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f56e4f6d3d
This re-architects the RISCV relocation handling to bring the implementation closer in line with the implementation in binutils. We would previously aggressively resolve the relocation. With this restructuring, we always will emit a paired relocation for any symbolic difference of the type of S±T[±C] where S and T are labels and C is a constant. GAS has a special target hook controlled by `RELOC_EXPANSION_POSSIBLE` which indicates that a fixup may be expanded into multiple relocations. This is used by the RISCV backend to always emit a paired relocation - either ADD[WIDTH] + SUB[WIDTH] for text relocations or SET[WIDTH] + SUB[WIDTH] for a debug info relocation. Irrespective of whether linker relaxation support is enabled, symbolic difference is always emitted as a paired relocation. This change also sinks the target specific behaviour down into the target specific area rather than exposing it to the shared relocation handling. In the process, we also sink the "special" handling for debug information down into the RISCV target. Although this improves the path for the other targets, this is not necessarily entirely ideal either. The changes in the debug info emission could be done through another type of hook as this functionality would be required by any other target which wishes to do linker relaxation. However, as there are no other targets in LLVM which currently do this, this is a reasonable thing to do until such time as the code needs to be shared. Improve the handling of the relocation (and add a reduced test case from the Linux kernel) to ensure that we handle complex expressions for symbolic difference. This ensures that we correct relocate symbols with the adddends normalized and associated with the addition portion of the paired relocation. This change also addresses some review comments from Alex Bradbury about the relocations meant for use in the DWARF CFA being named incorrectly (using ADD6 instead of SET6) in the original change which introduced the relocation type. This resolves the issues with the symbolic difference emission sufficiently to enable building the Linux kernel with clang+IAS+lld (without linker relaxation). Resolves PR50153, PR50156! Fixes: ClangBuiltLinux/linux#1023, ClangBuiltLinux/linux#1143 Reviewed By: nickdesaulniers, maskray Differential Revision: https://reviews.llvm.org/D103539
176 lines
6.2 KiB
C++
176 lines
6.2 KiB
C++
//===-- RISCVMCTargetDesc.cpp - RISCV Target Descriptions -----------------===//
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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 file provides RISCV-specific target descriptions.
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///
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//===----------------------------------------------------------------------===//
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#include "RISCVMCTargetDesc.h"
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#include "RISCVBaseInfo.h"
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#include "RISCVELFStreamer.h"
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#include "RISCVInstPrinter.h"
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#include "RISCVMCAsmInfo.h"
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#include "RISCVTargetStreamer.h"
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#include "TargetInfo/RISCVTargetInfo.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCCodeEmitter.h"
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#include "llvm/MC/MCInstrAnalysis.h"
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#include "llvm/MC/MCInstrInfo.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCRegisterInfo.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/TargetRegistry.h"
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#define GET_INSTRINFO_MC_DESC
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#include "RISCVGenInstrInfo.inc"
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#define GET_REGINFO_MC_DESC
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#include "RISCVGenRegisterInfo.inc"
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#define GET_SUBTARGETINFO_MC_DESC
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#include "RISCVGenSubtargetInfo.inc"
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using namespace llvm;
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static MCInstrInfo *createRISCVMCInstrInfo() {
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MCInstrInfo *X = new MCInstrInfo();
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InitRISCVMCInstrInfo(X);
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return X;
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}
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static MCRegisterInfo *createRISCVMCRegisterInfo(const Triple &TT) {
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MCRegisterInfo *X = new MCRegisterInfo();
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InitRISCVMCRegisterInfo(X, RISCV::X1);
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return X;
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}
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static MCAsmInfo *createRISCVMCAsmInfo(const MCRegisterInfo &MRI,
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const Triple &TT,
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const MCTargetOptions &Options) {
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MCAsmInfo *MAI = new RISCVMCAsmInfo(TT);
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MCRegister SP = MRI.getDwarfRegNum(RISCV::X2, true);
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MCCFIInstruction Inst = MCCFIInstruction::cfiDefCfa(nullptr, SP, 0);
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MAI->addInitialFrameState(Inst);
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return MAI;
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}
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static MCSubtargetInfo *createRISCVMCSubtargetInfo(const Triple &TT,
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StringRef CPU, StringRef FS) {
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if (CPU.empty())
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CPU = TT.isArch64Bit() ? "generic-rv64" : "generic-rv32";
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if (CPU == "generic")
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report_fatal_error(Twine("CPU 'generic' is not supported. Use ") +
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(TT.isArch64Bit() ? "generic-rv64" : "generic-rv32"));
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return createRISCVMCSubtargetInfoImpl(TT, CPU, /*TuneCPU*/ CPU, FS);
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}
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static MCInstPrinter *createRISCVMCInstPrinter(const Triple &T,
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unsigned SyntaxVariant,
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const MCAsmInfo &MAI,
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const MCInstrInfo &MII,
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const MCRegisterInfo &MRI) {
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return new RISCVInstPrinter(MAI, MII, MRI);
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}
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static MCTargetStreamer *
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createRISCVObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
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const Triple &TT = STI.getTargetTriple();
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if (TT.isOSBinFormatELF())
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return new RISCVTargetELFStreamer(S, STI);
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return nullptr;
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}
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static MCTargetStreamer *createRISCVAsmTargetStreamer(MCStreamer &S,
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formatted_raw_ostream &OS,
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MCInstPrinter *InstPrint,
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bool isVerboseAsm) {
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return new RISCVTargetAsmStreamer(S, OS);
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}
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static MCTargetStreamer *createRISCVNullTargetStreamer(MCStreamer &S) {
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return new RISCVTargetStreamer(S);
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}
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namespace {
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class RISCVMCInstrAnalysis : public MCInstrAnalysis {
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public:
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explicit RISCVMCInstrAnalysis(const MCInstrInfo *Info)
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: MCInstrAnalysis(Info) {}
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bool evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size,
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uint64_t &Target) const override {
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if (isConditionalBranch(Inst)) {
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int64_t Imm;
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if (Size == 2)
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Imm = Inst.getOperand(1).getImm();
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else
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Imm = Inst.getOperand(2).getImm();
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Target = Addr + Imm;
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return true;
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}
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if (Inst.getOpcode() == RISCV::C_JAL || Inst.getOpcode() == RISCV::C_J) {
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Target = Addr + Inst.getOperand(0).getImm();
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return true;
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}
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if (Inst.getOpcode() == RISCV::JAL) {
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Target = Addr + Inst.getOperand(1).getImm();
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return true;
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}
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return false;
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}
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};
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} // end anonymous namespace
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static MCInstrAnalysis *createRISCVInstrAnalysis(const MCInstrInfo *Info) {
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return new RISCVMCInstrAnalysis(Info);
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}
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namespace {
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MCStreamer *createRISCVELFStreamer(const Triple &T, MCContext &Context,
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std::unique_ptr<MCAsmBackend> &&MAB,
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std::unique_ptr<MCObjectWriter> &&MOW,
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std::unique_ptr<MCCodeEmitter> &&MCE,
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bool RelaxAll) {
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return createRISCVELFStreamer(Context, std::move(MAB), std::move(MOW),
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std::move(MCE), RelaxAll);
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}
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} // end anonymous namespace
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extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeRISCVTargetMC() {
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for (Target *T : {&getTheRISCV32Target(), &getTheRISCV64Target()}) {
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TargetRegistry::RegisterMCAsmInfo(*T, createRISCVMCAsmInfo);
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TargetRegistry::RegisterMCInstrInfo(*T, createRISCVMCInstrInfo);
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TargetRegistry::RegisterMCRegInfo(*T, createRISCVMCRegisterInfo);
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TargetRegistry::RegisterMCAsmBackend(*T, createRISCVAsmBackend);
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TargetRegistry::RegisterMCCodeEmitter(*T, createRISCVMCCodeEmitter);
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TargetRegistry::RegisterMCInstPrinter(*T, createRISCVMCInstPrinter);
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TargetRegistry::RegisterMCSubtargetInfo(*T, createRISCVMCSubtargetInfo);
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TargetRegistry::RegisterELFStreamer(*T, createRISCVELFStreamer);
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TargetRegistry::RegisterObjectTargetStreamer(
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*T, createRISCVObjectTargetStreamer);
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TargetRegistry::RegisterMCInstrAnalysis(*T, createRISCVInstrAnalysis);
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// Register the asm target streamer.
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TargetRegistry::RegisterAsmTargetStreamer(*T, createRISCVAsmTargetStreamer);
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// Register the null target streamer.
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TargetRegistry::RegisterNullTargetStreamer(*T,
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createRISCVNullTargetStreamer);
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}
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}
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