clang_9: fix compilation of HIP-code #77476
Conversation
When compiling HIP-code clang executes other llvm binaries, such as llvm-link, llc or opt. Clang expects these binaries in the folder with the clang-executable (...clang/bin/), this is not true for nix, because these binaris are in the llvm/bin folder. It is not possible to simply replace the path of the called library, because then the compilation with gcc fails. While I personally did not encounter a problem with clang failing due to calling lld I added it for completeness, this however means clang also depends on the llvm binutils.
DieGoldeneEnte
changed the title
|
Does this just effect clang 9 or should we do it for other clang versions as well? |
| sed -i -e 's|SmallString<128> ExecPath(C.getDriver().Dir);|SmallString<128> ExecPath(C.getDriver().Name.find("clang") != std::string::npos ? "${llvm}/bin" : C.getDriver().Dir);|' \ | ||
| -e 's|SmallString<128> OptPath(C.getDriver().Dir);|SmallString<128> OptPath(C.getDriver().Name.find("clang") != std::string::npos ? "${llvm}/bin" : C.getDriver().Dir);|' \ | ||
| -e 's|SmallString<128> LlcPath(C.getDriver().Dir);|SmallString<128> LlcPath(C.getDriver().Name.find("clang") != std::string::npos ? "${llvm}/bin" : C.getDriver().Dir);|' \ | ||
| -e 's|SmallString<128> LldPath(C.getDriver().Dir);|SmallString<128> LldPath(C.getDriver().Name.find("clang") != std::string::npos ? "${bintools}/bin" : C.getDriver().Dir);|' \ |
There was a problem hiding this comment.
binutils only has lld for clang toolchains. We should use the lld package here instead.
Clang already has a runtime dependency on llvm, so this is no problem (or at the worst just a few extra wrappers). Ideally we could upstream this to LLVM. I think instead of using |
|
As far as I found, the commit introducing the code is present since llvm 7.0.0 (and will currently also be present in llvm 10). I haven't tried versions other than 9, because I haven't found good test code for checking. |
|
I confirmed the problem with clang 8 and 9, for clang7 I would need some more work to get older versions of the device libraries. |
This PR aims to fix the same problem as NixOS/nixpkgs PR NixOS#77476; enabling to compile HIP-code using the packaged clang compiler, by also searching in $PATH for required binaries. The change is committed upstream (https://reviews.llvm.org/D72903), but will not land in the clang versions in nixpkgs (only clang 10+). As such I have created patches for the affected versions. To compile HIP-code lld is needed, so I added it to the clang-package.<Paste>
Motivation for this change
When compiling HIP-code clang executes other llvm binaries, such as
llvm-link, llc or opt. Clang expects these binaries in the folder with
the clang-executable (...clang/bin/), this is not true for nix, because
these binaries are in the llvm/bin folder. It is not possible to simply
replace the path of the called library, because then the compilation
with gcc fails. While I personally did not encounter a problem with
clang failing due to calling lld I added it for completeness, this
however means clang also depends on the llvm binutils.
Maybe older clang versions have the same flaw, I did not check this yet since my test setup only works with clang9 at the moment. Also I am not sure whether this is the most elegant solution, since I don't have too much experience with clang or nix.
Things done
I checked for successful compilation using this this setup. Building this was not possible without this change.
sandboxinnix.confon non-NixOS linux)nix-shell -p nixpkgs-review --run "nixpkgs-review wip"./result/bin/)nix path-info -Sbefore and after)