use common::*; use syntax::{ast, ast_util, codemap, ast_map}; use base::get_insn_ctxt; fn const_lit(cx: @crate_ctxt, e: @ast::expr, lit: ast::lit) -> ValueRef { let _icx = cx.insn_ctxt("trans_lit"); match lit.node { ast::lit_int(i, t) => C_integral(T_int_ty(cx, t), i as u64, True), ast::lit_uint(u, t) => C_integral(T_uint_ty(cx, t), u, False), ast::lit_int_unsuffixed(i) => { let lit_int_ty = ty::node_id_to_type(cx.tcx, e.id); match ty::get(lit_int_ty).sty { ty::ty_int(t) => { C_integral(T_int_ty(cx, t), i as u64, True) } ty::ty_uint(t) => { C_integral(T_uint_ty(cx, t), i as u64, False) } _ => cx.sess.span_bug(lit.span, ~"integer literal doesn't have a type") } } ast::lit_float(fs, t) => C_floating(*fs, T_float_ty(cx, t)), ast::lit_float_unsuffixed(fs) => { let lit_float_ty = ty::node_id_to_type(cx.tcx, e.id); match ty::get(lit_float_ty).sty { ty::ty_float(t) => { C_floating(*fs, T_float_ty(cx, t)) } _ => { cx.sess.span_bug(lit.span, ~"floating point literal doesn't have the right \ type"); } } } ast::lit_bool(b) => C_bool(b), ast::lit_nil => C_nil(), ast::lit_str(s) => C_estr_slice(cx, *s) } } fn const_ptrcast(cx: @crate_ctxt, a: ValueRef, t: TypeRef) -> ValueRef { let b = llvm::LLVMConstPointerCast(a, T_ptr(t)); assert cx.const_globals.insert(b as int, a); b } fn const_vec(cx: @crate_ctxt, e: @ast::expr, es: &[@ast::expr]) -> (ValueRef, ValueRef, TypeRef) { let vec_ty = ty::expr_ty(cx.tcx, e); let unit_ty = ty::sequence_element_type(cx.tcx, vec_ty); let llunitty = type_of::type_of(cx, unit_ty); let v = C_array(llunitty, es.map(|e| const_expr(cx, *e))); let unit_sz = shape::llsize_of(cx, llunitty); let sz = llvm::LLVMConstMul(C_uint(cx, es.len()), unit_sz); return (v, sz, llunitty); } fn const_deref(cx: @crate_ctxt, v: ValueRef) -> ValueRef { let v = match cx.const_globals.find(v as int) { Some(v) => v, None => v }; assert llvm::LLVMIsGlobalConstant(v) == True; let v = llvm::LLVMGetInitializer(v); v } fn const_get_elt(cx: @crate_ctxt, v: ValueRef, us: &[c_uint]) -> ValueRef { let r = do vec::as_imm_buf(us) |p, len| { llvm::LLVMConstExtractValue(v, p, len as c_uint) }; debug!("const_get_elt(v=%s, us=%?, r=%s)", val_str(cx.tn, v), us, val_str(cx.tn, r)); return r; } fn const_autoderef(cx: @crate_ctxt, ty: ty::t, v: ValueRef) -> (ty::t, ValueRef) { let mut t1 = ty; let mut v1 = v; loop { // Only rptrs can be autoderef'ed in a const context. match ty::get(ty).sty { ty::ty_rptr(_, mt) => { t1 = mt.ty; v1 = const_deref(cx, v1); } _ => return (t1,v1) } } } fn const_expr(cx: @crate_ctxt, e: @ast::expr) -> ValueRef { let _icx = cx.insn_ctxt("const_expr"); return match e.node { ast::expr_lit(lit) => consts::const_lit(cx, e, *lit), ast::expr_binary(b, e1, e2) => { let te1 = const_expr(cx, e1); let te2 = const_expr(cx, e2); let te2 = base::cast_shift_const_rhs(b, te1, te2); /* Neither type is bottom, and we expect them to be unified already, * so the following is safe. */ let ty = ty::expr_ty(cx.tcx, e1); let is_float = ty::type_is_fp(ty); let signed = ty::type_is_signed(ty); return match b { ast::add => { if is_float { llvm::LLVMConstFAdd(te1, te2) } else { llvm::LLVMConstAdd(te1, te2) } } ast::subtract => { if is_float { llvm::LLVMConstFSub(te1, te2) } else { llvm::LLVMConstSub(te1, te2) } } ast::mul => { if is_float { llvm::LLVMConstFMul(te1, te2) } else { llvm::LLVMConstMul(te1, te2) } } ast::div => { if is_float { llvm::LLVMConstFDiv(te1, te2) } else if signed { llvm::LLVMConstSDiv(te1, te2) } else { llvm::LLVMConstUDiv(te1, te2) } } ast::rem => { if is_float { llvm::LLVMConstFRem(te1, te2) } else if signed { llvm::LLVMConstSRem(te1, te2) } else { llvm::LLVMConstURem(te1, te2) } } ast::and | ast::or => cx.sess.span_unimpl(e.span, ~"binop logic"), ast::bitxor => llvm::LLVMConstXor(te1, te2), ast::bitand => llvm::LLVMConstAnd(te1, te2), ast::bitor => llvm::LLVMConstOr(te1, te2), ast::shl => llvm::LLVMConstShl(te1, te2), ast::shr => { if signed { llvm::LLVMConstAShr(te1, te2) } else { llvm::LLVMConstLShr(te1, te2) } } ast::eq | ast::lt | ast::le | ast::ne | ast::ge | ast::gt => cx.sess.span_unimpl(e.span, ~"binop comparator") } } ast::expr_unary(u, e) => { let te = const_expr(cx, e); let ty = ty::expr_ty(cx.tcx, e); let is_float = ty::type_is_fp(ty); return match u { ast::box(_) | ast::uniq(_) | ast::deref => const_deref(cx, te), ast::not => llvm::LLVMConstNot(te), ast::neg => { if is_float { llvm::LLVMConstFNeg(te) } else { llvm::LLVMConstNeg(te) } } } } ast::expr_field(base, field, _) => { let bt = ty::expr_ty(cx.tcx, base); let bv = const_expr(cx, base); let (bt, bv) = const_autoderef(cx, bt, bv); do expr::with_field_tys(cx.tcx, bt, None) |_has_dtor, field_tys| { let ix = ty::field_idx_strict(cx.tcx, field, field_tys); // Note: ideally, we'd use `struct_field()` here instead // of hardcoding [0, ix], but we can't because it yields // the wrong type and also inserts an extra 0 that is // not needed in the constant variety: const_get_elt(cx, bv, [0, ix as c_uint]) } } ast::expr_index(base, index) => { let bt = ty::expr_ty(cx.tcx, base); let bv = const_expr(cx, base); let (bt, bv) = const_autoderef(cx, bt, bv); let iv = match const_eval::eval_const_expr(cx.tcx, index) { const_eval::const_int(i) => i as u64, const_eval::const_uint(u) => u, _ => cx.sess.span_bug(index.span, ~"index is not an integer-constant \ expression") }; let (arr, _len) = match ty::get(bt).sty { ty::ty_evec(_, vstore) | ty::ty_estr(vstore) => match vstore { ty::vstore_fixed(u) => (bv, C_uint(cx, u)), ty::vstore_slice(_) => { let unit_ty = ty::sequence_element_type(cx.tcx, bt); let llunitty = type_of::type_of(cx, unit_ty); let unit_sz = shape::llsize_of(cx, llunitty); (const_deref(cx, const_get_elt(cx, bv, [0])), llvm::LLVMConstUDiv(const_get_elt(cx, bv, [1]), unit_sz)) }, _ => cx.sess.span_bug(base.span, ~"index-expr base must be \ fixed-size or slice") }, _ => cx.sess.span_bug(base.span, ~"index-expr base must be \ a vector or string type") }; // FIXME #3169: This is a little odd but it arises due to a weird // wrinkle in LLVM: it doesn't appear willing to let us call // LLVMConstIntGetZExtValue on the size element of the slice, or // seemingly any integer-const involving a sizeof() call. Despite // that being "a const", it's not the kind of const you can ask // for the integer-value of, evidently. This might be an LLVM // bug, not sure. In any case, to work around this we drop down // to the array-type level here and just ask how long the // array-type itself is, ignoring the length we pulled out of the // slice. This in turn only works because we picked out the // original globalvar via const_deref and so can recover the // array-size of the underlying array, and all this will hold // together exactly as long as we _don't_ support const // sub-slices (that is, slices that represent something other // than a whole array). At that point we'll have more and uglier // work to do here, but for now this should work. // // In the future, what we should be doing here is the // moral equivalent of: // // let len = llvm::LLVMConstIntGetZExtValue(len) as u64; // // but we might have to do substantially more magic to // make it work. Or figure out what is causing LLVM to // not want to consider sizeof() a constant expression // we can get the value (as a number) out of. let len = llvm::LLVMGetArrayLength(val_ty(arr)) as u64; let len = match ty::get(bt).sty { ty::ty_estr(*) => {assert len > 0; len - 1}, _ => len }; if iv >= len { // FIXME #3170: report this earlier on in the const-eval // pass. Reporting here is a bit late. cx.sess.span_err(e.span, ~"const index-expr is out of bounds"); } const_get_elt(cx, arr, [iv as c_uint]) } ast::expr_cast(base, _) => { let ety = ty::expr_ty(cx.tcx, e), llty = type_of::type_of(cx, ety); let basety = ty::expr_ty(cx.tcx, base); let v = const_expr(cx, base); match (expr::cast_type_kind(basety), expr::cast_type_kind(ety)) { (expr::cast_integral, expr::cast_integral) => { let s = if ty::type_is_signed(basety) { True } else { False }; llvm::LLVMConstIntCast(v, llty, s) } (expr::cast_integral, expr::cast_float) => { if ty::type_is_signed(basety) { llvm::LLVMConstSIToFP(v, llty) } else { llvm::LLVMConstUIToFP(v, llty) } } (expr::cast_float, expr::cast_float) => { llvm::LLVMConstFPCast(v, llty) } (expr::cast_float, expr::cast_integral) => { if ty::type_is_signed(ety) { llvm::LLVMConstFPToSI(v, llty) } else { llvm::LLVMConstFPToUI(v, llty) } } _ => cx.sess.impossible_case(e.span, ~"bad combination of types for cast") } } ast::expr_addr_of(ast::m_imm, sub) => { let cv = const_expr(cx, sub); let subty = ty::expr_ty(cx.tcx, sub), llty = type_of::type_of(cx, subty); let gv = do str::as_c_str("const") |name| { llvm::LLVMAddGlobal(cx.llmod, llty, name) }; llvm::LLVMSetInitializer(gv, cv); llvm::LLVMSetGlobalConstant(gv, True); gv } ast::expr_tup(es) => { C_struct(es.map(|e| const_expr(cx, *e))) } ast::expr_rec(fs, None) => { C_struct([C_struct( fs.map(|f| const_expr(cx, f.node.expr)))]) } ast::expr_struct(_, ref fs, _) => { let ety = ty::expr_ty(cx.tcx, e); let cs = do expr::with_field_tys(cx.tcx, ety, None) |_hd, field_tys| { field_tys.map(|field_ty| { match fs.find(|f| field_ty.ident == f.node.ident) { Some(f) => const_expr(cx, f.node.expr), None => { cx.tcx.sess.span_bug( e.span, ~"missing struct field"); } } }) }; let llty = type_of::type_of(cx, ety); C_named_struct(llty, [C_struct(cs)]) } ast::expr_vec(es, ast::m_imm) => { let (v, _, _) = const_vec(cx, e, es); v } ast::expr_vstore(e, ast::expr_vstore_fixed(_)) => { const_expr(cx, e) } ast::expr_vstore(sub, ast::expr_vstore_slice) => { match sub.node { ast::expr_lit(lit) => { match lit.node { ast::lit_str(*) => { const_expr(cx, sub) } _ => { cx.sess.span_bug(e.span, ~"bad const-slice lit") } } } ast::expr_vec(es, ast::m_imm) => { let (cv, sz, llunitty) = const_vec(cx, e, es); let llty = val_ty(cv); let gv = do str::as_c_str("const") |name| { llvm::LLVMAddGlobal(cx.llmod, llty, name) }; llvm::LLVMSetInitializer(gv, cv); llvm::LLVMSetGlobalConstant(gv, True); let p = const_ptrcast(cx, gv, llunitty); C_struct(~[p, sz]) } _ => cx.sess.span_bug(e.span, ~"bad const-slice expr") } } ast::expr_path(pth) => { assert pth.types.len() == 0; match cx.tcx.def_map.find(e.id) { Some(ast::def_fn(def_id, _)) => { assert ast_util::is_local(def_id); let f = base::get_item_val(cx, def_id.node); C_struct(~[f, C_null(T_opaque_box_ptr(cx))]) } Some(ast::def_const(def_id)) => { assert ast_util::is_local(def_id); if ! cx.const_values.contains_key(def_id.node) { match cx.tcx.items.get(def_id.node) { ast_map::node_item(@{ node: ast::item_const(_, subexpr), _ }, _) => { trans_const(cx, subexpr, def_id.node); } _ => cx.sess.span_bug(e.span, ~"expected item") } } cx.const_values.get(def_id.node) } _ => cx.sess.span_bug(e.span, ~"expected a const or fn def") } } ast::expr_paren(e) => { return const_expr(cx, e); } _ => cx.sess.span_bug(e.span, ~"bad constant expression type in consts::const_expr") }; } fn trans_const(ccx: @crate_ctxt, e: @ast::expr, id: ast::node_id) { let _icx = ccx.insn_ctxt("trans_const"); let g = base::get_item_val(ccx, id); let v = const_expr(ccx, e); ccx.const_values.insert(id, v); llvm::LLVMSetInitializer(g, v); llvm::LLVMSetGlobalConstant(g, True); }