[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
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index af6f399..78b1ec0 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -1606,11 +1606,14 @@
// 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);
+ }
}
}