1 //===-- llvm/CodeGen/SelectionDAGAddressAnalysis.cpp ------- DAG Address
2 //Analysis ---*- C++ -*-===//
4 // The LLVM Compiler Infrastructure
6 // This file is distributed under the University of Illinois Open Source
7 // License. See LICENSE.TXT for details.
9 //===----------------------------------------------------------------------===//
12 #include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
13 #include "llvm/CodeGen/ISDOpcodes.h"
14 #include "llvm/CodeGen/MachineFrameInfo.h"
15 #include "llvm/CodeGen/SelectionDAG.h"
16 #include "llvm/CodeGen/SelectionDAGNodes.h"
20 bool BaseIndexOffset::equalBaseIndex(BaseIndexOffset &Other,
21 const SelectionDAG &DAG, int64_t &Off) {
22 // Initial Offset difference.
23 Off = Other.Offset - Offset;
25 if ((Other.Index == Index) && (Other.IsIndexSignExt == IsIndexSignExt)) {
27 if (Other.Base == Base)
30 // Match GlobalAddresses
31 if (auto *A = dyn_cast<GlobalAddressSDNode>(Base))
32 if (auto *B = dyn_cast<GlobalAddressSDNode>(Other.Base))
33 if (A->getGlobal() == B->getGlobal()) {
34 Off += B->getOffset() - A->getOffset();
38 const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
40 // Match non-equal FrameIndexes - If both frame indices are fixed
41 // we know their relative offsets and can compare them. Otherwise
42 // we must be conservative.
43 if (auto *A = dyn_cast<FrameIndexSDNode>(Base))
44 if (auto *B = dyn_cast<FrameIndexSDNode>(Other.Base))
45 if (MFI.isFixedObjectIndex(A->getIndex()) &&
46 MFI.isFixedObjectIndex(B->getIndex())) {
47 Off += MFI.getObjectOffset(B->getIndex()) -
48 MFI.getObjectOffset(A->getIndex());
55 /// Parses tree in Ptr for base, index, offset addresses.
56 BaseIndexOffset BaseIndexOffset::match(SDValue Ptr, const SelectionDAG &DAG) {
57 // (((B + I*M) + c)) + c ...
59 SDValue Index = SDValue();
61 bool IsIndexSignExt = false;
63 // Consume constant adds & ors with appropriate masking.
64 while (Base->getOpcode() == ISD::ADD || Base->getOpcode() == ISD::OR) {
65 if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
66 // Only consider ORs which act as adds.
67 if (Base->getOpcode() == ISD::OR &&
68 !DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue()))
70 Offset += C->getSExtValue();
71 Base = Base->getOperand(0);
77 if (Base->getOpcode() == ISD::ADD) {
78 // TODO: The following code appears to be needless as it just
79 // bails on some Ptrs early, reducing the cases where we
80 // find equivalence. We should be able to remove this.
81 // Inside a loop the current BASE pointer is calculated using an ADD and a
82 // MUL instruction. In this case Base is the actual BASE pointer.
83 // (i64 add (i64 %array_ptr)
84 // (i64 mul (i64 %induction_var)
85 // (i64 %element_size)))
86 if (Base->getOperand(1)->getOpcode() == ISD::MUL)
87 return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
89 // Look at Base + Index + Offset cases.
90 Index = Base->getOperand(1);
91 SDValue PotentialBase = Base->getOperand(0);
94 if (Index->getOpcode() == ISD::SIGN_EXTEND) {
95 Index = Index->getOperand(0);
96 IsIndexSignExt = true;
99 // Check if Index Offset pattern
100 if (Index->getOpcode() != ISD::ADD ||
101 !isa<ConstantSDNode>(Index->getOperand(1)))
102 return BaseIndexOffset(PotentialBase, Index, Offset, IsIndexSignExt);
104 Offset += cast<ConstantSDNode>(Index->getOperand(1))->getSExtValue();
105 Index = Index->getOperand(0);
106 if (Index->getOpcode() == ISD::SIGN_EXTEND) {
107 Index = Index->getOperand(0);
108 IsIndexSignExt = true;
110 IsIndexSignExt = false;
111 Base = PotentialBase;
113 return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
115 } // end namespace llvm