[InstCombine] Simplify MemTransferInst's source and dest alignments separately
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
InstCombine pass to cease using the deprecated MemoryIntrinsic::getAlignment() method, and
instead we use the separate getSourceAlignment and getDestAlignment APIs to simplify
the source and destination alignment attributes separately.
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, rL323891, rL324148, rL324273, rL324278,
rL324384, rL324395, rL324402, rL324626, rL324642, rL324653, rL324654, rL324773, rL324774,
rL324781, rL324784, rL324955 )
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
Reviewers: majnemer, bollu, efriedma
Reviewed By: efriedma
Subscribers: efriedma, llvm-commits
Differential Revision: https://reviews.llvm.org/D42871
llvm-svn: 324960
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 2ad37c0..e2a109c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -184,14 +184,18 @@
}
Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
- unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), DL, MI, &AC, &DT);
- unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), DL, MI, &AC, &DT);
- unsigned MinAlign = std::min(DstAlign, SrcAlign);
- unsigned CopyAlign = MI->getAlignment();
+ unsigned DstAlign = getKnownAlignment(MI->getRawDest(), DL, MI, &AC, &DT);
+ unsigned CopyDstAlign = MI->getDestAlignment();
+ if (CopyDstAlign < DstAlign){
+ MI->setDestAlignment(DstAlign);
+ return MI;
+ }
- // FIXME: Check & simplify source & dest alignments separately
- if (CopyAlign < MinAlign) {
- MI->setAlignment(MinAlign);
+ auto* MTI = cast<MemTransferInst>(MI);
+ unsigned SrcAlign = getKnownAlignment(MTI->getRawSource(), DL, MI, &AC, &DT);
+ unsigned CopySrcAlign = MTI->getSourceAlignment();
+ if (CopySrcAlign < SrcAlign) {
+ MTI->setSourceAlignment(SrcAlign);
return MI;
}
@@ -235,15 +239,11 @@
CopyMD = cast<MDNode>(M->getOperand(2));
}
- // If the memcpy/memmove provides better alignment info than we can
- // infer, use it.
- SrcAlign = std::max(SrcAlign, CopyAlign);
- DstAlign = std::max(DstAlign, CopyAlign);
-
Value *Src = Builder.CreateBitCast(MI->getArgOperand(1), NewSrcPtrTy);
Value *Dest = Builder.CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
LoadInst *L = Builder.CreateLoad(Src, MI->isVolatile());
- L->setAlignment(SrcAlign);
+ // Alignment from the mem intrinsic will be better, so use it.
+ L->setAlignment(CopySrcAlign);
if (CopyMD)
L->setMetadata(LLVMContext::MD_tbaa, CopyMD);
MDNode *LoopMemParallelMD =
@@ -252,7 +252,8 @@
L->setMetadata(LLVMContext::MD_mem_parallel_loop_access, LoopMemParallelMD);
StoreInst *S = Builder.CreateStore(L, Dest, MI->isVolatile());
- S->setAlignment(DstAlign);
+ // Alignment from the mem intrinsic will be better, so use it.
+ S->setAlignment(CopyDstAlign);
if (CopyMD)
S->setMetadata(LLVMContext::MD_tbaa, CopyMD);
if (LoopMemParallelMD)