mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Rollup merge of #117744 - quininer:add-z-sync-uw, r=bjorn3

Browse Source 
Add -Zuse-sync-unwind

Currently Rust uses async unwind by default, but async unwind will bring non-negligible size overhead. it would be nice to allow users to choose this.

In addition, async unwind currently prevents LLVM from generate compact unwind for MachO, if one wishes to generate compact unwind for MachO, then also needs this flag.
This commit is contained in:
Matthias Krüger 2024-01-09 05:33:20 +01:00 committed by GitHub
commit 9e4843e42e
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
compiler/rustc_codegen_llvm/src/allocator.rs
View File

@ -134,7 +134,8 @@ fn create_wrapper_function(
llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
}
if tcx.sess.must_emit_unwind_tables() {
let uwtable = attributes::uwtable_attr(llcx);
let uwtable =
attributes::uwtable_attr(llcx, tcx.sess.opts.unstable_opts.use_sync_unwind);
attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]);
}

7
compiler/rustc_codegen_llvm/src/attributes.rs
View File

@ -95,11 +95,12 @@ pub fn sanitize_attrs<'ll>(
/// Tell LLVM to emit or not emit the information necessary to unwind the stack for the function.
#[inline]
pub fn uwtable_attr(llcx: &llvm::Context) -> &Attribute {
pub fn uwtable_attr(llcx: &llvm::Context, use_sync_unwind: Option<bool>) -> &Attribute {
// NOTE: We should determine if we even need async unwind tables, as they
// take have more overhead and if we can use sync unwind tables we
// probably should.
llvm::CreateUWTableAttr(llcx, true)
let async_unwind = !use_sync_unwind.unwrap_or(false);
llvm::CreateUWTableAttr(llcx, async_unwind)
}
pub fn frame_pointer_type_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribute> {
@ -333,7 +334,7 @@ pub fn from_fn_attrs<'ll, 'tcx>(
// You can also find more info on why Windows always requires uwtables here:
// https://bugzilla.mozilla.org/show_bug.cgi?id=1302078
if cx.sess().must_emit_unwind_tables() {
to_add.push(uwtable_attr(cx.llcx));
to_add.push(uwtable_attr(cx.llcx, cx.sess().opts.unstable_opts.use_sync_unwind));
}
if cx.sess().opts.unstable_opts.profile_sample_use.is_some() {

2
compiler/rustc_session/src/options.rs
View File

@ -1960,6 +1960,8 @@ pub(crate) fn parse_function_return(slot: &mut FunctionReturn, v: Option<&str>)
"adds unstable command line options to rustc interface (default: no)"),
use_ctors_section: Option<bool> = (None, parse_opt_bool, [TRACKED],
"use legacy .ctors section for initializers rather than .init_array"),
use_sync_unwind: Option<bool> = (None, parse_opt_bool, [TRACKED],
"Generate sync unwind tables instead of async unwind tables (default: no)"),
validate_mir: bool = (false, parse_bool, [UNTRACKED],
"validate MIR after each transformation"),
#[rustc_lint_opt_deny_field_access("use `Session::verbose_internals` instead of this field")]