// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use libc::c_uint; use llvm::{self, ValueRef, BasicBlockRef}; use llvm::debuginfo::DIScope; use rustc::ty::{self, Ty, TypeFoldable}; use rustc::ty::layout::{self, LayoutTyper}; use rustc::mir::{self, Mir}; use rustc::mir::tcx::LvalueTy; use rustc::ty::subst::Substs; use rustc::infer::TransNormalize; use rustc::session::config::FullDebugInfo; use base; use builder::Builder; use common::{self, CrateContext, Funclet}; use debuginfo::{self, declare_local, VariableAccess, VariableKind, FunctionDebugContext}; use monomorphize::Instance; use abi::{ArgAttribute, FnType}; use type_of; use syntax_pos::{DUMMY_SP, NO_EXPANSION, BytePos, Span}; use syntax::symbol::keywords; use std::iter; use rustc_data_structures::bitvec::BitVector; use rustc_data_structures::indexed_vec::{IndexVec, Idx}; pub use self::constant::trans_static_initializer; use self::analyze::CleanupKind; use self::lvalue::{Alignment, LvalueRef}; use rustc::mir::traversal; use self::operand::{OperandRef, OperandValue}; /// Master context for translating MIR. pub struct MirContext<'a, 'tcx:'a> { mir: &'a mir::Mir<'tcx>, debug_context: debuginfo::FunctionDebugContext, llfn: ValueRef, ccx: &'a CrateContext<'a, 'tcx>, fn_ty: FnType<'tcx>, /// When unwinding is initiated, we have to store this personality /// value somewhere so that we can load it and re-use it in the /// resume instruction. The personality is (afaik) some kind of /// value used for C++ unwinding, which must filter by type: we /// don't really care about it very much. Anyway, this value /// contains an alloca into which the personality is stored and /// then later loaded when generating the DIVERGE_BLOCK. llpersonalityslot: Option, /// A `Block` for each MIR `BasicBlock` blocks: IndexVec, /// The funclet status of each basic block cleanup_kinds: IndexVec, /// When targeting MSVC, this stores the cleanup info for each funclet /// BB. This is initialized as we compute the funclets' head block in RPO. funclets: &'a IndexVec>, /// This stores the landing-pad block for a given BB, computed lazily on GNU /// and eagerly on MSVC. landing_pads: IndexVec>, /// Cached unreachable block unreachable_block: Option, /// The location where each MIR arg/var/tmp/ret is stored. This is /// usually an `LvalueRef` representing an alloca, but not always: /// sometimes we can skip the alloca and just store the value /// directly using an `OperandRef`, which makes for tighter LLVM /// IR. The conditions for using an `OperandRef` are as follows: /// /// - the type of the local must be judged "immediate" by `type_is_immediate` /// - the operand must never be referenced indirectly /// - we should not take its address using the `&` operator /// - nor should it appear in an lvalue path like `tmp.a` /// - the operand must be defined by an rvalue that can generate immediate /// values /// /// Avoiding allocs can also be important for certain intrinsics, /// notably `expect`. locals: IndexVec>, /// Debug information for MIR scopes. scopes: IndexVec, /// If this function is being monomorphized, this contains the type substitutions used. param_substs: &'tcx Substs<'tcx>, } impl<'a, 'tcx> MirContext<'a, 'tcx> { pub fn monomorphize(&self, value: &T) -> T where T: TransNormalize<'tcx> { self.ccx.tcx().trans_apply_param_substs(self.param_substs, value) } pub fn set_debug_loc(&mut self, bcx: &Builder, source_info: mir::SourceInfo) { let (scope, span) = self.debug_loc(source_info); debuginfo::set_source_location(&self.debug_context, bcx, scope, span); } pub fn debug_loc(&mut self, source_info: mir::SourceInfo) -> (DIScope, Span) { // Bail out if debug info emission is not enabled. match self.debug_context { FunctionDebugContext::DebugInfoDisabled | FunctionDebugContext::FunctionWithoutDebugInfo => { return (self.scopes[source_info.scope].scope_metadata, source_info.span); } FunctionDebugContext::RegularContext(_) =>{} } // In order to have a good line stepping behavior in debugger, we overwrite debug // locations of macro expansions with that of the outermost expansion site // (unless the crate is being compiled with `-Z debug-macros`). if source_info.span.ctxt() == NO_EXPANSION || self.ccx.sess().opts.debugging_opts.debug_macros { let scope = self.scope_metadata_for_loc(source_info.scope, source_info.span.lo()); (scope, source_info.span) } else { // Walk up the macro expansion chain until we reach a non-expanded span. // We also stop at the function body level because no line stepping can occur // at the level above that. let mut span = source_info.span; while span.ctxt() != NO_EXPANSION && span.ctxt() != self.mir.span.ctxt() { if let Some(info) = span.ctxt().outer().expn_info() { span = info.call_site; } else { break; } } let scope = self.scope_metadata_for_loc(source_info.scope, span.lo()); // Use span of the outermost expansion site, while keeping the original lexical scope. (scope, span) } } // DILocations inherit source file name from the parent DIScope. Due to macro expansions // it may so happen that the current span belongs to a different file than the DIScope // corresponding to span's containing visibility scope. If so, we need to create a DIScope // "extension" into that file. fn scope_metadata_for_loc(&self, scope_id: mir::VisibilityScope, pos: BytePos) -> llvm::debuginfo::DIScope { let scope_metadata = self.scopes[scope_id].scope_metadata; if pos < self.scopes[scope_id].file_start_pos || pos >= self.scopes[scope_id].file_end_pos { let cm = self.ccx.sess().codemap(); let defining_crate = self.debug_context.get_ref(DUMMY_SP).defining_crate; debuginfo::extend_scope_to_file(self.ccx, scope_metadata, &cm.lookup_char_pos(pos).file, defining_crate) } else { scope_metadata } } } enum LocalRef<'tcx> { Lvalue(LvalueRef<'tcx>), Operand(Option>), } impl<'tcx> LocalRef<'tcx> { fn new_operand<'a>(ccx: &CrateContext<'a, 'tcx>, ty: Ty<'tcx>) -> LocalRef<'tcx> { if common::type_is_zero_size(ccx, ty) { // Zero-size temporaries aren't always initialized, which // doesn't matter because they don't contain data, but // we need something in the operand. LocalRef::Operand(Some(OperandRef::new_zst(ccx, ty))) } else { LocalRef::Operand(None) } } } /////////////////////////////////////////////////////////////////////////// pub fn trans_mir<'a, 'tcx: 'a>( ccx: &'a CrateContext<'a, 'tcx>, llfn: ValueRef, mir: &'a Mir<'tcx>, instance: Instance<'tcx>, sig: ty::FnSig<'tcx>, ) { let fn_ty = FnType::new(ccx, sig, &[]); debug!("fn_ty: {:?}", fn_ty); let debug_context = debuginfo::create_function_debug_context(ccx, instance, sig, llfn, mir); let bcx = Builder::new_block(ccx, llfn, "start"); if mir.basic_blocks().iter().any(|bb| bb.is_cleanup) { bcx.set_personality_fn(ccx.eh_personality()); } let cleanup_kinds = analyze::cleanup_kinds(&mir); // Allocate a `Block` for every basic block, except // the start block, if nothing loops back to it. let reentrant_start_block = !mir.predecessors_for(mir::START_BLOCK).is_empty(); let block_bcxs: IndexVec = mir.basic_blocks().indices().map(|bb| { if bb == mir::START_BLOCK && !reentrant_start_block { bcx.llbb() } else { bcx.build_sibling_block(&format!("{:?}", bb)).llbb() } }).collect(); // Compute debuginfo scopes from MIR scopes. let scopes = debuginfo::create_mir_scopes(ccx, mir, &debug_context); let (landing_pads, funclets) = create_funclets(&bcx, &cleanup_kinds, &block_bcxs); let mut mircx = MirContext { mir, llfn, fn_ty, ccx, llpersonalityslot: None, blocks: block_bcxs, unreachable_block: None, cleanup_kinds, landing_pads, funclets: &funclets, scopes, locals: IndexVec::new(), debug_context, param_substs: { assert!(!instance.substs.needs_infer()); instance.substs }, }; let lvalue_locals = analyze::lvalue_locals(&mircx); // Allocate variable and temp allocas mircx.locals = { let args = arg_local_refs(&bcx, &mircx, &mircx.scopes, &lvalue_locals); let mut allocate_local = |local| { let decl = &mir.local_decls[local]; let ty = mircx.monomorphize(&decl.ty); if let Some(name) = decl.name { // User variable let debug_scope = mircx.scopes[decl.source_info.scope]; let dbg = debug_scope.is_valid() && bcx.sess().opts.debuginfo == FullDebugInfo; if !lvalue_locals.contains(local.index()) && !dbg { debug!("alloc: {:?} ({}) -> operand", local, name); return LocalRef::new_operand(bcx.ccx, ty); } debug!("alloc: {:?} ({}) -> lvalue", local, name); assert!(!ty.has_erasable_regions()); let lvalue = LvalueRef::alloca(&bcx, ty, &name.as_str()); if dbg { let (scope, span) = mircx.debug_loc(decl.source_info); declare_local(&bcx, &mircx.debug_context, name, ty, scope, VariableAccess::DirectVariable { alloca: lvalue.llval }, VariableKind::LocalVariable, span); } LocalRef::Lvalue(lvalue) } else { // Temporary or return pointer if local == mir::RETURN_POINTER && mircx.fn_ty.ret.is_indirect() { debug!("alloc: {:?} (return pointer) -> lvalue", local); let llretptr = llvm::get_param(llfn, 0); LocalRef::Lvalue(LvalueRef::new_sized(llretptr, LvalueTy::from_ty(ty), Alignment::AbiAligned)) } else if lvalue_locals.contains(local.index()) { debug!("alloc: {:?} -> lvalue", local); assert!(!ty.has_erasable_regions()); LocalRef::Lvalue(LvalueRef::alloca(&bcx, ty, &format!("{:?}", local))) } else { // If this is an immediate local, we do not create an // alloca in advance. Instead we wait until we see the // definition and update the operand there. debug!("alloc: {:?} -> operand", local); LocalRef::new_operand(bcx.ccx, ty) } } }; let retptr = allocate_local(mir::RETURN_POINTER); iter::once(retptr) .chain(args.into_iter()) .chain(mir.vars_and_temps_iter().map(allocate_local)) .collect() }; // Branch to the START block, if it's not the entry block. if reentrant_start_block { bcx.br(mircx.blocks[mir::START_BLOCK]); } // Up until here, IR instructions for this function have explicitly not been annotated with // source code location, so we don't step into call setup code. From here on, source location // emitting should be enabled. debuginfo::start_emitting_source_locations(&mircx.debug_context); let rpo = traversal::reverse_postorder(&mir); let mut visited = BitVector::new(mir.basic_blocks().len()); // Translate the body of each block using reverse postorder for (bb, _) in rpo { visited.insert(bb.index()); mircx.trans_block(bb); } // Remove blocks that haven't been visited, or have no // predecessors. for bb in mir.basic_blocks().indices() { // Unreachable block if !visited.contains(bb.index()) { debug!("trans_mir: block {:?} was not visited", bb); unsafe { llvm::LLVMDeleteBasicBlock(mircx.blocks[bb]); } } } } fn create_funclets<'a, 'tcx>( bcx: &Builder<'a, 'tcx>, cleanup_kinds: &IndexVec, block_bcxs: &IndexVec) -> (IndexVec>, IndexVec>) { block_bcxs.iter_enumerated().zip(cleanup_kinds).map(|((bb, &llbb), cleanup_kind)| { match *cleanup_kind { CleanupKind::Funclet if base::wants_msvc_seh(bcx.sess()) => { let cleanup_bcx = bcx.build_sibling_block(&format!("funclet_{:?}", bb)); let cleanup = cleanup_bcx.cleanup_pad(None, &[]); cleanup_bcx.br(llbb); (Some(cleanup_bcx.llbb()), Some(Funclet::new(cleanup))) } _ => (None, None) } }).unzip() } /// Produce, for each argument, a `ValueRef` pointing at the /// argument's value. As arguments are lvalues, these are always /// indirect. fn arg_local_refs<'a, 'tcx>(bcx: &Builder<'a, 'tcx>, mircx: &MirContext<'a, 'tcx>, scopes: &IndexVec, lvalue_locals: &BitVector) -> Vec> { let mir = mircx.mir; let tcx = bcx.tcx(); let mut idx = 0; let mut llarg_idx = mircx.fn_ty.ret.is_indirect() as usize; // Get the argument scope, if it exists and if we need it. let arg_scope = scopes[mir::ARGUMENT_VISIBILITY_SCOPE]; let arg_scope = if arg_scope.is_valid() && bcx.sess().opts.debuginfo == FullDebugInfo { Some(arg_scope.scope_metadata) } else { None }; let deref_op = unsafe { [llvm::LLVMRustDIBuilderCreateOpDeref()] }; mir.args_iter().enumerate().map(|(arg_index, local)| { let arg_decl = &mir.local_decls[local]; let arg_ty = mircx.monomorphize(&arg_decl.ty); let name = if let Some(name) = arg_decl.name { name.as_str().to_string() } else { format!("arg{}", arg_index) }; if Some(local) == mir.spread_arg { // This argument (e.g. the last argument in the "rust-call" ABI) // is a tuple that was spread at the ABI level and now we have // to reconstruct it into a tuple local variable, from multiple // individual LLVM function arguments. let tupled_arg_tys = match arg_ty.sty { ty::TyTuple(ref tys, _) => tys, _ => bug!("spread argument isn't a tuple?!") }; let lvalue = LvalueRef::alloca(bcx, arg_ty, &name); for (i, &tupled_arg_ty) in tupled_arg_tys.iter().enumerate() { let (dst, _) = lvalue.trans_field_ptr(bcx, i); let arg = &mircx.fn_ty.args[idx]; idx += 1; if common::type_is_fat_ptr(bcx.ccx, tupled_arg_ty) { // We pass fat pointers as two words, but inside the tuple // they are the two sub-fields of a single aggregate field. let meta = &mircx.fn_ty.args[idx]; idx += 1; arg.store_fn_arg(bcx, &mut llarg_idx, base::get_dataptr(bcx, dst)); meta.store_fn_arg(bcx, &mut llarg_idx, base::get_meta(bcx, dst)); } else { arg.store_fn_arg(bcx, &mut llarg_idx, dst); } } // 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: lvalue.llval }; declare_local( bcx, &mircx.debug_context, arg_decl.name.unwrap_or(keywords::Invalid.name()), arg_ty, scope, variable_access, VariableKind::ArgumentVariable(arg_index + 1), DUMMY_SP ); }); return LocalRef::Lvalue(lvalue); } let arg = &mircx.fn_ty.args[idx]; idx += 1; let llval = 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 if arg.pad.is_some() { llarg_idx += 1; } let llarg = llvm::get_param(bcx.llfn(), llarg_idx as c_uint); bcx.set_value_name(llarg, &name); llarg_idx += 1; llarg } else if !lvalue_locals.contains(local.index()) && arg.cast.is_none() && arg_scope.is_none() { if arg.is_ignore() { return LocalRef::new_operand(bcx.ccx, arg_ty); } // 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. if arg.pad.is_some() { llarg_idx += 1; } let llarg = llvm::get_param(bcx.llfn(), llarg_idx as c_uint); llarg_idx += 1; let val = if common::type_is_fat_ptr(bcx.ccx, arg_ty) { let meta = &mircx.fn_ty.args[idx]; idx += 1; assert_eq!((meta.cast, meta.pad), (None, None)); let llmeta = llvm::get_param(bcx.llfn(), llarg_idx as c_uint); llarg_idx += 1; // FIXME(eddyb) As we can't perfectly represent the data and/or // vtable pointer in a fat pointers in Rust's typesystem, and // because we split fat pointers into two ArgType's, they're // not the right type so we have to cast them for now. let pointee = match arg_ty.sty { ty::TyRef(_, ty::TypeAndMut{ty, ..}) | ty::TyRawPtr(ty::TypeAndMut{ty, ..}) => ty, ty::TyAdt(def, _) if def.is_box() => arg_ty.boxed_ty(), _ => bug!() }; let data_llty = type_of::in_memory_type_of(bcx.ccx, pointee); let meta_llty = type_of::unsized_info_ty(bcx.ccx, pointee); let llarg = bcx.pointercast(llarg, data_llty.ptr_to()); bcx.set_value_name(llarg, &(name.clone() + ".ptr")); let llmeta = bcx.pointercast(llmeta, meta_llty); bcx.set_value_name(llmeta, &(name + ".meta")); OperandValue::Pair(llarg, llmeta) } else { bcx.set_value_name(llarg, &name); OperandValue::Immediate(llarg) }; let operand = OperandRef { val, ty: arg_ty }; return LocalRef::Operand(Some(operand.unpack_if_pair(bcx))); } else { let lltemp = LvalueRef::alloca(bcx, arg_ty, &name); if common::type_is_fat_ptr(bcx.ccx, arg_ty) { // we pass fat pointers as two words, but we want to // represent them internally as a pointer to two words, // so make an alloca to store them in. let meta = &mircx.fn_ty.args[idx]; idx += 1; arg.store_fn_arg(bcx, &mut llarg_idx, base::get_dataptr(bcx, lltemp.llval)); meta.store_fn_arg(bcx, &mut llarg_idx, base::get_meta(bcx, lltemp.llval)); } else { // otherwise, arg is passed by value, so make a // temporary and store it there arg.store_fn_arg(bcx, &mut llarg_idx, lltemp.llval); } lltemp.llval }; 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 does the deref itself, so we must not add it. let variable_access = if arg.is_indirect() && !arg.attrs.contains(ArgAttribute::ByVal) { VariableAccess::IndirectVariable { alloca: llval, address_operations: &deref_op, } } else { VariableAccess::DirectVariable { alloca: llval } }; declare_local( bcx, &mircx.debug_context, arg_decl.name.unwrap_or(keywords::Invalid.name()), arg_ty, scope, variable_access, VariableKind::ArgumentVariable(arg_index + 1), DUMMY_SP ); return; } // Or is it the closure environment? let (closure_ty, env_ref) = match arg_ty.sty { ty::TyRef(_, mt) | ty::TyRawPtr(mt) => (mt.ty, true), _ => (arg_ty, false) }; let upvar_tys = match closure_ty.sty { ty::TyClosure(def_id, substs) | ty::TyGenerator(def_id, substs, _) => substs.upvar_tys(def_id, tcx), _ => bug!("upvar_decls with non-closure arg0 type `{}`", closure_ty) }; // Store the pointer to closure data in an alloca for debuginfo // because that's what the llvm.dbg.declare intrinsic expects. // FIXME(eddyb) this shouldn't be necessary but SROA seems to // mishandle DW_OP_plus not preceded by DW_OP_deref, i.e. it // doesn't actually strip the offset when splitting the closure // environment into its components so it ends up out of bounds. let env_ptr = if !env_ref { let alloc = bcx.alloca(common::val_ty(llval), "__debuginfo_env_ptr", None); bcx.store(llval, alloc, None); alloc } else { llval }; let layout = bcx.ccx.layout_of(closure_ty); let offsets = match *layout { layout::Univariant { ref variant, .. } => &variant.offsets[..], _ => bug!("Closures are only supposed to be Univariant") }; for (i, (decl, ty)) in mir.upvar_decls.iter().zip(upvar_tys).enumerate() { let byte_offset_of_var_in_env = offsets[i].bytes(); let ops = unsafe { [llvm::LLVMRustDIBuilderCreateOpDeref(), llvm::LLVMRustDIBuilderCreateOpPlus(), byte_offset_of_var_in_env as i64, llvm::LLVMRustDIBuilderCreateOpDeref()] }; // The environment and the capture can each be indirect. // FIXME(eddyb) see above why we have to keep // a pointer in an alloca for debuginfo atm. let mut ops = if env_ref || true { &ops[..] } else { &ops[1..] }; let ty = if let (true, &ty::TyRef(_, mt)) = (decl.by_ref, &ty.sty) { mt.ty } else { ops = &ops[..ops.len() - 1]; ty }; let variable_access = VariableAccess::IndirectVariable { alloca: env_ptr, address_operations: &ops }; declare_local( bcx, &mircx.debug_context, decl.debug_name, ty, scope, variable_access, VariableKind::CapturedVariable, DUMMY_SP ); } }); LocalRef::Lvalue(LvalueRef::new_sized(llval, LvalueTy::from_ty(arg_ty), Alignment::AbiAligned)) }).collect() } mod analyze; mod block; mod constant; pub mod lvalue; mod operand; mod rvalue; mod statement;