llvm-6502/lib/Target/ARM/ARMExpandPseudoInsts.cpp
Anton Korobeynikov 5cdc3a949a Materialize global addresses via movt/movw pair, this is always better
than doing the same via constpool:
1. Load from constpool costs 3 cycles on A9, movt/movw pair - just 2.
2. Load from constpool might stall up to 300 cycles due to cache miss.
3. Movt/movw does not use load/store unit.
4. Less constpool entries => better compiler performance.

This is only enabled on ELF systems, since darwin does not have needed
relocations (yet).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89720 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-24 00:44:37 +00:00

129 lines
4.0 KiB
C++

//===-- ARMExpandPseudoInsts.cpp - Expand pseudo instructions -----*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a pass that expand pseudo instructions into target
// instructions to allow proper scheduling, if-conversion, and other late
// optimizations. This pass should be run after register allocation but before
// post- regalloc scheduling pass.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "arm-pseudo"
#include "ARM.h"
#include "ARMBaseInstrInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
using namespace llvm;
namespace {
class ARMExpandPseudo : public MachineFunctionPass {
public:
static char ID;
ARMExpandPseudo() : MachineFunctionPass(&ID) {}
const TargetInstrInfo *TII;
virtual bool runOnMachineFunction(MachineFunction &Fn);
virtual const char *getPassName() const {
return "ARM pseudo instruction expansion pass";
}
private:
bool ExpandMBB(MachineBasicBlock &MBB);
};
char ARMExpandPseudo::ID = 0;
}
bool ARMExpandPseudo::ExpandMBB(MachineBasicBlock &MBB) {
bool Modified = false;
MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
while (MBBI != E) {
MachineInstr &MI = *MBBI;
MachineBasicBlock::iterator NMBBI = next(MBBI);
unsigned Opcode = MI.getOpcode();
switch (Opcode) {
default: break;
case ARM::tLDRpci_pic:
case ARM::t2LDRpci_pic: {
unsigned NewLdOpc = (Opcode == ARM::tLDRpci_pic)
? ARM::tLDRpci : ARM::t2LDRpci;
unsigned DstReg = MI.getOperand(0).getReg();
if (!MI.getOperand(0).isDead()) {
MachineInstr *NewMI =
AddDefaultPred(BuildMI(MBB, MBBI, MI.getDebugLoc(),
TII->get(NewLdOpc), DstReg)
.addOperand(MI.getOperand(1)));
NewMI->setMemRefs(MI.memoperands_begin(), MI.memoperands_end());
BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(ARM::tPICADD))
.addReg(DstReg, getDefRegState(true))
.addReg(DstReg)
.addOperand(MI.getOperand(2));
}
MI.eraseFromParent();
Modified = true;
break;
}
case ARM::t2MOVi32imm: {
unsigned DstReg = MI.getOperand(0).getReg();
if (!MI.getOperand(0).isDead()) {
const MachineOperand &MO = MI.getOperand(1);
MachineInstrBuilder LO16, HI16;
LO16 = BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(ARM::t2MOVi16),
DstReg);
HI16 = BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(ARM::t2MOVTi16))
.addReg(DstReg, getDefRegState(true)).addReg(DstReg);
if (MO.isImm()) {
unsigned Imm = MO.getImm();
unsigned Lo16 = Imm & 0xffff;
unsigned Hi16 = (Imm >> 16) & 0xffff;
LO16 = LO16.addImm(Lo16);
HI16 = HI16.addImm(Hi16);
} else {
GlobalValue *GV = MO.getGlobal();
unsigned TF = MO.getTargetFlags();
LO16 = LO16.addGlobalAddress(GV, MO.getOffset(), TF | ARMII::MO_LO16);
HI16 = HI16.addGlobalAddress(GV, MO.getOffset(), TF | ARMII::MO_HI16);
// FIXME: What's about memoperands?
}
AddDefaultPred(LO16);
AddDefaultPred(HI16);
}
MI.eraseFromParent();
Modified = true;
}
// FIXME: expand t2MOVi32imm
}
MBBI = NMBBI;
}
return Modified;
}
bool ARMExpandPseudo::runOnMachineFunction(MachineFunction &MF) {
TII = MF.getTarget().getInstrInfo();
bool Modified = false;
for (MachineFunction::iterator MFI = MF.begin(), E = MF.end(); MFI != E;
++MFI)
Modified |= ExpandMBB(*MFI);
return Modified;
}
/// createARMExpandPseudoPass - returns an instance of the pseudo instruction
/// expansion pass.
FunctionPass *llvm::createARMExpandPseudoPass() {
return new ARMExpandPseudo();
}