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Disable the machine outliner by default

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This addresses a codegen-issue that needs to be fixed upstream in LLVM.
While we wait for the fix, we can disable it.

Verified manually that the outliner is no longer run when
`-Copt-level=z` is specified, and also that you can override this with
`-Cllvm-args=-enable-machine-outliner` if you need it anyway.

A regression test is not really feasible in this instance, given that we
do not have any minimal reproducers.

Fixes #85351
This commit is contained in:
Simonas Kazlauskas 2021-06-05 14:35:19 +03:00
parent 4e20754629
commit c63a1c0a1b
1 changed files with 12 additions and 1 deletions
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13
compiler/rustc_codegen_llvm/src/llvm_util.rs
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@ -1,5 +1,5 @@
use crate::back::write::create_informational_target_machine;
use crate::llvm;
use crate::{llvm, llvm_util};
use libc::c_int;
use rustc_codegen_ssa::target_features::supported_target_features;
use rustc_data_structures::fx::FxHashSet;
@ -84,6 +84,17 @@ fn llvm_arg_to_arg_name(full_arg: &str) -> &str {
if !sess.opts.debugging_opts.no_generate_arange_section {
add("-generate-arange-section", false);
}
// FIXME(nagisa): disable the machine outliner by default in LLVM versions 11, where it was
// introduced and up.
//
// This should remain in place until https://reviews.llvm.org/D103167 is fixed. If LLVM
// has been upgraded since, consider adjusting the version check below to contain an upper
// bound.
if llvm_util::get_version() >= (11, 0, 0) {
add("-enable-machine-outliner=never", false);
}
match sess.opts.debugging_opts.merge_functions.unwrap_or(sess.target.merge_functions) {
MergeFunctions::Disabled | MergeFunctions::Trampolines => {}
MergeFunctions::Aliases => {