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[CodeGenPrepare] Improve source and dest alignments of memory intrinsics independently 

Summary:
  This change is part of step five in the series of changes to remove alignment argument from
memcpy/memmove/memset in favour of alignment attributes. In particular, this changes the
CodeGenPrepare pass to be more aggressive in improving the source and destination alignments
of memcpy/memmove/memset by exploiting our new ability to record independent alignments
for each argument.

Steps:
Step 1) Remove alignment parameter and create alignment parameter attributes for
memcpy/memmove/memset. ( rL322965, rC322964, rL322963 )
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
source and dest alignments. ( rL323597 )
Step 3) Update Clang to use the new IRBuilder API. ( rC323617 )
Step 4) Update Polly to use the new IRBuilder API. ( rL323618 )
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
and those that use use MemIntrinsicInst::[get|set]Alignment() to use [get|set]DestAlignment()
and [get|set]SourceAlignment() instead. ( rL323886 )
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
MemIntrinsicInst::[get|set]Alignment() methods.

Reference
   http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html
   http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

llvm-svn: 323891
This commit is contained in:
Daniel Neilson 2018-01-31 17:24:53 +00:00
parent e72cde57d2
commit be58a220e9
2 changed files with 51 additions and 5 deletions
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13
llvm/lib/CodeGen/CodeGenPrepare.cpp
View File

@ -1606,11 +1606,14 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
// If this is a memcpy (or similar) then we may be able to improve the
// alignment
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
unsigned Align = getKnownAlignment(MI->getDest(), *DL);
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))
Align = std::min(Align, getKnownAlignment(MTI->getSource(), *DL));
if (Align > MI->getAlignment())
MI->setAlignment(Align);
unsigned DestAlign = getKnownAlignment(MI->getDest(), *DL);
if (DestAlign > MI->getDestAlignment())
MI->setDestAlignment(DestAlign);
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
unsigned SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
if (SrcAlign > MTI->getSourceAlignment())
MTI->setSourceAlignment(SrcAlign);
}
}
}

43
llvm/test/Transforms/CodeGenPrepare/ARM/memory-intrinsics.ll Normal file
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@ -0,0 +1,43 @@
; RUN: opt -codegenprepare -mtriple=arm7-unknown-unknown -S < %s | FileCheck %s
declare void @llvm.memcpy.p0i8.p0i8.i32(i8*, i8*, i32, i1) nounwind
declare void @llvm.memmove.p0i8.p0i8.i32(i8*, i8*, i32, i1) nounwind
declare void @llvm.memset.p0i8.i32(i8*, i8, i32, i1) nounwind
define void @test_memcpy(i8* align 4 %dst, i8* align 8 %src, i32 %N) {
; CHECK-LABEL: @test_memcpy
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 %dst, i8* align 8 %src, i32 %N, i1 false)
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 %dst, i8* align 8 %src, i32 %N, i1 false)
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %dst, i8* align 16 %src, i32 %N, i1 false)
entry:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dst, i8* %src, i32 %N, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 2 %dst, i8* align 2 %src, i32 %N, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %dst, i8* align 16 %src, i32 %N, i1 false)
ret void
}
define void @test_memmove(i8* align 4 %dst, i8* align 8 %src, i32 %N) {
; CHECK-LABEL: @test_memmove
; CHECK: call void @llvm.memmove.p0i8.p0i8.i32(i8* align 4 %dst, i8* align 8 %src, i32 %N, i1 false)
; CHECK: call void @llvm.memmove.p0i8.p0i8.i32(i8* align 4 %dst, i8* align 8 %src, i32 %N, i1 false)
; CHECK: call void @llvm.memmove.p0i8.p0i8.i32(i8* align 8 %dst, i8* align 16 %src, i32 %N, i1 false)
entry:
call void @llvm.memmove.p0i8.p0i8.i32(i8* %dst, i8* %src, i32 %N, i1 false)
call void @llvm.memmove.p0i8.p0i8.i32(i8* align 2 %dst, i8* align 2 %src, i32 %N, i1 false)
call void @llvm.memmove.p0i8.p0i8.i32(i8* align 8 %dst, i8* align 16 %src, i32 %N, i1 false)
ret void
}
define void @test_memset(i8* align 4 %dst, i8 %val, i32 %N) {
; CHECK-LABEL: @test_memset
; CHECK: call void @llvm.memset.p0i8.i32(i8* align 4 %dst, i8 %val, i32 %N, i1 false)
; CHECK: call void @llvm.memset.p0i8.i32(i8* align 4 %dst, i8 %val, i32 %N, i1 false)
; CHECK: call void @llvm.memset.p0i8.i32(i8* align 8 %dst, i8 %val, i32 %N, i1 false)
entry:
call void @llvm.memset.p0i8.i32(i8* %dst, i8 %val, i32 %N, i1 false)
call void @llvm.memset.p0i8.i32(i8* align 2 %dst, i8 %val, i32 %N, i1 false)
call void @llvm.memset.p0i8.i32(i8* align 8 %dst, i8 %val, i32 %N, i1 false)
ret void
}