================
@@ -79,7 +79,14 @@ TYPE("c++-module-cpp-output", PP_CXXModule, INVALID,
"iim", phases
TYPE("ada", Ada, INVALID, nullptr,
phases::Compile, phases::Backend, phases::Assemble, phases::Link)
TYPE("assembler", PP_Asm, INVALID, "s",
phases::Assemble, phases::Link)
TYPE("assembler-with-cpp", Asm, PP_Asm, "S",
phases::Preprocess, phases::Assemble, phases::Link)
-TYPE("f95", PP_Fortran, INVALID, "i",
phases::Compile, phases::Backend, phases::Assemble, phases::Link)
+
+// Note: The `phases::Preprocess` phase is added to ".i" (i.e.
+// Fortran pre-processed) files. The reason is that Fortran
+// pre-processed files need further pre-proecessing when they
+// include modules from non-standard paths. In particular, we
+// need to add the search paths for these modules when flang
+// needs to emits pre-processed files.
----------------
banach-space wrote:
> (...) The reason is that Fortran
// pre-processed files
Could you clarify that this isn't really about "Fortran pre-processed files",
but more about "Fortran files pre-processed by LLVM Flang"?
> need further pre-proecessing when they
// include modules from non-standard paths
This is a bit misleading. IIUC, no further pre-processing happens, but the
pre-processor "phase" has to be re-run to make sure that e.g. the include flags
(i.e. `-I <dir>`) are preserved. That's because these include paths will
contain module files (could `-I <dir>` define any other dirs?) and, unlike C
header files, these module files wouldn't be included in the pre-processed file.
Please also add a note that `PP_TYPE` is set to `PP_Fortran` so that the driver
is fine with "pre-processing a pre-processed file".
Hope this makes sense and apologies if I come across as pedantic. I just find
this quite tricky and want to make sure that we throughly document these quirks
for our future selves :)
https://github.com/llvm/llvm-project/pull/104664
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
