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//===-- PIC16MemSelOpt.cpp - PIC16 banksel optimizer --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the pass which optimizes the emitting of banksel
// instructions before accessing data memory. This currently works within
// a basic block only and keep tracks of the last accessed memory bank.
// If memory access continues to be in the same bank it just makes banksel
// immediate, which is a part of the insn accessing the data memory, from 1
// to zero. The asm printer emits a banksel only if that immediate is 1.
//
// FIXME: this is not implemented yet. The banksel pass only works on local
// basic blocks.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "pic16-codegen"
#include "PIC16.h"
#include "PIC16ABINames.h"
#include "PIC16InstrInfo.h"
#include "PIC16MCAsmInfo.h"
#include "PIC16TargetMachine.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/GlobalValue.h"
#include "llvm/DerivedTypes.h"
using namespace llvm;
namespace {
struct MemSelOpt : public MachineFunctionPass {
static char ID;
MemSelOpt() : MachineFunctionPass(&ID) {}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const {
return "PIC16 Memsel Optimizer";
}
bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
bool processInstruction(MachineInstr *MI);
private:
const TargetInstrInfo *TII; // Machine instruction info.
MachineBasicBlock *MBB; // Current basic block
std::string CurBank;
};
char MemSelOpt::ID = 0;
}
FunctionPass *llvm::createPIC16MemSelOptimizerPass() {
return new MemSelOpt();
}
/// runOnMachineFunction - Loop over all of the basic blocks, transforming FP
/// register references into FP stack references.
///
bool MemSelOpt::runOnMachineFunction(MachineFunction &MF) {
TII = MF.getTarget().getInstrInfo();
bool Changed = false;
for (MachineFunction::iterator I = MF.begin(), E = MF.end();
I != E; ++I) {
Changed |= processBasicBlock(MF, *I);
}
return Changed;
}
/// processBasicBlock - Loop over all of the instructions in the basic block,
/// transforming FP instructions into their stack form.
///
bool MemSelOpt::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
bool Changed = false;
MBB = &BB;
// Let us assume that when entering a basic block now bank is selected.
// Ideally we should look at the predecessors for this information.
CurBank="";
for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) {
Changed |= processInstruction(I);
}
return Changed;
}
bool MemSelOpt::processInstruction(MachineInstr *MI) {
bool Changed = false;
unsigned NumOperands = MI->getNumOperands();
if (NumOperands == 0) return false;
// If this insn is not going to access any memory, return.
const TargetInstrDesc &TID = TII->get(MI->getOpcode());
if (!(TID.isBranch() || TID.isCall() || TID.mayLoad() || TID.mayStore()))
return false;
// Scan for the memory address operand.
// FIXME: Should we use standard interfaces like memoperands_iterator,
// hasMemOperand() etc ?
int MemOpPos = -1;
for (unsigned i = 0; i < NumOperands; i++) {
MachineOperand Op = MI->getOperand(i);
if (Op.getType() == MachineOperand::MO_GlobalAddress ||
Op.getType() == MachineOperand::MO_ExternalSymbol ||
Op.getType() == MachineOperand::MO_MachineBasicBlock) {
// We found one mem operand. Next one may be BS.
MemOpPos = i;
break;
}
}
// If we did not find an insn accessing memory. Continue.
if (MemOpPos == -1) return Changed;
// Get the MemOp.
MachineOperand &Op = MI->getOperand(MemOpPos);
// If this is a pagesel material, handle it first.
if (MI->getOpcode() == PIC16::CALL ||
MI->getOpcode() == PIC16::br_uncond) {
DebugLoc dl = MI->getDebugLoc();
BuildMI(*MBB, MI, dl, TII->get(PIC16::pagesel)).
addOperand(Op);
return true;
}
// Get the section name(NewBank) for MemOp.
// This assumes that the section names for globals are already set by
// AsmPrinter->doInitialization.
std::string NewBank = CurBank;
if (Op.getType() == MachineOperand::MO_GlobalAddress &&
Op.getGlobal()->getType()->getAddressSpace() == PIC16ISD::RAM_SPACE) {
NewBank = Op.getGlobal()->getSection();
} else if (Op.getType() == MachineOperand::MO_ExternalSymbol) {
// External Symbol is generated for temp data and arguments. They are
// in fpdata.<functionname>.# section.
std::string Sym = Op.getSymbolName();
NewBank = PAN::getSectionNameForSym(Sym);
}
// If the section is shared section, do not emit banksel.
if (NewBank == PAN::getSharedUDataSectionName())
return Changed;
// If the previous and new section names are same, we don't need to
// emit banksel.
if (NewBank.compare(CurBank) != 0 ) {
DebugLoc dl = MI->getDebugLoc();
BuildMI(*MBB, MI, dl, TII->get(PIC16::banksel)).
addOperand(Op);
Changed = true;
CurBank = NewBank;
}
return Changed;
}
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