Index: llvm/test/Transforms/MemCpyOpt/stack-move.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/MemCpyOpt/stack-move.ll
@@ -0,0 +1,892 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt < %s -passes=memcpyopt -S | FileCheck %s
+
+%struct.Foo = type { i32, i32, i32 }
+
+declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg)
+declare void @llvm.memcpy.p1.p0.i64(ptr addrspace(1) noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg)
+declare void @llvm.memcpy.p2.p1.i64(ptr addrspace(2) noalias nocapture writeonly, ptr addrspace(1) noalias nocapture readonly, i64, i1 immarg)
+declare void @llvm.memmove.p0.p0.i64(ptr nocapture writeonly, ptr nocapture readonly, i64, i1 immarg)
+
+declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
+declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
+declare void @llvm.lifetime.start.p1(i64, ptr addrspace(1) nocapture)
+declare void @llvm.lifetime.end.p1(i64, ptr addrspace(1) nocapture)
+declare void @llvm.lifetime.start.p2(i64, ptr addrspace(2) nocapture)
+declare void @llvm.lifetime.end.p2(i64, ptr addrspace(2) nocapture)
+
+declare i32 @use_nocapture(ptr nocapture)
+declare i32 @use_maycapture(ptr noundef)
+declare i32 @use_readonly(ptr readonly)
+declare i32 @use_writeonly(ptr noundef) memory(write)
+
+; TODO: Merge alloca and remove memcpy.
+define void @basic_memcpy() {
+; CHECK-LABEL: define void @basic_memcpy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Merge alloca and remove memmove.
+define void @basic_memmove() {
+; CHECK-LABEL: define void @basic_memmove() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memmove.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Merge alloca and remove load/store.
+; Tests that the optimization succeeds with a load/store pair.
+define void @load_store() {
+; CHECK-LABEL: define void @load_store() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 4, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 4, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store i32 42, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[SRC_VAL:%.*]] = load i32, ptr [[SRC]], align 4
+; CHECK-NEXT:    store i32 [[SRC_VAL]], ptr [[DEST]], align 4
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 4, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 4, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca i32, align 4
+  %dest = alloca i32, align 4
+  call void @llvm.lifetime.start.p0(i64 4, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 4, ptr nocapture %dest)
+  store i32 42, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  %src.val = load i32, ptr %src
+  store i32 %src.val, ptr %dest
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 4, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 4, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Merge alloca.
+; Tests that merging two allocas shouldn't be more poisonous, smaller aligned src is valid.
+define void @align_up() {
+; CHECK-LABEL: define void @align_up() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 8
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 8
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Merge alloca and remove memcpy, shrinkwrap lifetimes.
+; Tests that we correctly remove extra lifetime intrinsics when performing the
+; optimization.
+define void @remove_extra_lifetime_intrinsics() {
+; CHECK-LABEL: define void @remove_extra_lifetime_intrinsics() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  %3 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Merge alloca and remove memcpy, without inserting lifetime markers.
+; Tests that we won't insert lifetime markers if they don't exist originally.
+define void @no_lifetime() {
+; CHECK-LABEL: define void @no_lifetime() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  %3 = call i32 @use_nocapture(ptr nocapture %dest)
+  ret void
+}
+
+
+; TODO: Merge alloca and remove memcpy.
+; Tests that aliasing src or dest but no modification desn't prevent transformations.
+define void @alias_no_mod() {
+; CHECK-LABEL: define void @alias_no_mod() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    [[DEST_ALIAS:%.*]] = getelementptr [[STRUCT_FOO]], ptr [[DEST]], i32 0, i32 0
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[SRC_ALIAS:%.*]] = getelementptr [[STRUCT_FOO]], ptr [[SRC]], i32 0, i32 0
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  %dest.alias = getelementptr %struct.Foo, ptr %dest, i32 0, i32 0
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %src.alias = getelementptr %struct.Foo, ptr %src, i32 0, i32 0
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Scope domain
+!0 = !{!0}
+; Scope in that domain
+!1 = !{!1, !0}
+; Scope list
+!2 = !{!1}
+
+!3 = !{!"Whatever"}
+
+; TODO: Merge alloca and remove memcpy, remove noalias metadata on src.
+; Tests that we remove scoped noalias metadata from a call.
+define void @remove_scoped_noalias() {
+; CHECK-LABEL: define void @remove_scoped_noalias() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]]), !alias.scope [[META0:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]]), !noalias [[META0]]
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src), !alias.scope !2
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  %2 = call i32 @use_nocapture(ptr nocapture %dest), !noalias !2
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Merge alloca and remove memcpy, remove noalias metadata on src.
+; Tests that we remove metadata on the merged alloca.
+define void @remove_alloca_metadata() {
+; CHECK-LABEL: define void @remove_alloca_metadata() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4, !annotation [[META3:![0-9]+]]
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]]), !alias.scope [[META0]]
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]]), !noalias [[META0]]
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4, !annotation !3
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src), !alias.scope !2
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest), !noalias !2
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Merge alloca and remove memcpy.
+; Tests that we can merge alloca if the dest and src has only refs except lifetime intrinsics.
+define void @src_ref_dest_ref_after_copy() {
+; CHECK-LABEL: define void @src_ref_dest_ref_after_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_readonly(ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_readonly(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %1 = call i32 @use_readonly(ptr nocapture %src)
+  %2 = call i32 @use_readonly(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that we can merge alloca if the dest and src has only mods.
+define void @src_mod_dest_mod_after_copy() {
+; CHECK-LABEL: define void @src_mod_dest_mod_after_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_writeonly(ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_writeonly(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %1 = call i32 @use_writeonly(ptr nocapture %src)
+  %2 = call i32 @use_writeonly(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+
+; Optimization failures follow:
+
+; Tests that dynamically-sized allocas are never merged.
+define void @dynamically_sized_alloca(i64 %i) {
+; CHECK-LABEL: define void @dynamically_sized_alloca
+; CHECK-SAME: (i64 [[I:%.*]]) {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca i8, i64 [[I]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca i8, i64 [[I]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 -1, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 -1, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO:%.*]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 -1, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 -1, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca i8, i64 %i, align 4
+  %dest = alloca i8, i64 %i, align 4
+  call void @llvm.lifetime.start.p0(i64 -1, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 -1, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 -1, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 -1, ptr nocapture %dest)
+  ret void
+}
+
+
+; Tests that inalloca attributed allocas are never merged, to prevent stacksave/stackrestore handling.
+define void @inalloca() {
+; CHECK-LABEL: define void @inalloca() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca inalloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca inalloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that a memcpy with a dynamic size is never optimized.
+define void @dynamically_sized_memcpy(i64 %size) {
+; CHECK-LABEL: define void @dynamically_sized_memcpy
+; CHECK-SAME: (i64 [[SIZE:%.*]]) {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 [[SIZE]], i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 %size, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  ret void
+}
+
+; Tests that allocas with different sizes aren't merged together.
+define void @mismatched_alloca_size() {
+; CHECK-LABEL: define void @mismatched_alloca_size() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca i8, i64 24, align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca i8, i64 12, align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 24, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO:%.*]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 24, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca i8, i64 24, align 4
+  %dest = alloca i8, i64 12, align 4
+  call void @llvm.lifetime.start.p0(i64 24, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 24, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that allocas with mismatched address spaces aren't combined.
+define void @mismatched_alloca_addrspace() {
+; CHECK-LABEL: define void @mismatched_alloca_addrspace() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca i8, i64 24, align 4, addrspace(1)
+; CHECK-NEXT:    [[DEST:%.*]] = alloca i8, i64 12, align 4, addrspace(2)
+; CHECK-NEXT:    call void @llvm.lifetime.start.p1(i64 24, ptr addrspace(1) nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p2(i64 12, ptr addrspace(2) nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO:%.*]] { i32 10, i32 20, i32 30 }, ptr addrspace(1) [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr addrspace(1) nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p2.p1.i64(ptr addrspace(2) align 4 [[DEST]], ptr addrspace(1) align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    call void @llvm.lifetime.end.p1(i64 24, ptr addrspace(1) nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr addrspace(2) nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p2(i64 12, ptr addrspace(2) nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca i8, i64 24, align 4, addrspace(1)
+  %dest = alloca i8, i64 12, align 4, addrspace(2)
+  call void @llvm.lifetime.start.p1(i64 24, ptr addrspace(1) nocapture %src)
+  call void @llvm.lifetime.start.p2(i64 12, ptr addrspace(2) nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr addrspace(1) %src
+  %1 = call i32 @use_nocapture(ptr addrspace(1) nocapture %src)
+
+  call void @llvm.memcpy.p2.p1.i64(ptr addrspace(2) align 4 %dest, ptr addrspace(1) align 4 %src, i64 12, i1 false)
+
+  call void @llvm.lifetime.end.p1(i64 24, ptr addrspace(1) nocapture %src)
+  %2 = call i32 @use_nocapture(ptr addrspace(2) nocapture %dest)
+  call void @llvm.lifetime.end.p2(i64 12, ptr addrspace(2) nocapture %dest)
+  ret void
+}
+
+; Tests that volatile memcpys aren't removed.
+define void @volatile_memcpy() {
+; CHECK-LABEL: define void @volatile_memcpy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 true)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 true)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that the optimization isn't performed when the destination is captured.
+define void @dest_captured() {
+; CHECK-LABEL: define void @dest_captured() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_maycapture(ptr [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+  %2 = call i32 @use_maycapture(ptr %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that the optimization isn't performed when the source is captured.
+define void @src_captured() {
+; CHECK-LABEL: define void @src_captured() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_maycapture(ptr [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_maycapture(ptr %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Prevent this transformation
+; Tests that failure if any modref exists before the copy,
+; Exactly ref seems safe because no mod say ref would be always undefined, but to make simple and conservative.
+define void @mod_ref_before_copy() {
+; CHECK-LABEL: define void @mod_ref_before_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[R:%.*]] = call i32 @use_readonly(ptr nocapture [[DEST]])
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %r = call i32 @use_readonly(ptr nocapture %dest)
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Prevent this transformation
+; Tests that failure because copy semantics will change if dest is replaced with src.
+define void @mod_dest_before_copy() {
+; CHECK-LABEL: define void @mod_dest_before_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    store i32 13, ptr [[DEST]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  store i32 13, ptr %dest
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; TODO: Prevent transformations
+define void @mod_src_before_store_after_load() {
+; CHECK-LABEL: define void @mod_src_before_store_after_load() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    store i32 13, ptr [[DEST]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 13, i32 13, i32 13 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  store i32 13, ptr %dest
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  %src.val = load %struct.Foo, ptr %src
+  store %struct.Foo { i32 13, i32 13, i32 13 }, ptr %src
+  store %struct.Foo %src.val, ptr %dest
+
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that the optimization isn't performed,
+; when the source may have mod and dest may have ref after the full copy.
+define void @src_mod_dest_ref_after_copy() {
+; CHECK-LABEL: define void @src_mod_dest_ref_after_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 13, i32 13, i32 13 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  store %struct.Foo { i32 13, i32 13, i32 13 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that the optimization isn't performed.
+; Merging dest to src is no longer valid if conflicting Mod/Ref exist.
+define void @src_ref_dest_mod_after_copy() {
+; CHECK-LABEL: define void @src_ref_dest_mod_after_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 13, i32 13, i32 13 }, ptr [[DEST]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  store %struct.Foo { i32 13, i32 13, i32 13 }, ptr %dest
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that failure because alloca is modified through aliases, which requires recursive user ModRefChecks
+define void @dest_alias_mod_before_copy() {
+; CHECK-LABEL: define void @dest_alias_mod_before_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[DEST_ALIAS:%.*]] = getelementptr inbounds [[STRUCT_FOO]], ptr [[DEST]], i64 0, i32 1
+; CHECK-NEXT:    store i32 13, ptr [[DEST_ALIAS]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %dest.alias = getelementptr inbounds %struct.Foo, ptr %dest, i64 0, i32 1
+  store i32 13, ptr %dest.alias
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that failure because alloca is modified through aliases, which requires recursive user ModRefChecks
+define void @alias_src_ref_dest_mod_after_copy() {
+; CHECK-LABEL: define void @alias_src_ref_dest_mod_after_copy() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    [[DEST_ALIAS:%.*]] = getelementptr inbounds [[STRUCT_FOO]], ptr [[DEST]], i64 0, i32 1
+; CHECK-NEXT:    store i32 13, ptr [[DEST_ALIAS]], align 4
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  %dest.alias = getelementptr inbounds %struct.Foo, ptr %dest, i64 0, i32 1
+  store i32 13, ptr %dest.alias
+  %2 = call i32 @use_nocapture(ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}
+
+; Tests that failure because partial-sized lifetimes are counted as mod.
+define void @partial_lifetime() {
+; CHECK-LABEL: define void @partial_lifetime() {
+; CHECK-NEXT:    [[SRC:%.*]] = alloca [[STRUCT_FOO:%.*]], align 4
+; CHECK-NEXT:    [[DEST:%.*]] = alloca [[STRUCT_FOO]], align 4
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 3, ptr nocapture [[DEST]])
+; CHECK-NEXT:    store [[STRUCT_FOO]] { i32 10, i32 20, i32 30 }, ptr [[SRC]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @use_nocapture(ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[DEST]], ptr align 4 [[SRC]], i64 12, i1 false)
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 3, ptr nocapture [[SRC]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @use_nocapture(ptr nocapture [[DEST]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[SRC]])
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 12, ptr nocapture [[DEST]])
+; CHECK-NEXT:    ret void
+;
+  %src = alloca %struct.Foo, align 4
+  %dest = alloca %struct.Foo, align 4
+  call void @llvm.lifetime.start.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.start.p0(i64 3, ptr nocapture %dest)
+  store %struct.Foo { i32 10, i32 20, i32 30 }, ptr %src
+  %1 = call i32 @use_nocapture(ptr nocapture %src)
+
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %dest, ptr align 4 %src, i64 12, i1 false)
+
+  call void @llvm.lifetime.end.p0(i64 3, ptr nocapture %src)
+  %2 = call i32 @use_nocapture(ptr nocapture %dest)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %src)
+  call void @llvm.lifetime.end.p0(i64 12, ptr nocapture %dest)
+  ret void
+}