[llvm] r237858 - [MemCpyOpt] Don't move the memset when optimizing memset+memcpy.

Ahmed Bougacha ahmed.bougacha at gmail.com
Wed May 20 16:55:16 PDT 2015


Author: ab
Date: Wed May 20 18:55:16 2015
New Revision: 237858

URL: http://llvm.org/viewvc/llvm-project?rev=237858&view=rev
Log:
[MemCpyOpt] Don't move the memset when optimizing memset+memcpy.

Fixes PR23599, another miscompile introduced by r235232: when there is
another dependency on the destination of the created memset (i.e., the
part of the original destination that the memcpy doesn't depend on)
between the memcpy and the original memset, we would insert the created
memset after the memcpy, and thus after the other dependency.

Instead, insert the created memset right after the old one.

Modified:
    llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp
    llvm/trunk/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll

Modified: llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp?rev=237858&r1=237857&r2=237858&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp Wed May 20 18:55:16 2015
@@ -874,7 +874,7 @@ bool MemCpyOpt::processMemSetMemCpyDepen
     if (ConstantInt *SrcSizeC = dyn_cast<ConstantInt>(SrcSize))
       Align = MinAlign(SrcSizeC->getZExtValue(), DestAlign);
 
-  IRBuilder<> Builder(MemCpy->getNextNode());
+  IRBuilder<> Builder(MemSet->getNextNode());
 
   // If the sizes have different types, zext the smaller one.
   if (DestSize->getType() != SrcSize->getType()) {

Modified: llvm/trunk/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll?rev=237858&r1=237857&r2=237858&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll (original)
+++ llvm/trunk/test/Transforms/MemCpyOpt/memset-memcpy-redundant-memset.ll Wed May 20 18:55:16 2015
@@ -3,12 +3,12 @@
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 
 ; CHECK-LABEL: define void @test
-; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %src_size, i32 1, i1 false)
 ; CHECK-DAG: [[DST:%[0-9]+]] = getelementptr i8, i8* %dst, i64 %src_size
 ; CHECK-DAG: [[ULE:%[0-9]+]] = icmp ule i64 %dst_size, %src_size
 ; CHECK-DAG: [[SIZEDIFF:%[0-9]+]] = sub i64 %dst_size, %src_size
 ; CHECK-DAG: [[SIZE:%[0-9]+]] = select i1 [[ULE]], i64 0, i64 [[SIZEDIFF]]
 ; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[DST]], i8 %c, i64 [[SIZE]], i32 1, i1 false)
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %src_size, i32 1, i1 false)
 ; CHECK-NEXT: ret void
 define void @test(i8* %src, i64 %src_size, i8* %dst, i64 %dst_size, i8 %c) {
   call void @llvm.memset.p0i8.i64(i8* %dst, i8 %c, i64 %dst_size, i32 1, i1 false)
@@ -17,13 +17,13 @@ define void @test(i8* %src, i64 %src_siz
 }
 
 ; CHECK-LABEL: define void @test_different_types_i32_i64
-; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %src_size, i32 1, i1 false)
 ; CHECK-DAG: [[DSTSIZE:%[0-9]+]] = zext i32 %dst_size to i64
 ; CHECK-DAG: [[DST:%[0-9]+]] = getelementptr i8, i8* %dst, i64 %src_size
 ; CHECK-DAG: [[ULE:%[0-9]+]] = icmp ule i64 [[DSTSIZE]], %src_size
 ; CHECK-DAG: [[SIZEDIFF:%[0-9]+]] = sub i64 [[DSTSIZE]], %src_size
 ; CHECK-DAG: [[SIZE:%[0-9]+]] = select i1 [[ULE]], i64 0, i64 [[SIZEDIFF]]
 ; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[DST]], i8 %c, i64 [[SIZE]], i32 1, i1 false)
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %src_size, i32 1, i1 false)
 ; CHECK-NEXT: ret void
 define void @test_different_types_i32_i64(i8* %dst, i8* %src, i32 %dst_size, i64 %src_size, i8 %c) {
   call void @llvm.memset.p0i8.i32(i8* %dst, i8 %c, i32 %dst_size, i32 1, i1 false)
@@ -32,13 +32,13 @@ define void @test_different_types_i32_i6
 }
 
 ; CHECK-LABEL: define void @test_different_types_i128_i32
-; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dst, i8* %src, i32 %src_size, i32 1, i1 false)
 ; CHECK-DAG: [[SRCSIZE:%[0-9]+]] = zext i32 %src_size to i128
 ; CHECK-DAG: [[DST:%[0-9]+]] = getelementptr i8, i8* %dst, i128 [[SRCSIZE]]
 ; CHECK-DAG: [[ULE:%[0-9]+]] = icmp ule i128 %dst_size, [[SRCSIZE]]
 ; CHECK-DAG: [[SIZEDIFF:%[0-9]+]] = sub i128 %dst_size, [[SRCSIZE]]
 ; CHECK-DAG: [[SIZE:%[0-9]+]] = select i1 [[ULE]], i128 0, i128 [[SIZEDIFF]]
 ; CHECK-NEXT: call void @llvm.memset.p0i8.i128(i8* [[DST]], i8 %c, i128 [[SIZE]], i32 1, i1 false)
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dst, i8* %src, i32 %src_size, i32 1, i1 false)
 ; CHECK-NEXT: ret void
 define void @test_different_types_i128_i32(i8* %dst, i8* %src, i128 %dst_size, i32 %src_size, i8 %c) {
   call void @llvm.memset.p0i8.i128(i8* %dst, i8 %c, i128 %dst_size, i32 1, i1 false)
@@ -47,13 +47,13 @@ define void @test_different_types_i128_i
 }
 
 ; CHECK-LABEL: define void @test_different_types_i32_i128
-; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i128(i8* %dst, i8* %src, i128 %src_size, i32 1, i1 false)
 ; CHECK-DAG: [[DSTSIZE:%[0-9]+]] = zext i32 %dst_size to i128
 ; CHECK-DAG: [[DST:%[0-9]+]] = getelementptr i8, i8* %dst, i128 %src_size
 ; CHECK-DAG: [[ULE:%[0-9]+]] = icmp ule i128 [[DSTSIZE]], %src_size
 ; CHECK-DAG: [[SIZEDIFF:%[0-9]+]] = sub i128 [[DSTSIZE]], %src_size
 ; CHECK-DAG: [[SIZE:%[0-9]+]] = select i1 [[ULE]], i128 0, i128 [[SIZEDIFF]]
 ; CHECK-NEXT: call void @llvm.memset.p0i8.i128(i8* [[DST]], i8 %c, i128 [[SIZE]], i32 1, i1 false)
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i128(i8* %dst, i8* %src, i128 %src_size, i32 1, i1 false)
 ; CHECK-NEXT: ret void
 define void @test_different_types_i32_i128(i8* %dst, i8* %src, i32 %dst_size, i128 %src_size, i8 %c) {
   call void @llvm.memset.p0i8.i32(i8* %dst, i8 %c, i32 %dst_size, i32 1, i1 false)
@@ -62,13 +62,13 @@ define void @test_different_types_i32_i1
 }
 
 ; CHECK-LABEL: define void @test_different_types_i64_i32
-; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dst, i8* %src, i32 %src_size, i32 1, i1 false)
 ; CHECK-DAG: [[SRCSIZE:%[0-9]+]] = zext i32 %src_size to i64
 ; CHECK-DAG: [[DST:%[0-9]+]] = getelementptr i8, i8* %dst, i64 [[SRCSIZE]]
 ; CHECK-DAG: [[ULE:%[0-9]+]] = icmp ule i64 %dst_size, [[SRCSIZE]]
 ; CHECK-DAG: [[SIZEDIFF:%[0-9]+]] = sub i64 %dst_size, [[SRCSIZE]]
 ; CHECK-DAG: [[SIZE:%[0-9]+]] = select i1 [[ULE]], i64 0, i64 [[SIZEDIFF]]
 ; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[DST]], i8 %c, i64 [[SIZE]], i32 1, i1 false)
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dst, i8* %src, i32 %src_size, i32 1, i1 false)
 ; CHECK-NEXT: ret void
 define void @test_different_types_i64_i32(i8* %dst, i8* %src, i64 %dst_size, i32 %src_size, i8 %c) {
   call void @llvm.memset.p0i8.i64(i8* %dst, i8 %c, i64 %dst_size, i32 1, i1 false)
@@ -102,12 +102,12 @@ define void @test_align_memcpy(i8* %src,
 
 ; CHECK-LABEL: define void @test_non_i8_dst_type
 ; CHECK-NEXT: %dst = bitcast i64* %dst_pi64 to i8*
-; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %src_size, i32 1, i1 false)
 ; CHECK-DAG: [[DST:%[0-9]+]] = getelementptr i8, i8* %dst, i64 %src_size
 ; CHECK-DAG: [[ULE:%[0-9]+]] = icmp ule i64 %dst_size, %src_size
 ; CHECK-DAG: [[SIZEDIFF:%[0-9]+]] = sub i64 %dst_size, %src_size
 ; CHECK-DAG: [[SIZE:%[0-9]+]] = select i1 [[ULE]], i64 0, i64 [[SIZEDIFF]]
 ; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[DST]], i8 %c, i64 [[SIZE]], i32 1, i1 false)
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %src_size, i32 1, i1 false)
 ; CHECK-NEXT: ret void
 define void @test_non_i8_dst_type(i8* %src, i64 %src_size, i64* %dst_pi64, i64 %dst_size, i8 %c) {
   %dst = bitcast i64* %dst_pi64 to i8*





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