforms/IndVarSimplify/2009-04-22-IndvarCrash.ll

diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 3e944d3857a..b1cde4177bf 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -806,6 +806,7 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
         // (RHS doesn't have to be constant.  There should be a better approach
         // than bottom-up pattern matching for this...)
         if (UInst && UInst->getOpcode()==Instruction::And &&
+            !UInst->use_empty() &&
             allUsesAreSameTyped(Instruction::ZExt, UInst) &&
             isa<ConstantInt>(UInst->getOperand(1))) {
           uint64_t newBitSize = LargestType->getPrimitiveSizeInBits();
diff --git a/test/Transforms/IndVarSimplify/2009-04-22-IndvarCrash.ll b/test/Transforms/IndVarSimplify/2009-04-22-IndvarCrash.ll
new file mode 100644
index 00000000000..e42f3b33354
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/2009-04-22-IndvarCrash.ll
@@ -0,0 +1,17 @@
+; RUN: llvm-as < %s | opt -indvars
+
+define i32 @t() nounwind ssp {
+entry:
+	br label %bb32
+
+bb32:		; preds = %bb32, %entry
+	%mbPartIdx.0.reg2mem.0 = phi i8 [ %2, %bb32 ], [ 0, %entry ]		; <i8> [#uses=3]
+	%0 = and i8 %mbPartIdx.0.reg2mem.0, 1		; <i8> [#uses=0]
+	%1 = zext i8 %mbPartIdx.0.reg2mem.0 to i64		; <i64> [#uses=0]
+	%2 = add i8 %mbPartIdx.0.reg2mem.0, 1		; <i8> [#uses=2]
+	%3 = icmp ugt i8 %2, 3		; <i1> [#uses=1]
+	br i1 %3, label %bb41, label %bb32
+
+bb41:		; preds = %bb32
+	ret i32 0
+}