From c63a1c0a1b40ee4567fb91a606a542cbbc55a856 Mon Sep 17 00:00:00 2001 From: Simonas Kazlauskas Date: Sat, 5 Jun 2021 14:35:19 +0300 Subject: [PATCH] Disable the machine outliner by default 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 --- compiler/rustc_codegen_llvm/src/llvm_util.rs | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs index 387062a671d25..0dd3d2ae15bca 100644 --- a/compiler/rustc_codegen_llvm/src/llvm_util.rs +++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs @@ -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 @@ unsafe fn configure_llvm(sess: &Session) { 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 => {