[PATCH] D137058: [Driver] [Modules] Support -fmodule-output (1/2)

[David Blaikie via Phabricator via cfe-commits]

dblaikie added inline comments.


================
Comment at: clang/lib/Driver/Driver.cpp:5541-5545
+    if (Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o))
+      TempPath = FinalOutput->getValue();
+    else
+      TempPath = BaseInput;
+
----------------
dblaikie wrote:
> ChuanqiXu wrote:
> > dblaikie wrote:
> > > It'd be nice if we didn't have to recompute this/lookup `OPT_o` here - any way we can use the object file output path here (that's already handled `OPT_o` or using the base input name, etc)?
> > I didn't understand this a lot. We don't compute anything here and we just use the object file output path here if `-o` is provided and we replace the suffix then. I feel this is simple enough.
> Computing the path to write to is what I'm referring to - and the fact that this had a bug (was relative to the source path instead of the CWD)/divergence from the `-o` path logic is the sort of thing I want to avoid.
> 
> I'm not sure there's an easy way to do this - but looks like the logic to name the .o file output is in `Driver::GetNamedOutputPath` and gets stored in the `clang::driver::Compilation`.... which I guess is where we are, but we're going through here with a `PrecompileJobAction` insntead of the compile job action, I suppose.
> 
> Could we keep these two codepaths closer together?
> 
> It'd be really nice if we could reuse that in some way.
> 
> Hmm, actually, why doesn't this fall out of the existing algorithm without modification?
> 
> Ah, I see, since the precompile action isn't "at top level" it gets a temporary file name - so if we change only that, it seems to fall out naturally:
> ```
> diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
> index c7efe60b2335..db878cbfff46 100644
> --- a/clang/lib/Driver/Driver.cpp
> +++ b/clang/lib/Driver/Driver.cpp
> @@ -5556,9 +5556,9 @@ const char *Driver::GetNamedOutputPath(Compilation &C, const JobAction &JA,
>    }
>  
>    // Output to a temporary file?
> -  if ((!AtTopLevel && !isSaveTempsEnabled() &&
> +  if (((!AtTopLevel && !isSaveTempsEnabled() &&
>         !C.getArgs().hasArg(options::OPT__SLASH_Fo)) ||
> -      CCGenDiagnostics) {
> +      CCGenDiagnostics) && JA.getType() != types::TY_ModuleFile) {
>      StringRef Name = llvm::sys::path::filename(BaseInput);
>      std::pair<StringRef, StringRef> Split = Name.split('.');
>      const char *Suffix = types::getTypeTempSuffix(JA.getType(), IsCLMode());
> ```
> 
> Without the need to reimplement/duplicate the `-o` handling logic?
Oh, I should say, this patch didn't actually have the flag support, but it'd be something like this ^ but with the command line argument test as well (so "other stuff that's already there && !(TY_ModuleFile && hasArg fmodule-output)")


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137058/new/

https://reviews.llvm.org/D137058