| ; RUN: opt < %s -S -basicaa -memcpyopt | FileCheck %s |
| target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128" |
| |
| declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) unnamed_addr nounwind |
| declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind |
| |
| ; all bytes of %dst that are touch by the memset are dereferenceable |
| define void @must_remove_memcpy(i8* noalias nocapture dereferenceable(4096) %dst) { |
| ; CHECK-LABEL: @must_remove_memcpy( |
| ; CHECK: call void @llvm.memset.p0i8.i64 |
| ; CHECK-NOT: call void @llvm.memcpy.p0i8.p0i8.i64 |
| %src = alloca [4096 x i8], align 1 |
| %p = getelementptr inbounds [4096 x i8], [4096 x i8]* %src, i64 0, i64 0 |
| call void @llvm.memset.p0i8.i64(i8* %p, i8 0, i64 4096, i32 1, i1 false) |
| call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %p, i64 4096, i32 1, i1 false) #2 |
| ret void |
| } |
| |
| ; memset touch more bytes than those guaranteed to be dereferenceable |
| ; We can't remove the memcpy, but we can turn it into an independent memset. |
| define void @must_not_remove_memcpy(i8* noalias nocapture dereferenceable(1024) %dst) { |
| ; CHECK-LABEL: @must_not_remove_memcpy( |
| ; CHECK: call void @llvm.memset.p0i8.i64 |
| ; CHECK: call void @llvm.memset.p0i8.i64 |
| %src = alloca [4096 x i8], align 1 |
| %p = getelementptr inbounds [4096 x i8], [4096 x i8]* %src, i64 0, i64 0 |
| call void @llvm.memset.p0i8.i64(i8* %p, i8 0, i64 4096, i32 1, i1 false) |
| call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %p, i64 4096, i32 1, i1 false) #2 |
| ret void |
| } |
