Author: Fangrui Song Date: 2024-08-22T09:20:53-07:00 New Revision: eb549da9e5c1e626edb14ba9ce43e46ad3d088af
URL: https://github.com/llvm/llvm-project/commit/eb549da9e5c1e626edb14ba9ce43e46ad3d088af DIFF: https://github.com/llvm/llvm-project/commit/eb549da9e5c1e626edb14ba9ce43e46ad3d088af.diff LOG: [Driver] Add -Wa, options -mmapsyms={default,implicit} -Wa,-mmapsyms=implicit enables the alternative mapping symbol scheme discussed at #99718. While not conforming to the current aaelf64 ABI, the option is invaluable for those with full control over their toolchain, no reliance on weird relocatable files, and a strong focus on minimizing both relocatable and executable sizes. The option is discouraged when portability of the relocatable objects is a concern. https://maskray.me/blog/2024-07-21-mapping-symbols-rethinking-for-efficiency elaborates the risk. Pull Request: https://github.com/llvm/llvm-project/pull/104542 Added: clang/test/Driver/mmapsyms.c clang/test/Misc/cc1as-mmapsyms.c Modified: clang/include/clang/Basic/CodeGenOptions.def clang/include/clang/Driver/Options.td clang/lib/CodeGen/BackendUtil.cpp clang/lib/Driver/ToolChains/Clang.cpp clang/lib/Driver/ToolChains/CommonArgs.cpp clang/tools/driver/cc1as_main.cpp Removed: ################################################################################ diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def index ecea476abe3232..b600198998d85b 100644 --- a/clang/include/clang/Basic/CodeGenOptions.def +++ b/clang/include/clang/Basic/CodeGenOptions.def @@ -37,6 +37,7 @@ VALUE_CODEGENOPT(Name, Bits, Default) CODEGENOPT(DisableIntegratedAS, 1, 0) ///< -no-integrated-as CODEGENOPT(Crel, 1, 0) ///< -Wa,--crel +CODEGENOPT(ImplicitMapSyms, 1, 0) ///< -Wa,-mmapsyms=implicit CODEGENOPT(AsmVerbose , 1, 0) ///< -dA, -fverbose-asm. CODEGENOPT(PreserveAsmComments, 1, 1) ///< -dA, -fno-preserve-as-comments. CODEGENOPT(AssumeSaneOperatorNew , 1, 1) ///< implicit __attribute__((malloc)) operator new diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 5d8791727d2109..7a3c699a6a8e88 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -7142,6 +7142,12 @@ def massembler_fatal_warnings : Flag<["-"], "massembler-fatal-warnings">, def crel : Flag<["--"], "crel">, HelpText<"Enable CREL relocation format (ELF only)">, MarshallingInfoFlag<CodeGenOpts<"Crel">>; +def mmapsyms_implicit : Flag<["-"], "mmapsyms=implicit">, + HelpText<"Allow mapping symbol at section beginning to be implicit, " + "lowering number of mapping symbols at the expense of some " + "portability. Recommended for projects that can build all their " + "object files using this option">, + MarshallingInfoFlag<CodeGenOpts<"ImplicitMapSyms">>; def mrelax_relocations_no : Flag<["-"], "mrelax-relocations=no">, HelpText<"Disable x86 relax relocations">, MarshallingInfoNegativeFlag<CodeGenOpts<"X86RelaxRelocations">>; diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp index 34c08818dbb9ad..fdd89edd72e109 100644 --- a/clang/lib/CodeGen/BackendUtil.cpp +++ b/clang/lib/CodeGen/BackendUtil.cpp @@ -471,6 +471,7 @@ static bool initTargetOptions(DiagnosticsEngine &Diags, Options.MCOptions.Dwarf64 = CodeGenOpts.Dwarf64; Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments; Options.MCOptions.Crel = CodeGenOpts.Crel; + Options.MCOptions.ImplicitMapSyms = CodeGenOpts.ImplicitMapSyms; Options.MCOptions.X86RelaxRelocations = CodeGenOpts.X86RelaxRelocations; Options.MCOptions.CompressDebugSections = CodeGenOpts.getCompressDebugSections(); diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 53fdc29948508e..9f1d57f43b6565 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -2554,6 +2554,7 @@ static void CollectArgsForIntegratedAssembler(Compilation &C, const llvm::Triple &Triple = C.getDefaultToolChain().getTriple(); bool IsELF = Triple.isOSBinFormatELF(); bool Crel = false, ExperimentalCrel = false; + bool ImplicitMapSyms = false; bool UseRelaxRelocations = C.getDefaultToolChain().useRelaxRelocations(); bool UseNoExecStack = false; bool Msa = false; @@ -2642,6 +2643,15 @@ static void CollectArgsForIntegratedAssembler(Compilation &C, // recognize but skip over here. continue; break; + case llvm::Triple::aarch64: + case llvm::Triple::aarch64_be: + case llvm::Triple::aarch64_32: + if (Equal.first == "-mmapsyms") { + ImplicitMapSyms = Equal.second == "implicit"; + checkArg(IsELF, {"default", "implicit"}); + continue; + } + break; case llvm::Triple::mips: case llvm::Triple::mipsel: case llvm::Triple::mips64: @@ -2786,6 +2796,8 @@ static void CollectArgsForIntegratedAssembler(Compilation &C, << "-Wa,--crel" << D.getTargetTriple(); } } + if (ImplicitMapSyms) + CmdArgs.push_back("-mmapsyms=implicit"); if (Msa) CmdArgs.push_back("-mmsa"); if (!UseRelaxRelocations) diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp index 320d2901da06ed..0738ed18f54078 100644 --- a/clang/lib/Driver/ToolChains/CommonArgs.cpp +++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp @@ -1143,10 +1143,27 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args, addMachineOutlinerArgs(D, Args, CmdArgs, ToolChain.getEffectiveTriple(), /*IsLTO=*/true, PluginOptPrefix); + bool IsELF = Triple.isOSBinFormatELF(); bool Crel = false; + bool ImplicitMapSyms = false; for (const Arg *A : Args.filtered(options::OPT_Wa_COMMA)) { for (StringRef V : A->getValues()) { - if (V == "--crel") + auto Equal = V.split('='); + auto checkArg = [&](bool ValidTarget, + std::initializer_list<const char *> Set) { + if (!ValidTarget) { + D.Diag(diag::err_drv_unsupported_opt_for_target) + << (Twine("-Wa,") + Equal.first + "=").str() + << Triple.getTriple(); + } else if (!llvm::is_contained(Set, Equal.second)) { + D.Diag(diag::err_drv_unsupported_option_argument) + << (Twine("-Wa,") + Equal.first + "=").str() << Equal.second; + } + }; + if (Equal.first == "-mmapsyms") { + ImplicitMapSyms = Equal.second == "implicit"; + checkArg(IsELF && Triple.isAArch64(), {"default", "implicit"}); + } else if (V == "--crel") Crel = true; else if (V == "--no-crel") Crel = false; @@ -1156,13 +1173,16 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args, } } if (Crel) { - if (Triple.isOSBinFormatELF() && !Triple.isMIPS()) { + if (IsELF && !Triple.isMIPS()) { CmdArgs.push_back(Args.MakeArgString(Twine(PluginOptPrefix) + "-crel")); } else { D.Diag(diag::err_drv_unsupported_opt_for_target) << "-Wa,--crel" << D.getTargetTriple(); } } + if (ImplicitMapSyms) + CmdArgs.push_back( + Args.MakeArgString(Twine(PluginOptPrefix) + "-implicit-mapsyms")); } void tools::addOpenMPRuntimeLibraryPath(const ToolChain &TC, diff --git a/clang/test/Driver/mmapsyms.c b/clang/test/Driver/mmapsyms.c new file mode 100644 index 00000000000000..3535af3cf1cdda --- /dev/null +++ b/clang/test/Driver/mmapsyms.c @@ -0,0 +1,28 @@ +/// Alternative mapping symbol scheme for AArch64. +// RUN: %clang -### -c --target=aarch64 -Wa,-mmapsyms=implicit %s -Werror 2>&1 | FileCheck %s +// RUN: %clang -### -c --target=aarch64_be -Wa,-mmapsyms=implicit %s -Werror 2>&1 | FileCheck %s +// RUN: %clang -### -c --target=aarch64 -Wa,-mmapsyms=implicit,-mmapsyms=default %s -Werror 2>&1 | FileCheck %s --check-prefix=NO +// RUN: not %clang -### -c --target=arm64-apple-darwin -Wa,-mmapsyms=implicit %s 2>&1 | FileCheck %s --check-prefix=ERR +// RUN: not %clang -### -c --target=x86_64 -Wa,-mmapsyms=implicit %s 2>&1 | FileCheck %s --check-prefix=ERR2 + +// RUN: %clang -### -c --target=aarch64 -Werror -Wa,-mmapsyms=implicit -x assembler %s -Werror 2>&1 | FileCheck %s --check-prefix=ASM +// RUN: not %clang -### -c --target=x86_64 -Wa,-mmapsyms=implicit -x assembler %s 2>&1 | FileCheck %s --check-prefix=ERR2 + +// CHECK: "-cc1" {{.*}}"-mmapsyms=implicit" +// NO: "-cc1" +// NO-NOT: "-mmapsyms=implicit" +// ASM: "-cc1as" {{.*}}"-mmapsyms=implicit" +// ERR: error: unsupported option '-Wa,-mmapsyms=' for target 'arm64-apple-darwin' +// ERR2: error: unsupported argument '-mmapsyms=implicit' to option '-Wa,' + +/// Check LTO. +// RUN: %clang -### --target=aarch64-linux -Werror -flto -Wa,-mmapsyms=implicit %s 2>&1 | FileCheck %s --check-prefix=LTO +// RUN: %clang -### --target=aarch64-linux -Werror -flto -Wa,-mmapsyms=implicit -Wa,-mmapsyms=default %s 2>&1 | FileCheck %s --check-prefix=LTO-NO + +// LTO: "-plugin-opt=-implicit-mapsyms" +// LTO-NO-NOT: "-plugin-opt=-implicit-mapsyms" + +// RUN: touch %t.o +// RUN: not %clang -### --target=x86_64-unknown-linux -flto -Wa,-mmapsyms=implicit %t.o 2>&1 | FileCheck %s --check-prefix=LTO-ERR + +// LTO-ERR: error: unsupported option '-Wa,-mmapsyms=' for target 'x86_64-unknown-linux' diff --git a/clang/test/Misc/cc1as-mmapsyms.c b/clang/test/Misc/cc1as-mmapsyms.c new file mode 100644 index 00000000000000..550281903c216e --- /dev/null +++ b/clang/test/Misc/cc1as-mmapsyms.c @@ -0,0 +1,9 @@ +// REQUIRES: aarch64-registered-target +// RUN: %clang -cc1as -triple aarch64 %s -filetype obj -mmapsyms=implicit -o %t.o +// RUN: llvm-readelf -s %t.o | FileCheck %s + +// CHECK: Symbol table '.symtab' contains 1 entries: +nop + +.data +.quad 0 diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp index 070cf8b44e8eb6..7fe97cc6e6ace1 100644 --- a/clang/tools/driver/cc1as_main.cpp +++ b/clang/tools/driver/cc1as_main.cpp @@ -164,6 +164,8 @@ struct AssemblerInvocation { LLVM_PREFERRED_TYPE(bool) unsigned Crel : 1; + LLVM_PREFERRED_TYPE(bool) + unsigned ImplicitMapsyms : 1; LLVM_PREFERRED_TYPE(bool) unsigned X86RelaxRelocations : 1; @@ -211,6 +213,7 @@ struct AssemblerInvocation { EmitDwarfUnwind = EmitDwarfUnwindType::Default; EmitCompactUnwindNonCanonical = false; Crel = false; + ImplicitMapsyms = 0; X86RelaxRelocations = 0; X86Sse2Avx = 0; } @@ -382,6 +385,7 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts, Opts.EmitCompactUnwindNonCanonical = Args.hasArg(OPT_femit_compact_unwind_non_canonical); Opts.Crel = Args.hasArg(OPT_crel); + Opts.ImplicitMapsyms = Args.hasArg(OPT_mmapsyms_implicit); Opts.X86RelaxRelocations = !Args.hasArg(OPT_mrelax_relocations_no); Opts.X86Sse2Avx = Args.hasArg(OPT_msse2avx); @@ -442,6 +446,7 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts, MCOptions.EmitCompactUnwindNonCanonical = Opts.EmitCompactUnwindNonCanonical; MCOptions.MCSaveTempLabels = Opts.SaveTemporaryLabels; MCOptions.Crel = Opts.Crel; + MCOptions.ImplicitMapSyms = Opts.ImplicitMapsyms; MCOptions.X86RelaxRelocations = Opts.X86RelaxRelocations; MCOptions.X86Sse2Avx = Opts.X86Sse2Avx; MCOptions.CompressDebugSections = Opts.CompressDebugSections; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
