246 lines
8.3 KiB
Rust
246 lines
8.3 KiB
Rust
// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Set and unset common attributes on LLVM values.
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use std::ffi::{CStr, CString};
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use rustc::hir::{self, TransFnAttrFlags};
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use rustc::hir::def_id::{DefId, LOCAL_CRATE};
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use rustc::hir::itemlikevisit::ItemLikeVisitor;
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use rustc::session::config::Sanitizer;
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use rustc::ty::TyCtxt;
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use rustc::ty::maps::Providers;
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use rustc_data_structures::sync::Lrc;
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use rustc_data_structures::fx::FxHashMap;
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use llvm::{self, Attribute, ValueRef};
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use llvm::AttributePlace::Function;
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use llvm_util;
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pub use syntax::attr::{self, InlineAttr};
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use context::CodegenCx;
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/// Mark LLVM function to use provided inline heuristic.
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#[inline]
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pub fn inline(val: ValueRef, inline: InlineAttr) {
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use self::InlineAttr::*;
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match inline {
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Hint => Attribute::InlineHint.apply_llfn(Function, val),
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Always => Attribute::AlwaysInline.apply_llfn(Function, val),
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Never => Attribute::NoInline.apply_llfn(Function, val),
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None => {
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Attribute::InlineHint.unapply_llfn(Function, val);
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Attribute::AlwaysInline.unapply_llfn(Function, val);
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Attribute::NoInline.unapply_llfn(Function, val);
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},
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};
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}
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/// Tell LLVM to emit or not emit the information necessary to unwind the stack for the function.
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#[inline]
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pub fn emit_uwtable(val: ValueRef, emit: bool) {
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Attribute::UWTable.toggle_llfn(Function, val, emit);
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}
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/// Tell LLVM whether the function can or cannot unwind.
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#[inline]
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pub fn unwind(val: ValueRef, can_unwind: bool) {
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Attribute::NoUnwind.toggle_llfn(Function, val, !can_unwind);
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}
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/// Tell LLVM whether it should optimize function for size.
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#[inline]
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#[allow(dead_code)] // possibly useful function
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pub fn set_optimize_for_size(val: ValueRef, optimize: bool) {
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Attribute::OptimizeForSize.toggle_llfn(Function, val, optimize);
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}
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/// Tell LLVM if this function should be 'naked', i.e. skip the epilogue and prologue.
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#[inline]
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pub fn naked(val: ValueRef, is_naked: bool) {
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Attribute::Naked.toggle_llfn(Function, val, is_naked);
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}
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pub fn set_frame_pointer_elimination(cx: &CodegenCx, llfn: ValueRef) {
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// FIXME: #11906: Omitting frame pointers breaks retrieving the value of a
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// parameter.
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if cx.sess().must_not_eliminate_frame_pointers() {
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llvm::AddFunctionAttrStringValue(
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llfn, llvm::AttributePlace::Function,
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cstr("no-frame-pointer-elim\0"), cstr("true\0"));
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}
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}
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pub fn set_probestack(cx: &CodegenCx, llfn: ValueRef) {
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// Only use stack probes if the target specification indicates that we
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// should be using stack probes
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if !cx.sess().target.target.options.stack_probes {
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return
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}
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// Currently stack probes seem somewhat incompatible with the address
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// sanitizer. With asan we're already protected from stack overflow anyway
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// so we don't really need stack probes regardless.
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match cx.sess().opts.debugging_opts.sanitizer {
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Some(Sanitizer::Address) => return,
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_ => {}
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}
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// probestack doesn't play nice either with pgo-gen.
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if cx.sess().opts.debugging_opts.pgo_gen.is_some() {
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return;
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}
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// Flag our internal `__rust_probestack` function as the stack probe symbol.
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// This is defined in the `compiler-builtins` crate for each architecture.
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llvm::AddFunctionAttrStringValue(
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llfn, llvm::AttributePlace::Function,
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cstr("probe-stack\0"), cstr("__rust_probestack\0"));
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}
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/// Composite function which sets LLVM attributes for function depending on its AST (#[attribute])
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/// attributes.
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pub fn from_fn_attrs(cx: &CodegenCx, llfn: ValueRef, id: DefId) {
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let trans_fn_attrs = cx.tcx.trans_fn_attrs(id);
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inline(llfn, trans_fn_attrs.inline);
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set_frame_pointer_elimination(cx, llfn);
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set_probestack(cx, llfn);
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if trans_fn_attrs.flags.contains(TransFnAttrFlags::COLD) {
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Attribute::Cold.apply_llfn(Function, llfn);
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}
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if trans_fn_attrs.flags.contains(TransFnAttrFlags::NAKED) {
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naked(llfn, true);
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}
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if trans_fn_attrs.flags.contains(TransFnAttrFlags::ALLOCATOR) {
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Attribute::NoAlias.apply_llfn(
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llvm::AttributePlace::ReturnValue, llfn);
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}
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if trans_fn_attrs.flags.contains(TransFnAttrFlags::UNWIND) {
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unwind(llfn, true);
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}
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if trans_fn_attrs.flags.contains(TransFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND) {
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unwind(llfn, false);
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}
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let features =
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trans_fn_attrs.target_features
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.iter()
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.map(|f| {
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let feature = &*f.as_str();
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format!("+{}", llvm_util::to_llvm_feature(cx.tcx.sess, feature))
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})
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.collect::<Vec<String>>()
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.join(",");
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if !features.is_empty() {
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let val = CString::new(features).unwrap();
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llvm::AddFunctionAttrStringValue(
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llfn, llvm::AttributePlace::Function,
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cstr("target-features\0"), &val);
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}
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// Note that currently the `wasm-import-module` doesn't do anything, but
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// eventually LLVM 7 should read this and ferry the appropriate import
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// module to the output file.
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if cx.tcx.sess.target.target.arch == "wasm32" {
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if let Some(module) = wasm_import_module(cx.tcx, id) {
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llvm::AddFunctionAttrStringValue(
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llfn,
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llvm::AttributePlace::Function,
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cstr("wasm-import-module\0"),
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&module,
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);
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}
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}
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}
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fn cstr(s: &'static str) -> &CStr {
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CStr::from_bytes_with_nul(s.as_bytes()).expect("null-terminated string")
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}
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pub fn provide(providers: &mut Providers) {
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providers.target_features_whitelist = |tcx, cnum| {
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assert_eq!(cnum, LOCAL_CRATE);
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if tcx.sess.opts.actually_rustdoc {
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// rustdoc needs to be able to document functions that use all the features, so
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// whitelist them all
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Lrc::new(llvm_util::all_known_features()
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.map(|(a, b)| (a.to_string(), b.map(|s| s.to_string())))
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.collect())
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} else {
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Lrc::new(llvm_util::target_feature_whitelist(tcx.sess)
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.iter()
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.map(|&(a, b)| (a.to_string(), b.map(|s| s.to_string())))
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.collect())
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}
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};
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providers.wasm_custom_sections = |tcx, cnum| {
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assert_eq!(cnum, LOCAL_CRATE);
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let mut finder = WasmSectionFinder { tcx, list: Vec::new() };
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tcx.hir.krate().visit_all_item_likes(&mut finder);
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Lrc::new(finder.list)
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};
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provide_extern(providers);
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}
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struct WasmSectionFinder<'a, 'tcx: 'a> {
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tcx: TyCtxt<'a, 'tcx, 'tcx>,
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list: Vec<DefId>,
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}
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impl<'a, 'tcx: 'a> ItemLikeVisitor<'tcx> for WasmSectionFinder<'a, 'tcx> {
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fn visit_item(&mut self, i: &'tcx hir::Item) {
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match i.node {
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hir::ItemConst(..) => {}
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_ => return,
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}
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if i.attrs.iter().any(|i| i.check_name("wasm_custom_section")) {
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self.list.push(self.tcx.hir.local_def_id(i.id));
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}
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}
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fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem) {}
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fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem) {}
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}
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pub fn provide_extern(providers: &mut Providers) {
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providers.wasm_import_module_map = |tcx, cnum| {
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let mut ret = FxHashMap();
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for lib in tcx.foreign_modules(cnum).iter() {
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let attrs = tcx.get_attrs(lib.def_id);
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let mut module = None;
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for attr in attrs.iter().filter(|a| a.check_name("wasm_import_module")) {
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module = attr.value_str();
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}
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let module = match module {
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Some(s) => s,
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None => continue,
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};
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for id in lib.foreign_items.iter() {
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assert_eq!(id.krate, cnum);
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ret.insert(*id, module.to_string());
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}
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}
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Lrc::new(ret)
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}
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}
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fn wasm_import_module(tcx: TyCtxt, id: DefId) -> Option<CString> {
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tcx.wasm_import_module_map(id.krate)
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.get(&id)
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.map(|s| CString::new(&s[..]).unwrap())
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}
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