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//===-- NVPTXReplaceImageHandles.cpp - Replace image handles for Fermi ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// On Fermi, image handles are not supported. To work around this, we traverse
// the machine code and replace image handles with concrete symbols. For this
// to work reliably, inlining of all function call must be performed.
//
//===----------------------------------------------------------------------===//
#include "NVPTX.h"
#include "NVPTXMachineFunctionInfo.h"
#include "NVPTXSubtarget.h"
#include "NVPTXTargetMachine.h"
#include "MCTargetDesc/NVPTXBaseInfo.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class NVPTXReplaceImageHandles : public MachineFunctionPass {
private:
static char ID;
DenseSet<MachineInstr *> InstrsToRemove;
public:
NVPTXReplaceImageHandles();
bool runOnMachineFunction(MachineFunction &MF) override;
StringRef getPassName() const override {
return "NVPTX Replace Image Handles";
}
private:
bool processInstr(MachineInstr &MI);
void replaceImageHandle(MachineOperand &Op, MachineFunction &MF);
bool findIndexForHandle(MachineOperand &Op, MachineFunction &MF,
unsigned &Idx);
};
}
char NVPTXReplaceImageHandles::ID = 0;
NVPTXReplaceImageHandles::NVPTXReplaceImageHandles()
: MachineFunctionPass(ID) {}
bool NVPTXReplaceImageHandles::runOnMachineFunction(MachineFunction &MF) {
bool Changed = false;
InstrsToRemove.clear();
for (MachineFunction::iterator BI = MF.begin(), BE = MF.end(); BI != BE;
++BI) {
for (MachineBasicBlock::iterator I = (*BI).begin(), E = (*BI).end();
I != E; ++I) {
MachineInstr &MI = *I;
Changed |= processInstr(MI);
}
}
// Now clean up any handle-access instructions
// This is needed in debug mode when code cleanup passes are not executed,
// but we need the handle access to be eliminated because they are not
// valid instructions when image handles are disabled.
for (DenseSet<MachineInstr *>::iterator I = InstrsToRemove.begin(),
E = InstrsToRemove.end(); I != E; ++I) {
(*I)->eraseFromParent();
}
return Changed;
}
bool NVPTXReplaceImageHandles::processInstr(MachineInstr &MI) {
MachineFunction &MF = *MI.getParent()->getParent();
const MCInstrDesc &MCID = MI.getDesc();
if (MCID.TSFlags & NVPTXII::IsTexFlag) {
// This is a texture fetch, so operand 4 is a texref and operand 5 is
// a samplerref
MachineOperand &TexHandle = MI.getOperand(4);
replaceImageHandle(TexHandle, MF);
if (!(MCID.TSFlags & NVPTXII::IsTexModeUnifiedFlag)) {
MachineOperand &SampHandle = MI.getOperand(5);
replaceImageHandle(SampHandle, MF);
}
return true;
} else if (MCID.TSFlags & NVPTXII::IsSuldMask) {
unsigned VecSize =
1 << (((MCID.TSFlags & NVPTXII::IsSuldMask) >> NVPTXII::IsSuldShift) - 1);
// For a surface load of vector size N, the Nth operand will be the surfref
MachineOperand &SurfHandle = MI.getOperand(VecSize);
replaceImageHandle(SurfHandle, MF);
return true;
} else if (MCID.TSFlags & NVPTXII::IsSustFlag) {
// This is a surface store, so operand 0 is a surfref
MachineOperand &SurfHandle = MI.getOperand(0);
replaceImageHandle(SurfHandle, MF);
return true;
} else if (MCID.TSFlags & NVPTXII::IsSurfTexQueryFlag) {
// This is a query, so operand 1 is a surfref/texref
MachineOperand &Handle = MI.getOperand(1);
replaceImageHandle(Handle, MF);
return true;
}
return false;
}
void NVPTXReplaceImageHandles::
replaceImageHandle(MachineOperand &Op, MachineFunction &MF) {
unsigned Idx;
if (findIndexForHandle(Op, MF, Idx)) {
Op.ChangeToImmediate(Idx);
}
}
bool NVPTXReplaceImageHandles::
findIndexForHandle(MachineOperand &Op, MachineFunction &MF, unsigned &Idx) {
const MachineRegisterInfo &MRI = MF.getRegInfo();
NVPTXMachineFunctionInfo *MFI = MF.getInfo<NVPTXMachineFunctionInfo>();
assert(Op.isReg() && "Handle is not in a reg?");
// Which instruction defines the handle?
MachineInstr &TexHandleDef = *MRI.getVRegDef(Op.getReg());
switch (TexHandleDef.getOpcode()) {
case NVPTX::LD_i64_avar: {
// The handle is a parameter value being loaded, replace with the
// parameter symbol
const NVPTXTargetMachine &TM =
static_cast<const NVPTXTargetMachine &>(MF.getTarget());
if (TM.getDrvInterface() == NVPTX::CUDA) {
// For CUDA, we preserve the param loads coming from function arguments
return false;
}
assert(TexHandleDef.getOperand(6).isSymbol() && "Load is not a symbol!");
StringRef Sym = TexHandleDef.getOperand(6).getSymbolName();
std::string ParamBaseName = MF.getName();
ParamBaseName += "_param_";
assert(Sym.startswith(ParamBaseName) && "Invalid symbol reference");
unsigned Param = atoi(Sym.data()+ParamBaseName.size());
std::string NewSym;
raw_string_ostream NewSymStr(NewSym);
NewSymStr << MF.getName() << "_param_" << Param;
InstrsToRemove.insert(&TexHandleDef);
Idx = MFI->getImageHandleSymbolIndex(NewSymStr.str().c_str());
return true;
}
case NVPTX::texsurf_handles: {
// The handle is a global variable, replace with the global variable name
assert(TexHandleDef.getOperand(1).isGlobal() && "Load is not a global!");
const GlobalValue *GV = TexHandleDef.getOperand(1).getGlobal();
assert(GV->hasName() && "Global sampler must be named!");
InstrsToRemove.insert(&TexHandleDef);
Idx = MFI->getImageHandleSymbolIndex(GV->getName().data());
return true;
}
case NVPTX::nvvm_move_i64:
case TargetOpcode::COPY: {
bool Res = findIndexForHandle(TexHandleDef.getOperand(1), MF, Idx);
if (Res) {
InstrsToRemove.insert(&TexHandleDef);
}
return Res;
}
default:
llvm_unreachable("Unknown instruction operating on handle");
}
}
MachineFunctionPass *llvm::createNVPTXReplaceImageHandlesPass() {
return new NVPTXReplaceImageHandles();
}
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