lenary created this revision. lenary added reviewers: asb, luismarques. Herald added subscribers: cfe-commits, jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, jrtc27, shiva0217, kito-cheng, niosHD, sabuasal, apazos, simoncook, johnrusso, rbar. Herald added a project: clang.
The GCC RISC-V toolchain accepts `-msave-restore` and `-mno-save-restore` to control whether libcalls are used for saving and restoring the stack within prologues and epilogues. Clang currently errors if someone passes -msave-restore or -mno-save-restore. This means that people need to change build configurations to use clang. This patch adds these flags, so that clang invocations can now match gcc. As the RISC-V backend does not currently have a `save-restore` target feature, we emit a warning if someone requests `-msave-restore`. LLVM does not error if we pass the (unimplemented) target features `+save-restore` or `-save-restore`. Repository: rG LLVM Github Monorepo https://reviews.llvm.org/D63498 Files: clang/include/clang/Driver/Options.td clang/lib/Driver/ToolChains/Arch/RISCV.cpp clang/test/Driver/riscv-features.c Index: clang/test/Driver/riscv-features.c =================================================================== --- clang/test/Driver/riscv-features.c +++ clang/test/Driver/riscv-features.c @@ -3,11 +3,20 @@ // CHECK: fno-signed-char +// RUN: %clang -target riscv32-unknown-elf -### %s 2>&1 | FileCheck %s -check-prefix=DEFAULT + // RUN: %clang -target riscv32-unknown-elf -### %s -mrelax 2>&1 | FileCheck %s -check-prefix=RELAX // RUN: %clang -target riscv32-unknown-elf -### %s -mno-relax 2>&1 | FileCheck %s -check-prefix=NO-RELAX -// RUN: %clang -target riscv32-unknown-elf -### %s 2>&1 | FileCheck %s -check-prefix=DEFAULT // RELAX: "-target-feature" "+relax" // NO-RELAX: "-target-feature" "-relax" // DEFAULT: "-target-feature" "+relax" // DEFAULT-NOT: "-target-feature" "-relax" + +// RUN: %clang -target riscv32-unknown-elf -### %s -msave-restore 2>&1 | FileCheck %s -check-prefix=SAVE-RESTORE +// RUN: %clang -target riscv32-unknown-elf -### %s -mno-save-restore 2>&1 | FileCheck %s -check-prefix=NO-SAVE-RESTORE + +// SAVE-RESTORE: "-target-feature" "+save-restore" +// NO-SAVE-RESTORE: "-target-feature" "-save-restore" +// DEFAULT: "-target-feature" "-save-restore" +// DEFAULT-NOT: "-target-feature" "+save-restore" Index: clang/lib/Driver/ToolChains/Arch/RISCV.cpp =================================================================== --- clang/lib/Driver/ToolChains/Arch/RISCV.cpp +++ clang/lib/Driver/ToolChains/Arch/RISCV.cpp @@ -358,6 +358,16 @@ else Features.push_back("-relax"); + // -mno-save-restore is default, unless -msave-restore is specified. + if (Args.hasFlag(options::OPT_msave_restore, options::OPT_mno_save_restore, false)) { + Features.push_back("+save-restore"); + // ... but we don't yet support +save-restore, so issue a warning. + D.Diag(diag::warn_drv_clang_unsupported) + << Args.getLastArg(options::OPT_msave_restore)->getAsString(Args); + } else { + Features.push_back("-save-restore"); + } + // Now add any that the user explicitly requested on the command line, // which may override the defaults. handleTargetFeaturesGroup(Args, Features, options::OPT_m_riscv_Features_Group); Index: clang/include/clang/Driver/Options.td =================================================================== --- clang/include/clang/Driver/Options.td +++ clang/include/clang/Driver/Options.td @@ -2125,6 +2125,10 @@ HelpText<"Enable linker relaxation">; def mno_relax : Flag<["-"], "mno-relax">, Group<m_riscv_Features_Group>, HelpText<"Disable linker relaxation">; +def msave_restore : Flag<["-"], "msave-restore">, Group<m_riscv_Features_Group>, + HelpText<"Enable using library calls for save and restore">; +def mno_save_restore : Flag<["-"], "mno-save-restore">, Group<m_riscv_Features_Group>, + HelpText<"Disable using library calls for save and restore">; def munaligned_access : Flag<["-"], "munaligned-access">, Group<m_arm_Features_Group>, HelpText<"Allow memory accesses to be unaligned (AArch32/AArch64 only)">;
Index: clang/test/Driver/riscv-features.c =================================================================== --- clang/test/Driver/riscv-features.c +++ clang/test/Driver/riscv-features.c @@ -3,11 +3,20 @@ // CHECK: fno-signed-char +// RUN: %clang -target riscv32-unknown-elf -### %s 2>&1 | FileCheck %s -check-prefix=DEFAULT + // RUN: %clang -target riscv32-unknown-elf -### %s -mrelax 2>&1 | FileCheck %s -check-prefix=RELAX // RUN: %clang -target riscv32-unknown-elf -### %s -mno-relax 2>&1 | FileCheck %s -check-prefix=NO-RELAX -// RUN: %clang -target riscv32-unknown-elf -### %s 2>&1 | FileCheck %s -check-prefix=DEFAULT // RELAX: "-target-feature" "+relax" // NO-RELAX: "-target-feature" "-relax" // DEFAULT: "-target-feature" "+relax" // DEFAULT-NOT: "-target-feature" "-relax" + +// RUN: %clang -target riscv32-unknown-elf -### %s -msave-restore 2>&1 | FileCheck %s -check-prefix=SAVE-RESTORE +// RUN: %clang -target riscv32-unknown-elf -### %s -mno-save-restore 2>&1 | FileCheck %s -check-prefix=NO-SAVE-RESTORE + +// SAVE-RESTORE: "-target-feature" "+save-restore" +// NO-SAVE-RESTORE: "-target-feature" "-save-restore" +// DEFAULT: "-target-feature" "-save-restore" +// DEFAULT-NOT: "-target-feature" "+save-restore" Index: clang/lib/Driver/ToolChains/Arch/RISCV.cpp =================================================================== --- clang/lib/Driver/ToolChains/Arch/RISCV.cpp +++ clang/lib/Driver/ToolChains/Arch/RISCV.cpp @@ -358,6 +358,16 @@ else Features.push_back("-relax"); + // -mno-save-restore is default, unless -msave-restore is specified. + if (Args.hasFlag(options::OPT_msave_restore, options::OPT_mno_save_restore, false)) { + Features.push_back("+save-restore"); + // ... but we don't yet support +save-restore, so issue a warning. + D.Diag(diag::warn_drv_clang_unsupported) + << Args.getLastArg(options::OPT_msave_restore)->getAsString(Args); + } else { + Features.push_back("-save-restore"); + } + // Now add any that the user explicitly requested on the command line, // which may override the defaults. handleTargetFeaturesGroup(Args, Features, options::OPT_m_riscv_Features_Group); Index: clang/include/clang/Driver/Options.td =================================================================== --- clang/include/clang/Driver/Options.td +++ clang/include/clang/Driver/Options.td @@ -2125,6 +2125,10 @@ HelpText<"Enable linker relaxation">; def mno_relax : Flag<["-"], "mno-relax">, Group<m_riscv_Features_Group>, HelpText<"Disable linker relaxation">; +def msave_restore : Flag<["-"], "msave-restore">, Group<m_riscv_Features_Group>, + HelpText<"Enable using library calls for save and restore">; +def mno_save_restore : Flag<["-"], "mno-save-restore">, Group<m_riscv_Features_Group>, + HelpText<"Disable using library calls for save and restore">; def munaligned_access : Flag<["-"], "munaligned-access">, Group<m_arm_Features_Group>, HelpText<"Allow memory accesses to be unaligned (AArch32/AArch64 only)">;
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