// 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 back::abi; use llvm; use llvm::{ConstFCmp, ConstICmp, SetLinkage, SetUnnamedAddr}; use llvm::{InternalLinkage, ValueRef, Bool, True}; use middle::{check_const, def}; use middle::cstore::LOCAL_CRATE; use middle::const_eval::{self, ConstVal, ConstEvalErr}; use middle::const_eval::{const_int_checked_neg, const_uint_checked_neg}; use middle::const_eval::{const_int_checked_add, const_uint_checked_add}; use middle::const_eval::{const_int_checked_sub, const_uint_checked_sub}; use middle::const_eval::{const_int_checked_mul, const_uint_checked_mul}; use middle::const_eval::{const_int_checked_div, const_uint_checked_div}; use middle::const_eval::{const_int_checked_rem, const_uint_checked_rem}; use middle::const_eval::{const_int_checked_shl, const_uint_checked_shl}; use middle::const_eval::{const_int_checked_shr, const_uint_checked_shr}; use middle::const_eval::EvalHint::ExprTypeChecked; use middle::const_eval::eval_const_expr_partial; use middle::def_id::DefId; use trans::{adt, closure, debuginfo, expr, inline, machine}; use trans::base::{self, push_ctxt}; use trans::common::{self, type_is_sized, ExprOrMethodCall, node_id_substs, C_nil, const_get_elt}; use trans::common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty}; use trans::common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint}; use trans::common::{type_is_fat_ptr, Field, C_vector, C_array, C_null, ExprId, MethodCallKey}; use trans::declare; use trans::monomorphize; use trans::type_::Type; use trans::type_of; use trans::Disr; use middle::subst::Substs; use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer}; use middle::ty::adjustment::AdjustUnsafeFnPointer; use middle::ty::{self, Ty}; use middle::ty::cast::{CastTy,IntTy}; use util::nodemap::NodeMap; use rustc_front::hir; use std::ffi::{CStr, CString}; use std::borrow::Cow; use libc::c_uint; use syntax::ast; use syntax::attr; use syntax::parse::token; use syntax::ptr::P; 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 { ast::LitByte(b) => C_integral(Type::uint_from_ty(cx, ast::TyU8), b as u64, false), ast::LitChar(i) => C_integral(Type::char(cx), i as u64, false), ast::LitInt(i, ast::SignedIntLit(t, _)) => { C_integral(Type::int_from_ty(cx, t), i, true) } ast::LitInt(u, ast::UnsignedIntLit(t)) => { C_integral(Type::uint_from_ty(cx, t), u, false) } ast::LitInt(i, ast::UnsuffixedIntLit(_)) => { 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) } _ => cx.sess().span_bug(lit.span, &format!("integer literal has type {:?} (expected int \ or usize)", lit_int_ty)) } } ast::LitFloat(ref fs, t) => { C_floating(&fs, Type::float_from_ty(cx, t)) } ast::LitFloatUnsuffixed(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)) } _ => { cx.sess().span_bug(lit.span, "floating point literal doesn't have the right type"); } } } ast::LitBool(b) => C_bool(cx, b), ast::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()), ast::LitByteStr(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()) } } 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(||{ ccx.sess().bug(&format!("symbol `{}` is already defined", name)); }); llvm::LLVMSetInitializer(gv, cv); llvm::LLVMSetAlignment(gv, align); SetLinkage(gv, InternalLinkage); SetUnnamedAddr(gv, true); gv } } pub fn addr_of(ccx: &CrateContext, cv: ValueRef, align: machine::llalign, kind: &str) -> ValueRef { match ccx.const_globals().borrow().get(&cv) { Some(&gv) => { 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; } None => {} } let gv = addr_of_mut(ccx, cv, align, kind); unsafe { llvm::LLVMSetGlobalConstant(gv, True); } ccx.const_globals().borrow_mut().insert(cv, gv); gv } fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef { let v = match cx.const_unsized().borrow().get(&v) { Some(&v) => v, None => v }; unsafe { llvm::LLVMGetInitializer(v) } } 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) { (const_deref_ptr(cx, v), mt.ty) } else { // Derefing a fat pointer does not change the representation, // just the type to the unsized contents. (v, mt.ty) } } None => { cx.sess().bug(&format!("unexpected dereferenceable type {:?}", ty)) } } } fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, node: ExprOrMethodCall, def_id: DefId, arg_vals: &[ValueRef], param_substs: &'tcx Substs<'tcx>, trueconst: TrueConst) -> Result { let fn_like = const_eval::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 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(node_id_substs(ccx, node, param_substs)); match fn_like.body().expr { Some(ref expr) => { const_expr(ccx, &**expr, substs, Some(&fn_args), trueconst).map(|(res, _)| res) }, None => Ok(C_nil(ccx)), } } 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 def_id = inline::maybe_instantiate_inline(ccx, def_id); if def_id.krate != LOCAL_CRATE { ccx.sess().span_bug(ref_expr.span, "cross crate constant could not be inlined"); } match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id), Some(param_substs)) { Some(ref expr) => expr, None => { ccx.sess().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 description(&self) -> Cow { match self { &Runtime(ref e) => e.description(), &Compiletime(ref e) => e.description(), } } } #[derive(Copy, Clone)] 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::trans_empty()); match get_const_expr_as_global(ccx, expr, check_const::ConstQualif::empty(), empty_substs, TrueConst::Yes) { Err(Runtime(err)) => { ccx.tcx().sess.span_err(expr.span, &err.description()); Err(Compiletime(err)) }, other => other, } } pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, expr: &hir::Expr, qualif: check_const::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 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def(); match def { def::DefConst(def_id) | def::DefAssociatedConst(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(check_const::ConstQualif::NON_STATIC_BORROWS) { // Avoid autorefs as they would create global instead of stack // references, even when only the latter are correct. try!(const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst)) } else { try!(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 = try!(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(AdjustReifyFnPointer) => { // FIXME(#19925) once fn item types are // zero-sized, we'll need to do something here } Some(AdjustUnsafeFnPointer) => { // 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::ReStatic), ty); } } else { 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(cx, llconst, &[abi::FAT_PTR_ADDR as u32]), Some(const_get_elt(cx, 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, param_substs); 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)); } cx.sess().bug(&format!("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 result = match t.sty { ty::TyInt(int_type) => { let input = match const_to_opt_int(te) { Some(v) => v, None => return Ok(()), }; const_int_checked_neg( input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type))) } ty::TyUint(uint_type) => { let input = match const_to_opt_uint(te) { Some(v) => v, None => return Ok(()), }; const_uint_checked_neg( input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type))) } _ => return Ok(()), }; const_err(cx, e, result, trueconst) } else { Ok(()) } } fn const_err(cx: &CrateContext, e: &hir::Expr, result: Result, trueconst: TrueConst) -> Result<(), ConstEvalFailure> { match (result, trueconst) { (Ok(_), _) => { // We do not actually care about a successful result. Ok(()) }, (Err(err), TrueConst::Yes) => { cx.tcx().sess.span_err(e.span, &err.description()); Err(Compiletime(err)) }, (Err(err), TrueConst::No) => { cx.tcx().sess.span_warn(e.span, &err.description()); 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 { unreachable!() }; let result = match t.sty { ty::TyInt(int_type) => { let (lhs, rhs) = match (const_to_opt_int(te1), const_to_opt_int(te2)) { (Some(v1), Some(v2)) => (v1, v2), _ => return Ok(()), }; let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type)); match b.node { hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety), hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety), hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety), hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety), hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety), hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety), hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety), _ => return Ok(()), } } ty::TyUint(uint_type) => { let (lhs, rhs) = match (const_to_opt_uint(te1), const_to_opt_uint(te2)) { (Some(v1), Some(v2)) => (v1, v2), _ => return Ok(()), }; let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type)); match b.node { hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety), hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety), hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety), hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety), hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety), hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety), hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety), _ => return Ok(()), } } _ => return Ok(()), }; const_err(cx, e, result, trueconst) } 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) = try!(const_expr(cx, &**e1, param_substs, fn_args, trueconst)); debug!("const_expr_unadjusted: te1={}, ty={:?}", cx.tn().val_to_string(te1), ty); assert!(!ty.is_simd()); let is_float = ty.is_fp(); let signed = ty.is_signed(); let (te2, _) = try!(const_expr(cx, &**e2, param_substs, fn_args, trueconst)); try!(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(cx, b.node); ConstFCmp(cmp, te1, te2) } else { let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed); ConstICmp(cmp, te1, te2) } }, } } // unsafe { match b.node { }, hir::ExprUnary(u, ref inner_e) => { let (te, ty) = try!(const_expr(cx, &**inner_e, param_substs, fn_args, trueconst)); try!(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) = try!(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(cx, &*brepr, bv, vinfo.discr, ix) }, hir::ExprTupField(ref base, idx) => { let (bv, bt) = try!(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(cx, &*brepr, bv, vinfo.discr, idx.node) }, hir::ExprIndex(ref base, ref index) => { let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst)); let iv = match eval_const_expr_partial(cx.tcx(), &index, ExprTypeChecked, None) { Ok(ConstVal::Int(i)) => i as u64, Ok(ConstVal::Uint(u)) => u, _ => cx.sess().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(cx, bv, &[0]); (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1])) }, ty::TyRef(_, mt) => match mt.ty.sty { ty::TyArray(_, u) => { (const_deref_ptr(cx, bv), C_uint(cx, u)) }, _ => cx.sess().span_bug(base.span, &format!("index-expr base must be a vector \ or string type, found {:?}", bt)), }, _ => cx.sess().span_bug(base.span, &format!("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. span_err!(cx.sess(), e.span, E0515, "const index-expr is out of bounds"); C_undef(val_ty(arr).element_type()) } else { const_get_elt(cx, 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) = try!(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(cx, v, &[abi::FAT_PTR_ADDR as u32]), ptr_ty); if type_is_fat_ptr(cx.tcx(), t_cast) { let info = const_get_elt(cx, 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(cx, &*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()) }, _ => { cx.sess().impossible_case(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, } } let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def()); if let Some(def::DefStatic(def_id, _)) = opt_def { common::get_static_val(cx, def_id, ety) } else { // If this isn't the address of a static, then keep going through // normal constant evaluation. let (v, ty) = try!(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) = try!(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 = try!(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(try!(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(cx, &*repr, bv, discr, ix)), (_, None) => cx.sess().span_bug(e.span, "missing struct field"), } }) .collect::>>() .into_iter() .collect::,ConstEvalFailure>>(); let cs = try!(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 = try!(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 = cx.tcx().eval_repeat_count(count); let unit_val = try!(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(..) => { let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def(); match def { def::DefLocal(_, id) => { if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) { val } else { cx.sess().span_bug(e.span, "const fn argument not found") } } def::DefFn(..) | def::DefMethod(..) => { expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val } def::DefConst(def_id) | def::DefAssociatedConst(def_id) => { const_deref_ptr(cx, try!(get_const_val(cx, def_id, e, param_substs))) } def::DefVariant(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 => { expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val } ty::VariantKind::Struct => { cx.sess().span_bug(e.span, "path-expr refers to a dict variant!") } } } def::DefStruct(_) => { if let ty::TyBareFn(..) = ety.sty { // Tuple struct. expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val } else { // Unit struct. C_null(type_of::type_of(cx, ety)) } } _ => { cx.sess().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 def = cx.tcx().def_map.borrow()[&callee.id].full_def(); let arg_vals = try!(map_list(args)); match def { def::DefFn(did, _) | def::DefMethod(did) => { try!(const_fn_call( cx, ExprId(callee.id), did, &arg_vals, param_substs, trueconst, )) } def::DefStruct(_) => { 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::DefVariant(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[..]) } _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"), } }, hir::ExprMethodCall(_, _, ref args) => { let arg_vals = try!(map_list(args)); let method_call = ty::MethodCall::expr(e.id); let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id; try!(const_fn_call(cx, MethodCallKey(method_call), method_did, &arg_vals, param_substs, trueconst)) }, hir::ExprType(ref e, _) => try!(const_expr(cx, &**e, param_substs, fn_args, trueconst)).0, hir::ExprBlock(ref block) => { match block.expr { Some(ref expr) => try!(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, ref substs) => { closure::trans_closure_expr(closure::Dest::Ignore(cx), decl, body, e.id, def_id, substs, &e.attrs); } _ => cx.sess().span_bug( e.span, &format!("bad type for closure expr: {:?}", ety)) } C_null(type_of::type_of(cx, ety)) }, _ => cx.sess().span_bug(e.span, "bad constant expression type in consts::const_expr"), }) } 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 g = base::get_item_val(ccx, id); let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty()); let (v, _) = try!(const_expr( ccx, expr, empty_substs, None, TrueConst::Yes, ).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 = llvm::LLVMTypeOf(v); let v = if val_llty == Type::i1(ccx).to_ref() { val_llty = Type::i8(ccx).to_ref(); llvm::LLVMConstZExt(v, val_llty) } else { v }; let ty = ccx.tcx().node_id_to_type(id); let llty = type_of::type_of(ccx, ty); let g = if val_llty == llty.to_ref() { g } 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(g)); let name_string = CString::new(name_str_ref.to_bytes()).unwrap(); llvm::LLVMSetValueName(g, empty_string.as_ptr()); let new_g = llvm::LLVMGetOrInsertGlobal( ccx.llmod(), name_string.as_ptr(), val_llty); // 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((g, new_g)); new_g }; llvm::LLVMSetAlignment(g, type_of::align_of(ccx, 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 = 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); } Ok(g) } }