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89 lines
2.7 KiB
C++
89 lines
2.7 KiB
C++
//===------------ RISCVLandingPadSetup.cpp ---------------------------------==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This is a RISC-V pass to setup landing pad labels for indirect jumps.
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// Currently this pass only supports fixed labels.
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//
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//===----------------------------------------------------------------------===//
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#include "RISCV.h"
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#include "RISCVInstrInfo.h"
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#include "RISCVSubtarget.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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using namespace llvm;
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#define DEBUG_TYPE "riscv-lpad-setup"
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#define PASS_NAME "RISC-V Landing Pad Setup"
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extern cl::opt<uint32_t> PreferredLandingPadLabel;
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namespace {
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class RISCVLandingPadSetup : public MachineFunctionPass {
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public:
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static char ID;
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RISCVLandingPadSetup() : MachineFunctionPass(ID) {}
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bool runOnMachineFunction(MachineFunction &F) override;
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StringRef getPassName() const override { return PASS_NAME; }
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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};
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} // end anonymous namespace
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bool RISCVLandingPadSetup::runOnMachineFunction(MachineFunction &MF) {
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const auto &STI = MF.getSubtarget<RISCVSubtarget>();
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const RISCVInstrInfo &TII = *STI.getInstrInfo();
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if (!STI.hasStdExtZicfilp())
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return false;
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uint32_t Label = 0;
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if (PreferredLandingPadLabel.getNumOccurrences() > 0) {
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if (!isUInt<20>(PreferredLandingPadLabel))
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report_fatal_error("riscv-landing-pad-label=<val>, <val> needs to fit in "
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"unsigned 20-bits");
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Label = PreferredLandingPadLabel;
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}
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// Zicfilp does not check X7 if landing pad label is zero.
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if (Label == 0)
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return false;
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bool Changed = false;
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for (MachineBasicBlock &MBB : MF)
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for (MachineInstr &MI : llvm::make_early_inc_range(MBB)) {
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if (MI.getOpcode() != RISCV::PseudoBRINDNonX7 &&
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MI.getOpcode() != RISCV::PseudoCALLIndirectNonX7 &&
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MI.getOpcode() != RISCV::PseudoTAILIndirectNonX7)
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continue;
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BuildMI(MBB, MI, MI.getDebugLoc(), TII.get(RISCV::LUI), RISCV::X7)
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.addImm(Label);
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MachineInstrBuilder(MF, &MI).addUse(RISCV::X7, RegState::ImplicitKill);
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Changed = true;
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}
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return Changed;
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}
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INITIALIZE_PASS(RISCVLandingPadSetup, DEBUG_TYPE, PASS_NAME, false, false)
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char RISCVLandingPadSetup::ID = 0;
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FunctionPass *llvm::createRISCVLandingPadSetupPass() {
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return new RISCVLandingPadSetup();
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}
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