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Teach instcombine to respect and preserve inbounds. Add inbounds

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to a few tests where it is required for the expected transformation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77290 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-07-28 01:40:03 +00:00
parent eb045ecba0
commit d6aa02de10
5 changed files with 66 additions and 32 deletions
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4
lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -349,7 +349,9 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
return GEP;
}
// Insert a pretty getelementptr.
// Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
// because ScalarEvolution may have changed the address arithmetic to
// compute a value which is beyond the end of the allocated object.
Value *GEP = Builder.CreateGEP(V,
GepIndices.begin(),
GepIndices.end(),

74
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -213,7 +213,7 @@ namespace {
Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
ConstantInt *DivRHS);
Instruction *FoldGEPICmp(User *GEPLHS, Value *RHS,
Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
ICmpInst::Predicate Cond, Instruction &I);
Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
BinaryOperator &I);
@ -5559,20 +5559,19 @@ static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
/// else. At this point we know that the GEP is on the LHS of the comparison.
Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
ICmpInst::Predicate Cond,
Instruction &I) {
assert(isa<GEPOperator>(GEPLHS) && "LHS is not a getelementptr!");
// Look through bitcasts.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
RHS = BCI->getOperand(0);
Value *PtrBase = GEPLHS->getOperand(0);
if (TD && PtrBase == RHS) {
if (TD && PtrBase == RHS && GEPLHS->isInBounds()) {
// ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
// This transformation (ignoring the base and scales) is valid because we
// know pointers can't overflow. See if we can output an optimized form.
// know pointers can't overflow since the gep is inbounds. See if we can
// output an optimized form.
Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
// If not, synthesize the offset the hard way.
@ -5580,7 +5579,7 @@ Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
Offset = EmitGEPOffset(GEPLHS, I, *this);
return new ICmpInst(*Context, ICmpInst::getSignedPredicate(Cond), Offset,
Context->getNullValue(Offset->getType()));
} else if (User *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
} else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
// If the base pointers are different, but the indices are the same, just
// compare the base pointer.
if (PtrBase != GEPRHS->getOperand(0)) {
@ -6345,10 +6344,10 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
}
// If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
if (User *GEP = dyn_cast<GEPOperator>(Op0))
if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
return NI;
if (User *GEP = dyn_cast<GEPOperator>(Op1))
if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
if (Instruction *NI = FoldGEPICmp(GEP, Op0,
ICmpInst::getSwappedPredicate(I.getPredicate()), I))
return NI;
@ -8252,6 +8251,8 @@ Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
NewIndices.end(), "");
InsertNewInstBefore(NGEP, CI);
NGEP->takeName(GEP);
if (cast<GEPOperator>(GEP)->isInBounds())
cast<GEPOperator>(NGEP)->setIsInBounds(true);
if (isa<BitCastInst>(CI))
return new BitCastInst(NGEP, CI.getType());
@ -8981,8 +8982,11 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
// If we found a path from the src to dest, create the getelementptr now.
if (SrcElTy == DstElTy) {
SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
return GetElementPtrInst::Create(Src, Idxs.begin(), Idxs.end(), "",
((Instruction*) NULL));
Instruction *GEP = GetElementPtrInst::Create(Src,
Idxs.begin(), Idxs.end(), "",
((Instruction*) NULL));
cast<GEPOperator>(GEP)->setIsInBounds(true);
return GEP;
}
}
@ -10663,8 +10667,12 @@ Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
}
Value *Base = FixedOperands[0];
return GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
FixedOperands.end());
GetElementPtrInst *GEP =
GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
FixedOperands.end());
if (cast<GEPOperator>(FirstInst)->isInBounds())
cast<GEPOperator>(GEP)->setIsInBounds(true);
return GEP;
}
@ -11055,8 +11063,12 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
// getelementptr instructions into a single instruction.
//
SmallVector<Value*, 8> SrcGEPOperands;
if (User *Src = dyn_cast<GEPOperator>(PtrOp))
bool BothInBounds = cast<GEPOperator>(&GEP)->isInBounds();
if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
SrcGEPOperands.append(Src->op_begin(), Src->op_end());
if (!Src->isInBounds())
BothInBounds = false;
}
if (!SrcGEPOperands.empty()) {
// Note that if our source is a gep chain itself that we wait for that
@ -11140,9 +11152,15 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
}
if (!Indices.empty())
return GetElementPtrInst::Create(SrcGEPOperands[0], Indices.begin(),
Indices.end(), GEP.getName());
if (!Indices.empty()) {
GetElementPtrInst *NewGEP = GetElementPtrInst::Create(SrcGEPOperands[0],
Indices.begin(),
Indices.end(),
GEP.getName());
if (BothInBounds)
cast<GEPOperator>(NewGEP)->setIsInBounds(true);
return NewGEP;
}
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
// GEP of global variable. If all of the indices for this GEP are
@ -11180,8 +11198,12 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
if (CATy->getElementType() == XTy->getElementType()) {
// -> GEP i8* X, ...
SmallVector<Value*, 8> Indices(GEP.idx_begin()+1, GEP.idx_end());
return GetElementPtrInst::Create(X, Indices.begin(), Indices.end(),
GEP.getName());
GetElementPtrInst *NewGEP =
GetElementPtrInst::Create(X, Indices.begin(), Indices.end(),
GEP.getName());
if (cast<GEPOperator>(&GEP)->isInBounds())
cast<GEPOperator>(NewGEP)->setIsInBounds(true);
return NewGEP;
} else if (const ArrayType *XATy =
dyn_cast<ArrayType>(XTy->getElementType())) {
// GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
@ -11208,8 +11230,11 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
Value *Idx[2];
Idx[0] = Context->getNullValue(Type::Int32Ty);
Idx[1] = GEP.getOperand(1);
Value *V = InsertNewInstBefore(
GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName()), GEP);
GetElementPtrInst *NewGEP =
GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName());
if (cast<GEPOperator>(&GEP)->isInBounds())
cast<GEPOperator>(NewGEP)->setIsInBounds(true);
Value *V = InsertNewInstBefore(NewGEP, GEP);
// V and GEP are both pointer types --> BitCast
return new BitCastInst(V, GEP.getType());
}
@ -11271,6 +11296,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
Idx[1] = NewIdx;
Instruction *NewGEP =
GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName());
if (cast<GEPOperator>(&GEP)->isInBounds())
cast<GEPOperator>(NewGEP)->setIsInBounds(true);
NewGEP = InsertNewInstBefore(NewGEP, GEP);
// The NewGEP must be pointer typed, so must the old one -> BitCast
return new BitCastInst(NewGEP, GEP.getType());
@ -11323,6 +11350,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
GetElementPtrInst::Create(BCI->getOperand(0), NewIndices.begin(),
NewIndices.end());
if (NGEP->getType() == GEP.getType()) return NGEP;
if (cast<GEPOperator>(&GEP)->isInBounds())
cast<GEPOperator>(NGEP)->setIsInBounds(true);
InsertNewInstBefore(NGEP, GEP);
NGEP->takeName(&GEP);
return new BitCastInst(NGEP, GEP.getType());
@ -11366,6 +11395,7 @@ Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
Idx[1] = NullIdx;
Value *V = GetElementPtrInst::Create(New, Idx, Idx + 2,
New->getName()+".sub", It);
cast<GEPOperator>(V)->setIsInBounds(true);
// Now make everything use the getelementptr instead of the original
// allocation.
@ -11745,6 +11775,7 @@ static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
CastOp = IC.InsertNewInstBefore(
GetElementPtrInst::Create(CastOp, NewGEPIndices.begin(),
NewGEPIndices.end()), SI);
cast<GEPOperator>(CastOp)->setIsInBounds(true);
}
if (Constant *C = dyn_cast<Constant>(SIOp0))
@ -12428,6 +12459,7 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
Context->getPointerType(EI.getType(), AS),EI);
GetElementPtrInst *GEP =
GetElementPtrInst::Create(Ptr, EI.getOperand(1), I->getName()+".gep");
cast<GEPOperator>(GEP)->setIsInBounds(true);
InsertNewInstBefore(GEP, EI);
return new LoadInst(GEP);
}

4
test/Transforms/InstCombine/2008-02-04-GEPIdxBug.ll
View File

@ -10,7 +10,7 @@ define i32 @main() nounwind {
entry:
%orientations = alloca [1 x [1 x %struct.x]] ; <[1 x [1 x %struct.x]]*> [#uses=2]
%tmp3 = call i32 @puts( i8* getelementptr ([6 x i8]* @.str, i32 0, i32 0) ) nounwind ; <i32> [#uses=0]
%tmp45 = getelementptr [1 x [1 x %struct.x]]* %orientations, i32 1, i32 0, i32 0 ; <%struct.x*> [#uses=1]
%tmp45 = getelementptr inbounds [1 x [1 x %struct.x]]* %orientations, i32 1, i32 0, i32 0 ; <%struct.x*> [#uses=1]
%orientations62 = getelementptr [1 x [1 x %struct.x]]* %orientations, i32 0, i32 0, i32 0 ; <%struct.x*> [#uses=1]
br label %bb10
@ -18,7 +18,7 @@ bb10: ; preds = %bb10, %entry
%indvar = phi i32 [ 0, %entry ], [ %indvar.next, %bb10 ] ; <i32> [#uses=2]
%tmp.0.reg2mem.0.rec = mul i32 %indvar, -1 ; <i32> [#uses=1]
%tmp12.rec = add i32 %tmp.0.reg2mem.0.rec, -1 ; <i32> [#uses=1]
%tmp12 = getelementptr %struct.x* %tmp45, i32 %tmp12.rec ; <%struct.x*> [#uses=2]
%tmp12 = getelementptr inbounds %struct.x* %tmp45, i32 %tmp12.rec ; <%struct.x*> [#uses=2]
%tmp16 = call i32 (i8*, ...)* @printf( i8* getelementptr ([12 x i8]* @.str1, i32 0, i32 0), %struct.x* %tmp12 ) nounwind ; <i32> [#uses=0]
%tmp84 = icmp eq %struct.x* %tmp12, %orientations62 ; <i1> [#uses=1]
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]

12
test/Transforms/InstCombine/getelementptr-setcc.ll
View File

@ -2,28 +2,28 @@
; RUN: not grep getelementptr
define i1 @test1(i16* %P, i32 %I, i32 %J) {
%X = getelementptr i16* %P, i32 %I ; <i16*> [#uses=1]
%Y = getelementptr i16* %P, i32 %J ; <i16*> [#uses=1]
%X = getelementptr inbounds i16* %P, i32 %I ; <i16*> [#uses=1]
%Y = getelementptr inbounds i16* %P, i32 %J ; <i16*> [#uses=1]
%C = icmp ult i16* %X, %Y ; <i1> [#uses=1]
ret i1 %C
}
define i1 @test2(i16* %P, i32 %I) {
%X = getelementptr i16* %P, i32 %I ; <i16*> [#uses=1]
%X = getelementptr inbounds i16* %P, i32 %I ; <i16*> [#uses=1]
%C = icmp ult i16* %X, %P ; <i1> [#uses=1]
ret i1 %C
}
define i32 @test3(i32* %P, i32 %A, i32 %B) {
%tmp.4 = getelementptr i32* %P, i32 %A ; <i32*> [#uses=1]
%tmp.9 = getelementptr i32* %P, i32 %B ; <i32*> [#uses=1]
%tmp.4 = getelementptr inbounds i32* %P, i32 %A ; <i32*> [#uses=1]
%tmp.9 = getelementptr inbounds i32* %P, i32 %B ; <i32*> [#uses=1]
%tmp.10 = icmp eq i32* %tmp.4, %tmp.9 ; <i1> [#uses=1]
%tmp.11 = zext i1 %tmp.10 to i32 ; <i32> [#uses=1]
ret i32 %tmp.11
}
define i32 @test4(i32* %P, i32 %A, i32 %B) {
%tmp.4 = getelementptr i32* %P, i32 %A ; <i32*> [#uses=1]
%tmp.4 = getelementptr inbounds i32* %P, i32 %A ; <i32*> [#uses=1]
%tmp.6 = icmp eq i32* %tmp.4, %P ; <i1> [#uses=1]
%tmp.7 = zext i1 %tmp.6 to i32 ; <i32> [#uses=1]
ret i32 %tmp.7

4
test/Transforms/InstCombine/getelementptr-seteq.ll
View File

@ -5,8 +5,8 @@
%S = type { i32, [ 100 x i32] }
define i1 @test(i64 %X, %S* %P) {
%A = getelementptr %S* %P, i32 0, i32 1, i64 %X
%B = getelementptr %S* %P, i32 0, i32 0
%A = getelementptr inbounds %S* %P, i32 0, i32 1, i64 %X
%B = getelementptr inbounds %S* %P, i32 0, i32 0
%C = icmp eq i32* %A, %B
ret i1 %C
}