FS#62299 - [rust/llvm7] Target CPU help is not supported by this LLVM version.

Attached to Project: Community Packages
Opened by Jan Alexander Steffens (heftig) - Wednesday, 10 April 2019, 13:33 GMT
Last edited by Evangelos Foutras (foutrelis) - Saturday, 13 April 2019, 14:23 GMT
Task Type Bug Report
Category Packages
Status Closed
Assigned To Evangelos Foutras (foutrelis)
Johannes Löthberg (demize)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

The following parameters to the --print argument do not work:

> rustc --print target-cpus
Target CPU help is not supported by this LLVM version.

> rustc --print target-features
Target features help is not supported by this LLVM version.

rust 1.33.0-2
llvm7-libs 7.0.1-1
This task depends upon

Closed by  Evangelos Foutras (foutrelis)
Saturday, 13 April 2019, 14:23 GMT
Reason for closing:  Not a bug
Additional comments about closing:  The flags mentioned are unavailable when rust is built with system LLVM.
Comment by Evangelos Foutras (foutrelis) - Wednesday, 10 April 2019, 20:04 GMT
Those flags appear to work with bundled LLVM only: https://github.com/rust-lang/rust/commit/ce50bedd
Comment by Jan Alexander Steffens (heftig) - Wednesday, 10 April 2019, 20:06 GMT
If they carry significant (other) patches for LLVM, shouldn't we use the bundled one, then?
Comment by Evangelos Foutras (foutrelis) - Wednesday, 10 April 2019, 20:45 GMT
These are their changes on top of LLVM 8.0.0: https://github.com/rust-lang/llvm-project/compare/llvmorg-8.0.0...rustc/8.0-2019-03-18

As far as I know, their approach is to stay compatible with released LLVM versions, so there should be no need to use their LLVM fork.

It seems you can get a list of CPUs/features using: llc -march=x86-64 -mattr=help

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