Option -disable-fp-elim removed in 1.24.0-beta1?

[jondegenhardt]

My CI pipeline for tsv-utils has started failing on the MacOS builds with the new 1.24.0-beta1 LDC compiler. The problem is clear from the error message:

ldc2: Unknown command line argument '-disable-fp-elim'.  Try: 'ldc2 --help'

The -disable-fp-elim switch is something I added to the builds of one of my tools on MacOS a while ago, when using LTO with druntime/phobos. It avoids unhandled exception issues. See issue #2585. I don't use the flag on Linux builds.

I don't know if it's still needed for the latest compiler versions (haven't tested it in at least a year), but it is needed on the older versions.

Before I precede with looking into this further, can you give me some info on changes to this option in the beta?

[kinke]

It's not available with LLVM 11+ anymore (and has been a legacy alias for -frame-pointer=all since LLVM 8 and undocumented for a while now). Still supporting this legacy option was made impossible (or at least, tedious) by an LLVM 11 API change (see cacdc46 for some context):

ldc/driver/cl_options-llvm.cpp

Lines 64 to 76 in e8f331c

	llvm::Optional<llvm::FramePointer::FP> framePointerUsage() {
	#if LDC_LLVM_VER >= 1100
	// Defaults to `FP::None`; no way to check if set explicitly by user except
	// indirectly via setFunctionAttributes()...
	return codegen::getFramePointerUsage();
	#else
	if (::FramePointerUsage.getNumOccurrences() > 0)
	return ::FramePointerUsage.getValue();
	if (disableFPElim.getNumOccurrences() > 0)
	return disableFPElim ? llvm::FramePointer::All : llvm::FramePointer::None;
	return llvm::None;
	#endif
	}

[jondegenhardt]

Okay, thanks. I'll do some testing and find out if there are still uncaught exceptions errors without this flag.

[jondegenhardt]

Using 1.24.0-beta1 I was unable to reproduce the unhandled exception issues the -disable-fp-elim switch was guarding against. Closing this bug.