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[DAG] Simplify BaseIndexOffset. NFCI.

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Remove tail calls and cleanup codeflow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305768 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nirav Dave 2017-06-20 02:48:39 +00:00
parent 9f0d281d87
commit 9c490091f2
1 changed files with 55 additions and 57 deletions
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112
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -4726,74 +4726,72 @@ struct BaseIndexOffset {
}
/// Parses tree in Ptr for base, index, offset addresses.
static BaseIndexOffset match(SDValue Ptr, SelectionDAG &DAG,
int64_t PartialOffset = 0) {
static BaseIndexOffset match(SDValue Ptr, SelectionDAG &DAG) {
SDValue Base = Ptr;
SDValue Index = SDValue();
int64_t Offset = 0;
bool IsIndexSignExt = false;
// (((B + I*M) + O)) + O ...
//Consume constant adds
while (Base->getOpcode() == ISD::ADD &&
isa<ConstantSDNode>(Base->getOperand(1))) {
int64_t POffset = cast<ConstantSDNode>(Base->getOperand(1))->getSExtValue();
Offset += POffset;
Base = Base->getOperand(0);
}
// Split up a folded GlobalAddress+Offset into its component parts.
if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Ptr))
if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Base))
if (GA->getOpcode() == ISD::GlobalAddress && GA->getOffset() != 0) {
return BaseIndexOffset(DAG.getGlobalAddress(GA->getGlobal(),
SDLoc(GA),
GA->getValueType(0),
/*Offset=*/PartialOffset,
/*isTargetGA=*/false,
GA->getTargetFlags()),
SDValue(),
GA->getOffset(),
IsIndexSignExt);
Base = DAG.getGlobalAddress(GA->getGlobal(),
SDLoc(GA),
GA->getValueType(0),
/*Offset*/ 0,
/*isTargetGA=*/false,
GA->getTargetFlags());
Offset += GA->getOffset();
return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
}
// We only can pattern match BASE + INDEX + OFFSET. If Ptr is not an ADD
// instruction, then it could be just the BASE or everything else we don't
// know how to handle. Just use Ptr as BASE and give up.
if (Ptr->getOpcode() != ISD::ADD)
return BaseIndexOffset(Ptr, SDValue(), PartialOffset, IsIndexSignExt);
if (Base->getOpcode() == ISD::ADD) {
// TODO: The following code appears to be needless as it just
// bails on some Ptrs early, reducing the cases where we
// find equivalence. We should be able to remove this.
// Inside a loop the current BASE pointer is calculated using an ADD and a
// MUL instruction. In this case Base is the actual BASE pointer.
// (i64 add (i64 %array_ptr)
// (i64 mul (i64 %induction_var)
// (i64 %element_size)))
if (Base->getOperand(1)->getOpcode() == ISD::MUL)
return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
// We know that we have at least an ADD instruction. Try to pattern match
// the simple case of BASE + OFFSET.
if (isa<ConstantSDNode>(Ptr->getOperand(1))) {
int64_t Offset = cast<ConstantSDNode>(Ptr->getOperand(1))->getSExtValue();
return match(Ptr->getOperand(0), DAG, Offset + PartialOffset);
}
// Look at Base + Index + Offset cases.
Index = Base->getOperand(1);
SDValue PotentialBase = Base->getOperand(0);
// Inside a loop the current BASE pointer is calculated using an ADD and a
// MUL instruction. In this case Ptr is the actual BASE pointer.
// (i64 add (i64 %array_ptr)
// (i64 mul (i64 %induction_var)
// (i64 %element_size)))
if (Ptr->getOperand(1)->getOpcode() == ISD::MUL)
return BaseIndexOffset(Ptr, SDValue(), PartialOffset, IsIndexSignExt);
// Skip signextends.
if (Index->getOpcode() == ISD::SIGN_EXTEND) {
Index = Index->getOperand(0);
IsIndexSignExt = true;
}
// Look at Base + Index + Offset cases.
SDValue Base = Ptr->getOperand(0);
SDValue IndexOffset = Ptr->getOperand(1);
// Check if Index Offset pattern
if (Index->getOpcode() != ISD::ADD ||
!isa<ConstantSDNode>(Index->getOperand(1)))
return BaseIndexOffset(PotentialBase, Index, Offset, IsIndexSignExt);
// Skip signextends.
if (IndexOffset->getOpcode() == ISD::SIGN_EXTEND) {
IndexOffset = IndexOffset->getOperand(0);
IsIndexSignExt = true;
}
// Either the case of Base + Index (no offset) or something else.
if (IndexOffset->getOpcode() != ISD::ADD)
return BaseIndexOffset(Base, IndexOffset, PartialOffset, IsIndexSignExt);
// Now we have the case of Base + Index + offset.
SDValue Index = IndexOffset->getOperand(0);
SDValue Offset = IndexOffset->getOperand(1);
if (!isa<ConstantSDNode>(Offset))
return BaseIndexOffset(Ptr, SDValue(), PartialOffset, IsIndexSignExt);
// Ignore signextends.
if (Index->getOpcode() == ISD::SIGN_EXTEND) {
Offset += cast<ConstantSDNode>(Index->getOperand(1))->getSExtValue();
Index = Index->getOperand(0);
IsIndexSignExt = true;
} else IsIndexSignExt = false;
int64_t Off = cast<ConstantSDNode>(Offset)->getSExtValue();
return BaseIndexOffset(Base, Index, Off + PartialOffset, IsIndexSignExt);
if (Index->getOpcode() == ISD::SIGN_EXTEND) {
Index = Index->getOperand(0);
IsIndexSignExt = true;
} else IsIndexSignExt = false;
Base = PotentialBase;
}
return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
}
};
} // namespace