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//===-- llvm/CodeGen/SelectionDAGAddressAnalysis.cpp ------- DAG Address
//Analysis ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
namespace llvm {
bool BaseIndexOffset::equalBaseIndex(BaseIndexOffset &Other,
const SelectionDAG &DAG, int64_t &Off) {
// Initial Offset difference.
Off = Other.Offset - Offset;
if ((Other.Index == Index) && (Other.IsIndexSignExt == IsIndexSignExt)) {
// Trivial match.
if (Other.Base == Base)
return true;
// Match GlobalAddresses
if (auto *A = dyn_cast<GlobalAddressSDNode>(Base))
if (auto *B = dyn_cast<GlobalAddressSDNode>(Other.Base))
if (A->getGlobal() == B->getGlobal()) {
Off += B->getOffset() - A->getOffset();
return true;
}
const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
// Match non-equal FrameIndexes - If both frame indices are fixed
// we know their relative offsets and can compare them. Otherwise
// we must be conservative.
if (auto *A = dyn_cast<FrameIndexSDNode>(Base))
if (auto *B = dyn_cast<FrameIndexSDNode>(Other.Base))
if (MFI.isFixedObjectIndex(A->getIndex()) &&
MFI.isFixedObjectIndex(B->getIndex())) {
Off += MFI.getObjectOffset(B->getIndex()) -
MFI.getObjectOffset(A->getIndex());
return true;
}
}
return false;
}
/// Parses tree in Ptr for base, index, offset addresses.
BaseIndexOffset BaseIndexOffset::match(SDValue Ptr, const SelectionDAG &DAG) {
// (((B + I*M) + c)) + c ...
SDValue Base = Ptr;
SDValue Index = SDValue();
int64_t Offset = 0;
bool IsIndexSignExt = false;
// Consume constant adds & ors with appropriate masking.
while (Base->getOpcode() == ISD::ADD || Base->getOpcode() == ISD::OR) {
if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
// Only consider ORs which act as adds.
if (Base->getOpcode() == ISD::OR &&
!DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue()))
break;
Offset += C->getSExtValue();
Base = Base->getOperand(0);
continue;
}
break;
}
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);
// Look at Base + Index + Offset cases.
Index = Base->getOperand(1);
SDValue PotentialBase = Base->getOperand(0);
// Skip signextends.
if (Index->getOpcode() == ISD::SIGN_EXTEND) {
Index = Index->getOperand(0);
IsIndexSignExt = true;
}
// Check if Index Offset pattern
if (Index->getOpcode() != ISD::ADD ||
!isa<ConstantSDNode>(Index->getOperand(1)))
return BaseIndexOffset(PotentialBase, Index, Offset, IsIndexSignExt);
Offset += cast<ConstantSDNode>(Index->getOperand(1))->getSExtValue();
Index = Index->getOperand(0);
if (Index->getOpcode() == ISD::SIGN_EXTEND) {
Index = Index->getOperand(0);
IsIndexSignExt = true;
} else
IsIndexSignExt = false;
Base = PotentialBase;
}
return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
}
} // end namespace llvm
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