Auto merge of #131012 - GuillaumeGomez:rollup-e9ovh3a, r=GuillaumeGomez

Rollup of 5 pull requests

Successful merges:

 - #130383 (check if it's rust-lang/rust CI job in `llvm::is_ci_llvm_modified`)
 - #130416 (resolve #130122: reword 'sort-by' edge-conditions documentation)
 - #130537 (rustdoc: add doc comment to DocVisitor)
 - #130743 (Clarifications for set_nonblocking methods)
 - #131010 (extend comment in global_llvm_features regarding target-cpu=native)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 5 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index a2a5499597c..201cfbb1918 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -536,6 +536,11 @@ pub(crate) fn global_llvm_features(
     // -Ctarget-cpu=native
     match sess.opts.cg.target_cpu {
         Some(ref s) if s == "native" => {
+            // We have already figured out the actual CPU name with `LLVMRustGetHostCPUName` and set
+            // that for LLVM, so the features implied by that CPU name will be available everywhere.
+            // However, that is not sufficient: e.g. `skylake` alone is not sufficient to tell if
+            // some of the instructions are available or not. So we have to also explicitly ask for
+            // the exact set of features available on the host, and enable all of them.
             let features_string = unsafe {
                 let ptr = llvm::LLVMGetHostCPUFeatures();
                 let features_string = if !ptr.is_null() {