1;  RUN: llc < %s -mtriple=x86_64-unknown-linux -O2 | FileCheck %s
2
3; This test checks that:
4; (1)  mempcpy is lowered as memcpy, and
5; (2)  its return value is DST+N i.e. the dst pointer adjusted by the copy size.
6; To keep the testing of (2) independent of the exact instructions used to
7; adjust the dst pointer, DST+N is explicitly computed and stored to a global
8; variable G before the mempcpy call. This instance of DST+N causes the repeat
9; DST+N done in the context of the return value of mempcpy to be redundant, and
10; the first instance to be reused as the return value. This allows the check for
11; (2) to be expressed as verifying that the MOV to store DST+N to G and
12; the MOV to copy DST+N to %rax use the same source register.
13
14; Also see mempcpy-32.ll
15
16@G = common dso_local global i8* null, align 8
17
18; CHECK-LABEL: RET_MEMPCPY:
19; CHECK: movq [[REG:%r[a-z0-9]+]], {{.*}}G
20; CHECK: callq {{.*}}memcpy
21; CHECK: movq [[REG]], %rax
22;
23define dso_local i8* @RET_MEMPCPY(i8* %DST, i8* %SRC, i64 %N) {
24  %add.ptr = getelementptr inbounds i8, i8* %DST, i64 %N
25  store i8* %add.ptr, i8** @G, align 8
26  %call = tail call i8* @mempcpy(i8* %DST, i8* %SRC, i64 %N)
27  ret i8* %call
28}
29
30declare i8* @mempcpy(i8*, i8*, i64)
31