[PATCH] D150013: [Clang] Respect `-L` options when compiling directly for AMDGPU

[Joseph Huber via Phabricator via cfe-commits]

jhuber6 added a comment.

In D150013#4330452 <https://reviews.llvm.org/D150013#4330452>, @MaskRay wrote:

> So it seems that there are configurations that we need -L (cross compilation?). If we forward -L in some configurations, I think it'd be better to do this consistently.
>
> The `LIBRARY_PATH` options seems not useful and the conditional `if (not cross compiling) add LIBRARY_PATH` is more unfortunate. I wish that we don't add more cases that we do something with `LIBRARY_PATH`.
> (IMO the `LIBRARY_PATH`  users can just fix their build system or use `CCC_OVERRIDE_OPTIONS`)
>
> We definitely want to avoid more uses of `TC.isCrossCompiling()`.

The comment itself `// LIBRARY_PATH are included before user inputs and only supported on native toolchains.` suggests that something like this might be valid.

  // LIBRARY_PATH are included before user inputs and only supported on native
  // toolchains.
  if (!TC.isCrossCompiling())
    addDirectoryList(Args, CmdArgs, "-L", "LIBRARY_PATH");
  else 
    Args.AddAllArgs(CmdArgs, options::OPT_L);



  



================
Comment at: clang/lib/Driver/ToolChains/AMDGPU.cpp:546
   addLinkerCompressDebugSectionsOption(getToolChain(), Args, CmdArgs);
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);
+  Args.AddAllArgs(CmdArgs, options::OPT_L);
----------------
jhuber6 wrote:
> MaskRay wrote:
> > jhuber6 wrote:
> > > yaxunl wrote:
> > > > jhuber6 wrote:
> > > > > yaxunl wrote:
> > > > > > AddLinkerInputs has code doing that, and it handles env var LIBRARY_PATH. However that code is disabled for AMDGPU because AMDGPU returns true for isCrossCompiling.
> > > > > > 
> > > > > > https://github.com/llvm/llvm-project/blob/main/clang/lib/Driver/ToolChains/CommonArgs.cpp#L236
> > > > > > 
> > > > > > It seems isCrossCompiling is solely for controlling whether to consume `-L`. If we want amdgpu toolchain to accept `-L`, we can simply let isCrossCompiling return false.
> > > > > Good catch, we could maybe set `isCrossCompiling` to false if targeted directly by the user, e.g. `--target=amdgcn-amd-amdhsa` vs `--offload-arch`.
> > > > That would be better. Thanks.
> > > It still is technically cross compiling, since we are building for a target that does not match the system's architecture. The original code that prevents passing `-L` was contributed by @MaskRay. I understand that we may not want to pass `LIBRARY_PATH` defines, but what's the rationale for not passing any `-L` options manually specified by the user?
> > The `LIBRARY_PATH` code had been there when I moved it in 2019. It'd be best not to rely on `LIBRARY_PATH`. I think that forwarding `-L` seems reasonable but I am not familiar with the amdgpu ecosystem..
> The linker is just `lld` so it should be the same conceptually. I'm just figuring that even if the user is cross compiling we should respect `-L` passed on the command line. Should I change this patch to make that change?
For offloading I think the problem might be that we don't want to forward `-L` arguments from the host. In that case, we might be able to apply `


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https://reviews.llvm.org/D150013