DSE removes the unused gep\store, fix up the test to account

Author: farzonl

llvm/test/tools/dxil-dis/lifetimes.ll

@@ -4,10 +4,8 @@ target triple = "dxil-unknown-shadermodel6.7-library"
 define void @test_lifetimes()  {
 ; CHECK-LABEL: test_lifetimes
 ; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [2 x i32], align 4
-; CHECK-NEXT: [[GEP:%.*]] = getelementptr [2 x i32], [2 x i32]* [[ALLOCA]], i32 0, i32 0
 ; CHECK-NEXT: [[BITCAST:%.*]] = bitcast [2 x i32]* [[ALLOCA]] to i8*
 ; CHECK-NEXT: call void @llvm.lifetime.start(i64 8, i8* nonnull [[BITCAST]])
-; CHECK-NEXT: store i32 0, i32* [[GEP]], align 4
 ; CHECK-NEXT: [[BITCAST:%.*]] = bitcast [2 x i32]* [[ALLOCA]] to i8*
 ; CHECK-NEXT: call void @llvm.lifetime.end(i64 8, i8* nonnull [[BITCAST]])
 ; CHECK-NEXT: ret void