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//===-- HexagonMask.cpp - replace const ext tfri with mask ------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
#include "Hexagon.h"
#include "HexagonSubtarget.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetMachine.h"
#define DEBUG_TYPE "mask"
using namespace llvm;
namespace {
class HexagonMask : public MachineFunctionPass {
public:
static char ID;
HexagonMask() : MachineFunctionPass(ID) {}
StringRef getPassName() const override {
return "Hexagon replace const ext tfri with mask";
}
bool runOnMachineFunction(MachineFunction &MF) override;
private:
const HexagonInstrInfo *HII;
void replaceConstExtTransferImmWithMask(MachineFunction &MF);
};
} // end anonymous namespace
char HexagonMask::ID = 0;
void HexagonMask::replaceConstExtTransferImmWithMask(MachineFunction &MF) {
for (auto &MBB : MF) {
for (auto &MI : llvm::make_early_inc_range(MBB)) {
if (MI.getOpcode() != Hexagon::A2_tfrsi)
continue;
const MachineOperand &Op0 = MI.getOperand(0);
const MachineOperand &Op1 = MI.getOperand(1);
if (!Op1.isImm())
continue;
int32_t V = Op1.getImm();
if (isInt<16>(V))
continue;
unsigned Idx, Len;
if (!isShiftedMask_32(V, Idx, Len))
continue;
if (!isUInt<5>(Idx) || !isUInt<5>(Len))
continue;
BuildMI(MBB, MI, MI.getDebugLoc(), HII->get(Hexagon::S2_mask),
Op0.getReg())
.addImm(Len)
.addImm(Idx);
MBB.erase(MI);
}
}
}
bool HexagonMask::runOnMachineFunction(MachineFunction &MF) {
auto &HST = MF.getSubtarget<HexagonSubtarget>();
HII = HST.getInstrInfo();
const Function &F = MF.getFunction();
if (!F.hasFnAttribute(Attribute::OptimizeForSize))
return false;
// Mask instruction is available only from v66
if (!HST.hasV66Ops())
return false;
// The mask instruction available in v66 can be used to generate values in
// registers using 2 immediates Eg. to form 0x07fffffc in R0, you would write
// "R0 = mask(#25,#2)" Since it is a single-word instruction, it takes less
// code size than a constant-extended transfer at Os
replaceConstExtTransferImmWithMask(MF);
return true;
}
//===----------------------------------------------------------------------===//
// Public Constructor Functions
//===----------------------------------------------------------------------===//
INITIALIZE_PASS(HexagonMask, "hexagon-mask", "Hexagon mask", false, false)
FunctionPass *llvm::createHexagonMask() { return new HexagonMask(); }
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