1 //===-- X86SelectionDAGInfo.cpp - X86 SelectionDAG Info -------------------===//
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 // This file implements the X86SelectionDAGInfo class.
12 //===----------------------------------------------------------------------===//
14 #include "X86TargetMachine.h"
15 #include "llvm/CodeGen/SelectionDAG.h"
16 #include "llvm/IR/DerivedTypes.h"
19 #define DEBUG_TYPE "x86-selectiondag-info"
21 X86SelectionDAGInfo::X86SelectionDAGInfo(const X86TargetMachine &TM) :
22 TargetSelectionDAGInfo(TM),
23 Subtarget(&TM.getSubtarget<X86Subtarget>()),
24 TLI(*TM.getTargetLowering()) {
27 X86SelectionDAGInfo::~X86SelectionDAGInfo() {
31 X86SelectionDAGInfo::EmitTargetCodeForMemset(SelectionDAG &DAG, SDLoc dl,
33 SDValue Dst, SDValue Src,
34 SDValue Size, unsigned Align,
36 MachinePointerInfo DstPtrInfo) const {
37 ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
39 // If to a segment-relative address space, use the default lowering.
40 if (DstPtrInfo.getAddrSpace() >= 256)
43 // If not DWORD aligned or size is more than the threshold, call the library.
44 // The libc version is likely to be faster for these cases. It can use the
45 // address value and run time information about the CPU.
46 if ((Align & 3) != 0 ||
48 ConstantSize->getZExtValue() >
49 Subtarget->getMaxInlineSizeThreshold()) {
50 // Check to see if there is a specialized entry-point for memory zeroing.
51 ConstantSDNode *V = dyn_cast<ConstantSDNode>(Src);
53 if (const char *bzeroEntry = V &&
54 V->isNullValue() ? Subtarget->getBZeroEntry() : nullptr) {
55 EVT IntPtr = TLI.getPointerTy();
56 Type *IntPtrTy = getDataLayout()->getIntPtrType(*DAG.getContext());
57 TargetLowering::ArgListTy Args;
58 TargetLowering::ArgListEntry Entry;
61 Args.push_back(Entry);
63 Args.push_back(Entry);
65 CallLoweringInfo CLI(Chain, Type::getVoidTy(*DAG.getContext()),
66 false, false, false, false,
67 0, CallingConv::C, /*isTailCall=*/false,
68 /*doesNotRet=*/false, /*isReturnValueUsed=*/false,
69 DAG.getExternalSymbol(bzeroEntry, IntPtr), Args,
71 std::pair<SDValue,SDValue> CallResult =
73 return CallResult.second;
76 // Otherwise have the target-independent code call memset.
80 uint64_t SizeVal = ConstantSize->getZExtValue();
84 ConstantSDNode *ValC = dyn_cast<ConstantSDNode>(Src);
85 unsigned BytesLeft = 0;
86 bool TwoRepStos = false;
89 uint64_t Val = ValC->getZExtValue() & 255;
91 // If the value is a constant, then we can potentially use larger sets.
93 case 2: // WORD aligned
96 Val = (Val << 8) | Val;
98 case 0: // DWORD aligned
101 Val = (Val << 8) | Val;
102 Val = (Val << 16) | Val;
103 if (Subtarget->is64Bit() && ((Align & 0x7) == 0)) { // QWORD aligned
106 Val = (Val << 32) | Val;
109 default: // Byte aligned
112 Count = DAG.getIntPtrConstant(SizeVal);
116 if (AVT.bitsGT(MVT::i8)) {
117 unsigned UBytes = AVT.getSizeInBits() / 8;
118 Count = DAG.getIntPtrConstant(SizeVal / UBytes);
119 BytesLeft = SizeVal % UBytes;
122 Chain = DAG.getCopyToReg(Chain, dl, ValReg, DAG.getConstant(Val, AVT),
124 InFlag = Chain.getValue(1);
127 Count = DAG.getIntPtrConstant(SizeVal);
128 Chain = DAG.getCopyToReg(Chain, dl, X86::AL, Src, InFlag);
129 InFlag = Chain.getValue(1);
132 Chain = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RCX :
135 InFlag = Chain.getValue(1);
136 Chain = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RDI :
139 InFlag = Chain.getValue(1);
141 SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Glue);
142 SDValue Ops[] = { Chain, DAG.getValueType(AVT), InFlag };
143 Chain = DAG.getNode(X86ISD::REP_STOS, dl, Tys, Ops, array_lengthof(Ops));
146 InFlag = Chain.getValue(1);
148 EVT CVT = Count.getValueType();
149 SDValue Left = DAG.getNode(ISD::AND, dl, CVT, Count,
150 DAG.getConstant((AVT == MVT::i64) ? 7 : 3, CVT));
151 Chain = DAG.getCopyToReg(Chain, dl, (CVT == MVT::i64) ? X86::RCX :
154 InFlag = Chain.getValue(1);
155 Tys = DAG.getVTList(MVT::Other, MVT::Glue);
156 SDValue Ops[] = { Chain, DAG.getValueType(MVT::i8), InFlag };
157 Chain = DAG.getNode(X86ISD::REP_STOS, dl, Tys, Ops, array_lengthof(Ops));
158 } else if (BytesLeft) {
159 // Handle the last 1 - 7 bytes.
160 unsigned Offset = SizeVal - BytesLeft;
161 EVT AddrVT = Dst.getValueType();
162 EVT SizeVT = Size.getValueType();
164 Chain = DAG.getMemset(Chain, dl,
165 DAG.getNode(ISD::ADD, dl, AddrVT, Dst,
166 DAG.getConstant(Offset, AddrVT)),
168 DAG.getConstant(BytesLeft, SizeVT),
169 Align, isVolatile, DstPtrInfo.getWithOffset(Offset));
172 // TODO: Use a Tokenfactor, as in memcpy, instead of a single chain.
177 X86SelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc dl,
178 SDValue Chain, SDValue Dst, SDValue Src,
179 SDValue Size, unsigned Align,
180 bool isVolatile, bool AlwaysInline,
181 MachinePointerInfo DstPtrInfo,
182 MachinePointerInfo SrcPtrInfo) const {
183 // This requires the copy size to be a constant, preferably
184 // within a subtarget-specific limit.
185 ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
188 uint64_t SizeVal = ConstantSize->getZExtValue();
189 if (!AlwaysInline && SizeVal > Subtarget->getMaxInlineSizeThreshold())
192 /// If not DWORD aligned, it is more efficient to call the library. However
193 /// if calling the library is not allowed (AlwaysInline), then soldier on as
194 /// the code generated here is better than the long load-store sequence we
195 /// would otherwise get.
196 if (!AlwaysInline && (Align & 3) != 0)
199 // If to a segment-relative address space, use the default lowering.
200 if (DstPtrInfo.getAddrSpace() >= 256 ||
201 SrcPtrInfo.getAddrSpace() >= 256)
204 // ESI might be used as a base pointer, in that case we can't simply overwrite
205 // the register. Fall back to generic code.
206 const X86RegisterInfo *TRI =
207 static_cast<const X86RegisterInfo *>(DAG.getTarget().getRegisterInfo());
208 if (TRI->hasBasePointer(DAG.getMachineFunction()) &&
209 TRI->getBaseRegister() == X86::ESI)
222 AVT = Subtarget->is64Bit() ? MVT::i64 : MVT::i32;
224 unsigned UBytes = AVT.getSizeInBits() / 8;
225 unsigned CountVal = SizeVal / UBytes;
226 SDValue Count = DAG.getIntPtrConstant(CountVal);
227 unsigned BytesLeft = SizeVal % UBytes;
230 Chain = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RCX :
233 InFlag = Chain.getValue(1);
234 Chain = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RDI :
237 InFlag = Chain.getValue(1);
238 Chain = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RSI :
241 InFlag = Chain.getValue(1);
243 SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Glue);
244 SDValue Ops[] = { Chain, DAG.getValueType(AVT), InFlag };
245 SDValue RepMovs = DAG.getNode(X86ISD::REP_MOVS, dl, Tys, Ops,
246 array_lengthof(Ops));
248 SmallVector<SDValue, 4> Results;
249 Results.push_back(RepMovs);
251 // Handle the last 1 - 7 bytes.
252 unsigned Offset = SizeVal - BytesLeft;
253 EVT DstVT = Dst.getValueType();
254 EVT SrcVT = Src.getValueType();
255 EVT SizeVT = Size.getValueType();
256 Results.push_back(DAG.getMemcpy(Chain, dl,
257 DAG.getNode(ISD::ADD, dl, DstVT, Dst,
258 DAG.getConstant(Offset, DstVT)),
259 DAG.getNode(ISD::ADD, dl, SrcVT, Src,
260 DAG.getConstant(Offset, SrcVT)),
261 DAG.getConstant(BytesLeft, SizeVT),
262 Align, isVolatile, AlwaysInline,
263 DstPtrInfo.getWithOffset(Offset),
264 SrcPtrInfo.getWithOffset(Offset)));
267 return DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
268 &Results[0], Results.size());