1 //===-- SIPrepareScratchRegs.cpp - Use predicates for control flow --------===//
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 //===----------------------------------------------------------------------===//
12 /// This pass loads scratch pointer and scratch offset into a register or a
13 /// frame index which can be used anywhere in the program. These values will
14 /// be used for spilling VGPRs.
16 //===----------------------------------------------------------------------===//
19 #include "AMDGPUSubtarget.h"
20 #include "SIDefines.h"
21 #include "SIInstrInfo.h"
22 #include "SIMachineFunctionInfo.h"
23 #include "llvm/CodeGen/MachineFrameInfo.h"
24 #include "llvm/CodeGen/MachineFunction.h"
25 #include "llvm/CodeGen/MachineFunctionPass.h"
26 #include "llvm/CodeGen/MachineInstrBuilder.h"
27 #include "llvm/CodeGen/MachineRegisterInfo.h"
28 #include "llvm/CodeGen/RegisterScavenging.h"
29 #include "llvm/IR/Function.h"
30 #include "llvm/IR/LLVMContext.h"
32 #include "llvm/Support/Debug.h"
37 class SIPrepareScratchRegs : public MachineFunctionPass {
43 SIPrepareScratchRegs() : MachineFunctionPass(ID) { }
45 bool runOnMachineFunction(MachineFunction &MF) override;
47 const char *getPassName() const override {
48 return "SI prepare scratch registers";
53 } // End anonymous namespace
55 char SIPrepareScratchRegs::ID = 0;
57 FunctionPass *llvm::createSIPrepareScratchRegs() {
58 return new SIPrepareScratchRegs();
61 bool SIPrepareScratchRegs::runOnMachineFunction(MachineFunction &MF) {
62 SIMachineFunctionInfo *MFI = MF.getInfo<SIMachineFunctionInfo>();
63 const SIInstrInfo *TII =
64 static_cast<const SIInstrInfo *>(MF.getSubtarget().getInstrInfo());
65 const SIRegisterInfo *TRI = &TII->getRegisterInfo();
66 MachineRegisterInfo &MRI = MF.getRegInfo();
67 MachineFrameInfo *FrameInfo = MF.getFrameInfo();
68 MachineBasicBlock *Entry = MF.begin();
69 MachineBasicBlock::iterator I = Entry->begin();
70 DebugLoc DL = I->getDebugLoc();
72 // FIXME: If we don't have enough VGPRs for SGPR spilling we will need to
74 if (!MFI->hasSpilledVGPRs())
77 unsigned ScratchPtrPreloadReg =
78 TRI->getPreloadedValue(MF, SIRegisterInfo::SCRATCH_PTR);
79 unsigned ScratchOffsetPreloadReg =
80 TRI->getPreloadedValue(MF, SIRegisterInfo::SCRATCH_WAVE_OFFSET);
82 if (!Entry->isLiveIn(ScratchPtrPreloadReg))
83 Entry->addLiveIn(ScratchPtrPreloadReg);
85 if (!Entry->isLiveIn(ScratchOffsetPreloadReg))
86 Entry->addLiveIn(ScratchOffsetPreloadReg);
88 // Load the scratch offset.
89 unsigned ScratchOffsetReg =
90 TRI->findUnusedRegister(MRI, &AMDGPU::SGPR_32RegClass);
91 int ScratchOffsetFI = -1;
93 if (ScratchOffsetReg != AMDGPU::NoRegister) {
94 // Found an SGPR to use
95 MRI.setPhysRegUsed(ScratchOffsetReg);
96 BuildMI(*Entry, I, DL, TII->get(AMDGPU::S_MOV_B32), ScratchOffsetReg)
97 .addReg(ScratchOffsetPreloadReg);
99 // No SGPR is available, we must spill.
100 ScratchOffsetFI = FrameInfo->CreateSpillStackObject(4,4);
101 BuildMI(*Entry, I, DL, TII->get(AMDGPU::SI_SPILL_S32_SAVE))
102 .addReg(ScratchOffsetPreloadReg)
103 .addFrameIndex(ScratchOffsetFI);
107 // Now that we have the scratch pointer and offset values, we need to
108 // add them to all the SI_SPILL_V* instructions.
111 unsigned ScratchRsrcFI = FrameInfo->CreateSpillStackObject(16, 4);
112 RS.addScavengingFrameIndex(ScratchRsrcFI);
114 for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
117 MachineBasicBlock &MBB = *BI;
118 // Add the scratch offset reg as a live-in so that the register scavenger
119 // doesn't re-use it.
120 if (!MBB.isLiveIn(ScratchOffsetReg))
121 MBB.addLiveIn(ScratchOffsetReg);
122 RS.enterBasicBlock(&MBB);
124 for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
126 MachineInstr &MI = *I;
128 DebugLoc DL = MI.getDebugLoc();
129 switch(MI.getOpcode()) {
131 case AMDGPU::SI_SPILL_V512_SAVE:
132 case AMDGPU::SI_SPILL_V256_SAVE:
133 case AMDGPU::SI_SPILL_V128_SAVE:
134 case AMDGPU::SI_SPILL_V96_SAVE:
135 case AMDGPU::SI_SPILL_V64_SAVE:
136 case AMDGPU::SI_SPILL_V32_SAVE:
137 case AMDGPU::SI_SPILL_V32_RESTORE:
138 case AMDGPU::SI_SPILL_V64_RESTORE:
139 case AMDGPU::SI_SPILL_V128_RESTORE:
140 case AMDGPU::SI_SPILL_V256_RESTORE:
141 case AMDGPU::SI_SPILL_V512_RESTORE:
144 unsigned ScratchRsrcReg =
145 RS.scavengeRegister(&AMDGPU::SReg_128RegClass, 0);
147 uint64_t Rsrc = AMDGPU::RSRC_DATA_FORMAT | AMDGPU::RSRC_TID_ENABLE |
150 unsigned Rsrc0 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub0);
151 unsigned Rsrc1 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub1);
152 unsigned Rsrc2 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub2);
153 unsigned Rsrc3 = TRI->getSubReg(ScratchRsrcReg, AMDGPU::sub3);
155 BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc0)
156 .addExternalSymbol("SCRATCH_RSRC_DWORD0")
157 .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
159 BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc1)
160 .addExternalSymbol("SCRATCH_RSRC_DWORD1")
161 .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
163 BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc2)
164 .addImm(Rsrc & 0xffffffff)
165 .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
167 BuildMI(MBB, I, DL, TII->get(AMDGPU::S_MOV_B32), Rsrc3)
169 .addReg(ScratchRsrcReg, RegState::ImplicitDefine);
172 if (ScratchOffsetReg == AMDGPU::NoRegister) {
173 ScratchOffsetReg = RS.scavengeRegister(&AMDGPU::SGPR_32RegClass, 0);
174 BuildMI(MBB, I, DL, TII->get(AMDGPU::SI_SPILL_S32_RESTORE),
176 .addFrameIndex(ScratchOffsetFI)
177 .addReg(AMDGPU::NoRegister)
178 .addReg(AMDGPU::NoRegister);
179 } else if (!MBB.isLiveIn(ScratchOffsetReg)) {
180 MBB.addLiveIn(ScratchOffsetReg);
183 if (ScratchRsrcReg == AMDGPU::NoRegister ||
184 ScratchOffsetReg == AMDGPU::NoRegister) {
185 LLVMContext &Ctx = MF.getFunction()->getContext();
186 Ctx.emitError("ran out of SGPRs for spilling VGPRs");
187 ScratchRsrcReg = AMDGPU::SGPR0;
188 ScratchOffsetReg = AMDGPU::SGPR0;
190 MI.getOperand(2).setReg(ScratchRsrcReg);
191 MI.getOperand(2).setIsKill(true);
192 MI.getOperand(2).setIsUndef(false);
193 MI.getOperand(3).setReg(ScratchOffsetReg);
194 MI.getOperand(3).setIsUndef(false);
195 MI.addOperand(MachineOperand::CreateReg(Rsrc0, false, true, true));
196 MI.addOperand(MachineOperand::CreateReg(Rsrc1, false, true, true));
197 MI.addOperand(MachineOperand::CreateReg(Rsrc2, false, true, true));
198 MI.addOperand(MachineOperand::CreateReg(Rsrc3, false, true, true));