ARMSelectionDAGInfo.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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 TargetMachine &TM)
22  : TargetSelectionDAGInfo(TM),
23    Subtarget(&TM.getSubtarget<ARMSubtarget>()) {
24}
25
26ARMSelectionDAGInfo::~ARMSelectionDAGInfo() {
27}
28
29SDValue
30ARMSelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc dl,
31                                             SDValue Chain,
32                                             SDValue Dst, SDValue Src,
33                                             SDValue Size, unsigned Align,
34                                             bool isVolatile, bool AlwaysInline,
35                                             MachinePointerInfo DstPtrInfo,
36                                          MachinePointerInfo SrcPtrInfo) const {
37  // Do repeated 4-byte loads and stores. To be improved.
38  // This requires 4-byte alignment.
39  if ((Align & 3) != 0)
40    return SDValue();
41  // This requires the copy size to be a constant, preferably
42  // within a subtarget-specific limit.
43  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
44  if (!ConstantSize)
45    return SDValue();
46  uint64_t SizeVal = ConstantSize->getZExtValue();
47  if (!AlwaysInline && SizeVal > Subtarget->getMaxInlineSizeThreshold())
48    return SDValue();
49
50  unsigned BytesLeft = SizeVal & 3;
51  unsigned NumMemOps = SizeVal >> 2;
52  unsigned EmittedNumMemOps = 0;
53  EVT VT = MVT::i32;
54  unsigned VTSize = 4;
55  unsigned i = 0;
56  // Emit a maximum of 4 loads in Thumb1 since we have fewer registers
57  const unsigned MAX_LOADS_IN_LDM = Subtarget->isThumb1Only() ? 4 : 6;
58  SDValue TFOps[6];
59  SDValue Loads[6];
60  uint64_t SrcOff = 0, DstOff = 0;
61
62  // Emit up to MAX_LOADS_IN_LDM loads, then a TokenFactor barrier, then the
63  // same number of stores.  The loads and stores will get combined into
64  // ldm/stm later on.
65  while (EmittedNumMemOps < NumMemOps) {
66    for (i = 0;
67         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
68      Loads[i] = DAG.getLoad(VT, dl, Chain,
69                             DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
70                                         DAG.getConstant(SrcOff, MVT::i32)),
71                             SrcPtrInfo.getWithOffset(SrcOff), isVolatile,
72                             false, false, 0);
73      TFOps[i] = Loads[i].getValue(1);
74      SrcOff += VTSize;
75    }
76    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
77                        makeArrayRef(TFOps, i));
78
79    for (i = 0;
80         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
81      TFOps[i] = DAG.getStore(Chain, dl, Loads[i],
82                              DAG.getNode(ISD::ADD, dl, MVT::i32, Dst,
83                                          DAG.getConstant(DstOff, MVT::i32)),
84                              DstPtrInfo.getWithOffset(DstOff),
85                              isVolatile, false, 0);
86      DstOff += VTSize;
87    }
88    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
89                        makeArrayRef(TFOps, i));
90
91    EmittedNumMemOps += i;
92  }
93
94  if (BytesLeft == 0)
95    return Chain;
96
97  // Issue loads / stores for the trailing (1 - 3) bytes.
98  unsigned BytesLeftSave = BytesLeft;
99  i = 0;
100  while (BytesLeft) {
101    if (BytesLeft >= 2) {
102      VT = MVT::i16;
103      VTSize = 2;
104    } else {
105      VT = MVT::i8;
106      VTSize = 1;
107    }
108
109    Loads[i] = DAG.getLoad(VT, dl, Chain,
110                           DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
111                                       DAG.getConstant(SrcOff, MVT::i32)),
112                           SrcPtrInfo.getWithOffset(SrcOff),
113                           false, false, false, 0);
114    TFOps[i] = Loads[i].getValue(1);
115    ++i;
116    SrcOff += VTSize;
117    BytesLeft -= VTSize;
118  }
119  Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
120                      makeArrayRef(TFOps, i));
121
122  i = 0;
123  BytesLeft = BytesLeftSave;
124  while (BytesLeft) {
125    if (BytesLeft >= 2) {
126      VT = MVT::i16;
127      VTSize = 2;
128    } else {
129      VT = MVT::i8;
130      VTSize = 1;
131    }
132
133    TFOps[i] = DAG.getStore(Chain, dl, Loads[i],
134                            DAG.getNode(ISD::ADD, dl, MVT::i32, Dst,
135                                        DAG.getConstant(DstOff, MVT::i32)),
136                            DstPtrInfo.getWithOffset(DstOff), false, false, 0);
137    ++i;
138    DstOff += VTSize;
139    BytesLeft -= VTSize;
140  }
141  return DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
142                     makeArrayRef(TFOps, i));
143}
144
145// Adjust parameters for memset, EABI uses format (ptr, size, value),
146// GNU library uses (ptr, value, size)
147// See RTABI section 4.3.4
148SDValue ARMSelectionDAGInfo::
149EmitTargetCodeForMemset(SelectionDAG &DAG, SDLoc dl,
150                        SDValue Chain, SDValue Dst,
151                        SDValue Src, SDValue Size,
152                        unsigned Align, bool isVolatile,
153                        MachinePointerInfo DstPtrInfo) const {
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()), &Args, 0)
195    .setDiscardResult();
196
197  std::pair<SDValue,SDValue> CallResult = TLI.LowerCallTo(CLI);
198  return CallResult.second;
199}
200