622 lines
24 KiB
Rust
622 lines
24 KiB
Rust
// Copyright 2012-2014 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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use common::{C_i32, C_null};
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use libc::c_uint;
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use llvm::{self, ValueRef, BasicBlockRef};
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use llvm::debuginfo::DIScope;
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use rustc::ty::{self, Ty, TypeFoldable, UpvarSubsts};
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use rustc::ty::layout::{LayoutOf, TyLayout};
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use rustc::mir::{self, Mir};
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use rustc::ty::subst::Substs;
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use rustc::session::config::FullDebugInfo;
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use base;
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use builder::Builder;
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use common::{CodegenCx, Funclet};
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use debuginfo::{self, declare_local, VariableAccess, VariableKind, FunctionDebugContext};
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use monomorphize::Instance;
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use abi::{ArgTypeExt, FnType, FnTypeExt, PassMode};
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use type_::Type;
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use syntax_pos::{DUMMY_SP, NO_EXPANSION, BytePos, Span};
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use syntax::symbol::keywords;
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use std::iter;
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use rustc_data_structures::bitvec::BitVector;
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use rustc_data_structures::indexed_vec::{IndexVec, Idx};
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pub use self::constant::codegen_static_initializer;
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use self::analyze::CleanupKind;
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use self::place::PlaceRef;
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use rustc::mir::traversal;
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use self::operand::{OperandRef, OperandValue};
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/// Master context for codegenning from MIR.
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pub struct FunctionCx<'a, 'tcx:'a> {
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instance: Instance<'tcx>,
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mir: &'a mir::Mir<'tcx>,
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debug_context: debuginfo::FunctionDebugContext,
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llfn: ValueRef,
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cx: &'a CodegenCx<'a, 'tcx>,
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fn_ty: FnType<'tcx, Ty<'tcx>>,
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/// When unwinding is initiated, we have to store this personality
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/// value somewhere so that we can load it and re-use it in the
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/// resume instruction. The personality is (afaik) some kind of
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/// value used for C++ unwinding, which must filter by type: we
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/// don't really care about it very much. Anyway, this value
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/// contains an alloca into which the personality is stored and
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/// then later loaded when generating the DIVERGE_BLOCK.
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personality_slot: Option<PlaceRef<'tcx>>,
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/// A `Block` for each MIR `BasicBlock`
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blocks: IndexVec<mir::BasicBlock, BasicBlockRef>,
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/// The funclet status of each basic block
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cleanup_kinds: IndexVec<mir::BasicBlock, analyze::CleanupKind>,
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/// When targeting MSVC, this stores the cleanup info for each funclet
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/// BB. This is initialized as we compute the funclets' head block in RPO.
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funclets: &'a IndexVec<mir::BasicBlock, Option<Funclet>>,
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/// This stores the landing-pad block for a given BB, computed lazily on GNU
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/// and eagerly on MSVC.
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landing_pads: IndexVec<mir::BasicBlock, Option<BasicBlockRef>>,
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/// Cached unreachable block
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unreachable_block: Option<BasicBlockRef>,
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/// The location where each MIR arg/var/tmp/ret is stored. This is
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/// usually an `PlaceRef` representing an alloca, but not always:
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/// sometimes we can skip the alloca and just store the value
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/// directly using an `OperandRef`, which makes for tighter LLVM
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/// IR. The conditions for using an `OperandRef` are as follows:
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///
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/// - the type of the local must be judged "immediate" by `is_llvm_immediate`
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/// - the operand must never be referenced indirectly
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/// - we should not take its address using the `&` operator
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/// - nor should it appear in a place path like `tmp.a`
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/// - the operand must be defined by an rvalue that can generate immediate
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/// values
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///
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/// Avoiding allocs can also be important for certain intrinsics,
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/// notably `expect`.
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locals: IndexVec<mir::Local, LocalRef<'tcx>>,
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/// Debug information for MIR scopes.
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scopes: IndexVec<mir::SourceScope, debuginfo::MirDebugScope>,
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/// If this function is being monomorphized, this contains the type substitutions used.
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param_substs: &'tcx Substs<'tcx>,
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}
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impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
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pub fn monomorphize<T>(&self, value: &T) -> T
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where T: TypeFoldable<'tcx>
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{
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self.cx.tcx.subst_and_normalize_erasing_regions(
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self.param_substs,
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ty::ParamEnv::reveal_all(),
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value,
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)
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}
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pub fn set_debug_loc(&mut self, bx: &Builder, source_info: mir::SourceInfo) {
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let (scope, span) = self.debug_loc(source_info);
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debuginfo::set_source_location(&self.debug_context, bx, scope, span);
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}
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pub fn debug_loc(&mut self, source_info: mir::SourceInfo) -> (DIScope, Span) {
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// Bail out if debug info emission is not enabled.
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match self.debug_context {
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FunctionDebugContext::DebugInfoDisabled |
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FunctionDebugContext::FunctionWithoutDebugInfo => {
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return (self.scopes[source_info.scope].scope_metadata, source_info.span);
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}
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FunctionDebugContext::RegularContext(_) =>{}
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}
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// In order to have a good line stepping behavior in debugger, we overwrite debug
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// locations of macro expansions with that of the outermost expansion site
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// (unless the crate is being compiled with `-Z debug-macros`).
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if source_info.span.ctxt() == NO_EXPANSION ||
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self.cx.sess().opts.debugging_opts.debug_macros {
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let scope = self.scope_metadata_for_loc(source_info.scope, source_info.span.lo());
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(scope, source_info.span)
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} else {
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// Walk up the macro expansion chain until we reach a non-expanded span.
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// We also stop at the function body level because no line stepping can occur
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// at the level above that.
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let mut span = source_info.span;
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while span.ctxt() != NO_EXPANSION && span.ctxt() != self.mir.span.ctxt() {
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if let Some(info) = span.ctxt().outer().expn_info() {
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span = info.call_site;
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} else {
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break;
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}
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}
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let scope = self.scope_metadata_for_loc(source_info.scope, span.lo());
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// Use span of the outermost expansion site, while keeping the original lexical scope.
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(scope, span)
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}
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}
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// DILocations inherit source file name from the parent DIScope. Due to macro expansions
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// it may so happen that the current span belongs to a different file than the DIScope
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// corresponding to span's containing source scope. If so, we need to create a DIScope
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// "extension" into that file.
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fn scope_metadata_for_loc(&self, scope_id: mir::SourceScope, pos: BytePos)
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-> llvm::debuginfo::DIScope {
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let scope_metadata = self.scopes[scope_id].scope_metadata;
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if pos < self.scopes[scope_id].file_start_pos ||
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pos >= self.scopes[scope_id].file_end_pos {
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let cm = self.cx.sess().codemap();
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let defining_crate = self.debug_context.get_ref(DUMMY_SP).defining_crate;
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debuginfo::extend_scope_to_file(self.cx,
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scope_metadata,
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&cm.lookup_char_pos(pos).file,
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defining_crate)
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} else {
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scope_metadata
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}
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}
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}
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enum LocalRef<'tcx> {
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Place(PlaceRef<'tcx>),
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Operand(Option<OperandRef<'tcx>>),
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}
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impl<'a, 'tcx> LocalRef<'tcx> {
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fn new_operand(cx: &CodegenCx<'a, 'tcx>, layout: TyLayout<'tcx>) -> LocalRef<'tcx> {
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if layout.is_zst() {
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// Zero-size temporaries aren't always initialized, which
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// doesn't matter because they don't contain data, but
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// we need something in the operand.
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LocalRef::Operand(Some(OperandRef::new_zst(cx, layout)))
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} else {
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LocalRef::Operand(None)
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}
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}
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}
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///////////////////////////////////////////////////////////////////////////
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pub fn codegen_mir<'a, 'tcx: 'a>(
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cx: &'a CodegenCx<'a, 'tcx>,
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llfn: ValueRef,
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mir: &'a Mir<'tcx>,
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instance: Instance<'tcx>,
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sig: ty::FnSig<'tcx>,
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) {
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let fn_ty = FnType::new(cx, sig, &[]);
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debug!("fn_ty: {:?}", fn_ty);
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let debug_context =
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debuginfo::create_function_debug_context(cx, instance, sig, llfn, mir);
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let bx = Builder::new_block(cx, llfn, "start");
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if mir.basic_blocks().iter().any(|bb| bb.is_cleanup) {
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bx.set_personality_fn(cx.eh_personality());
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}
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let cleanup_kinds = analyze::cleanup_kinds(&mir);
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// Allocate a `Block` for every basic block, except
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// the start block, if nothing loops back to it.
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let reentrant_start_block = !mir.predecessors_for(mir::START_BLOCK).is_empty();
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let block_bxs: IndexVec<mir::BasicBlock, BasicBlockRef> =
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mir.basic_blocks().indices().map(|bb| {
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if bb == mir::START_BLOCK && !reentrant_start_block {
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bx.llbb()
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} else {
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bx.build_sibling_block(&format!("{:?}", bb)).llbb()
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}
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}).collect();
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// Compute debuginfo scopes from MIR scopes.
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let scopes = debuginfo::create_mir_scopes(cx, mir, &debug_context);
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let (landing_pads, funclets) = create_funclets(mir, &bx, &cleanup_kinds, &block_bxs);
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let mut fx = FunctionCx {
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instance,
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mir,
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llfn,
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fn_ty,
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cx,
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personality_slot: None,
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blocks: block_bxs,
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unreachable_block: None,
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cleanup_kinds,
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landing_pads,
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funclets: &funclets,
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scopes,
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locals: IndexVec::new(),
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debug_context,
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param_substs: {
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assert!(!instance.substs.needs_infer());
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instance.substs
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},
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};
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let memory_locals = analyze::non_ssa_locals(&fx);
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// Allocate variable and temp allocas
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fx.locals = {
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let args = arg_local_refs(&bx, &fx, &fx.scopes, &memory_locals);
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let mut allocate_local = |local| {
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let decl = &mir.local_decls[local];
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let layout = bx.cx.layout_of(fx.monomorphize(&decl.ty));
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assert!(!layout.ty.has_erasable_regions());
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if let Some(name) = decl.name {
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// User variable
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let debug_scope = fx.scopes[decl.visibility_scope];
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let dbg = debug_scope.is_valid() && bx.sess().opts.debuginfo == FullDebugInfo;
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if !memory_locals.contains(local.index()) && !dbg {
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debug!("alloc: {:?} ({}) -> operand", local, name);
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return LocalRef::new_operand(bx.cx, layout);
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}
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debug!("alloc: {:?} ({}) -> place", local, name);
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let place = PlaceRef::alloca(&bx, layout, &name.as_str());
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if dbg {
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let (scope, span) = fx.debug_loc(mir::SourceInfo {
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span: decl.source_info.span,
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scope: decl.visibility_scope,
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});
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declare_local(&bx, &fx.debug_context, name, layout.ty, scope,
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VariableAccess::DirectVariable { alloca: place.llval },
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VariableKind::LocalVariable, span);
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}
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LocalRef::Place(place)
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} else {
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// Temporary or return place
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if local == mir::RETURN_PLACE && fx.fn_ty.ret.is_indirect() {
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debug!("alloc: {:?} (return place) -> place", local);
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let llretptr = llvm::get_param(llfn, 0);
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LocalRef::Place(PlaceRef::new_sized(llretptr, layout, layout.align))
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} else if memory_locals.contains(local.index()) {
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debug!("alloc: {:?} -> place", local);
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LocalRef::Place(PlaceRef::alloca(&bx, layout, &format!("{:?}", local)))
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} else {
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// If this is an immediate local, we do not create an
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// alloca in advance. Instead we wait until we see the
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// definition and update the operand there.
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debug!("alloc: {:?} -> operand", local);
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LocalRef::new_operand(bx.cx, layout)
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}
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}
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};
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let retptr = allocate_local(mir::RETURN_PLACE);
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iter::once(retptr)
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.chain(args.into_iter())
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.chain(mir.vars_and_temps_iter().map(allocate_local))
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.collect()
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};
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// Branch to the START block, if it's not the entry block.
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if reentrant_start_block {
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bx.br(fx.blocks[mir::START_BLOCK]);
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}
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// Up until here, IR instructions for this function have explicitly not been annotated with
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// source code location, so we don't step into call setup code. From here on, source location
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// emitting should be enabled.
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debuginfo::start_emitting_source_locations(&fx.debug_context);
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let rpo = traversal::reverse_postorder(&mir);
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let mut visited = BitVector::new(mir.basic_blocks().len());
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// Codegen the body of each block using reverse postorder
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for (bb, _) in rpo {
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visited.insert(bb.index());
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fx.codegen_block(bb);
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}
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// Remove blocks that haven't been visited, or have no
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// predecessors.
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for bb in mir.basic_blocks().indices() {
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// Unreachable block
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if !visited.contains(bb.index()) {
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debug!("codegen_mir: block {:?} was not visited", bb);
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unsafe {
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llvm::LLVMDeleteBasicBlock(fx.blocks[bb]);
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}
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}
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}
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}
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fn create_funclets<'a, 'tcx>(
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mir: &'a Mir<'tcx>,
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bx: &Builder<'a, 'tcx>,
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cleanup_kinds: &IndexVec<mir::BasicBlock, CleanupKind>,
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block_bxs: &IndexVec<mir::BasicBlock, BasicBlockRef>)
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-> (IndexVec<mir::BasicBlock, Option<BasicBlockRef>>,
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IndexVec<mir::BasicBlock, Option<Funclet>>)
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{
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block_bxs.iter_enumerated().zip(cleanup_kinds).map(|((bb, &llbb), cleanup_kind)| {
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match *cleanup_kind {
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CleanupKind::Funclet if base::wants_msvc_seh(bx.sess()) => {}
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_ => return (None, None)
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}
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let cleanup;
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let ret_llbb;
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match mir[bb].terminator.as_ref().map(|t| &t.kind) {
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// This is a basic block that we're aborting the program for,
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// notably in an `extern` function. These basic blocks are inserted
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// so that we assert that `extern` functions do indeed not panic,
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// and if they do we abort the process.
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//
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// On MSVC these are tricky though (where we're doing funclets). If
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// we were to do a cleanuppad (like below) the normal functions like
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// `longjmp` would trigger the abort logic, terminating the
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// program. Instead we insert the equivalent of `catch(...)` for C++
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// which magically doesn't trigger when `longjmp` files over this
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// frame.
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//
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// Lots more discussion can be found on #48251 but this codegen is
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// modeled after clang's for:
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//
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// try {
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// foo();
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// } catch (...) {
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// bar();
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// }
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Some(&mir::TerminatorKind::Abort) => {
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let cs_bx = bx.build_sibling_block(&format!("cs_funclet{:?}", bb));
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let cp_bx = bx.build_sibling_block(&format!("cp_funclet{:?}", bb));
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ret_llbb = cs_bx.llbb();
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let cs = cs_bx.catch_switch(None, None, 1);
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cs_bx.add_handler(cs, cp_bx.llbb());
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// The "null" here is actually a RTTI type descriptor for the
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// C++ personality function, but `catch (...)` has no type so
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// it's null. The 64 here is actually a bitfield which
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// represents that this is a catch-all block.
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let null = C_null(Type::i8p(bx.cx));
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let sixty_four = C_i32(bx.cx, 64);
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cleanup = cp_bx.catch_pad(cs, &[null, sixty_four, null]);
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cp_bx.br(llbb);
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}
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_ => {
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let cleanup_bx = bx.build_sibling_block(&format!("funclet_{:?}", bb));
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ret_llbb = cleanup_bx.llbb();
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cleanup = cleanup_bx.cleanup_pad(None, &[]);
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cleanup_bx.br(llbb);
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}
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};
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(Some(ret_llbb), Some(Funclet::new(cleanup)))
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}).unzip()
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}
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/// Produce, for each argument, a `ValueRef` pointing at the
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/// argument's value. As arguments are places, these are always
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/// indirect.
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fn arg_local_refs<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
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fx: &FunctionCx<'a, 'tcx>,
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scopes: &IndexVec<mir::SourceScope, debuginfo::MirDebugScope>,
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memory_locals: &BitVector)
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-> Vec<LocalRef<'tcx>> {
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let mir = fx.mir;
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let tcx = bx.tcx();
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let mut idx = 0;
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let mut llarg_idx = fx.fn_ty.ret.is_indirect() as usize;
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// Get the argument scope, if it exists and if we need it.
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let arg_scope = scopes[mir::OUTERMOST_SOURCE_SCOPE];
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let arg_scope = if arg_scope.is_valid() && bx.sess().opts.debuginfo == FullDebugInfo {
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Some(arg_scope.scope_metadata)
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} else {
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None
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};
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mir.args_iter().enumerate().map(|(arg_index, local)| {
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let arg_decl = &mir.local_decls[local];
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let name = if let Some(name) = arg_decl.name {
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name.as_str().to_string()
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} else {
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format!("arg{}", arg_index)
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};
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if Some(local) == mir.spread_arg {
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// This argument (e.g. the last argument in the "rust-call" ABI)
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// is a tuple that was spread at the ABI level and now we have
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// to reconstruct it into a tuple local variable, from multiple
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// individual LLVM function arguments.
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let arg_ty = fx.monomorphize(&arg_decl.ty);
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let tupled_arg_tys = match arg_ty.sty {
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ty::TyTuple(ref tys) => tys,
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_ => bug!("spread argument isn't a tuple?!")
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};
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let place = PlaceRef::alloca(bx, bx.cx.layout_of(arg_ty), &name);
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for i in 0..tupled_arg_tys.len() {
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|
let arg = &fx.fn_ty.args[idx];
|
|
idx += 1;
|
|
if arg.pad.is_some() {
|
|
llarg_idx += 1;
|
|
}
|
|
arg.store_fn_arg(bx, &mut llarg_idx, place.project_field(bx, i));
|
|
}
|
|
|
|
// Now that we have one alloca that contains the aggregate value,
|
|
// we can create one debuginfo entry for the argument.
|
|
arg_scope.map(|scope| {
|
|
let variable_access = VariableAccess::DirectVariable {
|
|
alloca: place.llval
|
|
};
|
|
declare_local(
|
|
bx,
|
|
&fx.debug_context,
|
|
arg_decl.name.unwrap_or(keywords::Invalid.name()),
|
|
arg_ty, scope,
|
|
variable_access,
|
|
VariableKind::ArgumentVariable(arg_index + 1),
|
|
DUMMY_SP
|
|
);
|
|
});
|
|
|
|
return LocalRef::Place(place);
|
|
}
|
|
|
|
let arg = &fx.fn_ty.args[idx];
|
|
idx += 1;
|
|
if arg.pad.is_some() {
|
|
llarg_idx += 1;
|
|
}
|
|
|
|
if arg_scope.is_none() && !memory_locals.contains(local.index()) {
|
|
// We don't have to cast or keep the argument in the alloca.
|
|
// FIXME(eddyb): We should figure out how to use llvm.dbg.value instead
|
|
// of putting everything in allocas just so we can use llvm.dbg.declare.
|
|
let local = |op| LocalRef::Operand(Some(op));
|
|
match arg.mode {
|
|
PassMode::Ignore => {
|
|
return local(OperandRef::new_zst(bx.cx, arg.layout));
|
|
}
|
|
PassMode::Direct(_) => {
|
|
let llarg = llvm::get_param(bx.llfn(), llarg_idx as c_uint);
|
|
bx.set_value_name(llarg, &name);
|
|
llarg_idx += 1;
|
|
return local(
|
|
OperandRef::from_immediate_or_packed_pair(bx, llarg, arg.layout));
|
|
}
|
|
PassMode::Pair(..) => {
|
|
let a = llvm::get_param(bx.llfn(), llarg_idx as c_uint);
|
|
bx.set_value_name(a, &(name.clone() + ".0"));
|
|
llarg_idx += 1;
|
|
|
|
let b = llvm::get_param(bx.llfn(), llarg_idx as c_uint);
|
|
bx.set_value_name(b, &(name + ".1"));
|
|
llarg_idx += 1;
|
|
|
|
return local(OperandRef {
|
|
val: OperandValue::Pair(a, b),
|
|
layout: arg.layout
|
|
});
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
let place = if arg.is_indirect() {
|
|
// Don't copy an indirect argument to an alloca, the caller
|
|
// already put it in a temporary alloca and gave it up.
|
|
// FIXME: lifetimes
|
|
let llarg = llvm::get_param(bx.llfn(), llarg_idx as c_uint);
|
|
bx.set_value_name(llarg, &name);
|
|
llarg_idx += 1;
|
|
PlaceRef::new_sized(llarg, arg.layout, arg.layout.align)
|
|
} else {
|
|
let tmp = PlaceRef::alloca(bx, arg.layout, &name);
|
|
arg.store_fn_arg(bx, &mut llarg_idx, tmp);
|
|
tmp
|
|
};
|
|
arg_scope.map(|scope| {
|
|
// Is this a regular argument?
|
|
if arg_index > 0 || mir.upvar_decls.is_empty() {
|
|
// The Rust ABI passes indirect variables using a pointer and a manual copy, so we
|
|
// need to insert a deref here, but the C ABI uses a pointer and a copy using the
|
|
// byval attribute, for which LLVM always does the deref itself,
|
|
// so we must not add it.
|
|
let variable_access = VariableAccess::DirectVariable {
|
|
alloca: place.llval
|
|
};
|
|
|
|
declare_local(
|
|
bx,
|
|
&fx.debug_context,
|
|
arg_decl.name.unwrap_or(keywords::Invalid.name()),
|
|
arg.layout.ty,
|
|
scope,
|
|
variable_access,
|
|
VariableKind::ArgumentVariable(arg_index + 1),
|
|
DUMMY_SP
|
|
);
|
|
return;
|
|
}
|
|
|
|
// Or is it the closure environment?
|
|
let (closure_layout, env_ref) = match arg.layout.ty.sty {
|
|
ty::TyRawPtr(ty::TypeAndMut { ty, .. }) |
|
|
ty::TyRef(_, ty, _) => (bx.cx.layout_of(ty), true),
|
|
_ => (arg.layout, false)
|
|
};
|
|
|
|
let (def_id, upvar_substs) = match closure_layout.ty.sty {
|
|
ty::TyClosure(def_id, substs) => (def_id, UpvarSubsts::Closure(substs)),
|
|
ty::TyGenerator(def_id, substs, _) => (def_id, UpvarSubsts::Generator(substs)),
|
|
_ => bug!("upvar_decls with non-closure arg0 type `{}`", closure_layout.ty)
|
|
};
|
|
let upvar_tys = upvar_substs.upvar_tys(def_id, tcx);
|
|
|
|
for (i, (decl, ty)) in mir.upvar_decls.iter().zip(upvar_tys).enumerate() {
|
|
let byte_offset_of_var_in_env = closure_layout.fields.offset(i).bytes();
|
|
|
|
let ops = unsafe {
|
|
[llvm::LLVMRustDIBuilderCreateOpDeref(),
|
|
llvm::LLVMRustDIBuilderCreateOpPlusUconst(),
|
|
byte_offset_of_var_in_env as i64,
|
|
llvm::LLVMRustDIBuilderCreateOpDeref()]
|
|
};
|
|
|
|
// The environment and the capture can each be indirect.
|
|
let mut ops = if env_ref { &ops[..] } else { &ops[1..] };
|
|
|
|
let ty = if let (true, &ty::TyRef(_, ty, _)) = (decl.by_ref, &ty.sty) {
|
|
ty
|
|
} else {
|
|
ops = &ops[..ops.len() - 1];
|
|
ty
|
|
};
|
|
|
|
let variable_access = VariableAccess::IndirectVariable {
|
|
alloca: place.llval,
|
|
address_operations: &ops
|
|
};
|
|
declare_local(
|
|
bx,
|
|
&fx.debug_context,
|
|
decl.debug_name,
|
|
ty,
|
|
scope,
|
|
variable_access,
|
|
VariableKind::LocalVariable,
|
|
DUMMY_SP
|
|
);
|
|
}
|
|
});
|
|
LocalRef::Place(place)
|
|
}).collect()
|
|
}
|
|
|
|
mod analyze;
|
|
mod block;
|
|
mod constant;
|
|
pub mod place;
|
|
pub mod operand;
|
|
mod rvalue;
|
|
mod statement;
|