From ed297abb0a9317e7b58d66bc8671d6306d6e1fff Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Sat, 1 Nov 2014 23:46:05 +0000
Subject: [PATCH] InstCombine: Don't assume that m_ZExt matches an Instruction

m_ZExt might bind against a ConstantExpr instead of an Instruction.
Assuming this, using cast<Instruction>, results in InstCombine crashing.

Instead, introduce ZExtOperator to bridge both Instruction and
ConstantExpr ZExts.

This fixes PR21445.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221069 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/IR/Operator.h                         |  2 ++
 lib/Transforms/InstCombine/InstCombineCompares.cpp |  4 ++--
 test/Transforms/InstCombine/overflow-mul.ll        | 13 +++++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/llvm/IR/Operator.h b/include/llvm/IR/Operator.h
index dba44b94f15..0933f217023 100644
--- a/include/llvm/IR/Operator.h
+++ b/include/llvm/IR/Operator.h
@@ -358,6 +358,8 @@ class LShrOperator
 };
 
 
+class ZExtOperator : public ConcreteOperator<Operator, Instruction::ZExt> {};
+
 
 class GEPOperator
   : public ConcreteOperator<Operator, Instruction::GetElementPtr> {
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index bd1b67ddcfa..f7eb16cbb96 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2160,8 +2160,8 @@ static Instruction *ProcessUMulZExtIdiom(ICmpInst &I, Value *MulVal,
   Instruction *MulInstr = cast<Instruction>(MulVal);
   assert(MulInstr->getOpcode() == Instruction::Mul);
 
-  Instruction *LHS = cast<Instruction>(MulInstr->getOperand(0)),
-              *RHS = cast<Instruction>(MulInstr->getOperand(1));
+  auto *LHS = cast<ZExtOperator>(MulInstr->getOperand(0)),
+       *RHS = cast<ZExtOperator>(MulInstr->getOperand(1));
   assert(LHS->getOpcode() == Instruction::ZExt);
   assert(RHS->getOpcode() == Instruction::ZExt);
   Value *A = LHS->getOperand(0), *B = RHS->getOperand(0);
diff --git a/test/Transforms/InstCombine/overflow-mul.ll b/test/Transforms/InstCombine/overflow-mul.ll
index cbb2f5f9500..6d8d40bcac3 100644
--- a/test/Transforms/InstCombine/overflow-mul.ll
+++ b/test/Transforms/InstCombine/overflow-mul.ll
@@ -173,3 +173,16 @@ define <4 x i32> @pr20113(<4 x i16> %a, <4 x i16> %b) {
   %vcgez.i = sext <4 x i1> %tmp to <4 x i32>
   ret <4 x i32> %vcgez.i
 }
+
+@pr21445_data = external global i32
+define i1 @pr21445(i8 %a) {
+; CHECK-LABEL: @pr21445(
+; CHECK-NEXT:  %[[umul:.*]] = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 %a, i8 ptrtoint (i32* @pr21445_data to i8))
+; CHECK-NEXT:  %[[cmp:.*]] = extractvalue { i8, i1 } %[[umul]], 1
+; CHECK-NEXT:  ret i1 %[[cmp]]
+  %ext = zext i8 %a to i32
+  %mul = mul i32 %ext, zext (i8 ptrtoint (i32* @pr21445_data to i8) to i32)
+  %and = and i32 %mul, 255
+  %cmp = icmp ne i32 %mul, %and
+  ret i1 %cmp
+}
-- 
2.34.1