// Copyright 2012-2015 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. //! Translate the completed AST to the LLVM IR. //! //! Some functions here, such as trans_block and trans_expr, return a value -- //! the result of the translation to LLVM -- while others, such as trans_fn //! and trans_item, are called only for the side effect of adding a //! particular definition to the LLVM IR output we're producing. //! //! Hopefully useful general knowledge about trans: //! //! * There's no way to find out the Ty type of a ValueRef. Doing so //! would be "trying to get the eggs out of an omelette" (credit: //! pcwalton). You can, instead, find out its TypeRef by calling val_ty, //! but one TypeRef corresponds to many `Ty`s; for instance, tup(int, int, //! int) and rec(x=int, y=int, z=int) will have the same TypeRef. #![allow(non_camel_case_types)] use super::CrateTranslation; use super::ModuleLlvm; use super::ModuleSource; use super::ModuleTranslation; use assert_module_sources; use back::link; use back::linker::LinkerInfo; use llvm::{BasicBlockRef, Linkage, ValueRef, Vector, get_param}; use llvm; use rustc::cfg; use rustc::hir::def_id::DefId; use middle::lang_items::{LangItem, ExchangeMallocFnLangItem, StartFnLangItem}; use rustc::hir::pat_util::simple_name; use rustc::ty::subst::{self, Substs}; use rustc::traits; use rustc::ty::{self, Ty, TyCtxt, TypeFoldable}; use rustc::ty::adjustment::CustomCoerceUnsized; use rustc::dep_graph::{DepNode, WorkProduct}; use rustc::hir::map as hir_map; use rustc::util::common::time; use rustc::mir::mir_map::MirMap; use rustc_data_structures::graph::OUTGOING; use session::config::{self, NoDebugInfo, FullDebugInfo}; use session::Session; use _match; use abi::{self, Abi, FnType}; use adt; use attributes; use build::*; use builder::{Builder, noname}; use callee::{Callee, CallArgs, ArgExprs, ArgVals}; use cleanup::{self, CleanupMethods, DropHint}; use closure; use common::{Block, C_bool, C_bytes_in_context, C_i32, C_int, C_uint, C_integral}; use collector::{self, TransItemCollectionMode}; use common::{C_null, C_struct_in_context, C_u64, C_u8, C_undef}; use common::{CrateContext, DropFlagHintsMap, Field, FunctionContext}; use common::{Result, NodeIdAndSpan, VariantInfo}; use common::{node_id_type, fulfill_obligation}; use common::{type_is_immediate, type_is_zero_size, val_ty}; use common; use consts; use context::{SharedCrateContext, CrateContextList}; use controlflow; use datum; use debuginfo::{self, DebugLoc, ToDebugLoc}; use declare; use expr; use glue; use inline; use machine; use machine::{llalign_of_min, llsize_of}; use meth; use mir; use monomorphize::{self, Instance}; use partitioning::{self, PartitioningStrategy, CodegenUnit}; use symbol_map::SymbolMap; use symbol_names_test; use trans_item::TransItem; use tvec; use type_::Type; use type_of; use value::Value; use Disr; use util::common::indenter; use util::sha2::Sha256; use util::nodemap::{NodeMap, NodeSet, FnvHashSet}; use arena::TypedArena; use libc::c_uint; use std::ffi::{CStr, CString}; use std::borrow::Cow; use std::cell::{Cell, RefCell}; use std::collections::HashMap; use std::ptr; use std::rc::Rc; use std::str; use std::{i8, i16, i32, i64}; use syntax_pos::{Span, DUMMY_SP}; use syntax::parse::token::InternedString; use syntax::attr::AttrMetaMethods; use syntax::attr; use rustc::hir::intravisit::{self, Visitor}; use rustc::hir; use syntax::ast; thread_local! { static TASK_LOCAL_INSN_KEY: RefCell>> = { RefCell::new(None) } } pub fn with_insn_ctxt(blk: F) where F: FnOnce(&[&'static str]) { TASK_LOCAL_INSN_KEY.with(move |slot| { slot.borrow().as_ref().map(move |s| blk(s)); }) } pub fn init_insn_ctxt() { TASK_LOCAL_INSN_KEY.with(|slot| { *slot.borrow_mut() = Some(Vec::new()); }); } pub struct _InsnCtxt { _cannot_construct_outside_of_this_module: (), } impl Drop for _InsnCtxt { fn drop(&mut self) { TASK_LOCAL_INSN_KEY.with(|slot| { if let Some(ctx) = slot.borrow_mut().as_mut() { ctx.pop(); } }) } } pub fn push_ctxt(s: &'static str) -> _InsnCtxt { debug!("new InsnCtxt: {}", s); TASK_LOCAL_INSN_KEY.with(|slot| { if let Some(ctx) = slot.borrow_mut().as_mut() { ctx.push(s) } }); _InsnCtxt { _cannot_construct_outside_of_this_module: (), } } pub struct StatRecorder<'a, 'tcx: 'a> { ccx: &'a CrateContext<'a, 'tcx>, name: Option, istart: usize, } impl<'a, 'tcx> StatRecorder<'a, 'tcx> { pub fn new(ccx: &'a CrateContext<'a, 'tcx>, name: String) -> StatRecorder<'a, 'tcx> { let istart = ccx.stats().n_llvm_insns.get(); StatRecorder { ccx: ccx, name: Some(name), istart: istart, } } } impl<'a, 'tcx> Drop for StatRecorder<'a, 'tcx> { fn drop(&mut self) { if self.ccx.sess().trans_stats() { let iend = self.ccx.stats().n_llvm_insns.get(); self.ccx .stats() .fn_stats .borrow_mut() .push((self.name.take().unwrap(), iend - self.istart)); self.ccx.stats().n_fns.set(self.ccx.stats().n_fns.get() + 1); // Reset LLVM insn count to avoid compound costs. self.ccx.stats().n_llvm_insns.set(self.istart); } } } pub fn kind_for_closure(ccx: &CrateContext, closure_id: DefId) -> ty::ClosureKind { *ccx.tcx().tables.borrow().closure_kinds.get(&closure_id).unwrap() } fn require_alloc_fn<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, info_ty: Ty<'tcx>, it: LangItem) -> DefId { match bcx.tcx().lang_items.require(it) { Ok(id) => id, Err(s) => { bcx.sess().fatal(&format!("allocation of `{}` {}", info_ty, s)); } } } // The following malloc_raw_dyn* functions allocate a box to contain // a given type, but with a potentially dynamic size. pub fn malloc_raw_dyn<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, llty_ptr: Type, info_ty: Ty<'tcx>, size: ValueRef, align: ValueRef, debug_loc: DebugLoc) -> Result<'blk, 'tcx> { let _icx = push_ctxt("malloc_raw_exchange"); // Allocate space: let def_id = require_alloc_fn(bcx, info_ty, ExchangeMallocFnLangItem); let r = Callee::def(bcx.ccx(), def_id, bcx.tcx().mk_substs(Substs::empty())) .call(bcx, debug_loc, ArgVals(&[size, align]), None); Result::new(r.bcx, PointerCast(r.bcx, r.val, llty_ptr)) } pub fn bin_op_to_icmp_predicate(op: hir::BinOp_, signed: bool) -> llvm::IntPredicate { match op { hir::BiEq => llvm::IntEQ, hir::BiNe => llvm::IntNE, hir::BiLt => if signed { llvm::IntSLT } else { llvm::IntULT }, hir::BiLe => if signed { llvm::IntSLE } else { llvm::IntULE }, hir::BiGt => if signed { llvm::IntSGT } else { llvm::IntUGT }, hir::BiGe => if signed { llvm::IntSGE } else { llvm::IntUGE }, op => { bug!("comparison_op_to_icmp_predicate: expected comparison operator, \ found {:?}", op) } } } pub fn bin_op_to_fcmp_predicate(op: hir::BinOp_) -> llvm::RealPredicate { match op { hir::BiEq => llvm::RealOEQ, hir::BiNe => llvm::RealUNE, hir::BiLt => llvm::RealOLT, hir::BiLe => llvm::RealOLE, hir::BiGt => llvm::RealOGT, hir::BiGe => llvm::RealOGE, op => { bug!("comparison_op_to_fcmp_predicate: expected comparison operator, \ found {:?}", op); } } } pub fn compare_fat_ptrs<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, lhs_addr: ValueRef, lhs_extra: ValueRef, rhs_addr: ValueRef, rhs_extra: ValueRef, _t: Ty<'tcx>, op: hir::BinOp_, debug_loc: DebugLoc) -> ValueRef { match op { hir::BiEq => { let addr_eq = ICmp(bcx, llvm::IntEQ, lhs_addr, rhs_addr, debug_loc); let extra_eq = ICmp(bcx, llvm::IntEQ, lhs_extra, rhs_extra, debug_loc); And(bcx, addr_eq, extra_eq, debug_loc) } hir::BiNe => { let addr_eq = ICmp(bcx, llvm::IntNE, lhs_addr, rhs_addr, debug_loc); let extra_eq = ICmp(bcx, llvm::IntNE, lhs_extra, rhs_extra, debug_loc); Or(bcx, addr_eq, extra_eq, debug_loc) } hir::BiLe | hir::BiLt | hir::BiGe | hir::BiGt => { // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1) let (op, strict_op) = match op { hir::BiLt => (llvm::IntULT, llvm::IntULT), hir::BiLe => (llvm::IntULE, llvm::IntULT), hir::BiGt => (llvm::IntUGT, llvm::IntUGT), hir::BiGe => (llvm::IntUGE, llvm::IntUGT), _ => bug!(), }; let addr_eq = ICmp(bcx, llvm::IntEQ, lhs_addr, rhs_addr, debug_loc); let extra_op = ICmp(bcx, op, lhs_extra, rhs_extra, debug_loc); let addr_eq_extra_op = And(bcx, addr_eq, extra_op, debug_loc); let addr_strict = ICmp(bcx, strict_op, lhs_addr, rhs_addr, debug_loc); Or(bcx, addr_strict, addr_eq_extra_op, debug_loc) } _ => { bug!("unexpected fat ptr binop"); } } } pub fn compare_scalar_types<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, lhs: ValueRef, rhs: ValueRef, t: Ty<'tcx>, op: hir::BinOp_, debug_loc: DebugLoc) -> ValueRef { match t.sty { ty::TyTuple(ref tys) if tys.is_empty() => { // We don't need to do actual comparisons for nil. // () == () holds but () < () does not. match op { hir::BiEq | hir::BiLe | hir::BiGe => return C_bool(bcx.ccx(), true), hir::BiNe | hir::BiLt | hir::BiGt => return C_bool(bcx.ccx(), false), // refinements would be nice _ => bug!("compare_scalar_types: must be a comparison operator"), } } ty::TyFnDef(..) | ty::TyFnPtr(_) | ty::TyBool | ty::TyUint(_) | ty::TyChar => { ICmp(bcx, bin_op_to_icmp_predicate(op, false), lhs, rhs, debug_loc) } ty::TyRawPtr(mt) if common::type_is_sized(bcx.tcx(), mt.ty) => { ICmp(bcx, bin_op_to_icmp_predicate(op, false), lhs, rhs, debug_loc) } ty::TyRawPtr(_) => { let lhs_addr = Load(bcx, GEPi(bcx, lhs, &[0, abi::FAT_PTR_ADDR])); let lhs_extra = Load(bcx, GEPi(bcx, lhs, &[0, abi::FAT_PTR_EXTRA])); let rhs_addr = Load(bcx, GEPi(bcx, rhs, &[0, abi::FAT_PTR_ADDR])); let rhs_extra = Load(bcx, GEPi(bcx, rhs, &[0, abi::FAT_PTR_EXTRA])); compare_fat_ptrs(bcx, lhs_addr, lhs_extra, rhs_addr, rhs_extra, t, op, debug_loc) } ty::TyInt(_) => { ICmp(bcx, bin_op_to_icmp_predicate(op, true), lhs, rhs, debug_loc) } ty::TyFloat(_) => { FCmp(bcx, bin_op_to_fcmp_predicate(op), lhs, rhs, debug_loc) } // Should never get here, because t is scalar. _ => bug!("non-scalar type passed to compare_scalar_types"), } } pub fn compare_simd_types<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, lhs: ValueRef, rhs: ValueRef, t: Ty<'tcx>, ret_ty: Type, op: hir::BinOp_, debug_loc: DebugLoc) -> ValueRef { let signed = match t.sty { ty::TyFloat(_) => { let cmp = bin_op_to_fcmp_predicate(op); return SExt(bcx, FCmp(bcx, cmp, lhs, rhs, debug_loc), ret_ty); }, ty::TyUint(_) => false, ty::TyInt(_) => true, _ => bug!("compare_simd_types: invalid SIMD type"), }; let cmp = bin_op_to_icmp_predicate(op, signed); // LLVM outputs an `< size x i1 >`, so we need to perform a sign extension // to get the correctly sized type. This will compile to a single instruction // once the IR is converted to assembly if the SIMD instruction is supported // by the target architecture. SExt(bcx, ICmp(bcx, cmp, lhs, rhs, debug_loc), ret_ty) } // Iterates through the elements of a structural type. pub fn iter_structural_ty<'blk, 'tcx, F>(cx: Block<'blk, 'tcx>, av: ValueRef, t: Ty<'tcx>, mut f: F) -> Block<'blk, 'tcx> where F: FnMut(Block<'blk, 'tcx>, ValueRef, Ty<'tcx>) -> Block<'blk, 'tcx> { let _icx = push_ctxt("iter_structural_ty"); fn iter_variant<'blk, 'tcx, F>(cx: Block<'blk, 'tcx>, repr: &adt::Repr<'tcx>, av: adt::MaybeSizedValue, variant: ty::VariantDef<'tcx>, substs: &Substs<'tcx>, f: &mut F) -> Block<'blk, 'tcx> where F: FnMut(Block<'blk, 'tcx>, ValueRef, Ty<'tcx>) -> Block<'blk, 'tcx> { let _icx = push_ctxt("iter_variant"); let tcx = cx.tcx(); let mut cx = cx; for (i, field) in variant.fields.iter().enumerate() { let arg = monomorphize::field_ty(tcx, substs, field); cx = f(cx, adt::trans_field_ptr(cx, repr, av, Disr::from(variant.disr_val), i), arg); } return cx; } let value = if common::type_is_sized(cx.tcx(), t) { adt::MaybeSizedValue::sized(av) } else { let data = Load(cx, expr::get_dataptr(cx, av)); let info = Load(cx, expr::get_meta(cx, av)); adt::MaybeSizedValue::unsized_(data, info) }; let mut cx = cx; match t.sty { ty::TyStruct(..) => { let repr = adt::represent_type(cx.ccx(), t); let VariantInfo { fields, discr } = VariantInfo::from_ty(cx.tcx(), t, None); for (i, &Field(_, field_ty)) in fields.iter().enumerate() { let llfld_a = adt::trans_field_ptr(cx, &repr, value, Disr::from(discr), i); let val = if common::type_is_sized(cx.tcx(), field_ty) { llfld_a } else { let scratch = datum::rvalue_scratch_datum(cx, field_ty, "__fat_ptr_iter"); Store(cx, llfld_a, expr::get_dataptr(cx, scratch.val)); Store(cx, value.meta, expr::get_meta(cx, scratch.val)); scratch.val }; cx = f(cx, val, field_ty); } } ty::TyClosure(_, ref substs) => { let repr = adt::represent_type(cx.ccx(), t); for (i, upvar_ty) in substs.upvar_tys.iter().enumerate() { let llupvar = adt::trans_field_ptr(cx, &repr, value, Disr(0), i); cx = f(cx, llupvar, upvar_ty); } } ty::TyArray(_, n) => { let (base, len) = tvec::get_fixed_base_and_len(cx, value.value, n); let unit_ty = t.sequence_element_type(cx.tcx()); cx = tvec::iter_vec_raw(cx, base, unit_ty, len, f); } ty::TySlice(_) | ty::TyStr => { let unit_ty = t.sequence_element_type(cx.tcx()); cx = tvec::iter_vec_raw(cx, value.value, unit_ty, value.meta, f); } ty::TyTuple(ref args) => { let repr = adt::represent_type(cx.ccx(), t); for (i, arg) in args.iter().enumerate() { let llfld_a = adt::trans_field_ptr(cx, &repr, value, Disr(0), i); cx = f(cx, llfld_a, *arg); } } ty::TyEnum(en, substs) => { let fcx = cx.fcx; let ccx = fcx.ccx; let repr = adt::represent_type(ccx, t); let n_variants = en.variants.len(); // NB: we must hit the discriminant first so that structural // comparison know not to proceed when the discriminants differ. match adt::trans_switch(cx, &repr, av, false) { (_match::Single, None) => { if n_variants != 0 { assert!(n_variants == 1); cx = iter_variant(cx, &repr, adt::MaybeSizedValue::sized(av), &en.variants[0], substs, &mut f); } } (_match::Switch, Some(lldiscrim_a)) => { cx = f(cx, lldiscrim_a, cx.tcx().types.isize); // Create a fall-through basic block for the "else" case of // the switch instruction we're about to generate. Note that // we do **not** use an Unreachable instruction here, even // though most of the time this basic block will never be hit. // // When an enum is dropped it's contents are currently // overwritten to DTOR_DONE, which means the discriminant // could have changed value to something not within the actual // range of the discriminant. Currently this function is only // used for drop glue so in this case we just return quickly // from the outer function, and any other use case will only // call this for an already-valid enum in which case the `ret // void` will never be hit. let ret_void_cx = fcx.new_temp_block("enum-iter-ret-void"); RetVoid(ret_void_cx, DebugLoc::None); let llswitch = Switch(cx, lldiscrim_a, ret_void_cx.llbb, n_variants); let next_cx = fcx.new_temp_block("enum-iter-next"); for variant in &en.variants { let variant_cx = fcx.new_temp_block(&format!("enum-iter-variant-{}", &variant.disr_val .to_string())); let case_val = adt::trans_case(cx, &repr, Disr::from(variant.disr_val)); AddCase(llswitch, case_val, variant_cx.llbb); let variant_cx = iter_variant(variant_cx, &repr, value, variant, substs, &mut f); Br(variant_cx, next_cx.llbb, DebugLoc::None); } cx = next_cx; } _ => ccx.sess().unimpl("value from adt::trans_switch in iter_structural_ty"), } } _ => { cx.sess().unimpl(&format!("type in iter_structural_ty: {}", t)) } } return cx; } /// Retrieve the information we are losing (making dynamic) in an unsizing /// adjustment. /// /// The `old_info` argument is a bit funny. It is intended for use /// in an upcast, where the new vtable for an object will be drived /// from the old one. pub fn unsized_info<'ccx, 'tcx>(ccx: &CrateContext<'ccx, 'tcx>, source: Ty<'tcx>, target: Ty<'tcx>, old_info: Option) -> ValueRef { let (source, target) = ccx.tcx().struct_lockstep_tails(source, target); match (&source.sty, &target.sty) { (&ty::TyArray(_, len), &ty::TySlice(_)) => C_uint(ccx, len), (&ty::TyTrait(_), &ty::TyTrait(_)) => { // For now, upcasts are limited to changes in marker // traits, and hence never actually require an actual // change to the vtable. old_info.expect("unsized_info: missing old info for trait upcast") } (_, &ty::TyTrait(box ty::TraitTy { ref principal, .. })) => { // Note that we preserve binding levels here: let substs = principal.0.substs.with_self_ty(source).erase_regions(); let substs = ccx.tcx().mk_substs(substs); let trait_ref = ty::Binder(ty::TraitRef { def_id: principal.def_id(), substs: substs, }); consts::ptrcast(meth::get_vtable(ccx, trait_ref), Type::vtable_ptr(ccx)) } _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target), } } /// Coerce `src` to `dst_ty`. `src_ty` must be a thin pointer. pub fn unsize_thin_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, src: ValueRef, src_ty: Ty<'tcx>, dst_ty: Ty<'tcx>) -> (ValueRef, ValueRef) { debug!("unsize_thin_ptr: {:?} => {:?}", src_ty, dst_ty); match (&src_ty.sty, &dst_ty.sty) { (&ty::TyBox(a), &ty::TyBox(b)) | (&ty::TyRef(_, ty::TypeAndMut { ty: a, .. }), &ty::TyRef(_, ty::TypeAndMut { ty: b, .. })) | (&ty::TyRef(_, ty::TypeAndMut { ty: a, .. }), &ty::TyRawPtr(ty::TypeAndMut { ty: b, .. })) | (&ty::TyRawPtr(ty::TypeAndMut { ty: a, .. }), &ty::TyRawPtr(ty::TypeAndMut { ty: b, .. })) => { assert!(common::type_is_sized(bcx.tcx(), a)); let ptr_ty = type_of::in_memory_type_of(bcx.ccx(), b).ptr_to(); (PointerCast(bcx, src, ptr_ty), unsized_info(bcx.ccx(), a, b, None)) } _ => bug!("unsize_thin_ptr: called on bad types"), } } /// Coerce `src`, which is a reference to a value of type `src_ty`, /// to a value of type `dst_ty` and store the result in `dst` pub fn coerce_unsized_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, src: ValueRef, src_ty: Ty<'tcx>, dst: ValueRef, dst_ty: Ty<'tcx>) { match (&src_ty.sty, &dst_ty.sty) { (&ty::TyBox(..), &ty::TyBox(..)) | (&ty::TyRef(..), &ty::TyRef(..)) | (&ty::TyRef(..), &ty::TyRawPtr(..)) | (&ty::TyRawPtr(..), &ty::TyRawPtr(..)) => { let (base, info) = if common::type_is_fat_ptr(bcx.tcx(), src_ty) { // fat-ptr to fat-ptr unsize preserves the vtable // i.e. &'a fmt::Debug+Send => &'a fmt::Debug // So we need to pointercast the base to ensure // the types match up. let (base, info) = load_fat_ptr(bcx, src, src_ty); let llcast_ty = type_of::fat_ptr_base_ty(bcx.ccx(), dst_ty); let base = PointerCast(bcx, base, llcast_ty); (base, info) } else { let base = load_ty(bcx, src, src_ty); unsize_thin_ptr(bcx, base, src_ty, dst_ty) }; store_fat_ptr(bcx, base, info, dst, dst_ty); } // This can be extended to enums and tuples in the future. // (&ty::TyEnum(def_id_a, _), &ty::TyEnum(def_id_b, _)) | (&ty::TyStruct(def_a, _), &ty::TyStruct(def_b, _)) => { assert_eq!(def_a, def_b); let src_repr = adt::represent_type(bcx.ccx(), src_ty); let src_fields = match &*src_repr { &adt::Repr::Univariant(ref s, _) => &s.fields, _ => bug!("struct has non-univariant repr"), }; let dst_repr = adt::represent_type(bcx.ccx(), dst_ty); let dst_fields = match &*dst_repr { &adt::Repr::Univariant(ref s, _) => &s.fields, _ => bug!("struct has non-univariant repr"), }; let src = adt::MaybeSizedValue::sized(src); let dst = adt::MaybeSizedValue::sized(dst); let iter = src_fields.iter().zip(dst_fields).enumerate(); for (i, (src_fty, dst_fty)) in iter { if type_is_zero_size(bcx.ccx(), dst_fty) { continue; } let src_f = adt::trans_field_ptr(bcx, &src_repr, src, Disr(0), i); let dst_f = adt::trans_field_ptr(bcx, &dst_repr, dst, Disr(0), i); if src_fty == dst_fty { memcpy_ty(bcx, dst_f, src_f, src_fty); } else { coerce_unsized_into(bcx, src_f, src_fty, dst_f, dst_fty); } } } _ => bug!("coerce_unsized_into: invalid coercion {:?} -> {:?}", src_ty, dst_ty), } } pub fn custom_coerce_unsize_info<'scx, 'tcx>(scx: &SharedCrateContext<'scx, 'tcx>, source_ty: Ty<'tcx>, target_ty: Ty<'tcx>) -> CustomCoerceUnsized { let trait_substs = Substs::new(subst::VecPerParamSpace::new(vec![target_ty], vec![source_ty], Vec::new()), subst::VecPerParamSpace::empty()); let trait_ref = ty::Binder(ty::TraitRef { def_id: scx.tcx().lang_items.coerce_unsized_trait().unwrap(), substs: scx.tcx().mk_substs(trait_substs) }); match fulfill_obligation(scx, DUMMY_SP, trait_ref) { traits::VtableImpl(traits::VtableImplData { impl_def_id, .. }) => { scx.tcx().custom_coerce_unsized_kind(impl_def_id) } vtable => { bug!("invalid CoerceUnsized vtable: {:?}", vtable); } } } pub fn cast_shift_expr_rhs(cx: Block, op: hir::BinOp_, lhs: ValueRef, rhs: ValueRef) -> ValueRef { cast_shift_rhs(op, lhs, rhs, |a, b| Trunc(cx, a, b), |a, b| ZExt(cx, a, b)) } pub fn cast_shift_const_rhs(op: hir::BinOp_, lhs: ValueRef, rhs: ValueRef) -> ValueRef { cast_shift_rhs(op, lhs, rhs, |a, b| unsafe { llvm::LLVMConstTrunc(a, b.to_ref()) }, |a, b| unsafe { llvm::LLVMConstZExt(a, b.to_ref()) }) } fn cast_shift_rhs(op: hir::BinOp_, lhs: ValueRef, rhs: ValueRef, trunc: F, zext: G) -> ValueRef where F: FnOnce(ValueRef, Type) -> ValueRef, G: FnOnce(ValueRef, Type) -> ValueRef { // Shifts may have any size int on the rhs if op.is_shift() { let mut rhs_llty = val_ty(rhs); let mut lhs_llty = val_ty(lhs); if rhs_llty.kind() == Vector { rhs_llty = rhs_llty.element_type() } if lhs_llty.kind() == Vector { lhs_llty = lhs_llty.element_type() } let rhs_sz = rhs_llty.int_width(); let lhs_sz = lhs_llty.int_width(); if lhs_sz < rhs_sz { trunc(rhs, lhs_llty) } else if lhs_sz > rhs_sz { // FIXME (#1877: If shifting by negative // values becomes not undefined then this is wrong. zext(rhs, lhs_llty) } else { rhs } } else { rhs } } pub fn llty_and_min_for_signed_ty<'blk, 'tcx>(cx: Block<'blk, 'tcx>, val_t: Ty<'tcx>) -> (Type, u64) { match val_t.sty { ty::TyInt(t) => { let llty = Type::int_from_ty(cx.ccx(), t); let min = match t { ast::IntTy::Is if llty == Type::i32(cx.ccx()) => i32::MIN as u64, ast::IntTy::Is => i64::MIN as u64, ast::IntTy::I8 => i8::MIN as u64, ast::IntTy::I16 => i16::MIN as u64, ast::IntTy::I32 => i32::MIN as u64, ast::IntTy::I64 => i64::MIN as u64, }; (llty, min) } _ => bug!(), } } pub fn fail_if_zero_or_overflows<'blk, 'tcx>(cx: Block<'blk, 'tcx>, call_info: NodeIdAndSpan, divrem: hir::BinOp, lhs: ValueRef, rhs: ValueRef, rhs_t: Ty<'tcx>) -> Block<'blk, 'tcx> { use rustc_const_math::{ConstMathErr, Op}; let (zero_err, overflow_err) = if divrem.node == hir::BiDiv { (ConstMathErr::DivisionByZero, ConstMathErr::Overflow(Op::Div)) } else { (ConstMathErr::RemainderByZero, ConstMathErr::Overflow(Op::Rem)) }; let debug_loc = call_info.debug_loc(); let (is_zero, is_signed) = match rhs_t.sty { ty::TyInt(t) => { let zero = C_integral(Type::int_from_ty(cx.ccx(), t), 0, false); (ICmp(cx, llvm::IntEQ, rhs, zero, debug_loc), true) } ty::TyUint(t) => { let zero = C_integral(Type::uint_from_ty(cx.ccx(), t), 0, false); (ICmp(cx, llvm::IntEQ, rhs, zero, debug_loc), false) } ty::TyStruct(def, _) if def.is_simd() => { let mut res = C_bool(cx.ccx(), false); for i in 0..rhs_t.simd_size(cx.tcx()) { res = Or(cx, res, IsNull(cx, ExtractElement(cx, rhs, C_int(cx.ccx(), i as i64))), debug_loc); } (res, false) } _ => { bug!("fail-if-zero on unexpected type: {}", rhs_t); } }; let bcx = with_cond(cx, is_zero, |bcx| { controlflow::trans_fail(bcx, call_info, InternedString::new(zero_err.description())) }); // To quote LLVM's documentation for the sdiv instruction: // // Division by zero leads to undefined behavior. Overflow also leads // to undefined behavior; this is a rare case, but can occur, for // example, by doing a 32-bit division of -2147483648 by -1. // // In order to avoid undefined behavior, we perform runtime checks for // signed division/remainder which would trigger overflow. For unsigned // integers, no action beyond checking for zero need be taken. if is_signed { let (llty, min) = llty_and_min_for_signed_ty(cx, rhs_t); let minus_one = ICmp(bcx, llvm::IntEQ, rhs, C_integral(llty, !0, false), debug_loc); with_cond(bcx, minus_one, |bcx| { let is_min = ICmp(bcx, llvm::IntEQ, lhs, C_integral(llty, min, true), debug_loc); with_cond(bcx, is_min, |bcx| { controlflow::trans_fail(bcx, call_info, InternedString::new(overflow_err.description())) }) }) } else { bcx } } pub fn invoke<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, llfn: ValueRef, llargs: &[ValueRef], debug_loc: DebugLoc) -> (ValueRef, Block<'blk, 'tcx>) { let _icx = push_ctxt("invoke_"); if bcx.unreachable.get() { return (C_null(Type::i8(bcx.ccx())), bcx); } match bcx.opt_node_id { None => { debug!("invoke at ???"); } Some(id) => { debug!("invoke at {}", bcx.tcx().map.node_to_string(id)); } } if need_invoke(bcx) { debug!("invoking {:?} at {:?}", Value(llfn), bcx.llbb); for &llarg in llargs { debug!("arg: {:?}", Value(llarg)); } let normal_bcx = bcx.fcx.new_temp_block("normal-return"); let landing_pad = bcx.fcx.get_landing_pad(); let llresult = Invoke(bcx, llfn, &llargs[..], normal_bcx.llbb, landing_pad, debug_loc); return (llresult, normal_bcx); } else { debug!("calling {:?} at {:?}", Value(llfn), bcx.llbb); for &llarg in llargs { debug!("arg: {:?}", Value(llarg)); } let llresult = Call(bcx, llfn, &llargs[..], debug_loc); return (llresult, bcx); } } /// Returns whether this session's target will use SEH-based unwinding. /// /// This is only true for MSVC targets, and even then the 64-bit MSVC target /// currently uses SEH-ish unwinding with DWARF info tables to the side (same as /// 64-bit MinGW) instead of "full SEH". pub fn wants_msvc_seh(sess: &Session) -> bool { sess.target.target.options.is_like_msvc } pub fn avoid_invoke(bcx: Block) -> bool { bcx.sess().no_landing_pads() || bcx.lpad().is_some() } pub fn need_invoke(bcx: Block) -> bool { if avoid_invoke(bcx) { false } else { bcx.fcx.needs_invoke() } } pub fn load_if_immediate<'blk, 'tcx>(cx: Block<'blk, 'tcx>, v: ValueRef, t: Ty<'tcx>) -> ValueRef { let _icx = push_ctxt("load_if_immediate"); if type_is_immediate(cx.ccx(), t) { return load_ty(cx, v, t); } return v; } /// Helper for loading values from memory. Does the necessary conversion if the in-memory type /// differs from the type used for SSA values. Also handles various special cases where the type /// gives us better information about what we are loading. pub fn load_ty<'blk, 'tcx>(cx: Block<'blk, 'tcx>, ptr: ValueRef, t: Ty<'tcx>) -> ValueRef { if cx.unreachable.get() { return C_undef(type_of::type_of(cx.ccx(), t)); } load_ty_builder(&B(cx), ptr, t) } pub fn load_ty_builder<'a, 'tcx>(b: &Builder<'a, 'tcx>, ptr: ValueRef, t: Ty<'tcx>) -> ValueRef { let ccx = b.ccx; if type_is_zero_size(ccx, t) { return C_undef(type_of::type_of(ccx, t)); } unsafe { let global = llvm::LLVMIsAGlobalVariable(ptr); if !global.is_null() && llvm::LLVMIsGlobalConstant(global) == llvm::True { let val = llvm::LLVMGetInitializer(global); if !val.is_null() { if t.is_bool() { return llvm::LLVMConstTrunc(val, Type::i1(ccx).to_ref()); } return val; } } } if t.is_bool() { b.trunc(b.load_range_assert(ptr, 0, 2, llvm::False), Type::i1(ccx)) } else if t.is_char() { // a char is a Unicode codepoint, and so takes values from 0 // to 0x10FFFF inclusive only. b.load_range_assert(ptr, 0, 0x10FFFF + 1, llvm::False) } else if (t.is_region_ptr() || t.is_unique()) && !common::type_is_fat_ptr(ccx.tcx(), t) { b.load_nonnull(ptr) } else { b.load(ptr) } } /// Helper for storing values in memory. Does the necessary conversion if the in-memory type /// differs from the type used for SSA values. pub fn store_ty<'blk, 'tcx>(cx: Block<'blk, 'tcx>, v: ValueRef, dst: ValueRef, t: Ty<'tcx>) { if cx.unreachable.get() { return; } debug!("store_ty: {:?} : {:?} <- {:?}", Value(dst), t, Value(v)); if common::type_is_fat_ptr(cx.tcx(), t) { Store(cx, ExtractValue(cx, v, abi::FAT_PTR_ADDR), expr::get_dataptr(cx, dst)); Store(cx, ExtractValue(cx, v, abi::FAT_PTR_EXTRA), expr::get_meta(cx, dst)); } else { Store(cx, from_immediate(cx, v), dst); } } pub fn store_fat_ptr<'blk, 'tcx>(cx: Block<'blk, 'tcx>, data: ValueRef, extra: ValueRef, dst: ValueRef, _ty: Ty<'tcx>) { // FIXME: emit metadata Store(cx, data, expr::get_dataptr(cx, dst)); Store(cx, extra, expr::get_meta(cx, dst)); } pub fn load_fat_ptr<'blk, 'tcx>(cx: Block<'blk, 'tcx>, src: ValueRef, _ty: Ty<'tcx>) -> (ValueRef, ValueRef) { // FIXME: emit metadata (Load(cx, expr::get_dataptr(cx, src)), Load(cx, expr::get_meta(cx, src))) } pub fn from_immediate(bcx: Block, val: ValueRef) -> ValueRef { if val_ty(val) == Type::i1(bcx.ccx()) { ZExt(bcx, val, Type::i8(bcx.ccx())) } else { val } } pub fn to_immediate(bcx: Block, val: ValueRef, ty: Ty) -> ValueRef { if ty.is_bool() { Trunc(bcx, val, Type::i1(bcx.ccx())) } else { val } } pub fn init_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, local: &hir::Local) -> Block<'blk, 'tcx> { debug!("init_local(bcx={}, local.id={})", bcx.to_str(), local.id); let _indenter = indenter(); let _icx = push_ctxt("init_local"); _match::store_local(bcx, local) } pub fn raw_block<'blk, 'tcx>(fcx: &'blk FunctionContext<'blk, 'tcx>, llbb: BasicBlockRef) -> Block<'blk, 'tcx> { common::BlockS::new(llbb, None, fcx) } pub fn with_cond<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>, val: ValueRef, f: F) -> Block<'blk, 'tcx> where F: FnOnce(Block<'blk, 'tcx>) -> Block<'blk, 'tcx> { let _icx = push_ctxt("with_cond"); if bcx.unreachable.get() || common::const_to_opt_uint(val) == Some(0) { return bcx; } let fcx = bcx.fcx; let next_cx = fcx.new_temp_block("next"); let cond_cx = fcx.new_temp_block("cond"); CondBr(bcx, val, cond_cx.llbb, next_cx.llbb, DebugLoc::None); let after_cx = f(cond_cx); if !after_cx.terminated.get() { Br(after_cx, next_cx.llbb, DebugLoc::None); } next_cx } pub enum Lifetime { Start, End } // If LLVM lifetime intrinsic support is enabled (i.e. optimizations // on), and `ptr` is nonzero-sized, then extracts the size of `ptr` // and the intrinsic for `lt` and passes them to `emit`, which is in // charge of generating code to call the passed intrinsic on whatever // block of generated code is targetted for the intrinsic. // // If LLVM lifetime intrinsic support is disabled (i.e. optimizations // off) or `ptr` is zero-sized, then no-op (does not call `emit`). fn core_lifetime_emit<'blk, 'tcx, F>(ccx: &'blk CrateContext<'blk, 'tcx>, ptr: ValueRef, lt: Lifetime, emit: F) where F: FnOnce(&'blk CrateContext<'blk, 'tcx>, machine::llsize, ValueRef) { if ccx.sess().opts.optimize == config::OptLevel::No { return; } let _icx = push_ctxt(match lt { Lifetime::Start => "lifetime_start", Lifetime::End => "lifetime_end" }); let size = machine::llsize_of_alloc(ccx, val_ty(ptr).element_type()); if size == 0 { return; } let lifetime_intrinsic = ccx.get_intrinsic(match lt { Lifetime::Start => "llvm.lifetime.start", Lifetime::End => "llvm.lifetime.end" }); emit(ccx, size, lifetime_intrinsic) } impl Lifetime { pub fn call(self, b: &Builder, ptr: ValueRef) { core_lifetime_emit(b.ccx, ptr, self, |ccx, size, lifetime_intrinsic| { let ptr = b.pointercast(ptr, Type::i8p(ccx)); b.call(lifetime_intrinsic, &[C_u64(ccx, size), ptr], None); }); } } pub fn call_lifetime_start(bcx: Block, ptr: ValueRef) { if !bcx.unreachable.get() { Lifetime::Start.call(&bcx.build(), ptr); } } pub fn call_lifetime_end(bcx: Block, ptr: ValueRef) { if !bcx.unreachable.get() { Lifetime::End.call(&bcx.build(), ptr); } } // Generates code for resumption of unwind at the end of a landing pad. pub fn trans_unwind_resume(bcx: Block, lpval: ValueRef) { if !bcx.sess().target.target.options.custom_unwind_resume { Resume(bcx, lpval); } else { let exc_ptr = ExtractValue(bcx, lpval, 0); bcx.fcx.eh_unwind_resume() .call(bcx, DebugLoc::None, ArgVals(&[exc_ptr]), None); } } pub fn call_memcpy<'bcx, 'tcx>(b: &Builder<'bcx, 'tcx>, dst: ValueRef, src: ValueRef, n_bytes: ValueRef, align: u32) { let _icx = push_ctxt("call_memcpy"); let ccx = b.ccx; let ptr_width = &ccx.sess().target.target.target_pointer_width[..]; let key = format!("llvm.memcpy.p0i8.p0i8.i{}", ptr_width); let memcpy = ccx.get_intrinsic(&key); let src_ptr = b.pointercast(src, Type::i8p(ccx)); let dst_ptr = b.pointercast(dst, Type::i8p(ccx)); let size = b.intcast(n_bytes, ccx.int_type()); let align = C_i32(ccx, align as i32); let volatile = C_bool(ccx, false); b.call(memcpy, &[dst_ptr, src_ptr, size, align, volatile], None); } pub fn memcpy_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, dst: ValueRef, src: ValueRef, t: Ty<'tcx>) { let _icx = push_ctxt("memcpy_ty"); let ccx = bcx.ccx(); if type_is_zero_size(ccx, t) || bcx.unreachable.get() { return; } if t.is_structural() { let llty = type_of::type_of(ccx, t); let llsz = llsize_of(ccx, llty); let llalign = type_of::align_of(ccx, t); call_memcpy(&B(bcx), dst, src, llsz, llalign as u32); } else if common::type_is_fat_ptr(bcx.tcx(), t) { let (data, extra) = load_fat_ptr(bcx, src, t); store_fat_ptr(bcx, data, extra, dst, t); } else { store_ty(bcx, load_ty(bcx, src, t), dst, t); } } pub fn drop_done_fill_mem<'blk, 'tcx>(cx: Block<'blk, 'tcx>, llptr: ValueRef, t: Ty<'tcx>) { if cx.unreachable.get() { return; } let _icx = push_ctxt("drop_done_fill_mem"); let bcx = cx; memfill(&B(bcx), llptr, t, adt::DTOR_DONE); } pub fn init_zero_mem<'blk, 'tcx>(cx: Block<'blk, 'tcx>, llptr: ValueRef, t: Ty<'tcx>) { if cx.unreachable.get() { return; } let _icx = push_ctxt("init_zero_mem"); let bcx = cx; memfill(&B(bcx), llptr, t, 0); } // Always use this function instead of storing a constant byte to the memory // in question. e.g. if you store a zero constant, LLVM will drown in vreg // allocation for large data structures, and the generated code will be // awful. (A telltale sign of this is large quantities of // `mov [byte ptr foo],0` in the generated code.) fn memfill<'a, 'tcx>(b: &Builder<'a, 'tcx>, llptr: ValueRef, ty: Ty<'tcx>, byte: u8) { let _icx = push_ctxt("memfill"); let ccx = b.ccx; let llty = type_of::type_of(ccx, ty); let llptr = b.pointercast(llptr, Type::i8(ccx).ptr_to()); let llzeroval = C_u8(ccx, byte); let size = machine::llsize_of(ccx, llty); let align = C_i32(ccx, type_of::align_of(ccx, ty) as i32); call_memset(b, llptr, llzeroval, size, align, false); } pub fn call_memset<'bcx, 'tcx>(b: &Builder<'bcx, 'tcx>, ptr: ValueRef, fill_byte: ValueRef, size: ValueRef, align: ValueRef, volatile: bool) { let ccx = b.ccx; let ptr_width = &ccx.sess().target.target.target_pointer_width[..]; let intrinsic_key = format!("llvm.memset.p0i8.i{}", ptr_width); let llintrinsicfn = ccx.get_intrinsic(&intrinsic_key); let volatile = C_bool(ccx, volatile); b.call(llintrinsicfn, &[ptr, fill_byte, size, align, volatile], None); } /// In general, when we create an scratch value in an alloca, the /// creator may not know if the block (that initializes the scratch /// with the desired value) actually dominates the cleanup associated /// with the scratch value. /// /// To deal with this, when we do an alloca (at the *start* of whole /// function body), we optionally can also set the associated /// dropped-flag state of the alloca to "dropped." #[derive(Copy, Clone, Debug)] pub enum InitAlloca { /// Indicates that the state should have its associated drop flag /// set to "dropped" at the point of allocation. Dropped, /// Indicates the value of the associated drop flag is irrelevant. /// The embedded string literal is a programmer provided argument /// for why. This is a safeguard forcing compiler devs to /// document; it might be a good idea to also emit this as a /// comment with the alloca itself when emitting LLVM output.ll. Uninit(&'static str), } pub fn alloc_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, t: Ty<'tcx>, name: &str) -> ValueRef { // pnkfelix: I do not know why alloc_ty meets the assumptions for // passing Uninit, but it was never needed (even back when we had // the original boolean `zero` flag on `lvalue_scratch_datum`). alloc_ty_init(bcx, t, InitAlloca::Uninit("all alloc_ty are uninit"), name) } /// This variant of `fn alloc_ty` does not necessarily assume that the /// alloca should be created with no initial value. Instead the caller /// controls that assumption via the `init` flag. /// /// Note that if the alloca *is* initialized via `init`, then we will /// also inject an `llvm.lifetime.start` before that initialization /// occurs, and thus callers should not call_lifetime_start /// themselves. But if `init` says "uninitialized", then callers are /// in charge of choosing where to call_lifetime_start and /// subsequently populate the alloca. /// /// (See related discussion on PR #30823.) pub fn alloc_ty_init<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, t: Ty<'tcx>, init: InitAlloca, name: &str) -> ValueRef { let _icx = push_ctxt("alloc_ty"); let ccx = bcx.ccx(); let ty = type_of::type_of(ccx, t); assert!(!t.has_param_types()); match init { InitAlloca::Dropped => alloca_dropped(bcx, t, name), InitAlloca::Uninit(_) => alloca(bcx, ty, name), } } pub fn alloca_dropped<'blk, 'tcx>(cx: Block<'blk, 'tcx>, ty: Ty<'tcx>, name: &str) -> ValueRef { let _icx = push_ctxt("alloca_dropped"); let llty = type_of::type_of(cx.ccx(), ty); if cx.unreachable.get() { unsafe { return llvm::LLVMGetUndef(llty.ptr_to().to_ref()); } } let p = alloca(cx, llty, name); let b = cx.fcx.ccx.builder(); b.position_before(cx.fcx.alloca_insert_pt.get().unwrap()); // This is just like `call_lifetime_start` (but latter expects a // Block, which we do not have for `alloca_insert_pt`). core_lifetime_emit(cx.ccx(), p, Lifetime::Start, |ccx, size, lifetime_start| { let ptr = b.pointercast(p, Type::i8p(ccx)); b.call(lifetime_start, &[C_u64(ccx, size), ptr], None); }); memfill(&b, p, ty, adt::DTOR_DONE); p } pub fn alloca(cx: Block, ty: Type, name: &str) -> ValueRef { let _icx = push_ctxt("alloca"); if cx.unreachable.get() { unsafe { return llvm::LLVMGetUndef(ty.ptr_to().to_ref()); } } DebugLoc::None.apply(cx.fcx); Alloca(cx, ty, name) } pub fn set_value_name(val: ValueRef, name: &str) { unsafe { let name = CString::new(name).unwrap(); llvm::LLVMSetValueName(val, name.as_ptr()); } } struct FindNestedReturn { found: bool, } impl FindNestedReturn { fn new() -> FindNestedReturn { FindNestedReturn { found: false, } } } impl<'v> Visitor<'v> for FindNestedReturn { fn visit_expr(&mut self, e: &hir::Expr) { match e.node { hir::ExprRet(..) => { self.found = true; } _ => intravisit::walk_expr(self, e), } } } fn build_cfg<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: ast::NodeId) -> (ast::NodeId, Option) { let blk = match tcx.map.find(id) { Some(hir_map::NodeItem(i)) => { match i.node { hir::ItemFn(_, _, _, _, _, ref blk) => { blk } _ => bug!("unexpected item variant in has_nested_returns"), } } Some(hir_map::NodeTraitItem(trait_item)) => { match trait_item.node { hir::MethodTraitItem(_, Some(ref body)) => body, _ => { bug!("unexpected variant: trait item other than a provided method in \ has_nested_returns") } } } Some(hir_map::NodeImplItem(impl_item)) => { match impl_item.node { hir::ImplItemKind::Method(_, ref body) => body, _ => { bug!("unexpected variant: non-method impl item in has_nested_returns") } } } Some(hir_map::NodeExpr(e)) => { match e.node { hir::ExprClosure(_, _, ref blk, _) => blk, _ => bug!("unexpected expr variant in has_nested_returns"), } } Some(hir_map::NodeVariant(..)) | Some(hir_map::NodeStructCtor(..)) => return (ast::DUMMY_NODE_ID, None), // glue, shims, etc None if id == ast::DUMMY_NODE_ID => return (ast::DUMMY_NODE_ID, None), _ => bug!("unexpected variant in has_nested_returns: {}", tcx.node_path_str(id)), }; (blk.id, Some(cfg::CFG::new(tcx, blk))) } // Checks for the presence of "nested returns" in a function. // Nested returns are when the inner expression of a return expression // (the 'expr' in 'return expr') contains a return expression. Only cases // where the outer return is actually reachable are considered. Implicit // returns from the end of blocks are considered as well. // // This check is needed to handle the case where the inner expression is // part of a larger expression that may have already partially-filled the // return slot alloca. This can cause errors related to clean-up due to // the clobbering of the existing value in the return slot. fn has_nested_returns(tcx: TyCtxt, cfg: &cfg::CFG, blk_id: ast::NodeId) -> bool { for index in cfg.graph.depth_traverse(cfg.entry, OUTGOING) { let n = cfg.graph.node_data(index); match tcx.map.find(n.id()) { Some(hir_map::NodeExpr(ex)) => { if let hir::ExprRet(Some(ref ret_expr)) = ex.node { let mut visitor = FindNestedReturn::new(); intravisit::walk_expr(&mut visitor, &ret_expr); if visitor.found { return true; } } } Some(hir_map::NodeBlock(blk)) if blk.id == blk_id => { let mut visitor = FindNestedReturn::new(); walk_list!(&mut visitor, visit_expr, &blk.expr); if visitor.found { return true; } } _ => {} } } return false; } impl<'blk, 'tcx> FunctionContext<'blk, 'tcx> { /// Create a function context for the given function. /// Beware that you must call `fcx.init` or `fcx.bind_args` /// before doing anything with the returned function context. pub fn new(ccx: &'blk CrateContext<'blk, 'tcx>, llfndecl: ValueRef, fn_ty: FnType, definition: Option<(Instance<'tcx>, &ty::FnSig<'tcx>, Abi, ast::NodeId)>, block_arena: &'blk TypedArena>) -> FunctionContext<'blk, 'tcx> { let (param_substs, def_id, inlined_id) = match definition { Some((instance, _, _, inlined_id)) => { common::validate_substs(instance.substs); (instance.substs, Some(instance.def), Some(inlined_id)) } None => (ccx.tcx().mk_substs(Substs::empty()), None, None) }; let local_id = def_id.and_then(|id| ccx.tcx().map.as_local_node_id(id)); debug!("FunctionContext::new({})", definition.map_or(String::new(), |d| d.0.to_string())); let cfg = inlined_id.map(|id| build_cfg(ccx.tcx(), id)); let nested_returns = if let Some((blk_id, Some(ref cfg))) = cfg { has_nested_returns(ccx.tcx(), cfg, blk_id) } else { false }; let check_attrs = |attrs: &[ast::Attribute]| { let default_to_mir = ccx.sess().opts.debugging_opts.orbit; let invert = if default_to_mir { "rustc_no_mir" } else { "rustc_mir" }; (default_to_mir ^ attrs.iter().any(|item| item.check_name(invert)), attrs.iter().any(|item| item.check_name("no_debug"))) }; let (use_mir, no_debug) = if let Some(id) = local_id { check_attrs(ccx.tcx().map.attrs(id)) } else if let Some(def_id) = def_id { check_attrs(&ccx.sess().cstore.item_attrs(def_id)) } else { check_attrs(&[]) }; let mir = if use_mir { def_id.and_then(|id| ccx.get_mir(id)) } else { None }; let debug_context = if let (false, Some(definition)) = (no_debug, definition) { let (instance, sig, abi, _) = definition; debuginfo::create_function_debug_context(ccx, instance, sig, abi, llfndecl) } else { debuginfo::empty_function_debug_context(ccx) }; FunctionContext { needs_ret_allocas: nested_returns && mir.is_none(), mir: mir, llfn: llfndecl, llretslotptr: Cell::new(None), param_env: ccx.tcx().empty_parameter_environment(), alloca_insert_pt: Cell::new(None), llreturn: Cell::new(None), landingpad_alloca: Cell::new(None), lllocals: RefCell::new(NodeMap()), llupvars: RefCell::new(NodeMap()), lldropflag_hints: RefCell::new(DropFlagHintsMap::new()), fn_ty: fn_ty, param_substs: param_substs, span: inlined_id.and_then(|id| ccx.tcx().map.opt_span(id)), block_arena: block_arena, lpad_arena: TypedArena::new(), ccx: ccx, debug_context: debug_context, scopes: RefCell::new(Vec::new()), cfg: cfg.and_then(|(_, cfg)| cfg) } } /// Performs setup on a newly created function, creating the entry /// scope block and allocating space for the return pointer. pub fn init(&'blk self, skip_retptr: bool, fn_did: Option) -> Block<'blk, 'tcx> { let entry_bcx = self.new_temp_block("entry-block"); // Use a dummy instruction as the insertion point for all allocas. // This is later removed in FunctionContext::cleanup. self.alloca_insert_pt.set(Some(unsafe { Load(entry_bcx, C_null(Type::i8p(self.ccx))); llvm::LLVMGetFirstInstruction(entry_bcx.llbb) })); if !self.fn_ty.ret.is_ignore() && !skip_retptr { // We normally allocate the llretslotptr, unless we // have been instructed to skip it for immediate return // values, or there is nothing to return at all. // We create an alloca to hold a pointer of type `ret.original_ty` // which will hold the pointer to the right alloca which has the // final ret value let llty = self.fn_ty.ret.memory_ty(self.ccx); let slot = if self.needs_ret_allocas { // Let's create the stack slot let slot = AllocaFcx(self, llty.ptr_to(), "llretslotptr"); // and if we're using an out pointer, then store that in our newly made slot if self.fn_ty.ret.is_indirect() { let outptr = get_param(self.llfn, 0); let b = self.ccx.builder(); b.position_before(self.alloca_insert_pt.get().unwrap()); b.store(outptr, slot); } slot } else { // But if there are no nested returns, we skip the indirection // and have a single retslot if self.fn_ty.ret.is_indirect() { get_param(self.llfn, 0) } else { AllocaFcx(self, llty, "sret_slot") } }; self.llretslotptr.set(Some(slot)); } // Create the drop-flag hints for every unfragmented path in the function. let tcx = self.ccx.tcx(); let tables = tcx.tables.borrow(); let mut hints = self.lldropflag_hints.borrow_mut(); let fragment_infos = tcx.fragment_infos.borrow(); // Intern table for drop-flag hint datums. let mut seen = HashMap::new(); let fragment_infos = fn_did.and_then(|did| fragment_infos.get(&did)); if let Some(fragment_infos) = fragment_infos { for &info in fragment_infos { let make_datum = |id| { let init_val = C_u8(self.ccx, adt::DTOR_NEEDED_HINT); let llname = &format!("dropflag_hint_{}", id); debug!("adding hint {}", llname); let ty = tcx.types.u8; let ptr = alloc_ty(entry_bcx, ty, llname); Store(entry_bcx, init_val, ptr); let flag = datum::Lvalue::new_dropflag_hint("FunctionContext::init"); datum::Datum::new(ptr, ty, flag) }; let (var, datum) = match info { ty::FragmentInfo::Moved { var, .. } | ty::FragmentInfo::Assigned { var, .. } => { let opt_datum = seen.get(&var).cloned().unwrap_or_else(|| { let ty = tables.node_types[&var]; if self.type_needs_drop(ty) { let datum = make_datum(var); seen.insert(var, Some(datum.clone())); Some(datum) } else { // No drop call needed, so we don't need a dropflag hint None } }); if let Some(datum) = opt_datum { (var, datum) } else { continue } } }; match info { ty::FragmentInfo::Moved { move_expr: expr_id, .. } => { debug!("FragmentInfo::Moved insert drop hint for {}", expr_id); hints.insert(expr_id, DropHint::new(var, datum)); } ty::FragmentInfo::Assigned { assignee_id: expr_id, .. } => { debug!("FragmentInfo::Assigned insert drop hint for {}", expr_id); hints.insert(expr_id, DropHint::new(var, datum)); } } } } entry_bcx } /// Creates lvalue datums for each of the incoming function arguments, /// matches all argument patterns against them to produce bindings, /// and returns the entry block (see FunctionContext::init). fn bind_args(&'blk self, args: &[hir::Arg], abi: Abi, id: ast::NodeId, closure_env: closure::ClosureEnv, arg_scope: cleanup::CustomScopeIndex) -> Block<'blk, 'tcx> { let _icx = push_ctxt("FunctionContext::bind_args"); let fn_did = self.ccx.tcx().map.local_def_id(id); let mut bcx = self.init(false, Some(fn_did)); let arg_scope_id = cleanup::CustomScope(arg_scope); let mut idx = 0; let mut llarg_idx = self.fn_ty.ret.is_indirect() as usize; let has_tupled_arg = match closure_env { closure::ClosureEnv::NotClosure => abi == Abi::RustCall, closure::ClosureEnv::Closure(..) => { closure_env.load(bcx, arg_scope_id); let env_arg = &self.fn_ty.args[idx]; idx += 1; if env_arg.pad.is_some() { llarg_idx += 1; } if !env_arg.is_ignore() { llarg_idx += 1; } false } }; let tupled_arg_id = if has_tupled_arg { args[args.len() - 1].id } else { ast::DUMMY_NODE_ID }; // Return an array wrapping the ValueRefs that we get from `get_param` for // each argument into datums. // // For certain mode/type combinations, the raw llarg values are passed // by value. However, within the fn body itself, we want to always // have all locals and arguments be by-ref so that we can cancel the // cleanup and for better interaction with LLVM's debug info. So, if // the argument would be passed by value, we store it into an alloca. // This alloca should be optimized away by LLVM's mem-to-reg pass in // the event it's not truly needed. let uninit_reason = InitAlloca::Uninit("fn_arg populate dominates dtor"); for hir_arg in args { let arg_ty = node_id_type(bcx, hir_arg.id); let arg_datum = if hir_arg.id != tupled_arg_id { let arg = &self.fn_ty.args[idx]; idx += 1; if arg.is_indirect() && bcx.sess().opts.debuginfo != FullDebugInfo { // Don't copy an indirect argument to an alloca, the caller // already put it in a temporary alloca and gave it up, unless // we emit extra-debug-info, which requires local allocas :(. let llarg = get_param(self.llfn, llarg_idx as c_uint); llarg_idx += 1; self.schedule_lifetime_end(arg_scope_id, llarg); self.schedule_drop_mem(arg_scope_id, llarg, arg_ty, None); datum::Datum::new(llarg, arg_ty, datum::Lvalue::new("FunctionContext::bind_args")) } else { unpack_datum!(bcx, datum::lvalue_scratch_datum(bcx, arg_ty, "", uninit_reason, arg_scope_id, |bcx, dst| { debug!("FunctionContext::bind_args: {:?}: {:?}", hir_arg, arg_ty); let b = &bcx.build(); if common::type_is_fat_ptr(bcx.tcx(), arg_ty) { let meta = &self.fn_ty.args[idx]; idx += 1; arg.store_fn_arg(b, &mut llarg_idx, expr::get_dataptr(bcx, dst)); meta.store_fn_arg(b, &mut llarg_idx, expr::get_meta(bcx, dst)); } else { arg.store_fn_arg(b, &mut llarg_idx, dst); } bcx })) } } else { // FIXME(pcwalton): Reduce the amount of code bloat this is responsible for. let tupled_arg_tys = match arg_ty.sty { ty::TyTuple(ref tys) => tys, _ => bug!("last argument of `rust-call` fn isn't a tuple?!") }; unpack_datum!(bcx, datum::lvalue_scratch_datum(bcx, arg_ty, "tupled_args", uninit_reason, arg_scope_id, |bcx, llval| { debug!("FunctionContext::bind_args: tupled {:?}: {:?}", hir_arg, arg_ty); for (j, &tupled_arg_ty) in tupled_arg_tys.iter().enumerate() { let dst = StructGEP(bcx, llval, j); let arg = &self.fn_ty.args[idx]; idx += 1; let b = &bcx.build(); if common::type_is_fat_ptr(bcx.tcx(), tupled_arg_ty) { let meta = &self.fn_ty.args[idx]; idx += 1; arg.store_fn_arg(b, &mut llarg_idx, expr::get_dataptr(bcx, dst)); meta.store_fn_arg(b, &mut llarg_idx, expr::get_meta(bcx, dst)); } else { arg.store_fn_arg(b, &mut llarg_idx, dst); } } bcx })) }; let pat = &hir_arg.pat; bcx = if let Some(name) = simple_name(pat) { // Generate nicer LLVM for the common case of fn a pattern // like `x: T` set_value_name(arg_datum.val, &bcx.name(name)); self.lllocals.borrow_mut().insert(pat.id, arg_datum); bcx } else { // General path. Copy out the values that are used in the // pattern. _match::bind_irrefutable_pat(bcx, pat, arg_datum.match_input(), arg_scope_id) }; debuginfo::create_argument_metadata(bcx, hir_arg); } bcx } /// Ties up the llstaticallocas -> llloadenv -> lltop edges, /// and builds the return block. pub fn finish(&'blk self, last_bcx: Block<'blk, 'tcx>, ret_debug_loc: DebugLoc) { let _icx = push_ctxt("FunctionContext::finish"); let ret_cx = match self.llreturn.get() { Some(llreturn) => { if !last_bcx.terminated.get() { Br(last_bcx, llreturn, DebugLoc::None); } raw_block(self, llreturn) } None => last_bcx, }; self.build_return_block(ret_cx, ret_debug_loc); DebugLoc::None.apply(self); self.cleanup(); } // Builds the return block for a function. pub fn build_return_block(&self, ret_cx: Block<'blk, 'tcx>, ret_debug_location: DebugLoc) { if self.llretslotptr.get().is_none() || ret_cx.unreachable.get() || (!self.needs_ret_allocas && self.fn_ty.ret.is_indirect()) { return RetVoid(ret_cx, ret_debug_location); } let retslot = if self.needs_ret_allocas { Load(ret_cx, self.llretslotptr.get().unwrap()) } else { self.llretslotptr.get().unwrap() }; let retptr = Value(retslot); let llty = self.fn_ty.ret.original_ty; match (retptr.get_dominating_store(ret_cx), self.fn_ty.ret.cast) { // If there's only a single store to the ret slot, we can directly return // the value that was stored and omit the store and the alloca. // However, we only want to do this when there is no cast needed. (Some(s), None) => { let mut retval = s.get_operand(0).unwrap().get(); s.erase_from_parent(); if retptr.has_no_uses() { retptr.erase_from_parent(); } if self.fn_ty.ret.is_indirect() { Store(ret_cx, retval, get_param(self.llfn, 0)); RetVoid(ret_cx, ret_debug_location) } else { if llty == Type::i1(self.ccx) { retval = Trunc(ret_cx, retval, llty); } Ret(ret_cx, retval, ret_debug_location) } } (_, cast_ty) if self.fn_ty.ret.is_indirect() => { // Otherwise, copy the return value to the ret slot. assert_eq!(cast_ty, None); let llsz = llsize_of(self.ccx, self.fn_ty.ret.ty); let llalign = llalign_of_min(self.ccx, self.fn_ty.ret.ty); call_memcpy(&B(ret_cx), get_param(self.llfn, 0), retslot, llsz, llalign as u32); RetVoid(ret_cx, ret_debug_location) } (_, Some(cast_ty)) => { let load = Load(ret_cx, PointerCast(ret_cx, retslot, cast_ty.ptr_to())); let llalign = llalign_of_min(self.ccx, self.fn_ty.ret.ty); unsafe { llvm::LLVMSetAlignment(load, llalign); } Ret(ret_cx, load, ret_debug_location) } (_, None) => { let retval = if llty == Type::i1(self.ccx) { let val = LoadRangeAssert(ret_cx, retslot, 0, 2, llvm::False); Trunc(ret_cx, val, llty) } else { Load(ret_cx, retslot) }; Ret(ret_cx, retval, ret_debug_location) } } } } /// Builds an LLVM function out of a source function. /// /// If the function closes over its environment a closure will be returned. pub fn trans_closure<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, decl: &hir::FnDecl, body: &hir::Block, llfndecl: ValueRef, instance: Instance<'tcx>, inlined_id: ast::NodeId, sig: &ty::FnSig<'tcx>, abi: Abi, closure_env: closure::ClosureEnv) { ccx.stats().n_closures.set(ccx.stats().n_closures.get() + 1); let _icx = push_ctxt("trans_closure"); if !ccx.sess().no_landing_pads() { attributes::emit_uwtable(llfndecl, true); } // this is an info! to allow collecting monomorphization statistics // and to allow finding the last function before LLVM aborts from // release builds. info!("trans_closure(..., {})", instance); let fn_ty = FnType::new(ccx, abi, sig, &[]); let (arena, fcx): (TypedArena<_>, FunctionContext); arena = TypedArena::new(); fcx = FunctionContext::new(ccx, llfndecl, fn_ty, Some((instance, sig, abi, inlined_id)), &arena); if fcx.mir.is_some() { return mir::trans_mir(&fcx); } debuginfo::fill_scope_map_for_function(&fcx, decl, body, inlined_id); // cleanup scope for the incoming arguments let fn_cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node( ccx, inlined_id, body.span, true); let arg_scope = fcx.push_custom_cleanup_scope_with_debug_loc(fn_cleanup_debug_loc); // Set up arguments to the function. debug!("trans_closure: function: {:?}", Value(fcx.llfn)); let bcx = fcx.bind_args(&decl.inputs, abi, inlined_id, closure_env, arg_scope); // 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(&fcx); let dest = if fcx.fn_ty.ret.is_ignore() { expr::Ignore } else { expr::SaveIn(fcx.get_ret_slot(bcx, "iret_slot")) }; // This call to trans_block is the place where we bridge between // translation calls that don't have a return value (trans_crate, // trans_mod, trans_item, et cetera) and those that do // (trans_block, trans_expr, et cetera). let mut bcx = controlflow::trans_block(bcx, body, dest); match dest { expr::SaveIn(slot) if fcx.needs_ret_allocas => { Store(bcx, slot, fcx.llretslotptr.get().unwrap()); } _ => {} } match fcx.llreturn.get() { Some(_) => { Br(bcx, fcx.return_exit_block(), DebugLoc::None); fcx.pop_custom_cleanup_scope(arg_scope); } None => { // Microoptimization writ large: avoid creating a separate // llreturn basic block bcx = fcx.pop_and_trans_custom_cleanup_scope(bcx, arg_scope); } }; // Put return block after all other blocks. // This somewhat improves single-stepping experience in debugger. unsafe { let llreturn = fcx.llreturn.get(); if let Some(llreturn) = llreturn { llvm::LLVMMoveBasicBlockAfter(llreturn, bcx.llbb); } } // Insert the mandatory first few basic blocks before lltop. fcx.finish(bcx, fn_cleanup_debug_loc.debug_loc()); } pub fn trans_instance<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, instance: Instance<'tcx>) { let local_instance = inline::maybe_inline_instance(ccx, instance); let fn_node_id = ccx.tcx().map.as_local_node_id(local_instance.def).unwrap(); let _s = StatRecorder::new(ccx, ccx.tcx().node_path_str(fn_node_id)); debug!("trans_instance(instance={:?})", instance); let _icx = push_ctxt("trans_instance"); let item = ccx.tcx().map.find(fn_node_id).unwrap(); let fn_ty = ccx.tcx().lookup_item_type(instance.def).ty; let fn_ty = ccx.tcx().erase_regions(&fn_ty); let fn_ty = monomorphize::apply_param_substs(ccx.tcx(), instance.substs, &fn_ty); let sig = ccx.tcx().erase_late_bound_regions(fn_ty.fn_sig()); let sig = ccx.tcx().normalize_associated_type(&sig); let abi = fn_ty.fn_abi(); let lldecl = match ccx.instances().borrow().get(&local_instance) { Some(&val) => val, None => bug!("Instance `{:?}` not already declared", instance) }; match item { hir_map::NodeItem(&hir::Item { node: hir::ItemFn(ref decl, _, _, _, _, ref body), .. }) | hir_map::NodeTraitItem(&hir::TraitItem { node: hir::MethodTraitItem( hir::MethodSig { ref decl, .. }, Some(ref body)), .. }) | hir_map::NodeImplItem(&hir::ImplItem { node: hir::ImplItemKind::Method( hir::MethodSig { ref decl, .. }, ref body), .. }) => { trans_closure(ccx, decl, body, lldecl, instance, fn_node_id, &sig, abi, closure::ClosureEnv::NotClosure); } _ => bug!("Instance is a {:?}?", item) } } pub fn trans_named_tuple_constructor<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>, ctor_ty: Ty<'tcx>, disr: Disr, args: CallArgs, dest: expr::Dest, debug_loc: DebugLoc) -> Result<'blk, 'tcx> { let ccx = bcx.fcx.ccx; let sig = ccx.tcx().erase_late_bound_regions(&ctor_ty.fn_sig()); let sig = ccx.tcx().normalize_associated_type(&sig); let result_ty = sig.output; // Get location to store the result. If the user does not care about // the result, just make a stack slot let llresult = match dest { expr::SaveIn(d) => d, expr::Ignore => { if !type_is_zero_size(ccx, result_ty) { let llresult = alloc_ty(bcx, result_ty, "constructor_result"); call_lifetime_start(bcx, llresult); llresult } else { C_undef(type_of::type_of(ccx, result_ty).ptr_to()) } } }; if !type_is_zero_size(ccx, result_ty) { match args { ArgExprs(exprs) => { let fields = exprs.iter().map(|x| &**x).enumerate().collect::>(); bcx = expr::trans_adt(bcx, result_ty, disr, &fields[..], None, expr::SaveIn(llresult), debug_loc); } _ => bug!("expected expr as arguments for variant/struct tuple constructor"), } } else { // Just eval all the expressions (if any). Since expressions in Rust can have arbitrary // contents, there could be side-effects we need from them. match args { ArgExprs(exprs) => { for expr in exprs { bcx = expr::trans_into(bcx, expr, expr::Ignore); } } _ => (), } } // If the caller doesn't care about the result // drop the temporary we made let bcx = match dest { expr::SaveIn(_) => bcx, expr::Ignore => { let bcx = glue::drop_ty(bcx, llresult, result_ty, debug_loc); if !type_is_zero_size(ccx, result_ty) { call_lifetime_end(bcx, llresult); } bcx } }; Result::new(bcx, llresult) } pub fn trans_ctor_shim<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, ctor_id: ast::NodeId, disr: Disr, param_substs: &'tcx Substs<'tcx>, llfndecl: ValueRef) { let ctor_ty = ccx.tcx().node_id_to_type(ctor_id); let ctor_ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs, &ctor_ty); let sig = ccx.tcx().erase_late_bound_regions(&ctor_ty.fn_sig()); let sig = ccx.tcx().normalize_associated_type(&sig); let fn_ty = FnType::new(ccx, Abi::Rust, &sig, &[]); let (arena, fcx): (TypedArena<_>, FunctionContext); arena = TypedArena::new(); fcx = FunctionContext::new(ccx, llfndecl, fn_ty, None, &arena); let bcx = fcx.init(false, None); assert!(!fcx.needs_ret_allocas); if !fcx.fn_ty.ret.is_ignore() { let dest = fcx.get_ret_slot(bcx, "eret_slot"); let dest_val = adt::MaybeSizedValue::sized(dest); // Can return unsized value let repr = adt::represent_type(ccx, sig.output); let mut llarg_idx = fcx.fn_ty.ret.is_indirect() as usize; let mut arg_idx = 0; for (i, arg_ty) in sig.inputs.into_iter().enumerate() { let lldestptr = adt::trans_field_ptr(bcx, &repr, dest_val, Disr::from(disr), i); let arg = &fcx.fn_ty.args[arg_idx]; arg_idx += 1; let b = &bcx.build(); if common::type_is_fat_ptr(bcx.tcx(), arg_ty) { let meta = &fcx.fn_ty.args[arg_idx]; arg_idx += 1; arg.store_fn_arg(b, &mut llarg_idx, expr::get_dataptr(bcx, lldestptr)); meta.store_fn_arg(b, &mut llarg_idx, expr::get_meta(bcx, lldestptr)); } else { arg.store_fn_arg(b, &mut llarg_idx, lldestptr); } } adt::trans_set_discr(bcx, &repr, dest, disr); } fcx.finish(bcx, DebugLoc::None); } pub fn llvm_linkage_by_name(name: &str) -> Option { // Use the names from src/llvm/docs/LangRef.rst here. Most types are only // applicable to variable declarations and may not really make sense for // Rust code in the first place but whitelist them anyway and trust that // the user knows what s/he's doing. Who knows, unanticipated use cases // may pop up in the future. // // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported // and don't have to be, LLVM treats them as no-ops. match name { "appending" => Some(llvm::AppendingLinkage), "available_externally" => Some(llvm::AvailableExternallyLinkage), "common" => Some(llvm::CommonLinkage), "extern_weak" => Some(llvm::ExternalWeakLinkage), "external" => Some(llvm::ExternalLinkage), "internal" => Some(llvm::InternalLinkage), "linkonce" => Some(llvm::LinkOnceAnyLinkage), "linkonce_odr" => Some(llvm::LinkOnceODRLinkage), "private" => Some(llvm::PrivateLinkage), "weak" => Some(llvm::WeakAnyLinkage), "weak_odr" => Some(llvm::WeakODRLinkage), _ => None, } } pub fn set_link_section(ccx: &CrateContext, llval: ValueRef, attrs: &[ast::Attribute]) { if let Some(sect) = attr::first_attr_value_str_by_name(attrs, "link_section") { if contains_null(§) { ccx.sess().fatal(&format!("Illegal null byte in link_section value: `{}`", §)); } unsafe { let buf = CString::new(sect.as_bytes()).unwrap(); llvm::LLVMSetSection(llval, buf.as_ptr()); } } } /// Create the `main` function which will initialise the rust runtime and call /// users’ main function. pub fn maybe_create_entry_wrapper(ccx: &CrateContext) { let (main_def_id, span) = match *ccx.sess().entry_fn.borrow() { Some((id, span)) => { (ccx.tcx().map.local_def_id(id), span) } None => return, }; // check for the #[rustc_error] annotation, which forces an // error in trans. This is used to write compile-fail tests // that actually test that compilation succeeds without // reporting an error. if ccx.tcx().has_attr(main_def_id, "rustc_error") { ccx.tcx().sess.span_fatal(span, "compilation successful"); } let instance = Instance::mono(ccx.shared(), main_def_id); if !ccx.codegen_unit().contains_item(&TransItem::Fn(instance)) { // We want to create the wrapper in the same codegen unit as Rust's main // function. return; } let main_llfn = Callee::def(ccx, main_def_id, instance.substs).reify(ccx).val; let et = ccx.sess().entry_type.get().unwrap(); match et { config::EntryMain => { create_entry_fn(ccx, span, main_llfn, true); } config::EntryStart => create_entry_fn(ccx, span, main_llfn, false), config::EntryNone => {} // Do nothing. } fn create_entry_fn(ccx: &CrateContext, sp: Span, rust_main: ValueRef, use_start_lang_item: bool) { let llfty = Type::func(&[ccx.int_type(), Type::i8p(ccx).ptr_to()], &ccx.int_type()); if declare::get_defined_value(ccx, "main").is_some() { // FIXME: We should be smart and show a better diagnostic here. ccx.sess().struct_span_err(sp, "entry symbol `main` defined multiple times") .help("did you use #[no_mangle] on `fn main`? Use #[start] instead") .emit(); ccx.sess().abort_if_errors(); bug!(); } let llfn = declare::declare_cfn(ccx, "main", llfty); let llbb = unsafe { llvm::LLVMAppendBasicBlockInContext(ccx.llcx(), llfn, "top\0".as_ptr() as *const _) }; let bld = ccx.raw_builder(); unsafe { llvm::LLVMPositionBuilderAtEnd(bld, llbb); debuginfo::gdb::insert_reference_to_gdb_debug_scripts_section_global(ccx); let (start_fn, args) = if use_start_lang_item { let start_def_id = match ccx.tcx().lang_items.require(StartFnLangItem) { Ok(id) => id, Err(s) => ccx.sess().fatal(&s) }; let empty_substs = ccx.tcx().mk_substs(Substs::empty()); let start_fn = Callee::def(ccx, start_def_id, empty_substs).reify(ccx).val; let args = { let opaque_rust_main = llvm::LLVMBuildPointerCast(bld, rust_main, Type::i8p(ccx).to_ref(), "rust_main\0".as_ptr() as *const _); vec![opaque_rust_main, get_param(llfn, 0), get_param(llfn, 1)] }; (start_fn, args) } else { debug!("using user-defined start fn"); let args = vec![get_param(llfn, 0 as c_uint), get_param(llfn, 1 as c_uint)]; (rust_main, args) }; let result = llvm::LLVMRustBuildCall(bld, start_fn, args.as_ptr(), args.len() as c_uint, ptr::null_mut(), noname()); llvm::LLVMBuildRet(bld, result); } } } fn contains_null(s: &str) -> bool { s.bytes().any(|b| b == 0) } fn write_metadata(cx: &SharedCrateContext, reachable_ids: &NodeSet) -> Vec { use flate; let any_library = cx.sess() .crate_types .borrow() .iter() .any(|ty| *ty != config::CrateTypeExecutable); if !any_library { return Vec::new(); } let cstore = &cx.tcx().sess.cstore; let metadata = cstore.encode_metadata(cx.tcx(), cx.export_map(), cx.link_meta(), reachable_ids, cx.mir_map(), cx.tcx().map.krate()); let mut compressed = cstore.metadata_encoding_version().to_vec(); compressed.extend_from_slice(&flate::deflate_bytes(&metadata)); let llmeta = C_bytes_in_context(cx.metadata_llcx(), &compressed[..]); let llconst = C_struct_in_context(cx.metadata_llcx(), &[llmeta], false); let name = cx.metadata_symbol_name(); let buf = CString::new(name).unwrap(); let llglobal = unsafe { llvm::LLVMAddGlobal(cx.metadata_llmod(), val_ty(llconst).to_ref(), buf.as_ptr()) }; unsafe { llvm::LLVMSetInitializer(llglobal, llconst); let name = cx.tcx().sess.cstore.metadata_section_name(&cx.sess().target.target); let name = CString::new(name).unwrap(); llvm::LLVMSetSection(llglobal, name.as_ptr()) } return metadata; } /// Find any symbols that are defined in one compilation unit, but not declared /// in any other compilation unit. Give these symbols internal linkage. fn internalize_symbols<'a, 'tcx>(sess: &Session, ccxs: &CrateContextList<'a, 'tcx>, symbol_map: &SymbolMap<'tcx>, reachable: &FnvHashSet<&str>) { let scx = ccxs.shared(); let tcx = scx.tcx(); // In incr. comp. mode, we can't necessarily see all refs since we // don't generate LLVM IR for reused modules, so skip this // step. Later we should get smarter. if sess.opts.debugging_opts.incremental.is_some() { return; } // 'unsafe' because we are holding on to CStr's from the LLVM module within // this block. unsafe { let mut referenced_somewhere = FnvHashSet(); // Collect all symbols that need to stay externally visible because they // are referenced via a declaration in some other codegen unit. for ccx in ccxs.iter_need_trans() { for val in iter_globals(ccx.llmod()).chain(iter_functions(ccx.llmod())) { let linkage = llvm::LLVMGetLinkage(val); // We only care about external declarations (not definitions) // and available_externally definitions. let is_available_externally = linkage == llvm::AvailableExternallyLinkage as c_uint; let is_decl = llvm::LLVMIsDeclaration(val) != 0; if is_decl || is_available_externally { let symbol_name = CStr::from_ptr(llvm::LLVMGetValueName(val)); referenced_somewhere.insert(symbol_name); } } } // Also collect all symbols for which we cannot adjust linkage, because // it is fixed by some directive in the source code (e.g. #[no_mangle]). let linkage_fixed_explicitly: FnvHashSet<_> = scx .translation_items() .borrow() .iter() .cloned() .filter(|trans_item|{ let def_id = match *trans_item { TransItem::DropGlue(..) => { return false }, TransItem::Fn(ref instance) => { instance.def } TransItem::Static(node_id) => { tcx.map.local_def_id(node_id) } }; trans_item.explicit_linkage(tcx).is_some() || attr::contains_extern_indicator(tcx.sess.diagnostic(), &tcx.get_attrs(def_id)) }) .map(|trans_item| symbol_map.get_or_compute(scx, trans_item)) .collect(); // Examine each external definition. If the definition is not used in // any other compilation unit, and is not reachable from other crates, // then give it internal linkage. for ccx in ccxs.iter_need_trans() { for val in iter_globals(ccx.llmod()).chain(iter_functions(ccx.llmod())) { let linkage = llvm::LLVMGetLinkage(val); let is_externally_visible = (linkage == llvm::ExternalLinkage as c_uint) || (linkage == llvm::LinkOnceODRLinkage as c_uint) || (linkage == llvm::WeakODRLinkage as c_uint); let is_definition = llvm::LLVMIsDeclaration(val) == 0; // If this is a definition (as opposed to just a declaration) // and externally visible, check if we can internalize it if is_definition && is_externally_visible { let name_cstr = CStr::from_ptr(llvm::LLVMGetValueName(val)); let name_str = name_cstr.to_str().unwrap(); let name_cow = Cow::Borrowed(name_str); let is_referenced_somewhere = referenced_somewhere.contains(&name_cstr); let is_reachable = reachable.contains(&name_str); let has_fixed_linkage = linkage_fixed_explicitly.contains(&name_cow); if !is_referenced_somewhere && !is_reachable && !has_fixed_linkage { llvm::LLVMSetLinkage(val, llvm::InternalLinkage); llvm::LLVMSetDLLStorageClass(val, llvm::DLLStorageClass::Default); llvm::UnsetComdat(val); } } } } } } // Create a `__imp_ = &symbol` global for every public static `symbol`. // This is required to satisfy `dllimport` references to static data in .rlibs // when using MSVC linker. We do this only for data, as linker can fix up // code references on its own. // See #26591, #27438 fn create_imps(cx: &CrateContextList) { // The x86 ABI seems to require that leading underscores are added to symbol // names, so we need an extra underscore on 32-bit. There's also a leading // '\x01' here which disables LLVM's symbol mangling (e.g. no extra // underscores added in front). let prefix = if cx.shared().sess().target.target.target_pointer_width == "32" { "\x01__imp__" } else { "\x01__imp_" }; unsafe { for ccx in cx.iter_need_trans() { let exported: Vec<_> = iter_globals(ccx.llmod()) .filter(|&val| { llvm::LLVMGetLinkage(val) == llvm::ExternalLinkage as c_uint && llvm::LLVMIsDeclaration(val) == 0 }) .collect(); let i8p_ty = Type::i8p(&ccx); for val in exported { let name = CStr::from_ptr(llvm::LLVMGetValueName(val)); let mut imp_name = prefix.as_bytes().to_vec(); imp_name.extend(name.to_bytes()); let imp_name = CString::new(imp_name).unwrap(); let imp = llvm::LLVMAddGlobal(ccx.llmod(), i8p_ty.to_ref(), imp_name.as_ptr() as *const _); let init = llvm::LLVMConstBitCast(val, i8p_ty.to_ref()); llvm::LLVMSetInitializer(imp, init); llvm::LLVMSetLinkage(imp, llvm::ExternalLinkage); } } } } struct ValueIter { cur: ValueRef, step: unsafe extern "C" fn(ValueRef) -> ValueRef, } impl Iterator for ValueIter { type Item = ValueRef; fn next(&mut self) -> Option { let old = self.cur; if !old.is_null() { self.cur = unsafe { (self.step)(old) }; Some(old) } else { None } } } fn iter_globals(llmod: llvm::ModuleRef) -> ValueIter { unsafe { ValueIter { cur: llvm::LLVMGetFirstGlobal(llmod), step: llvm::LLVMGetNextGlobal, } } } fn iter_functions(llmod: llvm::ModuleRef) -> ValueIter { unsafe { ValueIter { cur: llvm::LLVMGetFirstFunction(llmod), step: llvm::LLVMGetNextFunction, } } } /// The context provided lists a set of reachable ids as calculated by /// middle::reachable, but this contains far more ids and symbols than we're /// actually exposing from the object file. This function will filter the set in /// the context to the set of ids which correspond to symbols that are exposed /// from the object file being generated. /// /// This list is later used by linkers to determine the set of symbols needed to /// be exposed from a dynamic library and it's also encoded into the metadata. pub fn filter_reachable_ids(tcx: TyCtxt, reachable: NodeSet) -> NodeSet { reachable.into_iter().filter(|&id| { // Next, we want to ignore some FFI functions that are not exposed from // this crate. Reachable FFI functions can be lumped into two // categories: // // 1. Those that are included statically via a static library // 2. Those included otherwise (e.g. dynamically or via a framework) // // Although our LLVM module is not literally emitting code for the // statically included symbols, it's an export of our library which // needs to be passed on to the linker and encoded in the metadata. // // As a result, if this id is an FFI item (foreign item) then we only // let it through if it's included statically. match tcx.map.get(id) { hir_map::NodeForeignItem(..) => { tcx.sess.cstore.is_statically_included_foreign_item(id) } // Only consider nodes that actually have exported symbols. hir_map::NodeItem(&hir::Item { node: hir::ItemStatic(..), .. }) | hir_map::NodeItem(&hir::Item { node: hir::ItemFn(..), .. }) | hir_map::NodeImplItem(&hir::ImplItem { node: hir::ImplItemKind::Method(..), .. }) => { let def_id = tcx.map.local_def_id(id); let scheme = tcx.lookup_item_type(def_id); scheme.generics.types.is_empty() } _ => false } }).collect() } pub fn trans_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, mir_map: &MirMap<'tcx>, analysis: ty::CrateAnalysis) -> CrateTranslation { let _task = tcx.dep_graph.in_task(DepNode::TransCrate); // Be careful with this krate: obviously it gives access to the // entire contents of the krate. So if you push any subtasks of // `TransCrate`, you need to be careful to register "reads" of the // particular items that will be processed. let krate = tcx.map.krate(); let ty::CrateAnalysis { export_map, reachable, name, .. } = analysis; let reachable = filter_reachable_ids(tcx, reachable); let check_overflow = if let Some(v) = tcx.sess.opts.debugging_opts.force_overflow_checks { v } else { tcx.sess.opts.debug_assertions }; let check_dropflag = if let Some(v) = tcx.sess.opts.debugging_opts.force_dropflag_checks { v } else { tcx.sess.opts.debug_assertions }; let link_meta = link::build_link_meta(tcx, name); let shared_ccx = SharedCrateContext::new(tcx, &mir_map, export_map, Sha256::new(), link_meta.clone(), reachable, check_overflow, check_dropflag); // Translate the metadata. let metadata = time(tcx.sess.time_passes(), "write metadata", || { write_metadata(&shared_ccx, shared_ccx.reachable()) }); let metadata_module = ModuleTranslation { name: "metadata".to_string(), symbol_name_hash: 0, // we always rebuild metadata, at least for now source: ModuleSource::Translated(ModuleLlvm { llcx: shared_ccx.metadata_llcx(), llmod: shared_ccx.metadata_llmod(), }), }; let no_builtins = attr::contains_name(&krate.attrs, "no_builtins"); // Run the translation item collector and partition the collected items into // codegen units. let (codegen_units, symbol_map) = collect_and_partition_translation_items(&shared_ccx); let symbol_map = Rc::new(symbol_map); let previous_work_products = trans_reuse_previous_work_products(tcx, &codegen_units, &symbol_map); let crate_context_list = CrateContextList::new(&shared_ccx, codegen_units, previous_work_products, symbol_map.clone()); let modules: Vec<_> = crate_context_list.iter_all() .map(|ccx| { let source = match ccx.previous_work_product() { Some(buf) => ModuleSource::Preexisting(buf.clone()), None => ModuleSource::Translated(ModuleLlvm { llcx: ccx.llcx(), llmod: ccx.llmod(), }), }; ModuleTranslation { name: String::from(ccx.codegen_unit().name()), symbol_name_hash: ccx.codegen_unit().compute_symbol_name_hash(tcx, &symbol_map), source: source, } }) .collect(); assert_module_sources::assert_module_sources(tcx, &modules); // Skip crate items and just output metadata in -Z no-trans mode. if tcx.sess.opts.no_trans { let linker_info = LinkerInfo::new(&shared_ccx, &[]); return CrateTranslation { modules: modules, metadata_module: metadata_module, link: link_meta, metadata: metadata, reachable: vec![], no_builtins: no_builtins, linker_info: linker_info }; } // Instantiate translation items without filling out definitions yet... for ccx in crate_context_list.iter_need_trans() { let cgu = ccx.codegen_unit(); let trans_items = cgu.items_in_deterministic_order(tcx, &symbol_map); tcx.dep_graph.with_task(cgu.work_product_dep_node(), || { for (trans_item, linkage) in trans_items { trans_item.predefine(&ccx, linkage); } }); } // ... and now that we have everything pre-defined, fill out those definitions. for ccx in crate_context_list.iter_need_trans() { let cgu = ccx.codegen_unit(); let trans_items = cgu.items_in_deterministic_order(tcx, &symbol_map); tcx.dep_graph.with_task(cgu.work_product_dep_node(), || { for (trans_item, _) in trans_items { trans_item.define(&ccx); } // If this codegen unit contains the main function, also create the // wrapper here maybe_create_entry_wrapper(&ccx); // Run replace-all-uses-with for statics that need it for &(old_g, new_g) in ccx.statics_to_rauw().borrow().iter() { unsafe { let bitcast = llvm::LLVMConstPointerCast(new_g, llvm::LLVMTypeOf(old_g)); llvm::LLVMReplaceAllUsesWith(old_g, bitcast); llvm::LLVMDeleteGlobal(old_g); } } // Finalize debuginfo if ccx.sess().opts.debuginfo != NoDebugInfo { debuginfo::finalize(&ccx); } }); } symbol_names_test::report_symbol_names(&shared_ccx); if shared_ccx.sess().trans_stats() { let stats = shared_ccx.stats(); println!("--- trans stats ---"); println!("n_glues_created: {}", stats.n_glues_created.get()); println!("n_null_glues: {}", stats.n_null_glues.get()); println!("n_real_glues: {}", stats.n_real_glues.get()); println!("n_fallback_instantiations: {}", stats.n_fallback_instantiations.get()); println!("n_fns: {}", stats.n_fns.get()); println!("n_monos: {}", stats.n_monos.get()); println!("n_inlines: {}", stats.n_inlines.get()); println!("n_closures: {}", stats.n_closures.get()); println!("fn stats:"); stats.fn_stats.borrow_mut().sort_by(|&(_, insns_a), &(_, insns_b)| { insns_b.cmp(&insns_a) }); for tuple in stats.fn_stats.borrow().iter() { match *tuple { (ref name, insns) => { println!("{} insns, {}", insns, *name); } } } } if shared_ccx.sess().count_llvm_insns() { for (k, v) in shared_ccx.stats().llvm_insns.borrow().iter() { println!("{:7} {}", *v, *k); } } let sess = shared_ccx.sess(); let mut reachable_symbols = shared_ccx.reachable().iter().map(|&id| { let def_id = shared_ccx.tcx().map.local_def_id(id); symbol_for_def_id(def_id, &shared_ccx, &symbol_map) }).collect::>(); if sess.entry_fn.borrow().is_some() { reachable_symbols.push("main".to_string()); } if sess.crate_types.borrow().contains(&config::CrateTypeDylib) { reachable_symbols.push(shared_ccx.metadata_symbol_name()); } // For the purposes of LTO or when creating a cdylib, we add to the // reachable set all of the upstream reachable extern fns. These functions // are all part of the public ABI of the final product, so we need to // preserve them. // // Note that this happens even if LTO isn't requested or we're not creating // a cdylib. In those cases, though, we're not even reading the // `reachable_symbols` list later on so it should be ok. for cnum in sess.cstore.crates() { let syms = sess.cstore.reachable_ids(cnum); reachable_symbols.extend(syms.into_iter().filter(|did| { sess.cstore.is_extern_item(shared_ccx.tcx(), *did) }).map(|did| { symbol_for_def_id(did, &shared_ccx, &symbol_map) })); } time(shared_ccx.sess().time_passes(), "internalize symbols", || { internalize_symbols(sess, &crate_context_list, &symbol_map, &reachable_symbols.iter() .map(|s| &s[..]) .collect()) }); if sess.target.target.options.is_like_msvc && sess.crate_types.borrow().iter().any(|ct| *ct == config::CrateTypeRlib) { create_imps(&crate_context_list); } let linker_info = LinkerInfo::new(&shared_ccx, &reachable_symbols); CrateTranslation { modules: modules, metadata_module: metadata_module, link: link_meta, metadata: metadata, reachable: reachable_symbols, no_builtins: no_builtins, linker_info: linker_info } } /// For each CGU, identify if we can reuse an existing object file (or /// maybe other context). fn trans_reuse_previous_work_products(tcx: TyCtxt, codegen_units: &[CodegenUnit], symbol_map: &SymbolMap) -> Vec> { debug!("trans_reuse_previous_work_products()"); codegen_units .iter() .map(|cgu| { let id = cgu.work_product_id(); let hash = cgu.compute_symbol_name_hash(tcx, symbol_map); debug!("trans_reuse_previous_work_products: id={:?} hash={}", id, hash); if let Some(work_product) = tcx.dep_graph.previous_work_product(&id) { if work_product.input_hash == hash { debug!("trans_reuse_previous_work_products: reusing {:?}", work_product); return Some(work_product); } else { debug!("trans_reuse_previous_work_products: \ not reusing {:?} because hash changed to {:?}", work_product, hash); } } None }) .collect() } fn collect_and_partition_translation_items<'a, 'tcx>(scx: &SharedCrateContext<'a, 'tcx>) -> (Vec>, SymbolMap<'tcx>) { let time_passes = scx.sess().time_passes(); let collection_mode = match scx.sess().opts.debugging_opts.print_trans_items { Some(ref s) => { let mode_string = s.to_lowercase(); let mode_string = mode_string.trim(); if mode_string == "eager" { TransItemCollectionMode::Eager } else { if mode_string != "lazy" { let message = format!("Unknown codegen-item collection mode '{}'. \ Falling back to 'lazy' mode.", mode_string); scx.sess().warn(&message); } TransItemCollectionMode::Lazy } } None => TransItemCollectionMode::Lazy }; let (items, inlining_map) = time(time_passes, "translation item collection", || { collector::collect_crate_translation_items(&scx, collection_mode) }); let symbol_map = SymbolMap::build(scx, items.iter().cloned()); let strategy = if scx.sess().opts.debugging_opts.incremental.is_some() { PartitioningStrategy::PerModule } else { PartitioningStrategy::FixedUnitCount(scx.sess().opts.cg.codegen_units) }; let codegen_units = time(time_passes, "codegen unit partitioning", || { partitioning::partition(scx.tcx(), items.iter().cloned(), strategy, &inlining_map, scx.reachable()) }); assert!(scx.tcx().sess.opts.cg.codegen_units == codegen_units.len() || scx.tcx().sess.opts.debugging_opts.incremental.is_some()); { let mut ccx_map = scx.translation_items().borrow_mut(); for trans_item in items.iter().cloned() { ccx_map.insert(trans_item); } } if scx.sess().opts.debugging_opts.print_trans_items.is_some() { let mut item_to_cgus = HashMap::new(); for cgu in &codegen_units { for (&trans_item, &linkage) in cgu.items() { item_to_cgus.entry(trans_item) .or_insert(Vec::new()) .push((cgu.name().clone(), linkage)); } } let mut item_keys: Vec<_> = items .iter() .map(|i| { let mut output = i.to_string(scx.tcx()); output.push_str(" @@"); let mut empty = Vec::new(); let mut cgus = item_to_cgus.get_mut(i).unwrap_or(&mut empty); cgus.as_mut_slice().sort_by_key(|&(ref name, _)| name.clone()); cgus.dedup(); for &(ref cgu_name, linkage) in cgus.iter() { output.push_str(" "); output.push_str(&cgu_name[..]); let linkage_abbrev = match linkage { llvm::ExternalLinkage => "External", llvm::AvailableExternallyLinkage => "Available", llvm::LinkOnceAnyLinkage => "OnceAny", llvm::LinkOnceODRLinkage => "OnceODR", llvm::WeakAnyLinkage => "WeakAny", llvm::WeakODRLinkage => "WeakODR", llvm::AppendingLinkage => "Appending", llvm::InternalLinkage => "Internal", llvm::PrivateLinkage => "Private", llvm::ExternalWeakLinkage => "ExternalWeak", llvm::CommonLinkage => "Common", }; output.push_str("["); output.push_str(linkage_abbrev); output.push_str("]"); } output }) .collect(); item_keys.sort(); for item in item_keys { println!("TRANS_ITEM {}", item); } } (codegen_units, symbol_map) } fn symbol_for_def_id<'a, 'tcx>(def_id: DefId, scx: &SharedCrateContext<'a, 'tcx>, symbol_map: &SymbolMap<'tcx>) -> String { // Just try to look things up in the symbol map. If nothing's there, we // recompute. if let Some(node_id) = scx.tcx().map.as_local_node_id(def_id) { if let Some(sym) = symbol_map.get(TransItem::Static(node_id)) { return sym.to_owned(); } } let instance = Instance::mono(scx, def_id); symbol_map.get(TransItem::Fn(instance)) .map(str::to_owned) .unwrap_or_else(|| instance.symbol_name(scx)) }