[ELF] Handle GCC collect2 -plugin-opt= on Windows

[bwerl]

Summary

Follows up on commit cd5d5ce235081005173566c99c592550021de058 by
additionally ignoring relative paths ending in "lto-wrapper.exe" as
can be the case for GCC cross-compiled for Windows.

[tejohnson]

Seems fine to me but can you also update lld/test/ELF/lto-plugin-ignore.s to test this case?

[bwerl]

In D138065#3928836, @tejohnson wrote:

Seems fine to me but can you also update lld/test/ELF/lto-plugin-ignore.s to test this case?

Sure, that makes sense, and will do.

[bwerl]

Made the suggested change to lld/test/ELF/lto-plugin-ignore.s

[tejohnson]

lgtm

[bwerl]

@tejohnson, Thanks for the review! I'm a newbie here, not sure that I have the ability to commit or see this all the way through. Is there any further action required on my part?

[tejohnson]

In D138065#3930986, @bwerl wrote:

@tejohnson, Thanks for the review! I'm a newbie here, not sure that I have the ability to commit or see this all the way through. Is there any further action required on my part?

I can commit it for you today. If you plan to become an LLVM developer see the instructions here to obtain commit access: https://llvm.org/docs/Contributing.html#for-developers-to-commit-changes-from-git

[bwerl]

@tejohnson, forgive my ignorance - Will this be included in an upcoming release, and if so do you know when that would be? Any chance it could be back-ported to the 15.0.x release track?

[tejohnson]

In D138065#3931660, @bwerl wrote:

@tejohnson, forgive my ignorance - Will this be included in an upcoming release, and if so do you know when that would be? Any chance it could be back-ported to the 15.0.x release track?

I think by default it would be released with 16.x, but it could presumably be backported to the next 15.0.x release.

I haven't done this before, but it looks like to get this backported to 15.0.5 you could follow the instructions at https://llvm.org/docs/GitHub.html to create an issue here:
https://github.com/llvm/llvm-project/milestone/16

and then add the necessary cherrypick command to it as described in the instructions. Is that something you can try? I haven't done it myself but let me know if you run into issues.

lld/ELF/Driver.cpp

static void readConfigs(opt::InputArgList &args) {
   if (auto *arg = args.getLastArg(OPT_plugin_opt_mcpu_eq))
     parseClangOption(saver().save("-mcpu=" + StringRef(arg->getValue())),
                      arg->getSpelling());
 
   for (opt::Arg *arg : args.filtered(OPT_plugin_opt_eq_minus))
     parseClangOption(std::string("-") + arg->getValue(), arg->getSpelling());
 
   // GCC collect2 passes -plugin-opt=path/to/lto-wrapper with an absolute or
-  // relative path. Just ignore. If not ended with "lto-wrapper", consider it an
+  // relative path. Just ignore. If not ended with "lto-wrapper" (or
+  // "lto-wrapper.exe" for GCC cross-compiled for Windows), consider it an
   // unsupported LLVMgold.so option and error.
-  for (opt::Arg *arg : args.filtered(OPT_plugin_opt_eq))
-    if (!StringRef(arg->getValue()).endswith("lto-wrapper"))
+  for (opt::Arg *arg : args.filtered(OPT_plugin_opt_eq)) {
+    StringRef v(arg->getValue());
+    if (!v.endswith("lto-wrapper") && !v.endswith("lto-wrapper.exe"))
       error(arg->getSpelling() + ": unknown plugin option '" + arg->getValue() +
             "'");
+  }
 
   config->passPlugins = args::getStrings(args, OPT_load_pass_plugins);
 
   // Parse -mllvm options.
   for (const auto *arg : args.filtered(OPT_mllvm)) {
     parseClangOption(arg->getValue(), arg->getSpelling());
     config->mllvmOpts.emplace_back(arg->getValue());
   }

lld/test/ELF/lto-plugin-ignore.s

 # REQUIRES: x86
 ## Test we ignore some LTO related options from clang/GCC collect2.
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
 
 ## GCC collect2 passes several LTO related options to the linker even if -flto is not used.
 ## We need to ignore them. Note that the lto-wrapper path can be relative.
 # RUN: ld.lld %t.o -o /dev/null \
 # RUN:   -plugin path/to/liblto_plugin.so \
 # RUN:   -plugin-opt=/path/to/lto-wrapper \
+# RUN:   -plugin-opt=/path/to/lto-wrapper.exe \
 # RUN:   -plugin-opt=relative/path/to/lto-wrapper \
+# RUN:   -plugin-opt=relative/path/to/lto-wrapper.exe \
 # RUN:   -plugin-opt=-fresolution=zed \
 # RUN:   -plugin-opt=-pass-through=-lgcc \
 # RUN:   -plugin-opt=-pass-through=-lgcc_eh \
 # RUN:   -plugin-opt=-pass-through=-lc
 
 ## Clang LTO passes several options to the linker, which are intended to be consumed by
 ## LLVMgold.so. We need to ignore them.
 # RUN: ld.lld %t.o -o /dev/null -plugin /path/to/LLVMgold.so -plugin-opt=thinlto