Add element-atomic mem intrinsic canary tests for InstCombine.

[dneilson]

Summary

Add canary tests to verify that InstCombine currently does nothing with the element atomic memory intrinsics for memmove and memset.

Placeholder tests that will fail once element atomic @llvm.mem[move|set] instrinsics have been added to the MemIntrinsic class hierarchy. These will act as a reminder to verify that inst combine handles these intrinsics properly once they have been added to that class hierarchy.

[reames]

FYI, Daniel and I are talking about this one offline and are going to iterate quickly on testing style. You'll see a couple rounds of updated patches on this within the next few minutes.

[dneilson]

Refactor tests to make intent clearer.

[dneilson]

Header comment was ambiguous about memcpy/memmove being element atomic forms.

[reames]

LGTM w/minor comment optional

test/Transforms/InstCombine/element-atomic-memintrins.ll

10

minor: I'd add "(yet)" to each of your comments.

20

I mentioned to Daniel that instcombine also contains trivial DSE which should eventually trigger here, but given both cases are covered, I didn't ask for a separate test.

test/Transforms/InstCombine/element-atomic-memintrins.ll

+;; Placeholder tests that will fail once element atomic @llvm.mem[move|set] instrinsics have
+;; been added to the MemIntrinsic class hierarchy. These will act as a reminder to
+;; verify that inst combine handles these intrinsics properly once they have been
+;; added to that class hierarchy.
+
+; RUN: opt -instcombine -S < %s | FileCheck %s
+
+;; ---- memset -----
+
+; Ensure 0-length memset isn't removed
+define void @test_memset_zero_length(i8* %dest) {
+  ; CHECK-LABEL: test_memset_zero_length
+  ; CHECK-NEXT: call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 0, i32 1)
+  ; CHECK-NEXT: ret void
+  call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 0, i32 1)
+  ret void
+}
+
+; Ensure that small-sized memsets don't convert to stores
+define void @test_memset_to_store(i8* %dest) {
+  ; CHECK-LABEL: test_memset_to_store
+  ; CHECK-NEXT: call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 1, i32 1)
+  ; CHECK-NEXT: call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 2, i32 1)
+  ; CHECK-NEXT: call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 4, i32 1)
+  ; CHECK-NEXT: call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 8, i32 1)
+  ; CHECK-NEXT: ret void
+  call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 1, i32 1)
+  call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 2, i32 1)
+  call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 4, i32 1)
+  call void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* align 1 %dest, i8 1, i32 8, i32 1)
+  ret void
+}
+
+declare void @llvm.memset.element.unordered.atomic.p0i8.i32(i8* nocapture writeonly, i8, i32, i32) nounwind argmemonly
+
+
+;; =========================================
+;; ----- memmove ------
+
+; memmove from a global constant source does not become memcpy
+@gconst = constant [8 x i8] c"0123456\00"
+define void @test_memmove_to_memcpy(i8* %dest) {
+  ; CHECK-LABEL: test_memmove_to_memcpy
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 getelementptr inbounds ([8 x i8], [8 x i8]* @gconst, i64 0, i64 0), i32 8, i32 1)
+  ; CHECK-NEXT: ret void
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 getelementptr inbounds ([8 x i8], [8 x i8]* @gconst, i64 0, i64 0), i32 8, i32 1)
+  ret void
+}
+
+define void @test_memmove_zero_length(i8* %dest, i8* %src) {
+  ; CHECK-LABEL: test_memmove_zero_length
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 0, i32 1)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 2 %dest, i8* align 2 %src, i32 0, i32 2)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 4 %dest, i8* align 4 %src, i32 0, i32 4)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 8 %dest, i8* align 8 %src, i32 0, i32 8)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 16 %dest, i8* align 16 %src, i32 0, i32 16)
+  ; CHECK-NEXT: ret void
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 0, i32 1)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 2 %dest, i8* align 2 %src, i32 0, i32 2)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 4 %dest, i8* align 4 %src, i32 0, i32 4)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 8 %dest, i8* align 8 %src, i32 0, i32 8)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 16 %dest, i8* align 16 %src, i32 0, i32 16)
+  ret void  
+}
+
+; memmove with src==dest is removed
+define void @test_memmove_removed(i8* %srcdest, i32 %sz) {
+  ; CHECK-LABEL: test_memmove_removed
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %srcdest, i8* align 1 %srcdest, i32 %sz, i32 1)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 2 %srcdest, i8* align 2 %srcdest, i32 %sz, i32 2)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 4 %srcdest, i8* align 4 %srcdest, i32 %sz, i32 4)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 8 %srcdest, i8* align 8 %srcdest, i32 %sz, i32 8)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 16 %srcdest, i8* align 16 %srcdest, i32 %sz, i32 16)
+  ; CHECK-NEXT: ret void
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %srcdest, i8* align 1 %srcdest, i32 %sz, i32 1)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 2 %srcdest, i8* align 2 %srcdest, i32 %sz, i32 2)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 4 %srcdest, i8* align 4 %srcdest, i32 %sz, i32 4)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 8 %srcdest, i8* align 8 %srcdest, i32 %sz, i32 8)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 16 %srcdest, i8* align 16 %srcdest, i32 %sz, i32 16)
+  ret void
+}
+
+; memmove with a small constant length is converted to a load/store pair
+define void @test_memmove_loadstore(i8* %dest, i8* %src) {
+  ; CHECK-LABEL: test_memmove_loadstore
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 1, i32 1)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 2, i32 1)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 4, i32 1)
+  ; CHECK-NEXT: call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 8, i32 1)
+  ; CHECK-NEXT: ret void
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 1, i32 1)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 2, i32 1)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 4, i32 1)
+  call void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* align 1 %dest, i8* align 1 %src, i32 8, i32 1)
+  ret void
+}
+
+declare void @llvm.memmove.element.unordered.atomic.p0i8.p0i8.i32(i8* nocapture writeonly, i8* nocapture readonly, i32, i32) nounwind argmemonly