From 2f76e2b27d9ddd4fa0a1098f77b96fa51905bdb1 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Thu, 23 Jan 2025 11:59:57 -0500 Subject: [PATCH] [Driver] -fno-plt: warn for unsupported targets -fno-plt is an ELF specific option that is only implemented for x86 (for a long time) and AArch64 (#78890). GCC doesn't bother to give a diagnostic on Windows. -fno-plt is somewhat popular and we've been ignoring it for unsupported targets for a while, so just report a warning for unsupported targets. Pull Request: https://github.com/llvm/llvm-project/pull/124081 --- clang/lib/Driver/ToolChains/Clang.cpp | 5 ++--- clang/test/Driver/fno-plt.c | 10 ++++++++++ 2 files changed, 12 insertions(+), 3 deletions(-) create mode 100644 clang/test/Driver/fno-plt.c diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 33f08cf28feca..518113e20cb06 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -6141,9 +6141,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, CmdArgs.push_back("-fno-direct-access-external-data"); } - if (Args.hasFlag(options::OPT_fno_plt, options::OPT_fplt, false)) { - CmdArgs.push_back("-fno-plt"); - } + if (Triple.isOSBinFormatELF() && (Triple.isAArch64() || Triple.isX86())) + Args.addOptOutFlag(CmdArgs, options::OPT_fplt, options::OPT_fno_plt); // -fhosted is default. // TODO: Audit uses of KernelOrKext and see where it'd be more appropriate to diff --git a/clang/test/Driver/fno-plt.c b/clang/test/Driver/fno-plt.c new file mode 100644 index 0000000000000..c7bd7130593be --- /dev/null +++ b/clang/test/Driver/fno-plt.c @@ -0,0 +1,10 @@ +// RUN: %clang -### -c --target=aarch64 -fno-plt -Werror %s 2>&1 | FileCheck %s --check-prefix=NOPLT +// RUN: %clang -### -c --target=x86_64 -fno-plt -Werror %s 2>&1 | FileCheck %s --check-prefix=NOPLT + +// RUN: %clang -### -c --target=aarch64 -fno-plt -fplt -Werror %s 2>&1 | FileCheck %s --check-prefix=DEFAULT +// RUN: %clang -### -c --target=powerpc64 -fno-plt %s 2>&1 | FileCheck %s --check-prefixes=WARN,DEFAULT +// RUN: %clang -### -c --target=aarch64-windows -fno-plt %s 2>&1 | FileCheck %s --check-prefixes=WARN,DEFAULT + +// WARN: warning: argument unused during compilation: '-fno-plt' [-Wunused-command-line-argument] +// NOPLT: "-fno-plt" +// DEFAULT-NOT: "-fno-plt"