ARMSelectionDAGInfo.cpp revision cd81d94322a39503e4a3e87b6ee03d4fcb3465fb 
1//===-- ARMSelectionDAGInfo.cpp - ARM SelectionDAG Info -------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the ARMSelectionDAGInfo class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "ARMTargetMachine.h"
15#include "llvm/CodeGen/SelectionDAG.h"
16#include "llvm/IR/DerivedTypes.h"
17using namespace llvm;
18
19#define DEBUG_TYPE "arm-selectiondag-info"
20
21ARMSelectionDAGInfo::ARMSelectionDAGInfo(const DataLayout &DL)
22    : TargetSelectionDAGInfo(&DL) {}
23
24ARMSelectionDAGInfo::~ARMSelectionDAGInfo() {
25}
26
27SDValue
28ARMSelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc dl,
29                                             SDValue Chain,
30                                             SDValue Dst, SDValue Src,
31                                             SDValue Size, unsigned Align,
32                                             bool isVolatile, bool AlwaysInline,
33                                             MachinePointerInfo DstPtrInfo,
34                                          MachinePointerInfo SrcPtrInfo) const {
35  const ARMSubtarget &Subtarget = DAG.getTarget().getSubtarget<ARMSubtarget>();
36  // Do repeated 4-byte loads and stores. To be improved.
37  // This requires 4-byte alignment.
38  if ((Align & 3) != 0)
39    return SDValue();
40  // This requires the copy size to be a constant, preferably
41  // within a subtarget-specific limit.
42  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
43  if (!ConstantSize)
44    return SDValue();
45  uint64_t SizeVal = ConstantSize->getZExtValue();
46  if (!AlwaysInline && SizeVal > Subtarget.getMaxInlineSizeThreshold())
47    return SDValue();
48
49  unsigned BytesLeft = SizeVal & 3;
50  unsigned NumMemOps = SizeVal >> 2;
51  unsigned EmittedNumMemOps = 0;
52  EVT VT = MVT::i32;
53  unsigned VTSize = 4;
54  unsigned i = 0;
55  // Emit a maximum of 4 loads in Thumb1 since we have fewer registers
56  const unsigned MAX_LOADS_IN_LDM = Subtarget.isThumb1Only() ? 4 : 6;
57  SDValue TFOps[6];
58  SDValue Loads[6];
59  uint64_t SrcOff = 0, DstOff = 0;
60
61  // Emit up to MAX_LOADS_IN_LDM loads, then a TokenFactor barrier, then the
62  // same number of stores.  The loads and stores will get combined into
63  // ldm/stm later on.
64  while (EmittedNumMemOps < NumMemOps) {
65    for (i = 0;
66         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
67      Loads[i] = DAG.getLoad(VT, dl, Chain,
68                             DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
69                                         DAG.getConstant(SrcOff, MVT::i32)),
70                             SrcPtrInfo.getWithOffset(SrcOff), isVolatile,
71                             false, false, 0);
72      TFOps[i] = Loads[i].getValue(1);
73      SrcOff += VTSize;
74    }
75    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
76                        makeArrayRef(TFOps, i));
77
78    for (i = 0;
79         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
80      TFOps[i] = DAG.getStore(Chain, dl, Loads[i],
81                              DAG.getNode(ISD::ADD, dl, MVT::i32, Dst,
82                                          DAG.getConstant(DstOff, MVT::i32)),
83                              DstPtrInfo.getWithOffset(DstOff),
84                              isVolatile, false, 0);
85      DstOff += VTSize;
86    }
87    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
88                        makeArrayRef(TFOps, i));
89
90    EmittedNumMemOps += i;
91  }
92
93  if (BytesLeft == 0)
94    return Chain;
95
96  // Issue loads / stores for the trailing (1 - 3) bytes.
97  unsigned BytesLeftSave = BytesLeft;
98  i = 0;
99  while (BytesLeft) {
100    if (BytesLeft >= 2) {
101      VT = MVT::i16;
102      VTSize = 2;
103    } else {
104      VT = MVT::i8;
105      VTSize = 1;
106    }
107
108    Loads[i] = DAG.getLoad(VT, dl, Chain,
109                           DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
110                                       DAG.getConstant(SrcOff, MVT::i32)),
111                           SrcPtrInfo.getWithOffset(SrcOff),
112                           false, false, false, 0);
113    TFOps[i] = Loads[i].getValue(1);
114    ++i;
115    SrcOff += VTSize;
116    BytesLeft -= VTSize;
117  }
118  Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
119                      makeArrayRef(TFOps, i));
120
121  i = 0;
122  BytesLeft = BytesLeftSave;
123  while (BytesLeft) {
124    if (BytesLeft >= 2) {
125      VT = MVT::i16;
126      VTSize = 2;
127    } else {
128      VT = MVT::i8;
129      VTSize = 1;
130    }
131
132    TFOps[i] = DAG.getStore(Chain, dl, Loads[i],
133                            DAG.getNode(ISD::ADD, dl, MVT::i32, Dst,
134                                        DAG.getConstant(DstOff, MVT::i32)),
135                            DstPtrInfo.getWithOffset(DstOff), false, false, 0);
136    ++i;
137    DstOff += VTSize;
138    BytesLeft -= VTSize;
139  }
140  return DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
141                     makeArrayRef(TFOps, i));
142}
143
144// Adjust parameters for memset, EABI uses format (ptr, size, value),
145// GNU library uses (ptr, value, size)
146// See RTABI section 4.3.4
147SDValue ARMSelectionDAGInfo::
148EmitTargetCodeForMemset(SelectionDAG &DAG, SDLoc dl,
149                        SDValue Chain, SDValue Dst,
150                        SDValue Src, SDValue Size,
151                        unsigned Align, bool isVolatile,
152                        MachinePointerInfo DstPtrInfo) const {
153  const ARMSubtarget &Subtarget = DAG.getTarget().getSubtarget<ARMSubtarget>();
154  // Use default for non-AAPCS (or MachO) subtargets
155  if (!Subtarget.isAAPCS_ABI() || Subtarget.isTargetMachO() ||
156      Subtarget.isTargetWindows())
157    return SDValue();
158
159  const ARMTargetLowering &TLI =
160    *static_cast<const ARMTargetLowering*>(DAG.getTarget().getTargetLowering());
161  TargetLowering::ArgListTy Args;
162  TargetLowering::ArgListEntry Entry;
163
164  // First argument: data pointer
165  Type *IntPtrTy = TLI.getDataLayout()->getIntPtrType(*DAG.getContext());
166  Entry.Node = Dst;
167  Entry.Ty = IntPtrTy;
168  Args.push_back(Entry);
169
170  // Second argument: buffer size
171  Entry.Node = Size;
172  Entry.Ty = IntPtrTy;
173  Entry.isSExt = false;
174  Args.push_back(Entry);
175
176  // Extend or truncate the argument to be an i32 value for the call.
177  if (Src.getValueType().bitsGT(MVT::i32))
178    Src = DAG.getNode(ISD::TRUNCATE, dl, MVT::i32, Src);
179  else
180    Src = DAG.getNode(ISD::ZERO_EXTEND, dl, MVT::i32, Src);
181
182  // Third argument: value to fill
183  Entry.Node = Src;
184  Entry.Ty = Type::getInt32Ty(*DAG.getContext());
185  Entry.isSExt = true;
186  Args.push_back(Entry);
187
188  // Emit __eabi_memset call
189  TargetLowering::CallLoweringInfo CLI(DAG);
190  CLI.setDebugLoc(dl).setChain(Chain)
191    .setCallee(TLI.getLibcallCallingConv(RTLIB::MEMSET),
192               Type::getVoidTy(*DAG.getContext()),
193               DAG.getExternalSymbol(TLI.getLibcallName(RTLIB::MEMSET),
194                                     TLI.getPointerTy()), std::move(Args), 0)
195    .setDiscardResult();
196
197  std::pair<SDValue,SDValue> CallResult = TLI.LowerCallTo(CLI);
198  return CallResult.second;
199}
200