Revert "Revert two GEP-related InstCombine commits"
This reverts commit r216698 which reverted r216523 and r216598.
We would attempt to perform the transformation even if the match()
failed because, as a side effect, it would set V. This would trick us
into believing that we correctly found a place to correctly apply the
transform.
An additional test case was added to getelementptr.ll so that we might
not regress in the future.
llvm-svn: 216890
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index f01dca7..a95f578 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1508,19 +1508,50 @@
GetElementPtrInst::Create(Src->getOperand(0), Indices, GEP.getName());
}
- // Canonicalize (gep i8* X, -(ptrtoint Y)) to (sub (ptrtoint X), (ptrtoint Y))
- // The GEP pattern is emitted by the SCEV expander for certain kinds of
- // pointer arithmetic.
- if (DL && GEP.getNumIndices() == 1 &&
- match(GEP.getOperand(1), m_Neg(m_PtrToInt(m_Value())))) {
+ if (DL && GEP.getNumIndices() == 1) {
unsigned AS = GEP.getPointerAddressSpace();
- if (GEP.getType() == Builder->getInt8PtrTy(AS) &&
- GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
+ if (GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
DL->getPointerSizeInBits(AS)) {
- Operator *Index = cast<Operator>(GEP.getOperand(1));
- Value *PtrToInt = Builder->CreatePtrToInt(PtrOp, Index->getType());
- Value *NewSub = Builder->CreateSub(PtrToInt, Index->getOperand(1));
- return CastInst::Create(Instruction::IntToPtr, NewSub, GEP.getType());
+ Type *PtrTy = GEP.getPointerOperandType();
+ Type *Ty = PtrTy->getPointerElementType();
+ uint64_t TyAllocSize = DL->getTypeAllocSize(Ty);
+
+ bool Matched = false;
+ uint64_t C;
+ Value *V = nullptr;
+ if (TyAllocSize == 1) {
+ V = GEP.getOperand(1);
+ Matched = true;
+ } else if (match(GEP.getOperand(1),
+ m_AShr(m_Value(V), m_ConstantInt(C)))) {
+ if (TyAllocSize == 1ULL << C)
+ Matched = true;
+ } else if (match(GEP.getOperand(1),
+ m_SDiv(m_Value(V), m_ConstantInt(C)))) {
+ if (TyAllocSize == C)
+ Matched = true;
+ }
+
+ if (Matched) {
+ // Canonicalize (gep i8* X, -(ptrtoint Y))
+ // to (inttoptr (sub (ptrtoint X), (ptrtoint Y)))
+ // The GEP pattern is emitted by the SCEV expander for certain kinds of
+ // pointer arithmetic.
+ if (match(V, m_Neg(m_PtrToInt(m_Value())))) {
+ Operator *Index = cast<Operator>(V);
+ Value *PtrToInt = Builder->CreatePtrToInt(PtrOp, Index->getType());
+ Value *NewSub = Builder->CreateSub(PtrToInt, Index->getOperand(1));
+ return CastInst::Create(Instruction::IntToPtr, NewSub, GEP.getType());
+ }
+ // Canonicalize (gep i8* X, (ptrtoint Y)-(ptrtoint X))
+ // to (bitcast Y)
+ Value *Y;
+ if (match(V, m_Sub(m_PtrToInt(m_Value(Y)),
+ m_PtrToInt(m_Specific(GEP.getOperand(0)))))) {
+ return CastInst::CreatePointerBitCastOrAddrSpaceCast(Y,
+ GEP.getType());
+ }
+ }
}
}