[PATCH] D142933: Add -print-multi-selection-flags argument

Thu Feb 2 07:27:42 PST 2023

michaelplatings marked an inline comment as done.
michaelplatings added a comment.

In D142933#4099587 <https://reviews.llvm.org/D142933#4099587>, @Joe wrote:

> Would it be weird for one target to have the `march=` but anothers not?

Yes I think it would be weird. Potentially you could have a toolchain supporting Arm and other architectures so it would be unfortunate for that to be inconsistent. I'd very much like the API to work as well as possible across all architectures now, because it's going to be hard to change later. It's great getting your feedback on this.

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Comment at: clang/lib/Driver/Driver.cpp:2213
+  if (C.getArgs().hasArg(options::OPT_print_multi_selection_flags)) {
+    for (StringRef Attr : TC.getMultiSelectionFlags(C.getArgs()))
+      llvm::outs() << Attr << '\n';
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Joe wrote:
> Do we want to parse the multilib.yaml here so we can print out custom flags as well? It could help diagnose issues people have with them.
Yes, I think that would be an improvement. Might need to go in a later patch though.

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Comment at: clang/lib/Driver/ToolChain.cpp:204
+    Result.push_back(
+        clang::driver::getDriverOptTable().getOptionName(Option).str());
+  }
----------------
Joe wrote:
> > 
> >> the form `x=y` is already broken when you add the flags from the flag list.
> > 
> > Can you give an example of what you mean by that? Sounds like something that might need fixing.
> For example the option name for OPT_fexceptions is just `fexceptions`, and this is added directly to `Results`
OK, I was thrown by the word "broken".
The syntax for the multilib flags is derived from the command line arguments so I think this is fine.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D142933/new/

https://reviews.llvm.org/D142933