1 //==- llvm/CodeGen/SelectionDAGAddressAnalysis.cpp - DAG Address Analysis --==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
11 #include "llvm/CodeGen/ISDOpcodes.h"
12 #include "llvm/CodeGen/MachineFrameInfo.h"
13 #include "llvm/CodeGen/MachineFunction.h"
14 #include "llvm/CodeGen/SelectionDAG.h"
15 #include "llvm/CodeGen/SelectionDAGNodes.h"
16 #include "llvm/CodeGen/TargetLowering.h"
17 #include "llvm/Support/Casting.h"
22 bool BaseIndexOffset::equalBaseIndex(BaseIndexOffset &Other,
23 const SelectionDAG &DAG, int64_t &Off) {
24 // Conservatively fail if we a match failed..
25 if (!Base.getNode() || !Other.Base.getNode())
27 // Initial Offset difference.
28 Off = Other.Offset - Offset;
30 if ((Other.Index == Index) && (Other.IsIndexSignExt == IsIndexSignExt)) {
32 if (Other.Base == Base)
35 // Match GlobalAddresses
36 if (auto *A = dyn_cast<GlobalAddressSDNode>(Base))
37 if (auto *B = dyn_cast<GlobalAddressSDNode>(Other.Base))
38 if (A->getGlobal() == B->getGlobal()) {
39 Off += B->getOffset() - A->getOffset();
44 if (auto *A = dyn_cast<ConstantPoolSDNode>(Base))
45 if (auto *B = dyn_cast<ConstantPoolSDNode>(Other.Base)) {
47 A->isMachineConstantPoolEntry() == B->isMachineConstantPoolEntry();
49 if (A->isMachineConstantPoolEntry())
50 IsMatch = A->getMachineCPVal() == B->getMachineCPVal();
52 IsMatch = A->getConstVal() == B->getConstVal();
55 Off += B->getOffset() - A->getOffset();
60 const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
62 // Match non-equal FrameIndexes - If both frame indices are fixed
63 // we know their relative offsets and can compare them. Otherwise
64 // we must be conservative.
65 if (auto *A = dyn_cast<FrameIndexSDNode>(Base))
66 if (auto *B = dyn_cast<FrameIndexSDNode>(Other.Base))
67 if (MFI.isFixedObjectIndex(A->getIndex()) &&
68 MFI.isFixedObjectIndex(B->getIndex())) {
69 Off += MFI.getObjectOffset(B->getIndex()) -
70 MFI.getObjectOffset(A->getIndex());
77 /// Parses tree in Ptr for base, index, offset addresses.
78 BaseIndexOffset BaseIndexOffset::match(LSBaseSDNode *N,
79 const SelectionDAG &DAG) {
80 SDValue Ptr = N->getBasePtr();
82 // (((B + I*M) + c)) + c ...
83 SDValue Base = DAG.getTargetLoweringInfo().unwrapAddress(Ptr);
84 SDValue Index = SDValue();
86 bool IsIndexSignExt = false;
88 // pre-inc/pre-dec ops are components of EA.
89 if (N->getAddressingMode() == ISD::PRE_INC) {
90 if (auto *C = dyn_cast<ConstantSDNode>(N->getOffset()))
91 Offset += C->getSExtValue();
92 else // If unknown, give up now.
93 return BaseIndexOffset(SDValue(), SDValue(), 0, false);
94 } else if (N->getAddressingMode() == ISD::PRE_DEC) {
95 if (auto *C = dyn_cast<ConstantSDNode>(N->getOffset()))
96 Offset -= C->getSExtValue();
97 else // If unknown, give up now.
98 return BaseIndexOffset(SDValue(), SDValue(), 0, false);
101 // Consume constant adds & ors with appropriate masking.
102 while (Base->getOpcode() == ISD::ADD || Base->getOpcode() == ISD::OR) {
103 if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
104 // Only consider ORs which act as adds.
105 if (Base->getOpcode() == ISD::OR &&
106 !DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue()))
108 Offset += C->getSExtValue();
109 Base = Base->getOperand(0);
115 if (Base->getOpcode() == ISD::ADD) {
116 // TODO: The following code appears to be needless as it just
117 // bails on some Ptrs early, reducing the cases where we
118 // find equivalence. We should be able to remove this.
119 // Inside a loop the current BASE pointer is calculated using an ADD and a
120 // MUL instruction. In this case Base is the actual BASE pointer.
121 // (i64 add (i64 %array_ptr)
122 // (i64 mul (i64 %induction_var)
123 // (i64 %element_size)))
124 if (Base->getOperand(1)->getOpcode() == ISD::MUL)
125 return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
127 // Look at Base + Index + Offset cases.
128 Index = Base->getOperand(1);
129 SDValue PotentialBase = Base->getOperand(0);
132 if (Index->getOpcode() == ISD::SIGN_EXTEND) {
133 Index = Index->getOperand(0);
134 IsIndexSignExt = true;
137 // Check if Index Offset pattern
138 if (Index->getOpcode() != ISD::ADD ||
139 !isa<ConstantSDNode>(Index->getOperand(1)))
140 return BaseIndexOffset(PotentialBase, Index, Offset, IsIndexSignExt);
142 Offset += cast<ConstantSDNode>(Index->getOperand(1))->getSExtValue();
143 Index = Index->getOperand(0);
144 if (Index->getOpcode() == ISD::SIGN_EXTEND) {
145 Index = Index->getOperand(0);
146 IsIndexSignExt = true;
148 IsIndexSignExt = false;
149 Base = PotentialBase;
151 return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);