/
consts.rs
531 lines (507 loc) · 21.4 KB
/
consts.rs
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// 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use core::prelude::*;
use lib::llvm::{llvm, ValueRef, TypeRef, Bool, True, False};
use middle::const_eval;
use middle::trans::base;
use middle::trans::base::get_insn_ctxt;
use middle::trans::common::*;
use middle::trans::consts;
use middle::trans::expr;
use middle::trans::machine;
use middle::trans::type_of;
use middle::ty;
use core::libc::c_uint;
use syntax::{ast, ast_util, codemap, ast_map};
pub fn const_lit(cx: @CrateContext, 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(/*bad*/copy *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(/*bad*/copy *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)
}
}
pub fn const_ptrcast(cx: @CrateContext, a: ValueRef, t: TypeRef) -> ValueRef {
unsafe {
let b = llvm::LLVMConstPointerCast(a, T_ptr(t));
assert cx.const_globals.insert(b as int, a);
b
}
}
pub fn const_vec(cx: @CrateContext, e: @ast::expr, es: &[@ast::expr])
-> (ValueRef, ValueRef, TypeRef) {
unsafe {
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 unit_sz = machine::llsize_of(cx, llunitty);
let sz = llvm::LLVMConstMul(C_uint(cx, es.len()), unit_sz);
let vs = es.map(|e| const_expr(cx, *e));
// If the vector contains enums, an LLVM array won't work.
let v = if vs.any(|vi| val_ty(*vi) != llunitty) {
C_struct(vs)
} else {
C_array(llunitty, vs)
};
return (v, sz, llunitty);
}
}
pub fn const_deref(cx: @CrateContext, v: ValueRef) -> ValueRef {
unsafe {
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
}
}
pub fn const_get_elt(cx: @CrateContext, v: ValueRef, us: &[c_uint])
-> ValueRef {
unsafe {
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;
}
}
pub fn const_autoderef(cx: @CrateContext, 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)
}
}
}
pub fn get_const_val(cx: @CrateContext, def_id: ast::def_id) -> ValueRef {
if !ast_util::is_local(def_id) {
cx.tcx.sess.bug(~"cross-crate constants");
}
if !cx.const_values.contains_key(&def_id.node) {
match cx.tcx.items.get(&def_id.node) {
ast_map::node_item(@ast::item {
node: ast::item_const(_, subexpr), _
}, _) => {
trans_const(cx, subexpr, def_id.node);
}
_ => cx.tcx.sess.bug(~"expected a const to be an item")
}
}
cx.const_values.get(&def_id.node)
}
pub fn const_expr(cx: @CrateContext, e: @ast::expr) -> ValueRef {
unsafe {
let _icx = cx.insn_ctxt("const_expr");
return match /*bad*/copy 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 => {
match ty::get(ty).sty {
ty::ty_bool => {
// Somewhat questionable, but I believe this is
// correct.
let te = llvm::LLVMConstTrunc(te, T_i1());
let te = llvm::LLVMConstNot(te);
llvm::LLVMConstZExt(te, T_bool())
}
_ => 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) |_, 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 = machine::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")
};
let len = llvm::LLVMConstIntGetZExtValue(len) 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);
let 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 = ty::type_is_signed(basety) as Bool;
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) }
}
(expr::cast_enum, expr::cast_integral) |
(expr::cast_enum, expr::cast_float) => {
let def = ty::resolve_expr(cx.tcx, base);
let (enum_did, variant_did) = match def {
ast::def_variant(enum_did, variant_did) => {
(enum_did, variant_did)
}
_ => cx.sess.bug(~"enum cast source is not enum")
};
// Note that we know this is a C-like (nullary) enum
// variant or we wouldn't have gotten here
let variants = ty::enum_variants(cx.tcx, enum_did);
let iv = if variants.len() == 1 {
// Univariants don't have a discriminant field,
// because there's only one value it could have:
C_integral(T_i64(),
variants[0].disr_val as u64, True)
} else {
base::get_discrim_val(cx, e.span, enum_did, variant_did)
};
let ety_cast = expr::cast_type_kind(ety);
match ety_cast {
expr::cast_integral => {
let s = ty::type_is_signed(ety) as Bool;
llvm::LLVMConstIntCast(iv, llty, s)
}
expr::cast_float => llvm::LLVMConstUIToFP(iv, llty),
_ => cx.sess.bug(~"enum cast destination is not \
integral or float")
}
}
_ => {
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 gv = do str::as_c_str("const") |name| {
llvm::LLVMAddGlobal(cx.llmod, val_ty(cv), 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(ref 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(ref f) => const_expr(cx, (*f).node.expr),
None => {
cx.tcx.sess.span_bug(
e.span, ~"missing struct field");
}
}
})
};
C_struct([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 /*bad*/copy 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, purity)) => {
assert ast_util::is_local(def_id);
let f = base::get_item_val(cx, def_id.node);
match purity {
ast::extern_fn =>
llvm::LLVMConstPointerCast(f, T_ptr(T_i8())),
_ => C_struct(~[f, C_null(T_opaque_box_ptr(cx))])
}
}
Some(ast::def_const(def_id)) => {
get_const_val(cx, def_id)
}
Some(ast::def_variant(enum_did, variant_did)) => {
// Note that we know this is a C-like (nullary) enum
// variant or we wouldn't have gotten here -- the constant
// checker forbids paths that don't map to C-like enum
// variants.
if ty::enum_is_univariant(cx.tcx, enum_did) {
// Univariants have no discriminant field.
C_struct(~[])
} else {
let lldiscrim = base::get_discrim_val(cx, e.span,
enum_did,
variant_did);
// However, we still have to pad it out to the
// size of the full enum; see the expr_call case,
// below.
let ety = ty::expr_ty(cx.tcx, e);
let size = machine::static_size_of_enum(cx, ety);
let padding = C_null(T_array(T_i8(), size));
C_struct(~[lldiscrim, padding])
}
}
Some(ast::def_struct(_)) => {
let ety = ty::expr_ty(cx.tcx, e);
let llty = type_of::type_of(cx, ety);
C_null(llty)
}
_ => {
cx.sess.span_bug(e.span,
~"expected a const, fn, or variant def")
}
}
}
ast::expr_call(callee, args, _) => {
match cx.tcx.def_map.find(&callee.id) {
Some(ast::def_struct(def_id)) => {
let llstructbody =
C_struct(args.map(|a| const_expr(cx, *a)));
if ty::ty_dtor(cx.tcx, def_id).is_present() {
C_struct(~[ llstructbody, C_u8(0) ])
} else {
C_struct(~[ llstructbody ])
}
}
Some(ast::def_variant(tid, vid)) => {
let ety = ty::expr_ty(cx.tcx, e);
let univar = ty::enum_is_univariant(cx.tcx, tid);
let size = machine::static_size_of_enum(cx, ety);
let discrim = base::get_discrim_val(cx, e.span, tid, vid);
let c_args = C_struct(args.map(|a| const_expr(cx, *a)));
// FIXME (#1645): enum body alignment is generaly wrong.
if !univar {
// Pad out the data to the size of its type_of;
// this is necessary if the enum is contained
// within an aggregate (tuple, struct, vector) so
// that the next element is at the right offset.
let actual_size =
machine::llsize_of_real(cx, llvm::LLVMTypeOf(c_args));
let padding =
C_null(T_array(T_i8(), size - actual_size));
// A packed_struct has an alignment of 1; thus,
// wrapping one around c_args will misalign it the
// same way we normally misalign enum bodies
// without affecting its internal alignment or
// changing the alignment of the enum.
C_struct(~[discrim, C_packed_struct(~[c_args]), padding])
} else {
C_struct(~[c_args])
}
}
_ => cx.sess.span_bug(e.span, ~"expected a struct def")
}
}
ast::expr_paren(e) => { return const_expr(cx, e); }
_ => cx.sess.span_bug(e.span,
~"bad constant expression type in consts::const_expr")
};
}
}
pub fn trans_const(ccx: @CrateContext, _e: @ast::expr, id: ast::node_id) {
unsafe {
let _icx = ccx.insn_ctxt("trans_const");
let g = base::get_item_val(ccx, id);
// At this point, get_item_val has already translated the
// constant's initializer to determine its LLVM type.
let v = ccx.const_values.get(&id);
llvm::LLVMSetInitializer(g, v);
llvm::LLVMSetGlobalConstant(g, True);
}
}