Explicitly check for presence of correct results in instcombine memmove test

[dneilson]

Summary

Rather than testing for expected results, test/Transforms/InstCombine/memmove.ll is testing for the absence of calls to llvm.memmove.

In the case of test3, the test has stopped testing for materialization of loads/stores, but remained passing due to testing for the absence of llvm.memset calls rather than the presence of load/store instructions. Right now this test ends up with an empty function body because the alloca is eliminated as safe-to-remove, which results in the llvm.memmove calls being eliminated due to a pointer arg being undef; so it is not testing for conversion of llvm.memmove into load/store instructions at all.

[efriedma]

LGTM.

test/Transforms/InstCombine/memmove.ll

 ; This test makes sure that memmove instructions are properly eliminated.
 ;
-; RUN: opt < %s -instcombine -S | not grep "call void @llvm.memmove"
+; RUN: opt < %s -instcombine -S | FileCheck %s
 
 @S = internal constant [33 x i8] c"panic: restorelist inconsistency\00"    ; <[33 x i8]*> [#uses=1]
 @h = constant [2 x i8] c"h\00"    ; <[2 x i8]*> [#uses=1]
 @hel = constant [4 x i8] c"hel\00"    ; <[4 x i8]*> [#uses=1]
 @hello_u = constant [8 x i8] c"hello_u\00"    ; <[8 x i8]*> [#uses=1]
 
 define void @test1(i8* %A, i8* %B, i32 %N) {
-  call void @llvm.memmove.p0i8.p0i8.i32(i8* %A, i8* %B, i32 0, i32 1, i1 false)
-  ret void
+  ;; CHECK-LABEL: test1
+  ;; CHECK-NEXT: ret void
+  call void @llvm.memmove.p0i8.p0i8.i32(i8* %A, i8* %B, i32 0, i32 1, i1 false)
+  ret void
 }
 
 define void @test2(i8* %A, i32 %N) {
-        ;; dest can't alias source since we can't write to source!
-  call void @llvm.memmove.p0i8.p0i8.i32(i8* %A, i8* getelementptr inbounds ([33 x i8], [33 x i8]* @S, i32 0, i32 0), i32 %N, i32 1, i1 false)
-  ret void
+  ;; CHECK-LABEL: test2
+  ;; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %A, i8* getelementptr inbounds ([33 x i8], [33 x i8]* @S, i{{32|64}} 0, i{{32|64}} 0), i32 %N, i32 1, i1 false)
+  ;; CHECK-NEXT: ret void
+  call void @llvm.memmove.p0i8.p0i8.i32(i8* %A, i8* getelementptr inbounds ([33 x i8], [33 x i8]* @S, i32 0, i32 0), i32 %N, i32 1, i1 false)
+  ret void
 }
 
-define i32 @test3() {
-  %h_p = getelementptr [2 x i8], [2 x i8]* @h, i32 0, i32 0    ; <i8*> [#uses=1]
-  %hel_p = getelementptr [4 x i8], [4 x i8]* @hel, i32 0, i32 0    ; <i8*> [#uses=1]
-  %hello_u_p = getelementptr [8 x i8], [8 x i8]* @hello_u, i32 0, i32 0    ; <i8*> [#uses=1]
-  %target = alloca [1024 x i8]    ; <[1024 x i8]*> [#uses=1]
-  %target_p = getelementptr [1024 x i8], [1024 x i8]* %target, i32 0, i32 0    ; <i8*> [#uses=3]
-        call void @llvm.memmove.p0i8.p0i8.i32(i8* %target_p, i8* %h_p, i32 2, i32 2, i1 false)
-        call void @llvm.memmove.p0i8.p0i8.i32(i8* %target_p, i8* %hel_p, i32 4, i32 4, i1 false)
-        call void @llvm.memmove.p0i8.p0i8.i32(i8* %target_p, i8* %hello_u_p, i32 8, i32 8, i1 false)
-  ret i32 0
+define i32 @test3([1024 x i8]* %target) { ; arg: [1024 x i8]*> [#uses=1]
+  ;; CHECK-LABEL: test3
+  ;; CHECK-NEXT: [[P1:%[^\s]+]] = bitcast [1024 x i8]* %target to i16*
+  ;; CHECK-NEXT: store i16 104, i16* [[P1]], align 2
+  ;; CHECK-NEXT: [[P2:%[^\s]+]] = bitcast [1024 x i8]* %target to i32*
+  ;; CHECK-NEXT: store i32 7103848, i32* [[P2]], align 4
+  ;; CHECK-NEXT: [[P3:%[^\s]+]] = bitcast [1024 x i8]* %target to i64*
+  ;; CHECK-NEXT: store i64 33037504440198504, i64* [[P3]], align 8
+  ;; CHECK-NEXT: ret i32 0
+  %h_p = getelementptr [2 x i8], [2 x i8]* @h, i32 0, i32 0    ; <i8*> [#uses=1]
+  %hel_p = getelementptr [4 x i8], [4 x i8]* @hel, i32 0, i32 0    ; <i8*> [#uses=1]
+  %hello_u_p = getelementptr [8 x i8], [8 x i8]* @hello_u, i32 0, i32 0    ; <i8*> [#uses=1]
+  %target_p = getelementptr [1024 x i8], [1024 x i8]* %target, i32 0, i32 0    ; <i8*> [#uses=3]
+  ret i32 0
 }
 
 ; PR2370
 define void @test4(i8* %a) {
+  ;; CHECK-LABEL: test4
+  ;; CHECK-NEXT: ret void
   tail call void @llvm.memmove.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 false)
   ret void
 }
 
-declare void @llvm.memmove.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
+declare void @llvm.memmove.p0i8.p0i8.i32(i8* nocapture, i8* nocapture readonly, i32, i32, i1) argmemonly nounwind