[MemCpyOpt] Fix lifetime marker sizes in tests (NFC)

As pointed out in #143782,
these tests were specifying the size in bits instead of bytes.

In order to preserve the intent of the tests, add a use of %src,
which prevents stack-move optimization. These are supposed to test
the handling of scoped alias metadata in call slot optimization.

Author: nikic

llvm/test/Analysis/ScopedNoAliasAA/alias-scope-merging.ll

@@ -1,17 +1,20 @@
 ; RUN: opt < %s -S -passes=memcpyopt | FileCheck --match-full-lines %s
 
+declare void @use(ptr)
+
 ; Alias scopes are merged by taking the intersection of domains, then the union of the scopes within those domains
 define i8 @test(i8 %input) {
   %tmp = alloca i8
   %dst = alloca i8
   %src = alloca i8
 ; CHECK:   call void @llvm.memcpy.p0.p0.i64(ptr align 8 %dst, ptr align 8 %src, i64 1, i1 false), !alias.scope ![[SCOPE:[0-9]+]]
-  call void @llvm.lifetime.start.p0(i64 8, ptr nonnull %src), !noalias !4
+  call void @llvm.lifetime.start.p0(i64 1, ptr nonnull %src), !noalias !4
   store i8 %input, ptr %src
   call void @llvm.memcpy.p0.p0.i64(ptr align 8 %tmp, ptr align 8 %src, i64 1, i1 false), !alias.scope !0
-  call void @llvm.lifetime.end.p0(i64 8, ptr nonnull %src), !noalias !4
+  call void @llvm.lifetime.end.p0(i64 1, ptr nonnull %src), !noalias !4
   call void @llvm.memcpy.p0.p0.i64(ptr align 8 %dst, ptr align 8 %tmp, i64 1, i1 false), !alias.scope !4
   %ret_value = load i8, ptr %dst
+  call void @use(ptr %src)
   ret i8 %ret_value
 }
 

llvm/test/Transforms/MemCpyOpt/callslot_badaa.ll

@@ -1,9 +1,11 @@
 ; RUN: opt < %s -S -passes=memcpyopt | FileCheck --match-full-lines %s
 
+declare void @use(ptr)
+
 ; Make sure callslot optimization merges alias.scope metadata correctly when it merges instructions.
 ; Merging here naively generates:
 ;  call void @llvm.memcpy.p0.p0.i64(ptr align 8 %dst, ptr align 8 %src, i64 1, i1 false), !alias.scope !3
-;  call void @llvm.lifetime.end.p0(i64 8, ptr nonnull %src), !noalias !0
+;  call void @llvm.lifetime.end.p0(i64 1, ptr nonnull %src), !noalias !0
 ;   ...
 ;  !0 = !{!1}
 ;  !1 = distinct !{!1, !2, !"callee1: %a"}
@@ -18,12 +20,13 @@ define i8 @test(i8 %input) {
   %src = alloca i8
 ; NOTE: we're matching the full line and looking for the lack of !alias.scope here
 ; CHECK:   call void @llvm.memcpy.p0.p0.i64(ptr align 8 %dst, ptr align 8 %src, i64 1, i1 false)
-  call void @llvm.lifetime.start.p0(i64 8, ptr nonnull %src), !noalias !3
+  call void @llvm.lifetime.start.p0(i64 1, ptr nonnull %src), !noalias !3
   store i8 %input, ptr %src
   call void @llvm.memcpy.p0.p0.i64(ptr align 8 %tmp, ptr align 8 %src, i64 1, i1 false), !alias.scope !0
-  call void @llvm.lifetime.end.p0(i64 8, ptr nonnull %src), !noalias !3
+  call void @llvm.lifetime.end.p0(i64 1, ptr nonnull %src), !noalias !3
   call void @llvm.memcpy.p0.p0.i64(ptr align 8 %dst, ptr align 8 %tmp, i64 1, i1 false), !alias.scope !3
   %ret_value = load i8, ptr %dst
+  call void @use(ptr %src)
   ret i8 %ret_value
 }