Just use the default gcc instead of clang 4.0.0.

It was a bit of a flight of fancy to use a pinned version of clang.
This would make sense if we were really depending on hyper-specific
behaviour of the C compiler, like some automatic SIMD parallization,
but in reality we're not. So don't be fussy and just keep it simple.

README.md

@@ -59,7 +59,7 @@ build environment. You can use Nix to build/test/benchmark RaptorJIT
 with suitable versions of all dependencies provided.
 
 Note: Building with nix will be slow the first time because it
-downloads the exact reference versions of the toolchain (clang, etc)
+downloads the exact reference versions of the toolchain (gcc, etc)
 and all dependencies (glibc, etc). This is all cached for future
 builds.
 
@@ -97,7 +97,7 @@ $ nix-shell # start sub-shell with pristine build environment in $PATH
 $ make
 ```
 
-... but make sure you have at least `make`, `clang`, and `luajit` in your `$PATH`.
+... but make sure you have at least `make`, `gcc`, and `luajit` in your `$PATH`.
 
 ### Run the benchmarks
 

raptorjit.nix

@@ -3,13 +3,14 @@
 { pkgs, source, version }:
 
 with pkgs;
-with llvmPackages_4.stdenv; # Use clang 4.0
+with stdenv;
 
 mkDerivation rec {
  name = "raptorjit-${version}";
  inherit version;
  src = source;
  buildInputs = [ luajit ]; # LuaJIT to bootstrap DynASM
+ dontStrip = true;
  installPhase = ''
  mkdir -p $out/bin
  cp src/raptorjit $out/bin/raptorjit

src/Makefile

@@ -377,6 +377,10 @@ $(HOST_O): %.o: %.c
  $(E) "HOSTCC $@"
  $(Q)$(HOST_CC) $(HOST_ACFLAGS) -c -o $@ $<
 
+$(DWARF_DWO): %.dwo: %.c
+ $(E) "CC(debug) $@"
+ $(Q)$(TARGET_CC) -g3 -fno-eliminate-unused-debug-types -gsplit-dwarf -c $<
+
 include Makefile.dep
 
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