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Handle the new !tbaa.struct metadata tags when converting a memcpy into scalar

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loads and stores.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163844 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2012-09-13 21:51:01 +00:00
parent e940c1bb6c
commit b998913ff4
2 changed files with 43 additions and 0 deletions
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17
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -94,6 +94,7 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
// dest address will be promotable. See if we can find a better type than the
// integer datatype.
Value *StrippedDest = MI->getArgOperand(0)->stripPointerCasts();
MDNode *CopyMD = 0;
if (StrippedDest != MI->getArgOperand(0)) {
Type *SrcETy = cast<PointerType>(StrippedDest->getType())
->getElementType();
@ -105,6 +106,18 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
if (SrcETy->isSingleValueType()) {
NewSrcPtrTy = PointerType::get(SrcETy, SrcAddrSp);
NewDstPtrTy = PointerType::get(SrcETy, DstAddrSp);
// If the memcpy has metadata describing the members, see if we can
// get the TBAA tag describing our copy.
if (MDNode *M = MI->getMetadata(LLVMContext::MD_tbaa_struct)) {
if (M->getNumOperands() == 3 &&
isa<ConstantInt>(M->getOperand(0)) &&
cast<ConstantInt>(M->getOperand(0))->isNullValue() &&
isa<ConstantInt>(M->getOperand(1)) &&
cast<ConstantInt>(M->getOperand(1))->getValue() == Size &&
isa<MDNode>(M->getOperand(2)))
CopyMD = cast<MDNode>(M->getOperand(2));
}
}
}
}
@ -118,8 +131,12 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
Value *Dest = Builder->CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
LoadInst *L = Builder->CreateLoad(Src, MI->isVolatile());
L->setAlignment(SrcAlign);
if (CopyMD)
L->setMetadata(LLVMContext::MD_tbaa, CopyMD);
StoreInst *S = Builder->CreateStore(L, Dest, MI->isVolatile());
S->setAlignment(DstAlign);
if (CopyMD)
S->setMetadata(LLVMContext::MD_tbaa, CopyMD);
// Set the size of the copy to 0, it will be deleted on the next iteration.
MI->setArgOperand(2, Constant::getNullValue(MemOpLength->getType()));

26
test/Transforms/InstCombine/struct-assign-tbaa.ll Normal file
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@ -0,0 +1,26 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
%struct.foo = type { float }
; Verify that instcombine preserves TBAA tags when converting a memcpy into
; a scalar load and store.
; CHECK: %2 = load float* %0, align 4, !tbaa !0
; CHECK: store float %2, float* %1, align 4, !tbaa !0
; CHECK: !0 = metadata !{metadata !"float", metadata !1}
define void @test(%struct.foo* nocapture %a, %struct.foo* nocapture %b) {
entry:
%0 = bitcast %struct.foo* %a to i8*
%1 = bitcast %struct.foo* %b to i8*
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* %1, i64 4, i32 4, i1 false), !tbaa.struct !3
ret void
}
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
!0 = metadata !{metadata !"Simple C/C++ TBAA"}
!1 = metadata !{metadata !"omnipotent char", metadata !0}
!2 = metadata !{metadata !"float", metadata !0}
!3 = metadata !{i64 0, i64 4, metadata !2}