From d20816fde95cb3c2467ef726790c06e8009a2653 Mon Sep 17 00:00:00 2001 From: Bjorn Steinbrink Date: Thu, 16 Oct 2014 19:43:08 +0000 Subject: Allow call-slop optzn for destinations with a suitable dereferenceable attribute Summary: Currently, call slot optimization requires that if the destination is an argument, the argument has the sret attribute. This is to ensure that the memory access won't trap. In addition to sret, we can also allow the optimization to happen for arguments that have the new dereferenceable attribute, which gives the same guarantee. Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D5832 llvm-svn: 219950 --- llvm/test/Transforms/MemCpyOpt/callslot_deref.ll | 29 ++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 llvm/test/Transforms/MemCpyOpt/callslot_deref.ll (limited to 'llvm/test/Transforms') diff --git a/llvm/test/Transforms/MemCpyOpt/callslot_deref.ll b/llvm/test/Transforms/MemCpyOpt/callslot_deref.ll new file mode 100644 index 00000000000..4d51552d015 --- /dev/null +++ b/llvm/test/Transforms/MemCpyOpt/callslot_deref.ll @@ -0,0 +1,29 @@ +; 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]* %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 +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.memcpy.p0i8.p0i8.i64 + %src = alloca [4096 x i8], align 1 + %p = getelementptr inbounds [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 +} -- cgit v1.2.3