[lld] MinGW backend does not support `-r`

[albinahlback]

LLD with MinGW backend does not seem to support the -r option or something equivalent. I've understood this option to be quite standard.

In order to compile FLINT, this option is required for MinGW since we otherwise go beyond the command line length limit when compiling the library. A proposal was brought up in flintlib/flint#2098 to avoid using lld -r when cross-compiling from Linux to Windows since the command line length is far greater than what is is on MinGW.

Can this feature be implemented here?

[llvmbot]

@llvm/issue-subscribers-lld-coff

Author: Albin Ahlbäck (albinahlback)

LLD with MinGW backend does not seem to support the `-r` option or something equivalent. I've understood this option to be quite standard.

In order to compile FLINT, this option is required for MinGW since we otherwise go beyond the command line length limit when compiling the library. A proposal was brought up in flintlib/flint#2098 to avoid using lld -r when cross-compiling from Linux to Windows since the command line length is far greater than what is is on MinGW.

Can this feature be implemented here?

[mstorsjo]

This option is indeed standard within GNU ld. I've considered implementing it a number of years ago, and while it probably would be doable, doing that would be a quite invasive change, for relatively little use in the wild.

this option is required for MinGW since we otherwise go beyond the command line length limit when compiling the library.

Have you considered using response files for passing command line arguments? That's supported essentially everywhere (in GNU ld as well), and is a much more straightforward operation. This is what most build systems do to tackle the command line length limit on Windows.

[albinahlback]

Please remind me, what are response files?

[alvinhochun]

Please remind me, what are response files?

You write the command line arguments to an intermediate file, then pass its path prefixed with @ as a command line argument to the tool.