| Anna Thomas | b2d12b8 | 2016-08-09 20:00:47 +0000 | [diff] [blame] | 1 | ; RUN: opt < %s -S -early-cse | FileCheck %s |
| 2 | ; RUN: opt < %s -S -passes=early-cse | FileCheck %s |
| 3 | |
| 4 | declare {}* @llvm.invariant.start.p0i8(i64, i8* nocapture) nounwind readonly |
| 5 | declare void @llvm.invariant.end.p0i8({}*, i64, i8* nocapture) nounwind |
| 6 | |
| 7 | ; Check that we do load-load forwarding over invariant.start, since it does not |
| 8 | ; clobber memory |
| 9 | define i8 @test1(i8 *%P) { |
| 10 | ; CHECK-LABEL: @test1( |
| 11 | ; CHECK-NEXT: %V1 = load i8, i8* %P |
| 12 | ; CHECK-NEXT: %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 13 | ; CHECK-NEXT: ret i8 0 |
| 14 | |
| 15 | |
| 16 | %V1 = load i8, i8* %P |
| 17 | %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 18 | %V2 = load i8, i8* %P |
| 19 | %Diff = sub i8 %V1, %V2 |
| 20 | ret i8 %Diff |
| 21 | } |
| 22 | |
| 23 | |
| 24 | ; Trivial Store->load forwarding over invariant.start |
| 25 | define i8 @test2(i8 *%P) { |
| 26 | ; CHECK-LABEL: @test2( |
| 27 | ; CHECK-NEXT: store i8 42, i8* %P |
| 28 | ; CHECK-NEXT: %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 29 | ; CHECK-NEXT: ret i8 42 |
| 30 | |
| 31 | |
| 32 | store i8 42, i8* %P |
| 33 | %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 34 | %V1 = load i8, i8* %P |
| 35 | ret i8 %V1 |
| 36 | } |
| 37 | |
| 38 | ; We can DSE over invariant.start calls, since the first store to |
| 39 | ; %P is valid, and the second store is actually unreachable based on semantics |
| 40 | ; of invariant.start. |
| 41 | define void @test3(i8* %P) { |
| 42 | |
| 43 | ; CHECK-LABEL: @test3( |
| 44 | ; CHECK-NEXT: %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 45 | ; CHECK-NEXT: store i8 60, i8* %P |
| 46 | |
| 47 | |
| 48 | store i8 50, i8* %P |
| 49 | %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 50 | store i8 60, i8* %P |
| 51 | ret void |
| 52 | } |
| 53 | |
| 54 | |
| 55 | ; FIXME: Now the first store can actually be eliminated, since there is no read within |
| 56 | ; the invariant region, between start and end. |
| 57 | define void @test4(i8* %P) { |
| 58 | |
| 59 | ; CHECK-LABEL: @test4( |
| 60 | ; CHECK-NEXT: store i8 50, i8* %P |
| 61 | ; CHECK-NEXT: %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 62 | ; CHECK-NEXT: call void @llvm.invariant.end.p0i8({}* %i, i64 1, i8* %P) |
| 63 | ; CHECK-NEXT: store i8 60, i8* %P |
| 64 | |
| 65 | |
| 66 | store i8 50, i8* %P |
| 67 | %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %P) |
| 68 | call void @llvm.invariant.end.p0i8({}* %i, i64 1, i8* %P) |
| 69 | store i8 60, i8* %P |
| 70 | ret void |
| 71 | } |