add initial support for llvm-flang #13323

h-vetinari · 2024-06-14T13:04:32Z

h-vetinari · 2024-07-15T00:34:59Z

mesonbuild/compilers/fortran.py

@@ -430,7 +430,61 @@
                          'everything': default_warn_args + ['-Mdclchk']}


-class FlangFortranCompiler(ClangCompiler, FortranCompiler):
+class LlvmFlangFortranCompiler(ClangCompiler, FortranCompiler):


Please let me know if you want the name of the class to be FlangLlvmFortranCompiler (to go with flang-llvm) or if I should leave it as LlvmFlangFortranCompiler. Same question goes for ClassicFlangFortranCompiler.

mesonbuild/compilers/fortran.py

+        return search_dirs + ['-lFortranRuntime', '-lFortranDecimal']
+
+
+class ClassicFlangFortranCompiler(ClangCompiler, FortranCompiler):


mesonbuild/compilers/fortran.py

h-vetinari

Just some comments; there's more in the diff itself. This isn't actually functional yet (e.g. for compiling SciPy 1.13.1), because llvm/llvm-project@9d6837d broke the ability to link to Fortran_main, which is required (even if perhaps spuriously so) by the scipy build.

h-vetinari · 2024-06-14T13:07:54Z

mesonbuild/compilers/detect.py

+        # capture help text for possible fallback
+        try:
+            _, help_out, help_err = Popen_safe_logged(compiler + ["--help"], msg='Detecting compiler via')
+        except OSError as e:
+            popen_exceptions[join_args(compiler + ["--help"])] = e
+            help_out = help_err = ""


@eli-schwartz said in #12306:

As long as meson can tell the difference between classic flang and new flang by parsing the output of --help / --version [...] we are good to go because that's what we'll base identification off of, not the executable name.

Since I couldn't see anything else using this, I've tentatively added this now. This is because flang-new --version outputs

flang-new version 17.0.6 Target: x86_64-pc-windows-msvc Thread model: posix InstalledDir: E:\miniforge\envs\<env_name>\Library\bin

-- IOW, nothing llvm-specific (especially once the rename from flang-new to flang lands) --, while flang-new --help outputs

OVERVIEW: flang LLVM compiler USAGE: flang-new.exe [options] file... OPTIONS: [...]

h-vetinari · 2024-06-14T13:08:51Z

mesonbuild/compilers/detect.py

+            def _get_linker_try_windows(cls):
                linker = None
                if 'windows' in out or env.machines[for_machine].is_windows():
                    # If we're in a MINGW context this actually will use a gnu


I broke this out into a separate function rather than duplicating it for both flang flavours. Not sure where this should ideally go. If it's not defined as a nested function, it would need a pretty extensive signature.

h-vetinari · 2024-06-14T13:15:13Z

There are several large potential changes still outstanding for flang, the biggest one of which will be the rename of the main binary from flang-new to flang. As of today, this hasn't happened yet, even though it was promised already over a year ago.

There's also a stalled refactor of the runtime libs which would change what we'd need to add under language_stdlib_only_link_flags.

mesonbuild/compilers/detect.py

h-vetinari · 2024-06-27T22:45:00Z

Good news! With this PR + flang 19 built from main, I can build SciPy successfully. 🥳

Unfortunately flang 18 is broken for this purpose, and backports won't happen anymore. Now that I have the pieces together though, it should be much easier to test the rc's for flang 19 and ensure that they keep working.

jpakkane · 2024-07-01T18:00:45Z

We are in RC freeze currently, so this will have to wait until the release.

jpakkane · 2024-07-10T19:11:52Z

Is this ready for merging in your opinion?

h-vetinari · 2024-07-10T19:49:43Z

If you don't mind how I'm adding the readout of <bin> --help or how I've structured the code, then IMO, it'd be OK to merge.

I'll ask again for the flang-new -> flang rename upstream (probably after llvm 19 branches later this month, it's already too tight for changes now), and there will certainly be other fixes, e.g. once upstream gains support for certain flags.

Another potential point is whether meson would consider it its job to detect and error out for the problem in llvm/llvm-project#92496, as compiling e.g. SciPy with this PR + flang 18 will fail deep into compilation (but passes with flang 17 & 19).

Other version-related concerns: flang <17 would require a -flang-experimental-exec flag to compile stuff, and realistically, anything <16 (or maaaaybe <15) is completely unusable.

Overall, if you are okay to ramp up support for flang gradually, and accept some sharp corners as things get ironed out over time, then I think we should merge this.

h-vetinari · 2024-07-10T19:57:45Z

I'd be happy to open a tracking issue with all the open potential improvements after this lands.

docs/markdown/Reference-tables.md

mesonbuild/compilers/fortran.py

jpakkane · 2024-07-28T16:07:59Z

Since we have settled on llvm-flang is there anything else that is still needed or is this one ready now?

h-vetinari · 2024-07-28T20:10:21Z

Good to go from my side at least. As I mentioned above, this will need some further testing and polish (e.g. follow-ups as currently unimplemented flags become available upstream), but it should be a good start.

jpakkane · 2024-07-28T20:44:45Z

This needs a release note snippet, though.

jpakkane · 2024-07-28T22:45:47Z

No point in having a separate commit for that. It only adds clutter. I can merge it with a squash, just remember this in the future.

eli-schwartz · 2024-07-28T23:01:13Z

In this case, it turns out we can avoid the fearsome idea of squash merging resulting in utterly mangled commit messages.

h-vetinari · 2024-07-29T00:42:05Z

Thank you! 🙏 🥳

eli-schwartz · 2024-07-29T00:47:06Z

Overall, if you are okay to ramp up support for flang gradually, and accept some sharp corners as things get ironed out over time, then I think we should merge this.

I'd be happy to open a tracking issue with all the open potential improvements after this lands.

We could also keep using #12306 I suppose.

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h-vetinari force-pushed the flang branch from 72cfdc5 to 188b531 Compare June 14, 2024 13:09

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Support LLVM flang #12306

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eli-schwartz reviewed Jun 19, 2024

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[dev] meson 1.5.0rc1 + new upstreaming effort conda-forge/meson-feedstock#106

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[flang][driver] impossible to combine -shared with linking to Fortran_main (flang 18.1) llvm/llvm-project#92496

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h-vetinari marked this pull request as ready for review June 27, 2024 23:42

h-vetinari requested review from dcbaker and jpakkane as code owners June 27, 2024 23:42

h-vetinari changed the title ~~WIP: add initial support for llvm-flang~~ add initial support for llvm-flang Jun 27, 2024

h-vetinari mentioned this pull request Jun 28, 2024

build with flang 19, fix lower bound for numpy conda-forge/scipy-feedstock#269

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REGR: cross-compilation fails for osx-arm64 with meson 1.5.0 #13403

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h-vetinari force-pushed the flang branch from d6ec347 to f4979b6 Compare July 21, 2024 07:49

h-vetinari mentioned this pull request Jul 26, 2024

BUG: flang support ? or meson flang support? installing scipy from source on android in termux scipy/scipy#18203

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add initial support for llvm-flang

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eli-schwartz force-pushed the flang branch from 701c1b1 to 1e26a88 Compare July 28, 2024 23:00

eli-schwartz merged commit 1e26a88 into mesonbuild:master Jul 29, 2024
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h-vetinari deleted the flang branch July 29, 2024 00:41

This was referenced Aug 2, 2024

[main] backport patch for flang support conda-forge/meson-feedstock#112

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[flang] Possible regression: fatal internal error: CHECK(range_.Contains(at)) llvm/llvm-project#102495

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h-vetinari mentioned this pull request Oct 10, 2024

1.6.0rc1: detection for llvm-flang not working #13772

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llvm-flang + scipy progress tracker pyodide/pyodide#5268

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add initial support for llvm-flang #13323

add initial support for llvm-flang #13323

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		return search_dirs + ['-lFortranRuntime', '-lFortranDecimal']


		class ClassicFlangFortranCompiler(ClangCompiler, FortranCompiler):

add initial support for llvm-flang #13323

add initial support for llvm-flang #13323

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