llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Simon Tatham (statham-arm) <details> <summary>Changes</summary> If a multilib collection contains libraries built for different methods of accessing global data (via absolute address, or via a GOT in -fPIC style, or as an offset from a fixed register in Arm -frwpi style), then `multilib.yaml` will need to know which relocation model an application is using in order to select the right library. Even if a multilib collection only supports one relocation model, it's still useful for `multilib.yaml` to be able to tell if the user has selected the right one, so as to give a useful error message if they haven't, instead of silently selecting a library that won't work. In this commit we determine the PIC / ROPI / RWPI status using the existing logic in `ParsePICArgs`, and translate it back into a canonical set of multilib selection flags. --- Full diff: https://github.com/llvm/llvm-project/pull/149132.diff 2 Files Affected: - (modified) clang/lib/Driver/ToolChain.cpp (+37) - (modified) clang/test/Driver/print-multi-selection-flags.c (+19) ``````````diff diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp index 3f9b808b2722e..5738c0aa9b1d2 100644 --- a/clang/lib/Driver/ToolChain.cpp +++ b/clang/lib/Driver/ToolChain.cpp @@ -343,6 +343,7 @@ ToolChain::getMultilibFlags(const llvm::opt::ArgList &Args) const { std::vector<std::string> Result; const llvm::Triple Triple(ComputeEffectiveClangTriple(Args)); Result.push_back("--target=" + Triple.str()); + bool IsARM = false; switch (Triple.getArch()) { case llvm::Triple::aarch64: @@ -355,6 +356,7 @@ ToolChain::getMultilibFlags(const llvm::opt::ArgList &Args) const { case llvm::Triple::thumb: case llvm::Triple::thumbeb: getARMMultilibFlags(D, Triple, Args, Result); + IsARM = true; // for ROPI/RWPI below break; case llvm::Triple::riscv32: case llvm::Triple::riscv64: @@ -376,6 +378,41 @@ ToolChain::getMultilibFlags(const llvm::opt::ArgList &Args) const { else Result.push_back("-fexceptions"); + // A difference of relocation model (absolutely addressed data, PIC, Arm + // ROPI/RWPI) is likely to change whether a particular multilib variant is + // compatible with a given link. Determine the relocation model of the + // current link, and add appropriate + { + RegisterEffectiveTriple TripleRAII( + *this, llvm::Triple(ComputeEffectiveClangTriple(Args))); + + auto [RelocationModel, PICLevel, IsPIE] = tools::ParsePICArgs(*this, Args); + + // ROPI and RWPI are only meaningful on Arm, so for other architectures, we + // expect never to find out they're enabled. But it seems confusing to add + // -fno-ropi and -fno-rwpi unconditionally to every other architecture's + // multilib flags, so instead we leave them out completely. + if (IsARM) { + if (RelocationModel == llvm::Reloc::ROPI || + RelocationModel == llvm::Reloc::ROPI_RWPI) + Result.push_back("-fropi"); + else + Result.push_back("-fno-ropi"); + + if (RelocationModel == llvm::Reloc::RWPI || + RelocationModel == llvm::Reloc::ROPI_RWPI) + Result.push_back("-frwpi"); + else + Result.push_back("-fno-rwpi"); + } + + if (RelocationModel == llvm::Reloc::PIC_) + Result.push_back(IsPIE ? (PICLevel > 1 ? "-fPIE" : "-fpie") + : (PICLevel > 1 ? "-fPIC" : "-fpic")); + else + Result.push_back("-fno-pic"); + } + // Sort and remove duplicates. std::sort(Result.begin(), Result.end()); Result.erase(llvm::unique(Result), Result.end()); diff --git a/clang/test/Driver/print-multi-selection-flags.c b/clang/test/Driver/print-multi-selection-flags.c index 5f9383fbed8f4..1d794091970d3 100644 --- a/clang/test/Driver/print-multi-selection-flags.c +++ b/clang/test/Driver/print-multi-selection-flags.c @@ -107,3 +107,22 @@ // CHECK-AARCH64-MULTILIB-CUSTOM-FLAG: --target=aarch64-unknown-none-eabi // CHECK-MULTILIB-CUSTOM-FLAG-DAG: -fmultilib-flag=foo // CHECK-MULTILIB-CUSTOM-FLAG-DAG: -fmultilib-flag=bar + +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fropi | FileCheck --check-prefixes=CHECK-ROPI,CHECK-NO-RWPI,CHECK-NO-PIC %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -frwpi | FileCheck --check-prefixes=CHECK-RWPI,CHECK-NO-ROPI,CHECK-NO-PIC %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fropi -frwpi | FileCheck --check-prefixes=CHECK-ROPI,CHECK-RWPI,CHECK-NO-PIC %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fno-ropi -fno-rwpi | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-NO-PIC %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-NO-PIC %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fpic | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIC1 %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fPIC | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIC2 %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fpie | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIE1 %s +// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fPIE | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIE2 %s +// CHECK-ROPI: -fropi +// CHECK-NO-ROPI: -fno-ropi +// CHECK-RWPI: -frwpi +// CHECK-NO-RWPI: -fno-rwpi +// CHECK-PIC1: -fpic +// CHECK-PIC2: -fPIC +// CHECK-PIE1: -fpie +// CHECK-PIE2: -fPIE +// CHECK-NO-PIC: -fno-pic `````````` </details> https://github.com/llvm/llvm-project/pull/149132 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
