https://github.com/zyedidia updated https://github.com/llvm/llvm-project/pull/172906
>From 9cb2b6018574a11d34e794a7cae02f274c8672e8 Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Wed, 21 Jan 2026 17:35:59 -0500 Subject: [PATCH 1/8] [LFI] Add MCLFIRewriter infrastructure --- clang/tools/driver/cc1as_main.cpp | 3 + llvm/include/llvm/MC/MCLFI.h | 23 ++++++ llvm/include/llvm/MC/MCLFIRewriter.h | 70 +++++++++++++++++ .../llvm/MC/MCParser/MCAsmParserExtension.h | 16 ++-- llvm/include/llvm/MC/MCStreamer.h | 7 ++ llvm/include/llvm/MC/TargetRegistry.h | 21 ++++++ llvm/lib/MC/CMakeLists.txt | 2 + llvm/lib/MC/MCAsmStreamer.cpp | 5 ++ llvm/lib/MC/MCLFI.cpp | 75 +++++++++++++++++++ llvm/lib/MC/MCLFIRewriter.cpp | 61 +++++++++++++++ llvm/lib/MC/MCObjectStreamer.cpp | 5 ++ llvm/lib/MC/MCParser/AsmParser.cpp | 9 ++- llvm/lib/MC/MCParser/CMakeLists.txt | 1 + llvm/lib/MC/MCParser/LFIAsmParser.cpp | 69 +++++++++++++++++ llvm/lib/MC/MCStreamer.cpp | 3 + llvm/tools/llvm-mc/llvm-mc.cpp | 14 ++++ 16 files changed, 375 insertions(+), 9 deletions(-) create mode 100644 llvm/include/llvm/MC/MCLFI.h create mode 100644 llvm/include/llvm/MC/MCLFIRewriter.h create mode 100644 llvm/lib/MC/MCLFI.cpp create mode 100644 llvm/lib/MC/MCLFIRewriter.cpp create mode 100644 llvm/lib/MC/MCParser/LFIAsmParser.cpp diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp index ccc48a77891d7..6cbccbc3d7408 100644 --- a/clang/tools/driver/cc1as_main.cpp +++ b/clang/tools/driver/cc1as_main.cpp @@ -28,6 +28,7 @@ #include "llvm/MC/MCContext.h" #include "llvm/MC/MCInstPrinter.h" #include "llvm/MC/MCInstrInfo.h" +#include "llvm/MC/MCLFI.h" #include "llvm/MC/MCObjectFileInfo.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCParser/MCAsmParser.h" @@ -593,6 +594,8 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts, Triple T(Opts.Triple); Str.reset(TheTarget->createMCObjectStreamer( T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI)); + if (T.isLFI()) + initializeLFIMCStreamer(*Str.get(), Ctx, T); if (T.isOSBinFormatMachO() && T.isOSDarwin()) { Triple *TVT = Opts.DarwinTargetVariantTriple ? &*Opts.DarwinTargetVariantTriple diff --git a/llvm/include/llvm/MC/MCLFI.h b/llvm/include/llvm/MC/MCLFI.h new file mode 100644 index 0000000000000..6598453952642 --- /dev/null +++ b/llvm/include/llvm/MC/MCLFI.h @@ -0,0 +1,23 @@ +//===- MCLFI.h - LFI-specific code for MC -----------------------*- C++ -*-===// +// +// 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 +// +// This file was written by the LFI and Native Client authors. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Compiler.h" + +namespace llvm { + +class MCContext; +class MCStreamer; +class Triple; + +LLVM_ABI void initializeLFIMCStreamer(MCStreamer &Streamer, MCContext &Ctx, + const Triple &TheTriple); + +} // namespace llvm diff --git a/llvm/include/llvm/MC/MCLFIRewriter.h b/llvm/include/llvm/MC/MCLFIRewriter.h new file mode 100644 index 0000000000000..06e1d03b21efe --- /dev/null +++ b/llvm/include/llvm/MC/MCLFIRewriter.h @@ -0,0 +1,70 @@ +//===- llvm/MC/MCLFIRewriter.h ----------------------------------*- C++ -*-===// +// +// 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 +// +// This file was written by the LFI and Native Client authors. +// +//===----------------------------------------------------------------------===// +// +// This file declares the MCLFIRewriter class. This is an abstract +// class that encapsulates the rewriting logic for MCInsts. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_MC_MCLFIREWRITER_H +#define LLVM_MC_MCLFIREWRITER_H + +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCInstrInfo.h" +#include "llvm/MC/MCRegisterInfo.h" +#include "llvm/Support/Compiler.h" + +namespace llvm { +class MCInst; +class MCSubtargetInfo; +class MCStreamer; +class MCSymbol; + +class MCLFIRewriter { +private: + MCContext &Ctx; + bool Enabled = true; + +protected: + std::unique_ptr<MCInstrInfo> InstInfo; + std::unique_ptr<MCRegisterInfo> RegInfo; + +public: + MCLFIRewriter(MCContext &Ctx, std::unique_ptr<MCRegisterInfo> &&RI, + std::unique_ptr<MCInstrInfo> &&II) + : Ctx(Ctx), InstInfo(std::move(II)), RegInfo(std::move(RI)) {} + + LLVM_ABI void error(const MCInst &Inst, const char Msg[]); + + LLVM_ABI void disable(); + LLVM_ABI void enable(); + LLVM_ABI bool isEnabled(); + + LLVM_ABI bool isCall(const MCInst &Inst) const; + LLVM_ABI bool isBranch(const MCInst &Inst) const; + LLVM_ABI bool isIndirectBranch(const MCInst &Inst) const; + LLVM_ABI bool isReturn(const MCInst &Inst) const; + + LLVM_ABI bool mayLoad(const MCInst &Inst) const; + LLVM_ABI bool mayStore(const MCInst &Inst) const; + + LLVM_ABI bool mayModifyRegister(const MCInst &Inst, MCRegister Reg) const; + + virtual ~MCLFIRewriter() = default; + virtual bool rewriteInst(const MCInst &Inst, MCStreamer &Out, + const MCSubtargetInfo &STI) = 0; + + // Called when a label is emitted. Used for optimizations that require + // information about jump targets, such as guard elimination. + virtual void onLabel(const MCSymbol *Symbol) {} +}; + +} // namespace llvm +#endif diff --git a/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h b/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h index 66fd28827065b..eb9a995c0a2be 100644 --- a/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h +++ b/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h @@ -11,6 +11,7 @@ #include "llvm/ADT/STLFunctionalExtras.h" #include "llvm/ADT/StringRef.h" +#include "llvm/MC/MCLFIRewriter.h" #include "llvm/MC/MCParser/MCAsmParser.h" #include "llvm/Support/Compiler.h" #include "llvm/Support/SMLoc.h" @@ -120,13 +121,14 @@ class LLVM_ABI MCAsmParserExtension { /// @} }; -MCAsmParserExtension *createDarwinAsmParser(); -MCAsmParserExtension *createELFAsmParser(); -MCAsmParserExtension *createCOFFAsmParser(); -MCAsmParserExtension *createCOFFMasmParser(); -MCAsmParserExtension *createGOFFAsmParser(); -MCAsmParserExtension *createXCOFFAsmParser(); -MCAsmParserExtension *createWasmAsmParser(); +LLVM_ABI MCAsmParserExtension *createDarwinAsmParser(); +LLVM_ABI MCAsmParserExtension *createELFAsmParser(); +LLVM_ABI MCAsmParserExtension *createCOFFAsmParser(); +LLVM_ABI MCAsmParserExtension *createCOFFMasmParser(); +LLVM_ABI MCAsmParserExtension *createGOFFAsmParser(); +LLVM_ABI MCAsmParserExtension *createXCOFFAsmParser(); +LLVM_ABI MCAsmParserExtension *createWasmAsmParser(); +LLVM_ABI MCAsmParserExtension *createLFIAsmParser(MCLFIRewriter *Exp); } // end namespace llvm diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h index a60a3dd21859f..339d10bd2fc30 100644 --- a/llvm/include/llvm/MC/MCStreamer.h +++ b/llvm/include/llvm/MC/MCStreamer.h @@ -19,6 +19,7 @@ #include "llvm/ADT/StringRef.h" #include "llvm/MC/MCDirectives.h" #include "llvm/MC/MCDwarf.h" +#include "llvm/MC/MCLFIRewriter.h" #include "llvm/MC/MCLinkerOptimizationHint.h" #include "llvm/MC/MCPseudoProbe.h" #include "llvm/MC/MCSection.h" @@ -291,6 +292,8 @@ class LLVM_ABI MCStreamer { /// Returns true if the .cv_loc directive is in the right section. bool checkCVLocSection(unsigned FuncId, unsigned FileNo, SMLoc Loc); + std::unique_ptr<MCLFIRewriter> LFIRewriter; + public: MCStreamer(const MCStreamer &) = delete; MCStreamer &operator=(const MCStreamer &) = delete; @@ -308,6 +311,10 @@ class LLVM_ABI MCStreamer { return StartTokLocPtr ? *StartTokLocPtr : SMLoc(); } + void setLFIRewriter(MCLFIRewriter *Exp) { LFIRewriter.reset(Exp); } + + MCLFIRewriter *getLFIRewriter() { return LFIRewriter.get(); } + /// State management /// virtual void reset(); diff --git a/llvm/include/llvm/MC/TargetRegistry.h b/llvm/include/llvm/MC/TargetRegistry.h index 4451dfa72a5f4..46c4076ba4aeb 100644 --- a/llvm/include/llvm/MC/TargetRegistry.h +++ b/llvm/include/llvm/MC/TargetRegistry.h @@ -46,6 +46,7 @@ class MCDisassembler; class MCInstPrinter; class MCInstrAnalysis; class MCInstrInfo; +class MCLFIRewriter; class MCObjectWriter; class MCRegisterInfo; class MCRelocationInfo; @@ -237,6 +238,11 @@ class Target { mca::InstrumentManager *(*)(const MCSubtargetInfo &STI, const MCInstrInfo &MCII); + using MCLFIRewriterCtorTy = + MCLFIRewriter *(*)(MCStreamer & S, + std::unique_ptr<MCRegisterInfo> &&RegInfo, + std::unique_ptr<MCInstrInfo> &&InstInfo); + private: /// Next - The next registered target in the linked list, maintained by the /// TargetRegistry. @@ -351,6 +357,10 @@ class Target { /// InstrumentManager, if registered (default = nullptr). InstrumentManagerCtorTy InstrumentManagerCtorFn = nullptr; + // MCLFIRewriterCtorFn - Construction function for this target's + // MCLFIRewriter, if registered (default = nullptr). + MCLFIRewriterCtorTy MCLFIRewriterCtorFn = nullptr; + public: Target() = default; @@ -566,6 +576,13 @@ class Target { return nullptr; } + void createMCLFIRewriter(MCStreamer &S, + std::unique_ptr<MCRegisterInfo> &&RegInfo, + std::unique_ptr<MCInstrInfo> &&InstInfo) const { + if (MCLFIRewriterCtorFn) + MCLFIRewriterCtorFn(S, std::move(RegInfo), std::move(InstInfo)); + } + /// createMCRelocationInfo - Create a target specific MCRelocationInfo. /// /// \param TT The target triple. @@ -1021,6 +1038,10 @@ struct TargetRegistry { T.InstrumentManagerCtorFn = Fn; } + static void RegisterMCLFIRewriter(Target &T, Target::MCLFIRewriterCtorTy Fn) { + T.MCLFIRewriterCtorFn = Fn; + } + /// @} }; diff --git a/llvm/lib/MC/CMakeLists.txt b/llvm/lib/MC/CMakeLists.txt index 1388f130bb806..7a9e26af415c6 100644 --- a/llvm/lib/MC/CMakeLists.txt +++ b/llvm/lib/MC/CMakeLists.txt @@ -31,6 +31,8 @@ add_llvm_component_library(LLVMMC MCInstrAnalysis.cpp MCInstrDesc.cpp MCInstrInfo.cpp + MCLFI.cpp + MCLFIRewriter.cpp MCLabel.cpp MCLinkerOptimizationHint.cpp MCMachOStreamer.cpp diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp index d9a22bc2716fd..6e9dc5d11822d 100644 --- a/llvm/lib/MC/MCAsmStreamer.cpp +++ b/llvm/lib/MC/MCAsmStreamer.cpp @@ -19,6 +19,7 @@ #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCInst.h" #include "llvm/MC/MCInstPrinter.h" +#include "llvm/MC/MCLFIRewriter.h" #include "llvm/MC/MCObjectFileInfo.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCPseudoProbe.h" @@ -2494,6 +2495,10 @@ void MCAsmStreamer::AddEncodingComment(const MCInst &Inst, void MCAsmStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) { + if (LFIRewriter && LFIRewriter->isEnabled() && + LFIRewriter->rewriteInst(Inst, *this, STI)) + return; + if (CurFrag) { MCSection *Sec = getCurrentSectionOnly(); Sec->setHasInstructions(true); diff --git a/llvm/lib/MC/MCLFI.cpp b/llvm/lib/MC/MCLFI.cpp new file mode 100644 index 0000000000000..6082edac1a781 --- /dev/null +++ b/llvm/lib/MC/MCLFI.cpp @@ -0,0 +1,75 @@ +//===- lib/MC/MCLFI.cpp - LFI-specific MC implementation ------------------===// +// +// 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 +// +// This file was written by the LFI and Native Client authors. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/MCLFI.h" +#include "llvm/BinaryFormat/ELF.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCLFIRewriter.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/MC/MCStreamer.h" +#include "llvm/MC/TargetRegistry.h" +#include "llvm/Support/Alignment.h" +#include "llvm/TargetParser/Triple.h" + +static const char NoteNamespace[] = "LFI"; + +namespace llvm { + +cl::opt<bool> FlagEnableRewriting("lfi-enable-rewriter", + cl::desc("Don't enable rewriting for LFI."), + cl::init(true)); + +void initializeLFIMCStreamer(MCStreamer &Streamer, MCContext &Ctx, + const Triple &TheTriple) { + assert(TheTriple.isLFI()); + const char *NoteName; + const char *NoteArch; + switch (TheTriple.getArch()) { + case Triple::aarch64: + NoteName = ".note.LFI.ABI.aarch64"; + NoteArch = "aarch64"; + break; + default: + report_fatal_error("Unsupported architecture for LFI"); + } + + std::string Error; // empty + const Target *TheTarget = TargetRegistry::lookupTarget(TheTriple, Error); + + // Create the Target specific MCLFIRewriter. + assert(TheTarget != nullptr); + if (FlagEnableRewriting) { + TheTarget->createMCLFIRewriter( + Streamer, + std::unique_ptr<MCRegisterInfo>(TheTarget->createMCRegInfo(TheTriple)), + std::unique_ptr<MCInstrInfo>(TheTarget->createMCInstrInfo())); + } + + // Emit an ELF Note section in its own COMDAT group which identifies LFI + // object files. + MCSectionELF *Note = Ctx.getELFSection(NoteName, ELF::SHT_NOTE, + ELF::SHF_ALLOC | ELF::SHF_GROUP, 0, + NoteName, /*IsComdat=*/true); + + Streamer.pushSection(); + Streamer.switchSection(Note); + Streamer.emitIntValue(strlen(NoteNamespace) + 1, 4); + Streamer.emitIntValue(strlen(NoteArch) + 1, 4); + Streamer.emitIntValue(ELF::NT_VERSION, 4); + Streamer.emitBytes(NoteNamespace); + Streamer.emitIntValue(0, 1); // NUL terminator + Streamer.emitValueToAlignment(Align(4)); + Streamer.emitBytes(NoteArch); + Streamer.emitIntValue(0, 1); // NUL terminator + Streamer.emitValueToAlignment(Align(4)); + Streamer.popSection(); +} + +} // namespace llvm diff --git a/llvm/lib/MC/MCLFIRewriter.cpp b/llvm/lib/MC/MCLFIRewriter.cpp new file mode 100644 index 0000000000000..5295a5c3e3771 --- /dev/null +++ b/llvm/lib/MC/MCLFIRewriter.cpp @@ -0,0 +1,61 @@ +//===- MCLFIRewriter.cpp ----------------------------------------*- C++ -*-===// +// +// 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 +// +// This file was written by the LFI and Native Client authors. +// +//===----------------------------------------------------------------------===// +// +// This file implements the MCLFIRewriter class. This is a base +// class that encapsulates the rewriting logic for MCInsts. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/MCLFIRewriter.h" +#include "llvm/MC/MCInst.h" +#include "llvm/MC/MCInstrInfo.h" +#include "llvm/MC/MCRegisterInfo.h" + +namespace llvm { + +void MCLFIRewriter::error(const MCInst &Inst, const char Msg[]) { + Ctx.reportError(Inst.getLoc(), Msg); +} + +void MCLFIRewriter::disable() { Enabled = false; } + +void MCLFIRewriter::enable() { Enabled = true; } + +bool MCLFIRewriter::isEnabled() { return Enabled; } + +bool MCLFIRewriter::isCall(const MCInst &Inst) const { + return InstInfo->get(Inst.getOpcode()).isCall(); +} + +bool MCLFIRewriter::isBranch(const MCInst &Inst) const { + return InstInfo->get(Inst.getOpcode()).isBranch(); +} + +bool MCLFIRewriter::isIndirectBranch(const MCInst &Inst) const { + return InstInfo->get(Inst.getOpcode()).isIndirectBranch(); +} + +bool MCLFIRewriter::isReturn(const MCInst &Inst) const { + return InstInfo->get(Inst.getOpcode()).isReturn(); +} + +bool MCLFIRewriter::mayLoad(const MCInst &Inst) const { + return InstInfo->get(Inst.getOpcode()).mayLoad(); +} + +bool MCLFIRewriter::mayStore(const MCInst &Inst) const { + return InstInfo->get(Inst.getOpcode()).mayStore(); +} + +bool MCLFIRewriter::mayModifyRegister(const MCInst &Inst, + MCRegister Reg) const { + return InstInfo->get(Inst.getOpcode()).hasDefOfPhysReg(Inst, Reg, *RegInfo); +} +} // namespace llvm diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp index 453d4d20d9727..f9d2bfc73069a 100644 --- a/llvm/lib/MC/MCObjectStreamer.cpp +++ b/llvm/lib/MC/MCObjectStreamer.cpp @@ -15,6 +15,7 @@ #include "llvm/MC/MCContext.h" #include "llvm/MC/MCDwarf.h" #include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCLFIRewriter.h" #include "llvm/MC/MCObjectFileInfo.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCSFrame.h" @@ -398,6 +399,10 @@ bool MCObjectStreamer::mayHaveInstructions(MCSection &Sec) const { void MCObjectStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) { + if (LFIRewriter && LFIRewriter->isEnabled() && + LFIRewriter->rewriteInst(Inst, *this, STI)) + return; + MCStreamer::emitInstruction(Inst, STI); MCSection *Sec = getCurrentSectionOnly(); diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp index 3277994701b78..fdce7999f492e 100644 --- a/llvm/lib/MC/MCParser/AsmParser.cpp +++ b/llvm/lib/MC/MCParser/AsmParser.cpp @@ -120,6 +120,7 @@ class AsmParser : public MCAsmParser { SourceMgr::DiagHandlerTy SavedDiagHandler; void *SavedDiagContext; std::unique_ptr<MCAsmParserExtension> PlatformParser; + std::unique_ptr<MCAsmParserExtension> LFIParser; SMLoc StartTokLoc; std::optional<SMLoc> CFIStartProcLoc; @@ -745,8 +746,8 @@ extern cl::opt<unsigned> AsmMacroMaxNestingDepth; AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out, const MCAsmInfo &MAI, unsigned CB = 0) - : MCAsmParser(Ctx, Out, SM, MAI), CurBuffer(CB ? CB : SM.getMainFileID()), - MacrosEnabledFlag(true) { + : MCAsmParser(Ctx, Out, SM, MAI), LFIParser(nullptr), + CurBuffer(CB ? CB : SM.getMainFileID()), MacrosEnabledFlag(true) { HadError = false; // Save the old handler. SavedDiagHandler = SrcMgr.getDiagHandler(); @@ -788,6 +789,10 @@ AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out, } PlatformParser->Initialize(*this); + if (Out.getLFIRewriter()) { + LFIParser.reset(createLFIAsmParser(Out.getLFIRewriter())); + LFIParser->Initialize(*this); + } initializeDirectiveKindMap(); initializeCVDefRangeTypeMap(); } diff --git a/llvm/lib/MC/MCParser/CMakeLists.txt b/llvm/lib/MC/MCParser/CMakeLists.txt index 008a50e9da660..c911874fc6540 100644 --- a/llvm/lib/MC/MCParser/CMakeLists.txt +++ b/llvm/lib/MC/MCParser/CMakeLists.txt @@ -6,6 +6,7 @@ add_llvm_component_library(LLVMMCParser GOFFAsmParser.cpp DarwinAsmParser.cpp ELFAsmParser.cpp + LFIAsmParser.cpp MCAsmParser.cpp MCAsmParserExtension.cpp MCTargetAsmParser.cpp diff --git a/llvm/lib/MC/MCParser/LFIAsmParser.cpp b/llvm/lib/MC/MCParser/LFIAsmParser.cpp new file mode 100644 index 0000000000000..4601052e0d65f --- /dev/null +++ b/llvm/lib/MC/MCParser/LFIAsmParser.cpp @@ -0,0 +1,69 @@ +//===- LFIAsmParser.cpp - LFI Assembly Parser -----------------------------===// +// +// 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 +// +//===----------------------------------------------------------------------===// +// +// This file was written by the LFI and Native Client authors. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/MCLFIRewriter.h" +#include "llvm/MC/MCParser/MCAsmParserExtension.h" +#include "llvm/MC/MCStreamer.h" + +using namespace llvm; + +class LFIAsmParser : public MCAsmParserExtension { + MCLFIRewriter *Rewriter; + template <bool (LFIAsmParser::*HandlerMethod)(StringRef, SMLoc)> + void addDirectiveHandler(StringRef Directive) { + MCAsmParser::ExtensionDirectiveHandler Handler = + std::make_pair(this, HandleDirective<LFIAsmParser, HandlerMethod>); + + getParser().addDirectiveHandler(Directive, Handler); + } + +public: + LFIAsmParser(MCLFIRewriter *Exp) : Rewriter(Exp) {} + void Initialize(MCAsmParser &Parser) override { + // Call the base implementation. + MCAsmParserExtension::Initialize(Parser); + addDirectiveHandler<&LFIAsmParser::parseRewriteDisable>( + ".lfi_rewrite_disable"); + addDirectiveHandler<&LFIAsmParser::parseRewriteEnable>( + ".lfi_rewrite_enable"); + } + + /// ::= {.lfi_rewrite_disable} + bool parseRewriteDisable(StringRef Directive, SMLoc Loc) { + getParser().checkForValidSection(); + if (getLexer().isNot(AsmToken::EndOfStatement)) + return TokError("unexpected token"); + Lex(); + + Rewriter->disable(); + + return false; + } + + /// ::= {.lfi_rewrite_enable} + bool parseRewriteEnable(StringRef Directive, SMLoc Loc) { + getParser().checkForValidSection(); + if (getLexer().isNot(AsmToken::EndOfStatement)) + return TokError("unexpected token"); + Lex(); + + Rewriter->enable(); + + return false; + } +}; + +namespace llvm { +MCAsmParserExtension *createLFIAsmParser(MCLFIRewriter *Exp) { + return new LFIAsmParser(Exp); +} +} // namespace llvm diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp index 5c7ebcf6b66e4..33c9a05bec114 100644 --- a/llvm/lib/MC/MCStreamer.cpp +++ b/llvm/lib/MC/MCStreamer.cpp @@ -399,6 +399,9 @@ void MCStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) { Symbol->setFragment(&getCurrentSectionOnly()->getDummyFragment()); + if (LFIRewriter) + LFIRewriter->onLabel(Symbol); + MCTargetStreamer *TS = getTargetStreamer(); if (TS) TS->emitLabel(Symbol); diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp index baf3b5536138b..b1f73433b1bb3 100644 --- a/llvm/tools/llvm-mc/llvm-mc.cpp +++ b/llvm/tools/llvm-mc/llvm-mc.cpp @@ -21,6 +21,7 @@ #include "llvm/MC/MCContext.h" #include "llvm/MC/MCInstPrinter.h" #include "llvm/MC/MCInstrInfo.h" +#include "llvm/MC/MCLFI.h" #include "llvm/MC/MCObjectFileInfo.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCParser/AsmLexer.h" @@ -626,6 +627,12 @@ int main(int argc, char **argv) { Str.reset(TheTarget->createAsmStreamer(Ctx, std::move(FOut), std::move(IP), std::move(CE), std::move(MAB))); + Triple T(TripleName); + if (T.isLFI()) { + Str->initSections(NoExecStack, *STI); + initializeLFIMCStreamer(*Str.get(), Ctx, T); + } + } else if (FileType == OFT_Null) { Str.reset(TheTarget->createNullStreamer(Ctx)); } else { @@ -646,6 +653,13 @@ int main(int argc, char **argv) { if (NoExecStack) Str->switchSection( Ctx.getAsmInfo()->getStackSection(Ctx, /*Exec=*/false)); + + Triple T(TripleName); + if (T.isLFI()) { + Str->initSections(NoExecStack, *STI); + initializeLFIMCStreamer(*Str.get(), Ctx, T); + } + Str->emitVersionForTarget(TheTriple, VersionTuple(), nullptr, VersionTuple()); } >From 32ea5c00d8823844002cb01626d7280d6670141b Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Mon, 26 Jan 2026 17:18:48 -0500 Subject: [PATCH 2/8] [LFI] Small fixes based on code review - Use `unique_ptr` for `setLFIRewriter`. - Fix `lfi-enable-rewriter` flag description. - No need to explicitly initialize LFIRewriter to null. --- llvm/include/llvm/MC/MCStreamer.h | 4 +++- llvm/lib/MC/MCLFI.cpp | 2 +- llvm/lib/MC/MCParser/AsmParser.cpp | 4 ++-- llvm/tools/llvm-mc/llvm-mc.cpp | 1 - 4 files changed, 6 insertions(+), 5 deletions(-) diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h index 339d10bd2fc30..9c0386dbacdad 100644 --- a/llvm/include/llvm/MC/MCStreamer.h +++ b/llvm/include/llvm/MC/MCStreamer.h @@ -311,7 +311,9 @@ class LLVM_ABI MCStreamer { return StartTokLocPtr ? *StartTokLocPtr : SMLoc(); } - void setLFIRewriter(MCLFIRewriter *Exp) { LFIRewriter.reset(Exp); } + void setLFIRewriter(std::unique_ptr<MCLFIRewriter> Rewriter) { + LFIRewriter = std::move(Rewriter); + } MCLFIRewriter *getLFIRewriter() { return LFIRewriter.get(); } diff --git a/llvm/lib/MC/MCLFI.cpp b/llvm/lib/MC/MCLFI.cpp index 6082edac1a781..af89d9bf3dc85 100644 --- a/llvm/lib/MC/MCLFI.cpp +++ b/llvm/lib/MC/MCLFI.cpp @@ -23,7 +23,7 @@ static const char NoteNamespace[] = "LFI"; namespace llvm { cl::opt<bool> FlagEnableRewriting("lfi-enable-rewriter", - cl::desc("Don't enable rewriting for LFI."), + cl::desc("Enable rewriting for LFI."), cl::init(true)); void initializeLFIMCStreamer(MCStreamer &Streamer, MCContext &Ctx, diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp index fdce7999f492e..3452708bcec8a 100644 --- a/llvm/lib/MC/MCParser/AsmParser.cpp +++ b/llvm/lib/MC/MCParser/AsmParser.cpp @@ -746,8 +746,8 @@ extern cl::opt<unsigned> AsmMacroMaxNestingDepth; AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out, const MCAsmInfo &MAI, unsigned CB = 0) - : MCAsmParser(Ctx, Out, SM, MAI), LFIParser(nullptr), - CurBuffer(CB ? CB : SM.getMainFileID()), MacrosEnabledFlag(true) { + : MCAsmParser(Ctx, Out, SM, MAI), CurBuffer(CB ? CB : SM.getMainFileID()), + MacrosEnabledFlag(true) { HadError = false; // Save the old handler. SavedDiagHandler = SrcMgr.getDiagHandler(); diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp index b1f73433b1bb3..6542612b5768c 100644 --- a/llvm/tools/llvm-mc/llvm-mc.cpp +++ b/llvm/tools/llvm-mc/llvm-mc.cpp @@ -632,7 +632,6 @@ int main(int argc, char **argv) { Str->initSections(NoExecStack, *STI); initializeLFIMCStreamer(*Str.get(), Ctx, T); } - } else if (FileType == OFT_Null) { Str.reset(TheTarget->createNullStreamer(Ctx)); } else { >From 56c05d533d2a1f1355b7a96daeb6eab73517649c Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Mon, 26 Jan 2026 17:28:22 -0500 Subject: [PATCH 3/8] [LFI] initializeMCLFIStreamer in createMCObjectStreamer - Still needs manual initialization for use with createAsmStreamer. --- clang/tools/driver/cc1as_main.cpp | 3 --- llvm/lib/MC/TargetRegistry.cpp | 3 +++ llvm/tools/llvm-mc/llvm-mc.cpp | 6 ------ 3 files changed, 3 insertions(+), 9 deletions(-) diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp index 6cbccbc3d7408..ccc48a77891d7 100644 --- a/clang/tools/driver/cc1as_main.cpp +++ b/clang/tools/driver/cc1as_main.cpp @@ -28,7 +28,6 @@ #include "llvm/MC/MCContext.h" #include "llvm/MC/MCInstPrinter.h" #include "llvm/MC/MCInstrInfo.h" -#include "llvm/MC/MCLFI.h" #include "llvm/MC/MCObjectFileInfo.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCParser/MCAsmParser.h" @@ -594,8 +593,6 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts, Triple T(Opts.Triple); Str.reset(TheTarget->createMCObjectStreamer( T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI)); - if (T.isLFI()) - initializeLFIMCStreamer(*Str.get(), Ctx, T); if (T.isOSBinFormatMachO() && T.isOSDarwin()) { Triple *TVT = Opts.DarwinTargetVariantTriple ? &*Opts.DarwinTargetVariantTriple diff --git a/llvm/lib/MC/TargetRegistry.cpp b/llvm/lib/MC/TargetRegistry.cpp index 9263dda65a8b0..db743ef9bdcb6 100644 --- a/llvm/lib/MC/TargetRegistry.cpp +++ b/llvm/lib/MC/TargetRegistry.cpp @@ -13,6 +13,7 @@ #include "llvm/MC/MCCodeEmitter.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCInstPrinter.h" +#include "llvm/MC/MCLFI.h" #include "llvm/MC/MCObjectStreamer.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/Support/raw_ostream.h" @@ -76,6 +77,8 @@ MCStreamer *Target::createMCObjectStreamer( } if (ObjectTargetStreamerCtorFn) ObjectTargetStreamerCtorFn(*S, STI); + if (T.isLFI()) + initializeLFIMCStreamer(*S, Ctx, T); return S; } diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp index 6542612b5768c..ea2c8c3b6427c 100644 --- a/llvm/tools/llvm-mc/llvm-mc.cpp +++ b/llvm/tools/llvm-mc/llvm-mc.cpp @@ -653,12 +653,6 @@ int main(int argc, char **argv) { Str->switchSection( Ctx.getAsmInfo()->getStackSection(Ctx, /*Exec=*/false)); - Triple T(TripleName); - if (T.isLFI()) { - Str->initSections(NoExecStack, *STI); - initializeLFIMCStreamer(*Str.get(), Ctx, T); - } - Str->emitVersionForTarget(TheTriple, VersionTuple(), nullptr, VersionTuple()); } >From 99cb10a0370044e469be5874f9cfe4bd10b3acd0 Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Tue, 27 Jan 2026 13:19:48 -0500 Subject: [PATCH 4/8] [LFI] Rely on rewriteInst to track Enabled --- llvm/include/llvm/MC/MCLFIRewriter.h | 3 +-- llvm/lib/MC/MCAsmStreamer.cpp | 3 +-- llvm/lib/MC/MCLFIRewriter.cpp | 2 -- llvm/lib/MC/MCObjectStreamer.cpp | 3 +-- 4 files changed, 3 insertions(+), 8 deletions(-) diff --git a/llvm/include/llvm/MC/MCLFIRewriter.h b/llvm/include/llvm/MC/MCLFIRewriter.h index 06e1d03b21efe..3736eeac2c10d 100644 --- a/llvm/include/llvm/MC/MCLFIRewriter.h +++ b/llvm/include/llvm/MC/MCLFIRewriter.h @@ -30,9 +30,9 @@ class MCSymbol; class MCLFIRewriter { private: MCContext &Ctx; - bool Enabled = true; protected: + bool Enabled = true; std::unique_ptr<MCInstrInfo> InstInfo; std::unique_ptr<MCRegisterInfo> RegInfo; @@ -45,7 +45,6 @@ class MCLFIRewriter { LLVM_ABI void disable(); LLVM_ABI void enable(); - LLVM_ABI bool isEnabled(); LLVM_ABI bool isCall(const MCInst &Inst) const; LLVM_ABI bool isBranch(const MCInst &Inst) const; diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp index 6e9dc5d11822d..1a50ae43cd9c9 100644 --- a/llvm/lib/MC/MCAsmStreamer.cpp +++ b/llvm/lib/MC/MCAsmStreamer.cpp @@ -2495,8 +2495,7 @@ void MCAsmStreamer::AddEncodingComment(const MCInst &Inst, void MCAsmStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) { - if (LFIRewriter && LFIRewriter->isEnabled() && - LFIRewriter->rewriteInst(Inst, *this, STI)) + if (LFIRewriter && LFIRewriter->rewriteInst(Inst, *this, STI)) return; if (CurFrag) { diff --git a/llvm/lib/MC/MCLFIRewriter.cpp b/llvm/lib/MC/MCLFIRewriter.cpp index 5295a5c3e3771..261afe1db23ba 100644 --- a/llvm/lib/MC/MCLFIRewriter.cpp +++ b/llvm/lib/MC/MCLFIRewriter.cpp @@ -28,8 +28,6 @@ void MCLFIRewriter::disable() { Enabled = false; } void MCLFIRewriter::enable() { Enabled = true; } -bool MCLFIRewriter::isEnabled() { return Enabled; } - bool MCLFIRewriter::isCall(const MCInst &Inst) const { return InstInfo->get(Inst.getOpcode()).isCall(); } diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp index f9d2bfc73069a..58aa7945d7393 100644 --- a/llvm/lib/MC/MCObjectStreamer.cpp +++ b/llvm/lib/MC/MCObjectStreamer.cpp @@ -399,8 +399,7 @@ bool MCObjectStreamer::mayHaveInstructions(MCSection &Sec) const { void MCObjectStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) { - if (LFIRewriter && LFIRewriter->isEnabled() && - LFIRewriter->rewriteInst(Inst, *this, STI)) + if (LFIRewriter && LFIRewriter->rewriteInst(Inst, *this, STI)) return; MCStreamer::emitInstruction(Inst, STI); >From 7a9a71e3a35f811dc37121069757dee38a83f10d Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Wed, 28 Jan 2026 13:30:29 -0500 Subject: [PATCH 5/8] [LFI] Some additional minor cleanup We could go further and remove the helpers in MCLFIRewriter.cpp entirely and just use InstrDesc directly from inside each rewriter. --- llvm/include/llvm/MC/MCLFI.h | 2 -- llvm/include/llvm/MC/MCLFIRewriter.h | 6 ++---- llvm/lib/MC/MCLFI.cpp | 4 +--- llvm/lib/MC/MCLFIRewriter.cpp | 6 ------ llvm/lib/MC/MCParser/LFIAsmParser.cpp | 4 ---- llvm/tools/llvm-mc/llvm-mc.cpp | 1 - 6 files changed, 3 insertions(+), 20 deletions(-) diff --git a/llvm/include/llvm/MC/MCLFI.h b/llvm/include/llvm/MC/MCLFI.h index 6598453952642..269fe9dd9911d 100644 --- a/llvm/include/llvm/MC/MCLFI.h +++ b/llvm/include/llvm/MC/MCLFI.h @@ -4,8 +4,6 @@ // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // -// This file was written by the LFI and Native Client authors. -// //===----------------------------------------------------------------------===// #include "llvm/Support/CommandLine.h" diff --git a/llvm/include/llvm/MC/MCLFIRewriter.h b/llvm/include/llvm/MC/MCLFIRewriter.h index 3736eeac2c10d..bf90c761942fa 100644 --- a/llvm/include/llvm/MC/MCLFIRewriter.h +++ b/llvm/include/llvm/MC/MCLFIRewriter.h @@ -4,8 +4,6 @@ // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // -// This file was written by the LFI and Native Client authors. -// //===----------------------------------------------------------------------===// // // This file declares the MCLFIRewriter class. This is an abstract @@ -43,8 +41,8 @@ class MCLFIRewriter { LLVM_ABI void error(const MCInst &Inst, const char Msg[]); - LLVM_ABI void disable(); - LLVM_ABI void enable(); + void disable() { Enabled = false; } + void enable() { Enabled = true; } LLVM_ABI bool isCall(const MCInst &Inst) const; LLVM_ABI bool isBranch(const MCInst &Inst) const; diff --git a/llvm/lib/MC/MCLFI.cpp b/llvm/lib/MC/MCLFI.cpp index af89d9bf3dc85..0a7f61bdaf05a 100644 --- a/llvm/lib/MC/MCLFI.cpp +++ b/llvm/lib/MC/MCLFI.cpp @@ -4,8 +4,6 @@ // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // -// This file was written by the LFI and Native Client authors. -// //===----------------------------------------------------------------------===// #include "llvm/MC/MCLFI.h" @@ -37,7 +35,7 @@ void initializeLFIMCStreamer(MCStreamer &Streamer, MCContext &Ctx, NoteArch = "aarch64"; break; default: - report_fatal_error("Unsupported architecture for LFI"); + reportFatalUsageError("Unsupported architecture for LFI"); } std::string Error; // empty diff --git a/llvm/lib/MC/MCLFIRewriter.cpp b/llvm/lib/MC/MCLFIRewriter.cpp index 261afe1db23ba..c7f551fa22148 100644 --- a/llvm/lib/MC/MCLFIRewriter.cpp +++ b/llvm/lib/MC/MCLFIRewriter.cpp @@ -4,8 +4,6 @@ // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // -// This file was written by the LFI and Native Client authors. -// //===----------------------------------------------------------------------===// // // This file implements the MCLFIRewriter class. This is a base @@ -24,10 +22,6 @@ void MCLFIRewriter::error(const MCInst &Inst, const char Msg[]) { Ctx.reportError(Inst.getLoc(), Msg); } -void MCLFIRewriter::disable() { Enabled = false; } - -void MCLFIRewriter::enable() { Enabled = true; } - bool MCLFIRewriter::isCall(const MCInst &Inst) const { return InstInfo->get(Inst.getOpcode()).isCall(); } diff --git a/llvm/lib/MC/MCParser/LFIAsmParser.cpp b/llvm/lib/MC/MCParser/LFIAsmParser.cpp index 4601052e0d65f..887c2bc44d886 100644 --- a/llvm/lib/MC/MCParser/LFIAsmParser.cpp +++ b/llvm/lib/MC/MCParser/LFIAsmParser.cpp @@ -5,10 +5,6 @@ // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// -// -// This file was written by the LFI and Native Client authors. -// -//===----------------------------------------------------------------------===// #include "llvm/MC/MCLFIRewriter.h" #include "llvm/MC/MCParser/MCAsmParserExtension.h" diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp index ea2c8c3b6427c..df7f813d1139e 100644 --- a/llvm/tools/llvm-mc/llvm-mc.cpp +++ b/llvm/tools/llvm-mc/llvm-mc.cpp @@ -652,7 +652,6 @@ int main(int argc, char **argv) { if (NoExecStack) Str->switchSection( Ctx.getAsmInfo()->getStackSection(Ctx, /*Exec=*/false)); - Str->emitVersionForTarget(TheTriple, VersionTuple(), nullptr, VersionTuple()); } >From 7c15a5e216f5031a56f9a652b799314917fe383d Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Thu, 19 Feb 2026 16:40:20 -0500 Subject: [PATCH 6/8] Update comment headers based on CodingStandards --- llvm/include/llvm/MC/MCLFI.h | 7 ++++++- llvm/include/llvm/MC/MCLFIRewriter.h | 11 ++++++----- llvm/lib/MC/MCLFI.cpp | 7 ++++++- llvm/lib/MC/MCLFIRewriter.cpp | 11 ++++++----- llvm/lib/MC/MCParser/LFIAsmParser.cpp | 7 ++++++- 5 files changed, 30 insertions(+), 13 deletions(-) diff --git a/llvm/include/llvm/MC/MCLFI.h b/llvm/include/llvm/MC/MCLFI.h index 269fe9dd9911d..6ceeb5b5051c3 100644 --- a/llvm/include/llvm/MC/MCLFI.h +++ b/llvm/include/llvm/MC/MCLFI.h @@ -1,10 +1,15 @@ -//===- MCLFI.h - LFI-specific code for MC -----------------------*- C++ -*-===// +//===----------------------------------------------------------------------===// // // 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 // //===----------------------------------------------------------------------===// +/// +/// \file +/// LFI-specific code for MC. +/// +//===----------------------------------------------------------------------===// #include "llvm/Support/CommandLine.h" #include "llvm/Support/Compiler.h" diff --git a/llvm/include/llvm/MC/MCLFIRewriter.h b/llvm/include/llvm/MC/MCLFIRewriter.h index bf90c761942fa..90f8a9b0e0c09 100644 --- a/llvm/include/llvm/MC/MCLFIRewriter.h +++ b/llvm/include/llvm/MC/MCLFIRewriter.h @@ -1,14 +1,15 @@ -//===- llvm/MC/MCLFIRewriter.h ----------------------------------*- C++ -*-===// +//===----------------------------------------------------------------------===// // // 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 // //===----------------------------------------------------------------------===// -// -// This file declares the MCLFIRewriter class. This is an abstract -// class that encapsulates the rewriting logic for MCInsts. -// +/// +/// \file +/// This file declares the MCLFIRewriter class, an abstract class that +/// encapsulates the rewriting logic for MCInsts. +/// //===----------------------------------------------------------------------===// #ifndef LLVM_MC_MCLFIREWRITER_H diff --git a/llvm/lib/MC/MCLFI.cpp b/llvm/lib/MC/MCLFI.cpp index 0a7f61bdaf05a..0092f867a8caa 100644 --- a/llvm/lib/MC/MCLFI.cpp +++ b/llvm/lib/MC/MCLFI.cpp @@ -1,10 +1,15 @@ -//===- lib/MC/MCLFI.cpp - LFI-specific MC implementation ------------------===// +//===----------------------------------------------------------------------===// // // 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 // //===----------------------------------------------------------------------===// +/// +/// \file +/// LFI-specific MC implementation. +/// +//===----------------------------------------------------------------------===// #include "llvm/MC/MCLFI.h" #include "llvm/BinaryFormat/ELF.h" diff --git a/llvm/lib/MC/MCLFIRewriter.cpp b/llvm/lib/MC/MCLFIRewriter.cpp index c7f551fa22148..0ffbc02689aa2 100644 --- a/llvm/lib/MC/MCLFIRewriter.cpp +++ b/llvm/lib/MC/MCLFIRewriter.cpp @@ -1,14 +1,15 @@ -//===- MCLFIRewriter.cpp ----------------------------------------*- C++ -*-===// +//===----------------------------------------------------------------------===// // // 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 // //===----------------------------------------------------------------------===// -// -// This file implements the MCLFIRewriter class. This is a base -// class that encapsulates the rewriting logic for MCInsts. -// +/// +/// \file +/// This file implements the MCLFIRewriter class, a base class that +/// encapsulates the rewriting logic for MCInsts. +/// //===----------------------------------------------------------------------===// #include "llvm/MC/MCLFIRewriter.h" diff --git a/llvm/lib/MC/MCParser/LFIAsmParser.cpp b/llvm/lib/MC/MCParser/LFIAsmParser.cpp index 887c2bc44d886..138b4500c50e1 100644 --- a/llvm/lib/MC/MCParser/LFIAsmParser.cpp +++ b/llvm/lib/MC/MCParser/LFIAsmParser.cpp @@ -1,10 +1,15 @@ -//===- LFIAsmParser.cpp - LFI Assembly Parser -----------------------------===// +//===----------------------------------------------------------------------===// // // 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 // //===----------------------------------------------------------------------===// +/// +/// \file +/// LFI assembly parser. +/// +//===----------------------------------------------------------------------===// #include "llvm/MC/MCLFIRewriter.h" #include "llvm/MC/MCParser/MCAsmParserExtension.h" >From 2b996415a7d5a42b207bb9c9fbe9f69aeb35e52a Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Thu, 19 Feb 2026 16:41:20 -0500 Subject: [PATCH 7/8] Remove LLVM_ABI annotations These will be added as part of a separate PR. --- .../llvm/MC/MCParser/MCAsmParserExtension.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h b/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h index eb9a995c0a2be..a32982ea315a8 100644 --- a/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h +++ b/llvm/include/llvm/MC/MCParser/MCAsmParserExtension.h @@ -121,14 +121,14 @@ class LLVM_ABI MCAsmParserExtension { /// @} }; -LLVM_ABI MCAsmParserExtension *createDarwinAsmParser(); -LLVM_ABI MCAsmParserExtension *createELFAsmParser(); -LLVM_ABI MCAsmParserExtension *createCOFFAsmParser(); -LLVM_ABI MCAsmParserExtension *createCOFFMasmParser(); -LLVM_ABI MCAsmParserExtension *createGOFFAsmParser(); -LLVM_ABI MCAsmParserExtension *createXCOFFAsmParser(); -LLVM_ABI MCAsmParserExtension *createWasmAsmParser(); -LLVM_ABI MCAsmParserExtension *createLFIAsmParser(MCLFIRewriter *Exp); +MCAsmParserExtension *createDarwinAsmParser(); +MCAsmParserExtension *createELFAsmParser(); +MCAsmParserExtension *createCOFFAsmParser(); +MCAsmParserExtension *createCOFFMasmParser(); +MCAsmParserExtension *createGOFFAsmParser(); +MCAsmParserExtension *createXCOFFAsmParser(); +MCAsmParserExtension *createWasmAsmParser(); +MCAsmParserExtension *createLFIAsmParser(MCLFIRewriter *Exp); } // end namespace llvm >From 4a27cef6b7489ed63c2c8b19453c6227f9e6de71 Mon Sep 17 00:00:00 2001 From: Zachary Yedidia <[email protected]> Date: Thu, 19 Feb 2026 16:47:53 -0500 Subject: [PATCH 8/8] Document .lfi_rewrite_enable/.lfi_rewrite_disable --- llvm/docs/LFI.rst | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/llvm/docs/LFI.rst b/llvm/docs/LFI.rst index 3c1cc96b2178d..65d8b70f17e0b 100644 --- a/llvm/docs/LFI.rst +++ b/llvm/docs/LFI.rst @@ -398,6 +398,33 @@ In certain cases, guards may be hoisted outside of loops. | | | +-----------------------+-------------------------------+ +Assembler Directives +==================== + +The LFI assembler supports the following directives for controlling the +rewriter. + +``.lfi_rewrite_disable`` +~~~~~~~~~~~~~~~~~~~~~~~~ + +Disables LFI assembly rewrites for all subsequent instructions, until +``.lfi_rewrite_enable`` is used. This can be useful for hand-written assembly +that is already safe and should not be modified by the rewriter. + +``.lfi_rewrite_enable`` +~~~~~~~~~~~~~~~~~~~~~~~ + +Re-enables LFI assembly rewrites after a previous ``.lfi_rewrite_disable``. + +Example: + +.. code-block:: gas + + .lfi_rewrite_disable + // No rewrites applied here. + ldr x0, [x27, w1, uxtw] + .lfi_rewrite_enable + References ++++++++++ _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
