// Copyright 2012 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 llvm; use llvm::{SetUnnamedAddr}; use llvm::{InternalLinkage, ValueRef, Bool, True}; use middle::const_qualif::ConstQualif; use rustc_const_eval::{ConstEvalErr, lookup_const_fn_by_id, lookup_const_by_id, ErrKind}; use rustc_const_eval::{eval_length, report_const_eval_err, note_const_eval_err}; use rustc::hir::def::Def; use rustc::hir::def_id::DefId; use rustc::hir::map as hir_map; use {abi, adt, closure, debuginfo, expr, machine}; use base::{self, push_ctxt}; use callee::Callee; use trans_item::TransItem; use common::{type_is_sized, C_nil, const_get_elt}; use common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty}; use common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint}; use common::{type_is_fat_ptr, Field, C_vector, C_array, C_null}; use datum::{Datum, Lvalue}; use declare; use monomorphize::{self, Instance}; use type_::Type; use type_of; use value::Value; use Disr; use rustc::ty::subst::Substs; use rustc::ty::adjustment::{AdjustNeverToAny, AdjustDerefRef, AdjustReifyFnPointer}; use rustc::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer}; use rustc::ty::{self, Ty, TyCtxt}; use rustc::ty::cast::{CastTy,IntTy}; use util::nodemap::NodeMap; use rustc_const_math::{ConstInt, ConstUsize, ConstIsize}; use rustc::hir; use std::ffi::{CStr, CString}; use libc::c_uint; use syntax::ast::{self, LitKind}; use syntax::attr::{self, AttrMetaMethods}; use syntax::parse::token; use syntax::ptr::P; use syntax_pos::Span; pub type FnArgMap<'a> = Option<&'a NodeMap>; pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit) -> ValueRef { let _icx = push_ctxt("trans_lit"); debug!("const_lit: {:?}", lit); match lit.node { LitKind::Byte(b) => C_integral(Type::uint_from_ty(cx, ast::UintTy::U8), b as u64, false), LitKind::Char(i) => C_integral(Type::char(cx), i as u64, false), LitKind::Int(i, ast::LitIntType::Signed(t)) => { C_integral(Type::int_from_ty(cx, t), i, true) } LitKind::Int(u, ast::LitIntType::Unsigned(t)) => { C_integral(Type::uint_from_ty(cx, t), u, false) } LitKind::Int(i, ast::LitIntType::Unsuffixed) => { let lit_int_ty = cx.tcx().node_id_to_type(e.id); match lit_int_ty.sty { ty::TyInt(t) => { C_integral(Type::int_from_ty(cx, t), i as u64, true) } ty::TyUint(t) => { C_integral(Type::uint_from_ty(cx, t), i as u64, false) } _ => span_bug!(lit.span, "integer literal has type {:?} (expected int \ or usize)", lit_int_ty) } } LitKind::Float(ref fs, t) => { C_floating(&fs, Type::float_from_ty(cx, t)) } LitKind::FloatUnsuffixed(ref fs) => { let lit_float_ty = cx.tcx().node_id_to_type(e.id); match lit_float_ty.sty { ty::TyFloat(t) => { C_floating(&fs, Type::float_from_ty(cx, t)) } _ => { span_bug!(lit.span, "floating point literal doesn't have the right type"); } } } LitKind::Bool(b) => C_bool(cx, b), LitKind::Str(ref s, _) => C_str_slice(cx, (*s).clone()), LitKind::ByteStr(ref data) => { addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str") } } } pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef { unsafe { llvm::LLVMConstPointerCast(val, ty.to_ref()) } } pub fn addr_of_mut(ccx: &CrateContext, cv: ValueRef, align: machine::llalign, kind: &str) -> ValueRef { unsafe { // FIXME: this totally needs a better name generation scheme, perhaps a simple global // counter? Also most other uses of gensym in trans. let gsym = token::gensym("_"); let name = format!("{}{}", kind, gsym.0); let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{ bug!("symbol `{}` is already defined", name); }); llvm::LLVMSetInitializer(gv, cv); llvm::LLVMSetAlignment(gv, align); llvm::LLVMSetLinkage(gv, InternalLinkage); SetUnnamedAddr(gv, true); gv } } pub fn addr_of(ccx: &CrateContext, cv: ValueRef, align: machine::llalign, kind: &str) -> ValueRef { if let Some(&gv) = ccx.const_globals().borrow().get(&cv) { unsafe { // Upgrade the alignment in cases where the same constant is used with different // alignment requirements if align > llvm::LLVMGetAlignment(gv) { llvm::LLVMSetAlignment(gv, align); } } return gv; } let gv = addr_of_mut(ccx, cv, align, kind); unsafe { llvm::LLVMSetGlobalConstant(gv, True); } ccx.const_globals().borrow_mut().insert(cv, gv); gv } /// Deref a constant pointer pub fn load_const(cx: &CrateContext, v: ValueRef, t: Ty) -> ValueRef { let v = match cx.const_unsized().borrow().get(&v) { Some(&v) => v, None => v }; let d = unsafe { llvm::LLVMGetInitializer(v) }; if !d.is_null() && t.is_bool() { unsafe { llvm::LLVMConstTrunc(d, Type::i1(cx).to_ref()) } } else { d } } fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, v: ValueRef, ty: Ty<'tcx>) -> (ValueRef, Ty<'tcx>) { match ty.builtin_deref(true, ty::NoPreference) { Some(mt) => { if type_is_sized(cx.tcx(), mt.ty) { (load_const(cx, v, mt.ty), mt.ty) } else { // Derefing a fat pointer does not change the representation, // just the type to the unsized contents. (v, mt.ty) } } None => { bug!("unexpected dereferenceable type {:?}", ty) } } } fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, def_id: DefId, substs: &'tcx Substs<'tcx>, arg_vals: &[ValueRef], param_substs: &'tcx Substs<'tcx>, trueconst: TrueConst) -> Result { let fn_like = lookup_const_fn_by_id(ccx.tcx(), def_id); let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call"); let body = match fn_like.body().expr { Some(ref expr) => expr, None => return Ok(C_nil(ccx)) }; let args = &fn_like.decl().inputs; assert_eq!(args.len(), arg_vals.len()); let arg_ids = args.iter().map(|arg| arg.pat.id); let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect(); let substs = ccx.tcx().mk_substs(substs.clone().erase_regions()); let substs = monomorphize::apply_param_substs(ccx.tcx(), param_substs, &substs); const_expr(ccx, body, substs, Some(&fn_args), trueconst).map(|(res, _)| res) } pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, def_id: DefId, ref_expr: &hir::Expr, param_substs: &'tcx Substs<'tcx>) -> &'tcx hir::Expr { let substs = ccx.tcx().node_id_item_substs(ref_expr.id).substs; let substs = ccx.tcx().mk_substs(substs.clone().erase_regions()); let substs = monomorphize::apply_param_substs(ccx.tcx(), param_substs, &substs); match lookup_const_by_id(ccx.tcx(), def_id, Some(substs)) { Some((ref expr, _ty)) => expr, None => { span_bug!(ref_expr.span, "constant item not found") } } } pub enum ConstEvalFailure { /// in case the const evaluator failed on something that panic at runtime /// as defined in RFC 1229 Runtime(ConstEvalErr), // in case we found a true constant Compiletime(ConstEvalErr), } impl ConstEvalFailure { fn into_inner(self) -> ConstEvalErr { match self { Runtime(e) => e, Compiletime(e) => e, } } pub fn as_inner(&self) -> &ConstEvalErr { match self { &Runtime(ref e) => e, &Compiletime(ref e) => e, } } } #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub enum TrueConst { Yes, No } use self::ConstEvalFailure::*; fn get_const_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, def_id: DefId, ref_expr: &hir::Expr, param_substs: &'tcx Substs<'tcx>) -> Result { let expr = get_const_expr(ccx, def_id, ref_expr, param_substs); let empty_substs = ccx.tcx().mk_substs(Substs::empty()); match get_const_expr_as_global(ccx, expr, ConstQualif::empty(), empty_substs, TrueConst::Yes) { Err(Runtime(err)) => { report_const_eval_err(ccx.tcx(), &err, expr.span, "expression").emit(); Err(Compiletime(err)) }, other => other, } } pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, expr: &hir::Expr, qualif: ConstQualif, param_substs: &'tcx Substs<'tcx>, trueconst: TrueConst) -> Result { debug!("get_const_expr_as_global: {:?}", expr.id); // Special-case constants to cache a common global for all uses. if let hir::ExprPath(..) = expr.node { // `def` must be its own statement and cannot be in the `match` // otherwise the `def_map` will be borrowed for the entire match instead // of just to get the `def` value match ccx.tcx().expect_def(expr.id) { Def::Const(def_id) | Def::AssociatedConst(def_id) => { if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) { debug!("get_const_expr_as_global ({:?}): found const {:?}", expr.id, def_id); return get_const_val(ccx, def_id, expr, param_substs); } }, _ => {}, } } let key = (expr.id, param_substs); if let Some(&val) = ccx.const_values().borrow().get(&key) { return Ok(val); } let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs, &ccx.tcx().expr_ty(expr)); let val = if qualif.intersects(ConstQualif::NON_STATIC_BORROWS) { // Avoid autorefs as they would create global instead of stack // references, even when only the latter are correct. const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst)? } else { const_expr(ccx, expr, param_substs, None, trueconst)?.0 }; // boolean SSA values are i1, but they have to be stored in i8 slots, // otherwise some LLVM optimization passes don't work as expected let val = unsafe { if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() { llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref()) } else { val } }; let lvalue = addr_of(ccx, val, type_of::align_of(ccx, ty), "const"); ccx.const_values().borrow_mut().insert(key, lvalue); Ok(lvalue) } pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, e: &hir::Expr, param_substs: &'tcx Substs<'tcx>, fn_args: FnArgMap, trueconst: TrueConst) -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> { let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs, &cx.tcx().expr_ty(e)); let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst)?; let mut llconst = llconst; let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs, &cx.tcx().expr_ty_adjusted(e)); let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned(); match opt_adj { Some(AdjustNeverToAny(..)) => span_bug!(e.span, "const expression of type ! encountered"), Some(AdjustReifyFnPointer) => { match ety.sty { ty::TyFnDef(def_id, substs, _) => { llconst = Callee::def(cx, def_id, substs).reify(cx).val; } _ => { bug!("{} cannot be reified to a fn ptr", ety) } } } Some(AdjustUnsafeFnPointer) | Some(AdjustMutToConstPointer) => { // purely a type-level thing } Some(AdjustDerefRef(adj)) => { let mut ty = ety; // Save the last autoderef in case we can avoid it. if adj.autoderefs > 0 { for _ in 0..adj.autoderefs-1 { let (dv, dt) = const_deref(cx, llconst, ty); llconst = dv; ty = dt; } } if adj.autoref.is_some() { if adj.autoderefs == 0 { // Don't copy data to do a deref+ref // (i.e., skip the last auto-deref). llconst = addr_of(cx, llconst, type_of::align_of(cx, ty), "autoref"); ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReErased), ty); } } else if adj.autoderefs > 0 { let (dv, dt) = const_deref(cx, llconst, ty); llconst = dv; // If we derefed a fat pointer then we will have an // open type here. So we need to update the type with // the one returned from const_deref. ety_adjusted = dt; } if let Some(target) = adj.unsize { let target = monomorphize::apply_param_substs(cx.tcx(), param_substs, &target); let pointee_ty = ty.builtin_deref(true, ty::NoPreference) .expect("consts: unsizing got non-pointer type").ty; let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) { // Normally, the source is a thin pointer and we are // adding extra info to make a fat pointer. The exception // is when we are upcasting an existing object fat pointer // to use a different vtable. In that case, we want to // load out the original data pointer so we can repackage // it. (const_get_elt(llconst, &[abi::FAT_PTR_ADDR as u32]), Some(const_get_elt(llconst, &[abi::FAT_PTR_EXTRA as u32]))) } else { (llconst, None) }; let unsized_ty = target.builtin_deref(true, ty::NoPreference) .expect("consts: unsizing got non-pointer target type").ty; let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to(); let base = ptrcast(base, ptr_ty); let info = base::unsized_info(cx, pointee_ty, unsized_ty, old_info); if old_info.is_none() { let prev_const = cx.const_unsized().borrow_mut() .insert(base, llconst); assert!(prev_const.is_none() || prev_const == Some(llconst)); } assert_eq!(abi::FAT_PTR_ADDR, 0); assert_eq!(abi::FAT_PTR_EXTRA, 1); llconst = C_struct(cx, &[base, info], false); } } None => {} }; let llty = type_of::sizing_type_of(cx, ety_adjusted); let csize = machine::llsize_of_alloc(cx, val_ty(llconst)); let tsize = machine::llsize_of_alloc(cx, llty); if csize != tsize { cx.sess().abort_if_errors(); unsafe { // FIXME these values could use some context llvm::LLVMDumpValue(llconst); llvm::LLVMDumpValue(C_undef(llty)); } bug!("const {:?} of type {:?} has size {} instead of {}", e, ety_adjusted, csize, tsize); } Ok((llconst, ety_adjusted)) } fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty, te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> { // The only kind of unary expression that we check for validity // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`). if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node { // An unfortunate special case: we parse e.g. -128 as a // negation of the literal 128, which means if we're expecting // a i8 (or if it was already suffixed, e.g. `-128_i8`), then // 128 will have already overflowed to -128, and so then the // constant evaluator thinks we're trying to negate -128. // // Catch this up front by looking for ExprLit directly, // and just accepting it. if let hir::ExprLit(_) = inner_e.node { return Ok(()); } let cval = match to_const_int(te, t, cx.tcx()) { Some(v) => v, None => return Ok(()), }; const_err(cx, e.span, (-cval).map_err(ErrKind::Math), trueconst)?; } Ok(()) } pub fn to_const_int(value: ValueRef, t: Ty, tcx: TyCtxt) -> Option { match t.sty { ty::TyInt(int_type) => const_to_opt_int(value).and_then(|input| match int_type { ast::IntTy::I8 => { assert_eq!(input as i8 as i64, input); Some(ConstInt::I8(input as i8)) }, ast::IntTy::I16 => { assert_eq!(input as i16 as i64, input); Some(ConstInt::I16(input as i16)) }, ast::IntTy::I32 => { assert_eq!(input as i32 as i64, input); Some(ConstInt::I32(input as i32)) }, ast::IntTy::I64 => { Some(ConstInt::I64(input)) }, ast::IntTy::Is => { ConstIsize::new(input, tcx.sess.target.int_type) .ok().map(ConstInt::Isize) }, }), ty::TyUint(uint_type) => const_to_opt_uint(value).and_then(|input| match uint_type { ast::UintTy::U8 => { assert_eq!(input as u8 as u64, input); Some(ConstInt::U8(input as u8)) }, ast::UintTy::U16 => { assert_eq!(input as u16 as u64, input); Some(ConstInt::U16(input as u16)) }, ast::UintTy::U32 => { assert_eq!(input as u32 as u64, input); Some(ConstInt::U32(input as u32)) }, ast::UintTy::U64 => { Some(ConstInt::U64(input)) }, ast::UintTy::Us => { ConstUsize::new(input, tcx.sess.target.uint_type) .ok().map(ConstInt::Usize) }, }), _ => None, } } pub fn const_err(cx: &CrateContext, span: Span, result: Result, trueconst: TrueConst) -> Result { match (result, trueconst) { (Ok(x), _) => Ok(x), (Err(err), TrueConst::Yes) => { let err = ConstEvalErr{ span: span, kind: err }; report_const_eval_err(cx.tcx(), &err, span, "expression").emit(); Err(Compiletime(err)) }, (Err(err), TrueConst::No) => { let err = ConstEvalErr{ span: span, kind: err }; let mut diag = cx.tcx().sess.struct_span_warn( span, "this expression will panic at run-time"); note_const_eval_err(cx.tcx(), &err, span, "expression", &mut diag); diag.emit(); Err(Runtime(err)) }, } } fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty, te1: ValueRef, te2: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> { let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { bug!() }; let (lhs, rhs) = match (to_const_int(te1, t, cx.tcx()), to_const_int(te2, t, cx.tcx())) { (Some(v1), Some(v2)) => (v1, v2), _ => return Ok(()), }; let result = match b.node { hir::BiAdd => lhs + rhs, hir::BiSub => lhs - rhs, hir::BiMul => lhs * rhs, hir::BiDiv => lhs / rhs, hir::BiRem => lhs % rhs, hir::BiShl => lhs << rhs, hir::BiShr => lhs >> rhs, _ => return Ok(()), }; const_err(cx, e.span, result.map_err(ErrKind::Math), trueconst)?; Ok(()) } fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, e: &hir::Expr, ety: Ty<'tcx>, param_substs: &'tcx Substs<'tcx>, fn_args: FnArgMap, trueconst: TrueConst) -> Result { debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})", e, ety, param_substs); let map_list = |exprs: &[P]| -> Result, ConstEvalFailure> { exprs.iter() .map(|e| const_expr(cx, &e, param_substs, fn_args, trueconst).map(|(l, _)| l)) .collect::>>() .into_iter() .collect() // this dance is necessary to eagerly run const_expr so all errors are reported }; let _icx = push_ctxt("const_expr"); Ok(match e.node { hir::ExprLit(ref lit) => const_lit(cx, e, &lit), hir::ExprBinary(b, ref e1, ref e2) => { /* Neither type is bottom, and we expect them to be unified * already, so the following is safe. */ let (te1, ty) = const_expr(cx, &e1, param_substs, fn_args, trueconst)?; debug!("const_expr_unadjusted: te1={:?}, ty={:?}", Value(te1), ty); assert!(!ty.is_simd()); let is_float = ty.is_fp(); let signed = ty.is_signed(); let (te2, ty2) = const_expr(cx, &e2, param_substs, fn_args, trueconst)?; debug!("const_expr_unadjusted: te2={:?}, ty={:?}", Value(te2), ty2); check_binary_expr_validity(cx, e, ty, te1, te2, trueconst)?; unsafe { match b.node { hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2), hir::BiAdd => llvm::LLVMConstAdd(te1, te2), hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2), hir::BiSub => llvm::LLVMConstSub(te1, te2), hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2), hir::BiMul => llvm::LLVMConstMul(te1, te2), hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2), hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2), hir::BiDiv => llvm::LLVMConstUDiv(te1, te2), hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2), hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2), hir::BiRem => llvm::LLVMConstURem(te1, te2), hir::BiAnd => llvm::LLVMConstAnd(te1, te2), hir::BiOr => llvm::LLVMConstOr(te1, te2), hir::BiBitXor => llvm::LLVMConstXor(te1, te2), hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2), hir::BiBitOr => llvm::LLVMConstOr(te1, te2), hir::BiShl => { let te2 = base::cast_shift_const_rhs(b.node, te1, te2); llvm::LLVMConstShl(te1, te2) }, hir::BiShr => { let te2 = base::cast_shift_const_rhs(b.node, te1, te2); if signed { llvm::LLVMConstAShr(te1, te2) } else { llvm::LLVMConstLShr(te1, te2) } }, hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => { if is_float { let cmp = base::bin_op_to_fcmp_predicate(b.node); llvm::LLVMConstFCmp(cmp, te1, te2) } else { let cmp = base::bin_op_to_icmp_predicate(b.node, signed); llvm::LLVMConstICmp(cmp, te1, te2) } }, } } // unsafe { match b.node { }, hir::ExprUnary(u, ref inner_e) => { let (te, ty) = const_expr(cx, &inner_e, param_substs, fn_args, trueconst)?; check_unary_expr_validity(cx, e, ty, te, trueconst)?; let is_float = ty.is_fp(); unsafe { match u { hir::UnDeref => const_deref(cx, te, ty).0, hir::UnNot => llvm::LLVMConstNot(te), hir::UnNeg if is_float => llvm::LLVMConstFNeg(te), hir::UnNeg => llvm::LLVMConstNeg(te), } } }, hir::ExprField(ref base, field) => { let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?; let brepr = adt::represent_type(cx, bt); let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None); let ix = vinfo.field_index(field.node); adt::const_get_field(&brepr, bv, vinfo.discr, ix) }, hir::ExprTupField(ref base, idx) => { let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?; let brepr = adt::represent_type(cx, bt); let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None); adt::const_get_field(&brepr, bv, vinfo.discr, idx.node) }, hir::ExprIndex(ref base, ref index) => { let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?; let iv = const_expr(cx, &index, param_substs, fn_args, TrueConst::Yes)?.0; let iv = if let Some(iv) = const_to_opt_uint(iv) { iv } else { span_bug!(index.span, "index is not an integer-constant expression"); }; let (arr, len) = match bt.sty { ty::TyArray(_, u) => (bv, C_uint(cx, u)), ty::TySlice(..) | ty::TyStr => { let e1 = const_get_elt(bv, &[0]); (load_const(cx, e1, bt), const_get_elt(bv, &[1])) }, ty::TyRef(_, mt) => match mt.ty.sty { ty::TyArray(_, u) => { (load_const(cx, bv, mt.ty), C_uint(cx, u)) }, _ => span_bug!(base.span, "index-expr base must be a vector \ or string type, found {:?}", bt), }, _ => span_bug!(base.span, "index-expr base must be a vector \ or string type, found {:?}", bt), }; let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 }; let len = match bt.sty { ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty { ty::TyStr => { assert!(len > 0); len - 1 }, _ => len, }, _ => len, }; if iv >= len { // FIXME #3170: report this earlier on in the const-eval // pass. Reporting here is a bit late. const_err(cx, e.span, Err(ErrKind::IndexOutOfBounds { len: len, index: iv }), trueconst)?; C_undef(val_ty(arr).element_type()) } else { const_get_elt(arr, &[iv as c_uint]) } }, hir::ExprCast(ref base, _) => { let t_cast = ety; let llty = type_of::type_of(cx, t_cast); let (v, t_expr) = const_expr(cx, &base, param_substs, fn_args, trueconst)?; debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast); if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) { return Ok(v); } if type_is_fat_ptr(cx.tcx(), t_expr) { // Fat pointer casts. let t_cast_inner = t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty; let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to(); let addr = ptrcast(const_get_elt(v, &[abi::FAT_PTR_ADDR as u32]), ptr_ty); if type_is_fat_ptr(cx.tcx(), t_cast) { let info = const_get_elt(v, &[abi::FAT_PTR_EXTRA as u32]); return Ok(C_struct(cx, &[addr, info], false)) } else { return Ok(addr); } } unsafe { match ( CastTy::from_ty(t_expr).expect("bad input type for cast"), CastTy::from_ty(t_cast).expect("bad output type for cast"), ) { (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => { let repr = adt::represent_type(cx, t_expr); let discr = adt::const_get_discrim(&repr, v); let iv = C_integral(cx.int_type(), discr.0, false); let s = adt::is_discr_signed(&repr) as Bool; llvm::LLVMConstIntCast(iv, llty.to_ref(), s) }, (CastTy::Int(_), CastTy::Int(_)) => { let s = t_expr.is_signed() as Bool; llvm::LLVMConstIntCast(v, llty.to_ref(), s) }, (CastTy::Int(_), CastTy::Float) => { if t_expr.is_signed() { llvm::LLVMConstSIToFP(v, llty.to_ref()) } else { llvm::LLVMConstUIToFP(v, llty.to_ref()) } }, (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()), (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()), (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()), (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_)) | (CastTy::RPtr(_), CastTy::Ptr(_)) => { ptrcast(v, llty) }, (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion? (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()), (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => { llvm::LLVMConstPtrToInt(v, llty.to_ref()) }, _ => { span_bug!(e.span, "bad combination of types for cast") }, } } // unsafe { match ( ... ) { }, hir::ExprAddrOf(hir::MutImmutable, ref sub) => { // If this is the address of some static, then we need to return // the actual address of the static itself (short circuit the rest // of const eval). let mut cur = sub; loop { match cur.node { hir::ExprBlock(ref blk) => { if let Some(ref sub) = blk.expr { cur = sub; } else { break; } }, _ => break, } } if let Some(Def::Static(def_id, _)) = cx.tcx().expect_def_or_none(cur.id) { get_static(cx, def_id).val } else { // If this isn't the address of a static, then keep going through // normal constant evaluation. let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?; addr_of(cx, v, type_of::align_of(cx, ty), "ref") } }, hir::ExprAddrOf(hir::MutMutable, ref sub) => { let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?; addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice") }, hir::ExprTup(ref es) => { let repr = adt::represent_type(cx, ety); let vals = map_list(&es[..])?; adt::trans_const(cx, &repr, Disr(0), &vals[..]) }, hir::ExprStruct(_, ref fs, ref base_opt) => { let repr = adt::represent_type(cx, ety); let base_val = match *base_opt { Some(ref base) => Some(const_expr( cx, &base, param_substs, fn_args, trueconst, )?), None => None }; let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id); let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| { match (fs.iter().find(|f| f_name == f.name.node), base_val) { (Some(ref f), _) => { const_expr(cx, &f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l) }, (_, Some((bv, _))) => Ok(adt::const_get_field(&repr, bv, discr, ix)), (_, None) => span_bug!(e.span, "missing struct field"), } }) .collect::>>() .into_iter() .collect::,ConstEvalFailure>>(); let cs = cs?; if ety.is_simd() { C_vector(&cs[..]) } else { adt::trans_const(cx, &repr, discr, &cs[..]) } }, hir::ExprVec(ref es) => { let unit_ty = ety.sequence_element_type(cx.tcx()); let llunitty = type_of::type_of(cx, unit_ty); let vs = es.iter() .map(|e| const_expr( cx, &e, param_substs, fn_args, trueconst, ).map(|(l, _)| l)) .collect::>>() .into_iter() .collect::, ConstEvalFailure>>(); let vs = vs?; // If the vector contains enums, an LLVM array won't work. if vs.iter().any(|vi| val_ty(*vi) != llunitty) { C_struct(cx, &vs[..], false) } else { C_array(llunitty, &vs[..]) } }, hir::ExprRepeat(ref elem, ref count) => { let unit_ty = ety.sequence_element_type(cx.tcx()); let llunitty = type_of::type_of(cx, unit_ty); let n = eval_length(cx.tcx(), count, "repeat count").unwrap(); let unit_val = const_expr(cx, &elem, param_substs, fn_args, trueconst)?.0; let vs = vec![unit_val; n]; if val_ty(unit_val) != llunitty { C_struct(cx, &vs[..], false) } else { C_array(llunitty, &vs[..]) } }, hir::ExprPath(..) => { match cx.tcx().expect_def(e.id) { Def::Local(_, id) => { if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) { val } else { span_bug!(e.span, "const fn argument not found") } } Def::Fn(..) | Def::Method(..) => C_nil(cx), Def::Const(def_id) | Def::AssociatedConst(def_id) => { load_const(cx, get_const_val(cx, def_id, e, param_substs)?, ety) } Def::Variant(enum_did, variant_did) => { let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did); match vinfo.kind { ty::VariantKind::Unit => { let repr = adt::represent_type(cx, ety); adt::trans_const(cx, &repr, Disr::from(vinfo.disr_val), &[]) } ty::VariantKind::Tuple => C_nil(cx), ty::VariantKind::Struct => { span_bug!(e.span, "path-expr refers to a dict variant!") } } } // Unit struct or ctor. Def::Struct(..) => C_null(type_of::type_of(cx, ety)), _ => { span_bug!(e.span, "expected a const, fn, struct, \ or variant def") } } }, hir::ExprCall(ref callee, ref args) => { let mut callee = &**callee; loop { callee = match callee.node { hir::ExprBlock(ref block) => match block.expr { Some(ref tail) => &tail, None => break, }, _ => break, }; } let arg_vals = map_list(args)?; match cx.tcx().expect_def(callee.id) { Def::Fn(did) | Def::Method(did) => { const_fn_call( cx, did, cx.tcx().node_id_item_substs(callee.id).substs, &arg_vals, param_substs, trueconst, )? } Def::Struct(..) => { if ety.is_simd() { C_vector(&arg_vals[..]) } else { let repr = adt::represent_type(cx, ety); adt::trans_const(cx, &repr, Disr(0), &arg_vals[..]) } } Def::Variant(enum_did, variant_did) => { let repr = adt::represent_type(cx, ety); let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did); adt::trans_const(cx, &repr, Disr::from(vinfo.disr_val), &arg_vals[..]) } _ => span_bug!(e.span, "expected a struct, variant, or const fn def"), } }, hir::ExprMethodCall(_, _, ref args) => { let arg_vals = map_list(args)?; let method_call = ty::MethodCall::expr(e.id); let method = cx.tcx().tables.borrow().method_map[&method_call]; const_fn_call(cx, method.def_id, method.substs, &arg_vals, param_substs, trueconst)? }, hir::ExprType(ref e, _) => const_expr(cx, &e, param_substs, fn_args, trueconst)?.0, hir::ExprBlock(ref block) => { match block.expr { Some(ref expr) => const_expr( cx, &expr, param_substs, fn_args, trueconst, )?.0, None => C_nil(cx), } }, hir::ExprClosure(_, ref decl, ref body, _) => { match ety.sty { ty::TyClosure(def_id, substs) => { closure::trans_closure_expr(closure::Dest::Ignore(cx), decl, body, e.id, def_id, substs); } _ => span_bug!( e.span, "bad type for closure expr: {:?}", ety) } C_null(type_of::type_of(cx, ety)) }, _ => span_bug!(e.span, "bad constant expression type in consts::const_expr"), }) } pub fn get_static<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, def_id: DefId) -> Datum<'tcx, Lvalue> { let ty = ccx.tcx().lookup_item_type(def_id).ty; let instance = Instance::mono(ccx.shared(), def_id); if let Some(&g) = ccx.instances().borrow().get(&instance) { return Datum::new(g, ty, Lvalue::new("static")); } let g = if let Some(id) = ccx.tcx().map.as_local_node_id(def_id) { let llty = type_of::type_of(ccx, ty); let (g, attrs) = match ccx.tcx().map.get(id) { hir_map::NodeItem(&hir::Item { ref attrs, span, node: hir::ItemStatic(..), .. }) => { let sym = ccx.symbol_map() .get(TransItem::Static(id)) .expect("Local statics should always be in the SymbolMap"); // Make sure that this is never executed for something inlined. assert!(!ccx.tcx().map.is_inlined_node_id(id)); let defined_in_current_codegen_unit = ccx.codegen_unit() .items() .contains_key(&TransItem::Static(id)); if defined_in_current_codegen_unit { if declare::get_declared_value(ccx, sym).is_none() { span_bug!(span, "trans: Static not properly pre-defined?"); } } else { if declare::get_declared_value(ccx, sym).is_some() { span_bug!(span, "trans: Conflicting symbol names for static?"); } } let g = declare::define_global(ccx, sym, llty).unwrap(); (g, attrs) } hir_map::NodeForeignItem(&hir::ForeignItem { ref attrs, span, node: hir::ForeignItemStatic(..), .. }) => { let sym = instance.symbol_name(ccx.shared()); let g = if let Some(name) = attr::first_attr_value_str_by_name(&attrs, "linkage") { // If this is a static with a linkage specified, then we need to handle // it a little specially. The typesystem prevents things like &T and // extern "C" fn() from being non-null, so we can't just declare a // static and call it a day. Some linkages (like weak) will make it such // that the static actually has a null value. let linkage = match base::llvm_linkage_by_name(&name) { Some(linkage) => linkage, None => { ccx.sess().span_fatal(span, "invalid linkage specified"); } }; let llty2 = match ty.sty { ty::TyRawPtr(ref mt) => type_of::type_of(ccx, mt.ty), _ => { ccx.sess().span_fatal(span, "must have type `*const T` or `*mut T`"); } }; unsafe { // Declare a symbol `foo` with the desired linkage. let g1 = declare::declare_global(ccx, &sym, llty2); llvm::LLVMSetLinkage(g1, linkage); // Declare an internal global `extern_with_linkage_foo` which // is initialized with the address of `foo`. If `foo` is // discarded during linking (for example, if `foo` has weak // linkage and there are no definitions), then // `extern_with_linkage_foo` will instead be initialized to // zero. let mut real_name = "_rust_extern_with_linkage_".to_string(); real_name.push_str(&sym); let g2 = declare::define_global(ccx, &real_name, llty).unwrap_or_else(||{ ccx.sess().span_fatal(span, &format!("symbol `{}` is already defined", &sym)) }); llvm::LLVMSetLinkage(g2, llvm::InternalLinkage); llvm::LLVMSetInitializer(g2, g1); g2 } } else { // Generate an external declaration. declare::declare_global(ccx, &sym, llty) }; (g, attrs) } item => bug!("get_static: expected static, found {:?}", item) }; for attr in attrs { if attr.check_name("thread_local") { llvm::set_thread_local(g, true); } } g } else { let sym = instance.symbol_name(ccx.shared()); // FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow? // FIXME(nagisa): investigate whether it can be changed into define_global let g = declare::declare_global(ccx, &sym, type_of::type_of(ccx, ty)); // Thread-local statics in some other crate need to *always* be linked // against in a thread-local fashion, so we need to be sure to apply the // thread-local attribute locally if it was present remotely. If we // don't do this then linker errors can be generated where the linker // complains that one object files has a thread local version of the // symbol and another one doesn't. for attr in ccx.tcx().get_attrs(def_id).iter() { if attr.check_name("thread_local") { llvm::set_thread_local(g, true); } } if ccx.use_dll_storage_attrs() { unsafe { llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport); } } g }; ccx.instances().borrow_mut().insert(instance, g); ccx.statics().borrow_mut().insert(g, def_id); Datum::new(g, ty, Lvalue::new("static")) } pub fn trans_static(ccx: &CrateContext, m: hir::Mutability, expr: &hir::Expr, id: ast::NodeId, attrs: &[ast::Attribute]) -> Result { unsafe { let _icx = push_ctxt("trans_static"); let def_id = ccx.tcx().map.local_def_id(id); let datum = get_static(ccx, def_id); 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)) }; let use_mir = check_attrs(ccx.tcx().map.attrs(id)); let v = if use_mir { ::mir::trans_static_initializer(ccx, def_id) } else { let empty_substs = ccx.tcx().mk_substs(Substs::empty()); const_expr(ccx, expr, empty_substs, None, TrueConst::Yes) .map(|(v, _)| v) }.map_err(|e| e.into_inner())?; // boolean SSA values are i1, but they have to be stored in i8 slots, // otherwise some LLVM optimization passes don't work as expected let mut val_llty = val_ty(v); let v = if val_llty == Type::i1(ccx) { val_llty = Type::i8(ccx); llvm::LLVMConstZExt(v, val_llty.to_ref()) } else { v }; let llty = type_of::type_of(ccx, datum.ty); let g = if val_llty == llty { datum.val } else { // If we created the global with the wrong type, // correct the type. let empty_string = CString::new("").unwrap(); let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(datum.val)); let name_string = CString::new(name_str_ref.to_bytes()).unwrap(); llvm::LLVMSetValueName(datum.val, empty_string.as_ptr()); let new_g = llvm::LLVMRustGetOrInsertGlobal( ccx.llmod(), name_string.as_ptr(), val_llty.to_ref()); // To avoid breaking any invariants, we leave around the old // global for the moment; we'll replace all references to it // with the new global later. (See base::trans_crate.) ccx.statics_to_rauw().borrow_mut().push((datum.val, new_g)); new_g }; llvm::LLVMSetAlignment(g, type_of::align_of(ccx, datum.ty)); llvm::LLVMSetInitializer(g, v); // As an optimization, all shared statics which do not have interior // mutability are placed into read-only memory. if m != hir::MutMutable { let tcontents = datum.ty.type_contents(ccx.tcx()); if !tcontents.interior_unsafe() { llvm::LLVMSetGlobalConstant(g, llvm::True); } } debuginfo::create_global_var_metadata(ccx, id, g); if attr::contains_name(attrs, "thread_local") { llvm::set_thread_local(g, true); } base::set_link_section(ccx, g, attrs); Ok(g) } }