Getting `llvm-config --bindir` to point a joint binary folder of LLVM

kalhauge · August 17, 2022, 8:39am

Hi all,

I’m trying to build GitHub - AFLplusplus/AFLplusplus: The fuzzer afl++ is afl with community patches, qemu 5.1 upgrade, collision-free coverage, enhanced laf-intel & redqueen, AFLfast++ power schedules, MOpt mutators, unicorn_mode, and a lot more! with lto support; however while it builds it uses llvm-config --bindir to find the directory of the binaries, and expects to find ld.lld and clang here. The problem is that the binaries in nixos is not in the same folder. I have been trying different things, with very little success. My current build script looks like this:

{ fetchFromGitHub, makeWrapper, clang12Stdenv, llvmPackages_12, python3, automake, autoconf, which }:
clang12Stdenv.mkDerivation rec {
  pname = "aflplusplus";
  version = "4.02c";
  src = fetchFromGitHub {
    owner = "AFLplusplus";
    repo = "AFLplusplus";
    rev = version;
    sha256 = "sha256-H0H2vJFKYEj+UFfoLzMkxu/ScCmpx40IYYNpcm42IRM=";
  };
  nativeBuildInputs = [
    which
    makeWrapper
    llvmPackages_12.llvm
    llvmPackages_12.bintools
    automake
    autoconf
  ];
  buildInputs = [
    (python3.withPackages (p: with p; [ setuptools ]))
  ];
  makeFlags = [ "PREFIX=$(out)" "STATIC=1" ];
  buildPhase = ''
    # set -x 
    # llvm-config --bindir 
    # which ld.lld
    # which clang
    # to investigate the problem 
    make all
  '';

  postInstall = '' 
    patchShebangs $out/bin
  '';
}

Which results in that the LTO version is not built, because it fails some checks:

GNUmakefile.llvm:126: we have trouble finding clang - llvm-config is not helping us
GNUmakefile.llvm:141: we have trouble finding clang++ - llvm-config is not helping us
GNUmakefile.llvm:224: ld.lld not found, cannot enable LTO mode

Reading the file we see that it tries to lookup ld.lld in the LLVM_BINDIR

github.com

AFLplusplus/AFLplusplus/blob/3e2986dd78dbc45035b47a34eedd7dd1b9a4d0b3/GNUmakefile.llvm#L221


      
          else
           ifeq "$(shell echo 'int main() {return 0; }' | $(CLANG_BIN) -x c - -flto -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
                 AFL_CLANG_FLTO ?= -flto
           endif
          endif
          endif
          
          
ifeq "$(LLVM_LTO)" "1"
           ifneq "$(AFL_CLANG_FLTO)" ""
             ifeq "$(AFL_REAL_LD)" ""
               ifneq "$(shell readlink $(LLVM_BINDIR)/ld.lld 2>&1)" ""
                 AFL_REAL_LD = $(LLVM_BINDIR)/ld.lld
               else
                 $(warning ld.lld not found, cannot enable LTO mode)
                 LLVM_LTO = 0
               endif
             endif
           else
             $(warning clang option -flto is not working - maybe LLVMgold.so not found - cannot enable LTO mode)
             LLVM_LTO = 0
           endif

Which it tries to find using llvm-config:

github.com

AFLplusplus/AFLplusplus/blob/3e2986dd78dbc45035b47a34eedd7dd1b9a4d0b3/GNUmakefile.llvm#L53


      
          endif
          
          
LLVMVER  = $(shell $(LLVM_CONFIG) --version 2>/dev/null | sed 's/git//' | sed 's/svn//' )
          LLVM_MAJOR = $(shell $(LLVM_CONFIG) --version 2>/dev/null | sed 's/\..*//' )
          LLVM_MINOR = $(shell $(LLVM_CONFIG) --version 2>/dev/null | sed 's/.*\.//' | sed 's/git//' | sed 's/svn//' | sed 's/ .*//' )
          LLVM_UNSUPPORTED = $(shell $(LLVM_CONFIG) --version 2>/dev/null | egrep -q '^[0-2]\.|^3.[0-7]\.' && echo 1 || echo 0 )
          LLVM_TOO_NEW = $(shell $(LLVM_CONFIG) --version 2>/dev/null | egrep -q '^1[5-9]' && echo 1 || echo 0 )
          LLVM_NEW_API = $(shell $(LLVM_CONFIG) --version 2>/dev/null | egrep -q '^1[0-9]' && echo 1 || echo 0 )
          LLVM_10_OK = $(shell $(LLVM_CONFIG) --version 2>/dev/null | egrep -q '^1[1-9]|^10\.[1-9]|^10\.0.[1-9]' && echo 1 || echo 0 )
          LLVM_HAVE_LTO = $(shell $(LLVM_CONFIG) --version 2>/dev/null | egrep -q '^1[1-9]' && echo 1 || echo 0 )
          LLVM_BINDIR = $(shell $(LLVM_CONFIG) --bindir 2>/dev/null)
          LLVM_LIBDIR = $(shell $(LLVM_CONFIG) --libdir 2>/dev/null)
          LLVM_STDCXX = gnu++11
          LLVM_APPLE_XCODE = $(shell $(CC) -v 2>&1 | grep -q Apple && echo 1 || echo 0)
          LLVM_LTO   = 0
          
          
ifeq "$(LLVMVER)" ""
            $(warning [!] llvm_mode needs llvm-config, which was not found. Set LLVM_CONFIG to its path and retry.)
          endif
          
          
ifeq "$(LLVM_UNSUPPORTED)" "1"

Any help would be greatly appreciated!

TLATER · August 17, 2022, 9:49am

Since you’ve already found where it tries to set the paths, why not fix those lines with a patchPhase?

kalhauge · August 17, 2022, 12:05pm

Thanks, I tried that shortly after posting this, but the LLVM_BINDIR is also passed directly to the tool later, I’m assuming to give it access to “all” the LLVM tools.