1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 * # Compilation of match statements
15 * I will endeavor to explain the code as best I can. I have only a loose
16 * understanding of some parts of it.
20 * The basic state of the code is maintained in an array `m` of `Match`
21 * objects. Each `Match` describes some list of patterns, all of which must
22 * match against the current list of values. If those patterns match, then
23 * the arm listed in the match is the correct arm. A given arm may have
24 * multiple corresponding match entries, one for each alternative that
25 * remains. As we proceed these sets of matches are adjusted by the various
26 * `enter_XXX()` functions, each of which adjusts the set of options given
27 * some information about the value which has been matched.
29 * So, initially, there is one value and N matches, each of which have one
30 * constituent pattern. N here is usually the number of arms but may be
31 * greater, if some arms have multiple alternatives. For example, here:
33 * enum Foo { A, B(int), C(uint, uint) }
41 * The value would be `foo`. There would be four matches, each of which
42 * contains one pattern (and, in one case, a guard). We could collect the
43 * various options and then compile the code for the case where `foo` is an
44 * `A`, a `B`, and a `C`. When we generate the code for `C`, we would (1)
45 * drop the two matches that do not match a `C` and (2) expand the other two
46 * into two patterns each. In the first case, the two patterns would be `1u`
47 * and `2`, and the in the second case the _ pattern would be expanded into
48 * `_` and `_`. The two values are of course the arguments to `C`.
50 * Here is a quick guide to the various functions:
52 * - `compile_submatch()`: The main workhouse. It takes a list of values and
53 * a list of matches and finds the various possibilities that could occur.
55 * - `enter_XXX()`: modifies the list of matches based on some information
56 * about the value that has been matched. For example,
57 * `enter_rec_or_struct()` adjusts the values given that a record or struct
58 * has been matched. This is an infallible pattern, so *all* of the matches
59 * must be either wildcards or record/struct patterns. `enter_opt()`
60 * handles the fallible cases, and it is correspondingly more complex.
64 * We store information about the bound variables for each arm as part of the
65 * per-arm `ArmData` struct. There is a mapping from identifiers to
66 * `BindingInfo` structs. These structs contain the mode/id/type of the
67 * binding, but they also contain an LLVM value which points at an alloca
68 * called `llmatch`. For by value bindings that are Copy, we also create
69 * an extra alloca that we copy the matched value to so that any changes
70 * we do to our copy is not reflected in the original and vice-versa.
71 * We don't do this if it's a move since the original value can't be used
72 * and thus allowing us to cheat in not creating an extra alloca.
74 * The `llmatch` binding always stores a pointer into the value being matched
75 * which points at the data for the binding. If the value being matched has
76 * type `T`, then, `llmatch` will point at an alloca of type `T*` (and hence
77 * `llmatch` has type `T**`). So, if you have a pattern like:
81 * match (a, b) { (ref c, d) => { ... } }
83 * For `c` and `d`, we would generate allocas of type `C*` and `D*`
84 * respectively. These are called the `llmatch`. As we match, when we come
85 * up against an identifier, we store the current pointer into the
86 * corresponding alloca.
88 * Once a pattern is completely matched, and assuming that there is no guard
89 * pattern, we will branch to a block that leads to the body itself. For any
90 * by-value bindings, this block will first load the ptr from `llmatch` (the
91 * one of type `D*`) and then load a second time to get the actual value (the
92 * one of type `D`). For by ref bindings, the value of the local variable is
93 * simply the first alloca.
95 * So, for the example above, we would generate a setup kind of like this:
101 * +--------------------------------------------+
102 * | llmatch_c = (addr of first half of tuple) |
103 * | llmatch_d = (addr of second half of tuple) |
104 * +--------------------------------------------+
106 * +--------------------------------------+
107 * | *llbinding_d = **llmatch_d |
108 * +--------------------------------------+
110 * If there is a guard, the situation is slightly different, because we must
111 * execute the guard code. Moreover, we need to do so once for each of the
112 * alternatives that lead to the arm, because if the guard fails, they may
113 * have different points from which to continue the search. Therefore, in that
114 * case, we generate code that looks more like:
120 * +-------------------------------------------+
121 * | llmatch_c = (addr of first half of tuple) |
122 * | llmatch_d = (addr of first half of tuple) |
123 * +-------------------------------------------+
125 * +-------------------------------------------------+
126 * | *llbinding_d = **llmatch_d |
127 * | check condition |
128 * | if false { goto next case } |
129 * | if true { goto body } |
130 * +-------------------------------------------------+
132 * The handling for the cleanups is a bit... sensitive. Basically, the body
133 * is the one that invokes `add_clean()` for each binding. During the guard
134 * evaluation, we add temporary cleanups and revoke them after the guard is
135 * evaluated (it could fail, after all). Note that guards and moves are
136 * just plain incompatible.
138 * Some relevant helper functions that manage bindings:
139 * - `create_bindings_map()`
140 * - `insert_lllocals()`
143 * ## Notes on vector pattern matching.
145 * Vector pattern matching is surprisingly tricky. The problem is that
146 * the structure of the vector isn't fully known, and slice matches
147 * can be done on subparts of it.
149 * The way that vector pattern matches are dealt with, then, is as
150 * follows. First, we make the actual condition associated with a
151 * vector pattern simply a vector length comparison. So the pattern
152 * [1, .. x] gets the condition "vec len >= 1", and the pattern
153 * [.. x] gets the condition "vec len >= 0". The problem here is that
154 * having the condition "vec len >= 1" hold clearly does not mean that
155 * only a pattern that has exactly that condition will match. This
156 * means that it may well be the case that a condition holds, but none
157 * of the patterns matching that condition match; to deal with this,
158 * when doing vector length matches, we have match failures proceed to
159 * the next condition to check.
161 * There are a couple more subtleties to deal with. While the "actual"
162 * condition associated with vector length tests is simply a test on
163 * the vector length, the actual vec_len Opt entry contains more
164 * information used to restrict which matches are associated with it.
165 * So that all matches in a submatch are matching against the same
166 * values from inside the vector, they are split up by how many
167 * elements they match at the front and at the back of the vector. In
168 * order to make sure that arms are properly checked in order, even
169 * with the overmatching conditions, each vec_len Opt entry is
170 * associated with a range of matches.
171 * Consider the following:
175 * [1, 2, 2, .. _] => 1,
176 * [1, 2, 3, .. _] => 2,
180 * The proper arm to match is arm 2, but arms 0 and 3 both have the
181 * condition "len >= 2". If arm 3 was lumped in with arm 0, then the
182 * wrong branch would be taken. Instead, vec_len Opts are associated
183 * with a contiguous range of matches that have the same "shape".
184 * This is sort of ugly and requires a bunch of special handling of
189 #![allow(non_camel_case_types)]
192 use driver::config::FullDebugInfo;
194 use llvm::{ValueRef, BasicBlockRef};
195 use middle::const_eval;
197 use middle::check_match;
198 use middle::check_match::StaticInliner;
199 use middle::lang_items::StrEqFnLangItem;
200 use middle::pat_util::*;
201 use middle::resolve::DefMap;
202 use middle::trans::adt;
203 use middle::trans::base::*;
204 use middle::trans::build::*;
205 use middle::trans::build;
206 use middle::trans::callee;
207 use middle::trans::cleanup;
208 use middle::trans::cleanup::CleanupMethods;
209 use middle::trans::common::*;
210 use middle::trans::consts;
211 use middle::trans::datum::*;
212 use middle::trans::expr::Dest;
213 use middle::trans::expr;
214 use middle::trans::tvec;
215 use middle::trans::type_of;
216 use middle::trans::debuginfo;
218 use util::common::indenter;
219 use util::ppaux::{Repr, vec_map_to_string};
222 use std::collections::HashMap;
226 use syntax::ast::Ident;
227 use syntax::codemap::Span;
228 use syntax::fold::Folder;
230 #[deriving(PartialEq)]
233 vec_len_ge(/* length of prefix */uint)
236 // An option identifying a branch (either a literal, an enum variant or a
240 var(ty::Disr, Rc<adt::Repr>, ast::DefId),
241 range(Gc<ast::Expr>, Gc<ast::Expr>),
242 vec_len(/* length */ uint, VecLenOpt, /*range of matches*/(uint, uint))
245 fn opt_eq(tcx: &ty::ctxt, a: &Opt, b: &Opt) -> bool {
247 (&lit(a_expr), &lit(b_expr)) => {
248 match const_eval::compare_lit_exprs(tcx, &*a_expr, &*b_expr) {
249 Some(val1) => val1 == 0,
250 None => fail!("compare_list_exprs: type mismatch"),
253 (&range(ref a1, ref a2), &range(ref b1, ref b2)) => {
254 let m1 = const_eval::compare_lit_exprs(tcx, &**a1, &**b1);
255 let m2 = const_eval::compare_lit_exprs(tcx, &**a2, &**b2);
257 (Some(val1), Some(val2)) => (val1 == 0 && val2 == 0),
258 _ => fail!("compare_list_exprs: type mismatch"),
261 (&var(a, _, _), &var(b, _, _)) => a == b,
262 (&vec_len(a1, a2, _), &vec_len(b1, b2, _)) =>
263 a1 == b1 && a2 == b2,
268 pub enum opt_result<'a> {
269 single_result(Result<'a>),
270 lower_bound(Result<'a>),
271 range_result(Result<'a>, Result<'a>),
274 fn trans_opt<'a>(mut bcx: &'a Block<'a>, o: &Opt) -> opt_result<'a> {
275 let _icx = push_ctxt("match::trans_opt");
279 let lit_ty = ty::node_id_to_type(bcx.tcx(), lit_expr.id);
280 let (llval, _) = consts::const_expr(ccx, &*lit_expr, true);
281 let lit_datum = immediate_rvalue(llval, lit_ty);
282 let lit_datum = unpack_datum!(bcx, lit_datum.to_appropriate_datum(bcx));
283 return single_result(Result::new(bcx, lit_datum.val));
285 var(disr_val, ref repr, _) => {
286 return adt::trans_case(bcx, &**repr, disr_val);
288 range(ref l1, ref l2) => {
289 let (l1, _) = consts::const_expr(ccx, &**l1, true);
290 let (l2, _) = consts::const_expr(ccx, &**l2, true);
291 return range_result(Result::new(bcx, l1), Result::new(bcx, l2));
293 vec_len(n, vec_len_eq, _) => {
294 return single_result(Result::new(bcx, C_int(ccx, n as int)));
296 vec_len(n, vec_len_ge(_), _) => {
297 return lower_bound(Result::new(bcx, C_int(ccx, n as int)));
303 pub enum TransBindingMode {
304 TrByCopy(/* llbinding */ ValueRef),
310 * Information about a pattern binding:
311 * - `llmatch` is a pointer to a stack slot. The stack slot contains a
312 * pointer into the value being matched. Hence, llmatch has type `T**`
313 * where `T` is the value being matched.
314 * - `trmode` is the trans binding mode
315 * - `id` is the node id of the binding
316 * - `ty` is the Rust type of the binding */
318 pub struct BindingInfo {
319 pub llmatch: ValueRef,
320 pub trmode: TransBindingMode,
326 type BindingsMap = HashMap<Ident, BindingInfo>;
328 struct ArmData<'a, 'b> {
329 bodycx: &'b Block<'b>,
331 bindings_map: BindingsMap
336 * If all `pats` are matched then arm `data` will be executed.
337 * As we proceed `bound_ptrs` are filled with pointers to values to be bound,
338 * these pointers are stored in llmatch variables just before executing `data` arm.
340 struct Match<'a, 'b> {
341 pats: Vec<Gc<ast::Pat>>,
342 data: &'a ArmData<'a, 'b>,
343 bound_ptrs: Vec<(Ident, ValueRef)>
346 impl<'a, 'b> Repr for Match<'a, 'b> {
347 fn repr(&self, tcx: &ty::ctxt) -> String {
348 if tcx.sess.verbose() {
349 // for many programs, this just take too long to serialize
352 format!("{} pats", self.pats.len())
357 fn has_nested_bindings(m: &[Match], col: uint) -> bool {
359 match br.pats.get(col).node {
360 ast::PatIdent(_, _, Some(_)) => return true,
367 fn expand_nested_bindings<'a, 'b>(
369 m: &'a [Match<'a, 'b>],
372 -> Vec<Match<'a, 'b>> {
373 debug!("expand_nested_bindings(bcx={}, m={}, col={}, val={})",
377 bcx.val_to_string(val));
378 let _indenter = indenter();
381 let mut bound_ptrs = br.bound_ptrs.clone();
382 let mut pat = *br.pats.get(col);
384 pat = match pat.node {
385 ast::PatIdent(_, ref path, Some(inner)) => {
386 bound_ptrs.push((path.node, val));
393 let mut pats = br.pats.clone();
394 *pats.get_mut(col) = pat;
398 bound_ptrs: bound_ptrs
403 type enter_pats<'a> = |&[Gc<ast::Pat>]|: 'a -> Option<Vec<Gc<ast::Pat>>>;
405 fn enter_match<'a, 'b>(
408 m: &'a [Match<'a, 'b>],
412 -> Vec<Match<'a, 'b>> {
413 debug!("enter_match(bcx={}, m={}, col={}, val={})",
417 bcx.val_to_string(val));
418 let _indenter = indenter();
420 m.iter().filter_map(|br| {
421 e(br.pats.as_slice()).map(|pats| {
422 let this = *br.pats.get(col);
423 let mut bound_ptrs = br.bound_ptrs.clone();
425 ast::PatIdent(_, ref path1, None) => {
426 if pat_is_binding(dm, &*this) {
427 bound_ptrs.push((path1.node, val));
436 bound_ptrs: bound_ptrs
442 fn enter_default<'a, 'b>(
445 m: &'a [Match<'a, 'b>],
448 -> Vec<Match<'a, 'b>> {
449 debug!("enter_default(bcx={}, m={}, col={}, val={})",
453 bcx.val_to_string(val));
454 let _indenter = indenter();
456 // Collect all of the matches that can match against anything.
457 enter_match(bcx, dm, m, col, val, |pats| {
458 if pat_is_binding_or_wild(dm, &*pats[col]) {
459 Some(Vec::from_slice(pats.slice_to(col)).append(pats.slice_from(col + 1)))
466 // <pcwalton> nmatsakis: what does enter_opt do?
467 // <pcwalton> in trans/match
468 // <pcwalton> trans/match.rs is like stumbling around in a dark cave
469 // <nmatsakis> pcwalton: the enter family of functions adjust the set of
470 // patterns as needed
471 // <nmatsakis> yeah, at some point I kind of achieved some level of
473 // <nmatsakis> anyhow, they adjust the patterns given that something of that
474 // kind has been found
475 // <nmatsakis> pcwalton: ok, right, so enter_XXX() adjusts the patterns, as I
477 // <nmatsakis> enter_match() kind of embodies the generic code
478 // <nmatsakis> it is provided with a function that tests each pattern to see
479 // if it might possibly apply and so forth
480 // <nmatsakis> so, if you have a pattern like {a: _, b: _, _} and one like _
481 // <nmatsakis> then _ would be expanded to (_, _)
482 // <nmatsakis> one spot for each of the sub-patterns
483 // <nmatsakis> enter_opt() is one of the more complex; it covers the fallible
485 // <nmatsakis> enter_rec_or_struct() or enter_tuple() are simpler, since they
486 // are infallible patterns
487 // <nmatsakis> so all patterns must either be records (resp. tuples) or
490 /// The above is now outdated in that enter_match() now takes a function that
491 /// takes the complete row of patterns rather than just the first one.
492 /// Also, most of the enter_() family functions have been unified with
493 /// the check_match specialization step.
494 fn enter_opt<'a, 'b>(
498 m: &'a [Match<'a, 'b>],
503 -> Vec<Match<'a, 'b>> {
504 debug!("enter_opt(bcx={}, m={}, opt={:?}, col={}, val={})",
509 bcx.val_to_string(val));
510 let _indenter = indenter();
512 let ctor = match opt {
513 &lit(expr) => check_match::ConstantValue(
514 const_eval::eval_const_expr(bcx.tcx(), &*expr)
516 &range(lo, hi) => check_match::ConstantRange(
517 const_eval::eval_const_expr(bcx.tcx(), &*lo),
518 const_eval::eval_const_expr(bcx.tcx(), &*hi)
520 &vec_len(len, _, _) => check_match::Slice(len),
521 &var(_, _, def_id) => check_match::Variant(def_id)
526 let mcx = check_match::MatchCheckCtxt { tcx: bcx.tcx() };
527 enter_match(bcx, dm, m, col, val, |pats| {
528 let span = pats[col].span;
529 let specialized = match pats[col].node {
530 ast::PatVec(ref before, slice, ref after) => {
531 let (lo, hi) = match *opt {
532 vec_len(_, _, (lo, hi)) => (lo, hi),
533 _ => tcx.sess.span_bug(span,
534 "vec pattern but not vec opt")
537 let elems = match slice {
538 Some(slice) if i >= lo && i <= hi => {
539 let n = before.len() + after.len();
540 let this_opt = vec_len(n, vec_len_ge(before.len()),
542 if opt_eq(tcx, &this_opt, opt) {
543 let mut new_before = Vec::new();
544 for pat in before.iter() {
545 new_before.push(*pat);
547 new_before.push(slice);
548 for pat in after.iter() {
549 new_before.push(*pat);
556 None if i >= lo && i <= hi => {
557 let n = before.len();
558 if opt_eq(tcx, &vec_len(n, vec_len_eq, (lo,hi)), opt) {
559 let mut new_before = Vec::new();
560 for pat in before.iter() {
561 new_before.push(*pat);
570 elems.map(|head| head.append(pats.slice_to(col)).append(pats.slice_from(col + 1)))
573 check_match::specialize(&mcx, pats.as_slice(), &ctor, col, variant_size)
581 // Returns the options in one column of matches. An option is something that
582 // needs to be conditionally matched at runtime; for example, the discriminant
583 // on a set of enum variants or a literal.
584 fn get_options(bcx: &Block, m: &[Match], col: uint) -> Vec<Opt> {
586 fn add_to_set(tcx: &ty::ctxt, set: &mut Vec<Opt>, val: Opt) {
587 if set.iter().any(|l| opt_eq(tcx, l, &val)) {return;}
590 // Vector comparisons are special in that since the actual
591 // conditions over-match, we need to be careful about them. This
592 // means that in order to properly handle things in order, we need
593 // to not always merge conditions.
594 fn add_veclen_to_set(set: &mut Vec<Opt> , i: uint,
595 len: uint, vlo: VecLenOpt) {
597 // If the last condition in the list matches the one we want
598 // to add, then extend its range. Otherwise, make a new
599 // vec_len with a range just covering the new entry.
600 Some(&vec_len(len2, vlo2, (start, end)))
601 if len == len2 && vlo == vlo2 => {
602 let length = set.len();
603 *set.get_mut(length - 1) =
604 vec_len(len, vlo, (start, end+1))
606 _ => set.push(vec_len(len, vlo, (i, i)))
610 let mut found = Vec::new();
611 for (i, br) in m.iter().enumerate() {
612 let cur = *br.pats.get(col);
615 add_to_set(ccx.tcx(), &mut found, lit(l));
617 ast::PatIdent(..) | ast::PatEnum(..) | ast::PatStruct(..) => {
618 // This is either an enum variant or a variable binding.
619 let opt_def = ccx.tcx.def_map.borrow().find_copy(&cur.id);
621 Some(def::DefVariant(enum_id, var_id, _)) => {
622 let variant = ty::enum_variant_with_id(ccx.tcx(), enum_id, var_id);
623 add_to_set(ccx.tcx(), &mut found,
624 var(variant.disr_val,
625 adt::represent_node(bcx, cur.id), var_id));
630 ast::PatRange(l1, l2) => {
631 add_to_set(ccx.tcx(), &mut found, range(l1, l2));
633 ast::PatVec(ref before, slice, ref after) => {
634 let (len, vec_opt) = match slice {
635 None => (before.len(), vec_len_eq),
636 Some(_) => (before.len() + after.len(),
637 vec_len_ge(before.len()))
639 add_veclen_to_set(&mut found, i, len, vec_opt);
647 struct ExtractedBlock<'a> {
648 vals: Vec<ValueRef> ,
652 fn extract_variant_args<'a>(
657 -> ExtractedBlock<'a> {
658 let _icx = push_ctxt("match::extract_variant_args");
659 let args = Vec::from_fn(adt::num_args(repr, disr_val), |i| {
660 adt::trans_field_ptr(bcx, repr, val, disr_val, i)
663 ExtractedBlock { vals: args, bcx: bcx }
666 fn match_datum(bcx: &Block,
671 * Helper for converting from the ValueRef that we pass around in
672 * the match code, which is always an lvalue, into a Datum. Eventually
673 * we should just pass around a Datum and be done with it.
676 let ty = node_id_type(bcx, pat_id);
677 Datum::new(val, ty, Lvalue)
681 fn extract_vec_elems<'a>(
687 -> ExtractedBlock<'a> {
688 let _icx = push_ctxt("match::extract_vec_elems");
689 let vec_datum = match_datum(bcx, val, pat_id);
690 let (base, len) = vec_datum.get_vec_base_and_len(bcx);
691 let vec_ty = node_id_type(bcx, pat_id);
692 let vt = tvec::vec_types(bcx, ty::sequence_element_type(bcx.tcx(), vec_ty));
694 let mut elems = Vec::from_fn(elem_count, |i| {
696 None => GEPi(bcx, base, [i]),
697 Some(n) if i < n => GEPi(bcx, base, [i]),
698 Some(n) if i > n => {
699 InBoundsGEP(bcx, base, [
701 C_int(bcx.ccx(), (elem_count - i) as int))])
703 _ => unsafe { llvm::LLVMGetUndef(vt.llunit_ty.to_ref()) }
707 let n = slice.unwrap();
708 let slice_byte_offset = Mul(bcx, vt.llunit_size, C_uint(bcx.ccx(), n));
709 let slice_begin = tvec::pointer_add_byte(bcx, base, slice_byte_offset);
710 let slice_len_offset = C_uint(bcx.ccx(), elem_count - 1u);
711 let slice_len = Sub(bcx, len, slice_len_offset);
712 let slice_ty = ty::mk_slice(bcx.tcx(),
714 ty::mt {ty: vt.unit_ty, mutbl: ast::MutImmutable});
715 let scratch = rvalue_scratch_datum(bcx, slice_ty, "");
716 Store(bcx, slice_begin,
717 GEPi(bcx, scratch.val, [0u, abi::slice_elt_base]));
718 Store(bcx, slice_len, GEPi(bcx, scratch.val, [0u, abi::slice_elt_len]));
719 *elems.get_mut(n) = scratch.val;
722 ExtractedBlock { vals: elems, bcx: bcx }
725 // Macro for deciding whether any of the remaining matches fit a given kind of
726 // pattern. Note that, because the macro is well-typed, either ALL of the
727 // matches should fit that sort of pattern or NONE (however, some of the
728 // matches may be wildcards like _ or identifiers).
729 macro_rules! any_pat (
730 ($m:expr, $col:expr, $pattern:pat) => (
731 ($m).iter().any(|br| {
732 match br.pats.get($col).node {
740 fn any_uniq_pat(m: &[Match], col: uint) -> bool {
741 any_pat!(m, col, ast::PatBox(_))
744 fn any_region_pat(m: &[Match], col: uint) -> bool {
745 any_pat!(m, col, ast::PatRegion(_))
748 fn any_irrefutable_adt_pat(bcx: &Block, m: &[Match], col: uint) -> bool {
750 let pat = *br.pats.get(col);
752 ast::PatTup(_) => true,
753 ast::PatStruct(..) => {
754 match bcx.tcx().def_map.borrow().find(&pat.id) {
755 Some(&def::DefVariant(..)) => false,
759 ast::PatEnum(..) | ast::PatIdent(_, _, None) => {
760 match bcx.tcx().def_map.borrow().find(&pat.id) {
761 Some(&def::DefFn(..)) |
762 Some(&def::DefStruct(..)) => true,
771 /// What to do when the pattern match fails.
772 enum FailureHandler<'a> {
774 JumpToBasicBlock(BasicBlockRef),
778 impl<'a> FailureHandler<'a> {
779 fn is_infallible(&self) -> bool {
786 fn is_fallible(&self) -> bool {
787 !self.is_infallible()
790 fn handle_fail(&self, bcx: &Block) {
793 fail!("attempted to fail in infallible failure handler!"),
794 JumpToBasicBlock(basic_block) =>
795 Br(bcx, basic_block),
797 build::Unreachable(bcx)
802 fn pick_col(m: &[Match]) -> uint {
803 fn score(p: &ast::Pat) -> uint {
805 ast::PatLit(_) | ast::PatEnum(_, _) | ast::PatRange(_, _) => 1u,
806 ast::PatIdent(_, _, Some(ref p)) => score(&**p),
810 let mut scores = Vec::from_elem(m[0].pats.len(), 0u);
812 for (i, ref p) in br.pats.iter().enumerate() {
813 *scores.get_mut(i) += score(&***p);
816 let mut max_score = 0u;
817 let mut best_col = 0u;
818 for (i, score) in scores.iter().enumerate() {
821 // Irrefutable columns always go first, they'd only be duplicated in
823 if score == 0u { return i; }
824 // If no irrefutable ones are found, we pick the one with the biggest
826 if score > max_score { max_score = score; best_col = i; }
831 #[deriving(PartialEq)]
832 pub enum branch_kind { no_branch, single, switch, compare, compare_vec_len }
834 // Compiles a comparison between two things.
835 fn compare_values<'a>(
841 fn compare_str<'a>(cx: &'a Block<'a>,
846 let did = langcall(cx,
848 format!("comparison of `{}`",
849 cx.ty_to_string(rhs_t)).as_slice(),
851 callee::trans_lang_call(cx, did, [lhs, rhs], None)
854 let _icx = push_ctxt("compare_values");
855 if ty::type_is_scalar(rhs_t) {
856 let rs = compare_scalar_types(cx, lhs, rhs, rhs_t, ast::BiEq);
857 return Result::new(rs.bcx, rs.val);
860 match ty::get(rhs_t).sty {
861 ty::ty_rptr(_, mt) => match ty::get(mt.ty).sty {
862 ty::ty_str => compare_str(cx, lhs, rhs, rhs_t),
863 ty::ty_vec(mt, _) => match ty::get(mt.ty).sty {
864 ty::ty_uint(ast::TyU8) => {
865 // NOTE: cast &[u8] to &str and abuse the str_eq lang item,
866 // which calls memcmp().
867 let t = ty::mk_str_slice(cx.tcx(), ty::ReStatic, ast::MutImmutable);
868 let lhs = BitCast(cx, lhs, type_of::type_of(cx.ccx(), t).ptr_to());
869 let rhs = BitCast(cx, rhs, type_of::type_of(cx.ccx(), t).ptr_to());
870 compare_str(cx, lhs, rhs, rhs_t)
872 _ => cx.sess().bug("only byte strings supported in compare_values"),
874 _ => cx.sess().bug("only string and byte strings supported in compare_values"),
876 _ => cx.sess().bug("only scalars, byte strings, and strings supported in compare_values"),
880 fn insert_lllocals<'a>(mut bcx: &'a Block<'a>, bindings_map: &BindingsMap,
881 cs: Option<cleanup::ScopeId>)
884 * For each binding in `data.bindings_map`, adds an appropriate entry into
885 * the `fcx.lllocals` map
888 for (&ident, &binding_info) in bindings_map.iter() {
889 let llval = match binding_info.trmode {
890 // By value mut binding for a copy type: load from the ptr
891 // into the matched value and copy to our alloca
892 TrByCopy(llbinding) => {
893 let llval = Load(bcx, binding_info.llmatch);
894 let datum = Datum::new(llval, binding_info.ty, Lvalue);
895 bcx = datum.store_to(bcx, llbinding);
900 // By value move bindings: load from the ptr into the matched value
901 TrByMove => Load(bcx, binding_info.llmatch),
903 // By ref binding: use the ptr into the matched value
904 TrByRef => binding_info.llmatch
907 let datum = Datum::new(llval, binding_info.ty, Lvalue);
909 Some(cs) => bcx.fcx.schedule_drop_and_zero_mem(cs, llval, binding_info.ty),
913 debug!("binding {:?} to {}",
915 bcx.val_to_string(llval));
916 bcx.fcx.lllocals.borrow_mut().insert(binding_info.id, datum);
918 if bcx.sess().opts.debuginfo == FullDebugInfo {
919 debuginfo::create_match_binding_metadata(bcx,
927 fn compile_guard<'a, 'b>(
929 guard_expr: &ast::Expr,
931 m: &'a [Match<'a, 'b>],
933 chk: &FailureHandler,
934 has_genuine_default: bool)
936 debug!("compile_guard(bcx={}, guard_expr={}, m={}, vals={})",
938 bcx.expr_to_string(guard_expr),
940 vec_map_to_string(vals, |v| bcx.val_to_string(*v)));
941 let _indenter = indenter();
943 let mut bcx = insert_lllocals(bcx, &data.bindings_map, None);
945 let val = unpack_datum!(bcx, expr::trans(bcx, guard_expr));
946 let val = val.to_llbool(bcx);
948 return with_cond(bcx, Not(bcx, val), |bcx| {
949 // Guard does not match: remove all bindings from the lllocals table
950 for (_, &binding_info) in data.bindings_map.iter() {
951 bcx.fcx.lllocals.borrow_mut().remove(&binding_info.id);
954 // If the default arm is the only one left, move on to the next
955 // condition explicitly rather than (possibly) falling back to
957 &JumpToBasicBlock(_) if m.len() == 1 && has_genuine_default => {
958 chk.handle_fail(bcx);
961 compile_submatch(bcx, m, vals, chk, has_genuine_default);
968 fn compile_submatch<'a, 'b>(
970 m: &'a [Match<'a, 'b>],
972 chk: &FailureHandler,
973 has_genuine_default: bool) {
974 debug!("compile_submatch(bcx={}, m={}, vals={})",
977 vec_map_to_string(vals, |v| bcx.val_to_string(*v)));
978 let _indenter = indenter();
979 let _icx = push_ctxt("match::compile_submatch");
982 if chk.is_fallible() {
983 chk.handle_fail(bcx);
987 if m[0].pats.len() == 0u {
988 let data = &m[0].data;
989 for &(ref ident, ref value_ptr) in m[0].bound_ptrs.iter() {
990 let llmatch = data.bindings_map.get(ident).llmatch;
991 Store(bcx, *value_ptr, llmatch);
993 match data.arm.guard {
994 Some(ref guard_expr) => {
995 bcx = compile_guard(bcx,
1001 has_genuine_default);
1005 Br(bcx, data.bodycx.llbb);
1009 let col = pick_col(m);
1010 let val = vals[col];
1012 if has_nested_bindings(m, col) {
1013 let expanded = expand_nested_bindings(bcx, m, col, val);
1014 compile_submatch_continue(bcx,
1015 expanded.as_slice(),
1020 has_genuine_default)
1022 compile_submatch_continue(bcx, m, vals, chk, col, val, has_genuine_default)
1026 fn compile_submatch_continue<'a, 'b>(
1027 mut bcx: &'b Block<'b>,
1028 m: &'a [Match<'a, 'b>],
1030 chk: &FailureHandler,
1033 has_genuine_default: bool) {
1035 let tcx = bcx.tcx();
1036 let dm = &tcx.def_map;
1038 let vals_left = Vec::from_slice(vals.slice(0u, col)).append(vals.slice(col + 1u, vals.len()));
1039 let ccx = bcx.fcx.ccx;
1041 // Find a real id (we're adding placeholder wildcard patterns, but
1042 // each column is guaranteed to have at least one real pattern)
1043 let pat_id = m.iter().map(|br| br.pats.get(col).id).find(|&id| id != 0).unwrap_or(0);
1045 let left_ty = if pat_id == 0 {
1048 node_id_type(bcx, pat_id)
1051 let mcx = check_match::MatchCheckCtxt { tcx: bcx.tcx() };
1052 let adt_vals = if any_irrefutable_adt_pat(bcx, m, col) {
1053 let repr = adt::represent_type(bcx.ccx(), left_ty);
1054 let arg_count = adt::num_args(&*repr, 0);
1055 let field_vals: Vec<ValueRef> = std::iter::range(0, arg_count).map(|ix|
1056 adt::trans_field_ptr(bcx, &*repr, val, 0, ix)
1059 } else if any_uniq_pat(m, col) || any_region_pat(m, col) {
1060 Some(vec!(Load(bcx, val)))
1066 Some(field_vals) => {
1067 let pats = enter_match(bcx, dm, m, col, val, |pats|
1068 check_match::specialize(&mcx, pats, &check_match::Single, col, field_vals.len())
1070 let vals = field_vals.append(vals_left.as_slice());
1071 compile_submatch(bcx, pats.as_slice(), vals.as_slice(), chk, has_genuine_default);
1077 // Decide what kind of branch we need
1078 let opts = get_options(bcx, m, col);
1079 debug!("options={:?}", opts);
1080 let mut kind = no_branch;
1081 let mut test_val = val;
1082 debug!("test_val={}", bcx.val_to_string(test_val));
1083 if opts.len() > 0u {
1084 match *opts.get(0) {
1085 var(_, ref repr, _) => {
1086 let (the_kind, val_opt) = adt::trans_switch(bcx, &**repr, val);
1088 for &tval in val_opt.iter() { test_val = tval; }
1091 test_val = load_if_immediate(bcx, val, left_ty);
1092 kind = if ty::type_is_integral(left_ty) { switch }
1096 test_val = Load(bcx, val);
1100 let (_, len) = tvec::get_base_and_len(bcx, val, left_ty);
1102 kind = compare_vec_len;
1106 for o in opts.iter() {
1108 range(_, _) => { kind = compare; break }
1112 let else_cx = match kind {
1113 no_branch | single => bcx,
1114 _ => bcx.fcx.new_temp_block("match_else")
1116 let sw = if kind == switch {
1117 Switch(bcx, test_val, else_cx.llbb, opts.len())
1119 C_int(ccx, 0) // Placeholder for when not using a switch
1122 let defaults = enter_default(else_cx, dm, m, col, val);
1123 let exhaustive = chk.is_infallible() && defaults.len() == 0u;
1124 let len = opts.len();
1126 // Compile subtrees for each option
1127 for (i, opt) in opts.iter().enumerate() {
1128 // In some cases of range and vector pattern matching, we need to
1129 // override the failure case so that instead of failing, it proceeds
1130 // to try more matching. branch_chk, then, is the proper failure case
1131 // for the current conditional branch.
1132 let mut branch_chk = None;
1133 let mut opt_cx = else_cx;
1134 if !exhaustive || i+1 < len {
1135 opt_cx = bcx.fcx.new_temp_block("match_case");
1137 single => Br(bcx, opt_cx.llbb),
1139 match trans_opt(bcx, opt) {
1140 single_result(r) => {
1142 llvm::LLVMAddCase(sw, r.val, opt_cx.llbb);
1148 "in compile_submatch, expected \
1149 trans_opt to return a single_result")
1153 compare | compare_vec_len => {
1154 let t = if kind == compare {
1157 ty::mk_uint() // vector length
1159 let Result {bcx: after_cx, val: matches} = {
1160 match trans_opt(bcx, opt) {
1161 single_result(Result {bcx, val}) => {
1162 compare_values(bcx, test_val, val, t)
1164 lower_bound(Result {bcx, val}) => {
1165 compare_scalar_types(bcx, test_val, val, t, ast::BiGe)
1167 range_result(Result {val: vbegin, ..},
1168 Result {bcx, val: vend}) => {
1169 let Result {bcx, val: llge} =
1170 compare_scalar_types(
1172 vbegin, t, ast::BiGe);
1173 let Result {bcx, val: llle} =
1174 compare_scalar_types(
1175 bcx, test_val, vend,
1177 Result::new(bcx, And(bcx, llge, llle))
1181 bcx = fcx.new_temp_block("compare_next");
1183 // If none of the sub-cases match, and the current condition
1184 // is guarded or has multiple patterns, move on to the next
1185 // condition, if there is any, rather than falling back to
1187 let guarded = m[i].data.arm.guard.is_some();
1188 let multi_pats = m[i].pats.len() > 1;
1189 if i + 1 < len && (guarded || multi_pats || kind == compare_vec_len) {
1190 branch_chk = Some(JumpToBasicBlock(bcx.llbb));
1192 CondBr(after_cx, matches, opt_cx.llbb, bcx.llbb);
1196 } else if kind == compare || kind == compare_vec_len {
1197 Br(bcx, else_cx.llbb);
1201 let mut unpacked = Vec::new();
1203 var(disr_val, ref repr, _) => {
1204 let ExtractedBlock {vals: argvals, bcx: new_bcx} =
1205 extract_variant_args(opt_cx, &**repr, disr_val, val);
1206 size = argvals.len();
1210 vec_len(n, vt, _) => {
1211 let (n, slice) = match vt {
1212 vec_len_ge(i) => (n + 1u, Some(i)),
1213 vec_len_eq => (n, None)
1215 let args = extract_vec_elems(opt_cx, pat_id, n,
1217 size = args.vals.len();
1218 unpacked = args.vals.clone();
1221 lit(_) | range(_, _) => ()
1223 let opt_ms = enter_opt(opt_cx, pat_id, dm, m, opt, col, size, val);
1224 let opt_vals = unpacked.append(vals_left.as_slice());
1228 compile_submatch(opt_cx,
1230 opt_vals.as_slice(),
1232 has_genuine_default)
1234 Some(branch_chk) => {
1235 compile_submatch(opt_cx,
1237 opt_vals.as_slice(),
1239 has_genuine_default)
1244 // Compile the fall-through case, if any
1245 if !exhaustive && kind != single {
1246 if kind == compare || kind == compare_vec_len {
1247 Br(bcx, else_cx.llbb);
1250 // If there is only one default arm left, move on to the next
1251 // condition explicitly rather than (eventually) falling back to
1252 // the last default arm.
1253 &JumpToBasicBlock(_) if defaults.len() == 1 && has_genuine_default => {
1254 chk.handle_fail(else_cx);
1257 compile_submatch(else_cx,
1258 defaults.as_slice(),
1259 vals_left.as_slice(),
1261 has_genuine_default);
1267 pub fn trans_match<'a>(
1269 match_expr: &ast::Expr,
1270 discr_expr: &ast::Expr,
1274 let _icx = push_ctxt("match::trans_match");
1275 trans_match_inner(bcx, match_expr.id, discr_expr, arms, dest)
1278 fn create_bindings_map(bcx: &Block, pat: Gc<ast::Pat>) -> BindingsMap {
1279 // Create the bindings map, which is a mapping from each binding name
1280 // to an alloca() that will be the value for that local variable.
1281 // Note that we use the names because each binding will have many ids
1282 // from the various alternatives.
1283 let ccx = bcx.ccx();
1284 let tcx = bcx.tcx();
1285 let mut bindings_map = HashMap::new();
1286 pat_bindings(&tcx.def_map, &*pat, |bm, p_id, span, path1| {
1287 let ident = path1.node;
1288 let variable_ty = node_id_type(bcx, p_id);
1289 let llvariable_ty = type_of::type_of(ccx, variable_ty);
1290 let tcx = bcx.tcx();
1296 if !ty::type_moves_by_default(tcx, variable_ty) => {
1297 llmatch = alloca(bcx,
1298 llvariable_ty.ptr_to(),
1300 trmode = TrByCopy(alloca(bcx,
1302 bcx.ident(ident).as_slice()));
1304 ast::BindByValue(_) => {
1305 // in this case, the final type of the variable will be T,
1306 // but during matching we need to store a *T as explained
1308 llmatch = alloca(bcx,
1309 llvariable_ty.ptr_to(),
1310 bcx.ident(ident).as_slice());
1313 ast::BindByRef(_) => {
1314 llmatch = alloca(bcx,
1316 bcx.ident(ident).as_slice());
1320 bindings_map.insert(ident, BindingInfo {
1328 return bindings_map;
1331 fn trans_match_inner<'a>(scope_cx: &'a Block<'a>,
1332 match_id: ast::NodeId,
1333 discr_expr: &ast::Expr,
1335 dest: Dest) -> &'a Block<'a> {
1336 let _icx = push_ctxt("match::trans_match_inner");
1337 let fcx = scope_cx.fcx;
1338 let mut bcx = scope_cx;
1339 let tcx = bcx.tcx();
1341 let discr_datum = unpack_datum!(bcx, expr::trans_to_lvalue(bcx, discr_expr,
1343 if bcx.unreachable.get() {
1347 let t = node_id_type(bcx, discr_expr.id);
1348 let chk = if ty::type_is_empty(tcx, t) {
1354 let arm_datas: Vec<ArmData> = arms.iter().map(|arm| ArmData {
1355 bodycx: fcx.new_id_block("case_body", arm.body.id),
1357 bindings_map: create_bindings_map(bcx, *arm.pats.get(0))
1360 let mut static_inliner = StaticInliner { tcx: scope_cx.tcx() };
1361 let mut matches = Vec::new();
1362 for arm_data in arm_datas.iter() {
1363 matches.extend(arm_data.arm.pats.iter().map(|&p| Match {
1364 pats: vec![static_inliner.fold_pat(p)],
1366 bound_ptrs: Vec::new(),
1370 // `compile_submatch` works one column of arm patterns a time and
1371 // then peels that column off. So as we progress, it may become
1372 // impossible to tell whether we have a genuine default arm, i.e.
1373 // `_ => foo` or not. Sometimes it is important to know that in order
1374 // to decide whether moving on to the next condition or falling back
1375 // to the default arm.
1376 let has_default = arms.last().map_or(false, |arm| {
1378 && arm.pats.last().unwrap().node == ast::PatWild
1381 compile_submatch(bcx, matches.as_slice(), [discr_datum.val], &chk, has_default);
1383 let mut arm_cxs = Vec::new();
1384 for arm_data in arm_datas.iter() {
1385 let mut bcx = arm_data.bodycx;
1387 // insert bindings into the lllocals map and add cleanups
1388 let cs = fcx.push_custom_cleanup_scope();
1389 bcx = insert_lllocals(bcx, &arm_data.bindings_map, Some(cleanup::CustomScope(cs)));
1390 bcx = expr::trans_into(bcx, &*arm_data.arm.body, dest);
1391 bcx = fcx.pop_and_trans_custom_cleanup_scope(bcx, cs);
1395 bcx = scope_cx.fcx.join_blocks(match_id, arm_cxs.as_slice());
1399 enum IrrefutablePatternBindingMode {
1400 // Stores the association between node ID and LLVM value in `lllocals`.
1402 // Stores the association between node ID and LLVM value in `llargs`.
1406 pub fn store_local<'a>(bcx: &'a Block<'a>,
1410 * Generates code for a local variable declaration like
1411 * `let <pat>;` or `let <pat> = <opt_init_expr>`.
1413 let _icx = push_ctxt("match::store_local");
1415 let tcx = bcx.tcx();
1416 let pat = local.pat;
1417 let opt_init_expr = local.init;
1419 return match opt_init_expr {
1420 Some(init_expr) => {
1421 // Optimize the "let x = expr" case. This just writes
1422 // the result of evaluating `expr` directly into the alloca
1423 // for `x`. Often the general path results in similar or the
1424 // same code post-optimization, but not always. In particular,
1425 // in unsafe code, you can have expressions like
1427 // let x = intrinsics::uninit();
1429 // In such cases, the more general path is unsafe, because
1430 // it assumes it is matching against a valid value.
1431 match simple_identifier(&*pat) {
1433 let var_scope = cleanup::var_scope(tcx, local.id);
1434 return mk_binding_alloca(
1435 bcx, pat.id, ident, BindLocal, var_scope, (),
1436 |(), bcx, v, _| expr::trans_into(bcx, &*init_expr,
1445 unpack_datum!(bcx, expr::trans_to_lvalue(bcx, &*init_expr, "let"));
1446 if ty::type_is_bot(expr_ty(bcx, &*init_expr)) {
1447 create_dummy_locals(bcx, pat)
1449 if bcx.sess().asm_comments() {
1450 add_comment(bcx, "creating zeroable ref llval");
1452 let var_scope = cleanup::var_scope(tcx, local.id);
1453 bind_irrefutable_pat(bcx, pat, init_datum.val, BindLocal, var_scope)
1457 create_dummy_locals(bcx, pat)
1461 fn create_dummy_locals<'a>(mut bcx: &'a Block<'a>,
1464 // create dummy memory for the variables if we have no
1465 // value to store into them immediately
1466 let tcx = bcx.tcx();
1467 pat_bindings(&tcx.def_map, &*pat, |_, p_id, _, path1| {
1468 let scope = cleanup::var_scope(tcx, p_id);
1469 bcx = mk_binding_alloca(
1470 bcx, p_id, &path1.node, BindLocal, scope, (),
1471 |(), bcx, llval, ty| { zero_mem(bcx, llval, ty); bcx });
1477 pub fn store_arg<'a>(mut bcx: &'a Block<'a>,
1480 arg_scope: cleanup::ScopeId)
1483 * Generates code for argument patterns like `fn foo(<pat>: T)`.
1484 * Creates entries in the `llargs` map for each of the bindings
1489 * - `pat` is the argument pattern
1490 * - `llval` is a pointer to the argument value (in other words,
1491 * if the argument type is `T`, then `llval` is a `T*`). In some
1492 * cases, this code may zero out the memory `llval` points at.
1495 let _icx = push_ctxt("match::store_arg");
1497 match simple_identifier(&*pat) {
1499 // Generate nicer LLVM for the common case of fn a pattern
1501 let arg_ty = node_id_type(bcx, pat.id);
1502 if type_of::arg_is_indirect(bcx.ccx(), arg_ty)
1503 && bcx.sess().opts.debuginfo != FullDebugInfo {
1504 // Don't copy an indirect argument to an alloca, the caller
1505 // already put it in a temporary alloca and gave it up, unless
1506 // we emit extra-debug-info, which requires local allocas :(.
1507 let arg_val = arg.add_clean(bcx.fcx, arg_scope);
1508 bcx.fcx.llargs.borrow_mut()
1509 .insert(pat.id, Datum::new(arg_val, arg_ty, Lvalue));
1513 bcx, pat.id, ident, BindArgument, arg_scope, arg,
1514 |arg, bcx, llval, _| arg.store_to(bcx, llval))
1519 // General path. Copy out the values that are used in the
1521 let arg = unpack_datum!(
1522 bcx, arg.to_lvalue_datum_in_scope(bcx, "__arg", arg_scope));
1523 bind_irrefutable_pat(bcx, pat, arg.val,
1524 BindArgument, arg_scope)
1529 fn mk_binding_alloca<'a,A>(bcx: &'a Block<'a>,
1532 binding_mode: IrrefutablePatternBindingMode,
1533 cleanup_scope: cleanup::ScopeId,
1535 populate: |A, &'a Block<'a>, ValueRef, ty::t| -> &'a Block<'a>)
1537 let var_ty = node_id_type(bcx, p_id);
1539 // Allocate memory on stack for the binding.
1540 let llval = alloc_ty(bcx, var_ty, bcx.ident(*ident).as_slice());
1542 // Subtle: be sure that we *populate* the memory *before*
1543 // we schedule the cleanup.
1544 let bcx = populate(arg, bcx, llval, var_ty);
1545 bcx.fcx.schedule_lifetime_end(cleanup_scope, llval);
1546 bcx.fcx.schedule_drop_mem(cleanup_scope, llval, var_ty);
1548 // Now that memory is initialized and has cleanup scheduled,
1549 // create the datum and insert into the local variable map.
1550 let datum = Datum::new(llval, var_ty, Lvalue);
1551 let mut llmap = match binding_mode {
1552 BindLocal => bcx.fcx.lllocals.borrow_mut(),
1553 BindArgument => bcx.fcx.llargs.borrow_mut()
1555 llmap.insert(p_id, datum);
1559 fn bind_irrefutable_pat<'a>(
1563 binding_mode: IrrefutablePatternBindingMode,
1564 cleanup_scope: cleanup::ScopeId)
1567 * A simple version of the pattern matching code that only handles
1568 * irrefutable patterns. This is used in let/argument patterns,
1569 * not in match statements. Unifying this code with the code above
1570 * sounds nice, but in practice it produces very inefficient code,
1571 * since the match code is so much more general. In most cases,
1572 * LLVM is able to optimize the code, but it causes longer compile
1573 * times and makes the generated code nigh impossible to read.
1576 * - bcx: starting basic block context
1577 * - pat: the irrefutable pattern being matched.
1578 * - val: the value being matched -- must be an lvalue (by ref, with cleanup)
1579 * - binding_mode: is this for an argument or a local variable?
1582 debug!("bind_irrefutable_pat(bcx={}, pat={}, binding_mode={:?})",
1584 pat.repr(bcx.tcx()),
1587 if bcx.sess().asm_comments() {
1588 add_comment(bcx, format!("bind_irrefutable_pat(pat={})",
1589 pat.repr(bcx.tcx())).as_slice());
1592 let _indenter = indenter();
1594 let _icx = push_ctxt("match::bind_irrefutable_pat");
1596 let tcx = bcx.tcx();
1597 let ccx = bcx.ccx();
1599 ast::PatIdent(pat_binding_mode, ref path1, inner) => {
1600 if pat_is_binding(&tcx.def_map, &*pat) {
1601 // Allocate the stack slot where the value of this
1602 // binding will live and place it into the appropriate
1604 bcx = mk_binding_alloca(
1605 bcx, pat.id, &path1.node, binding_mode, cleanup_scope, (),
1606 |(), bcx, llval, ty| {
1607 match pat_binding_mode {
1608 ast::BindByValue(_) => {
1609 // By value binding: move the value that `val`
1610 // points at into the binding's stack slot.
1611 let d = Datum::new(val, ty, Lvalue);
1612 d.store_to(bcx, llval)
1615 ast::BindByRef(_) => {
1616 // By ref binding: the value of the variable
1617 // is the pointer `val` itself.
1618 Store(bcx, val, llval);
1625 for &inner_pat in inner.iter() {
1626 bcx = bind_irrefutable_pat(bcx, inner_pat, val,
1627 binding_mode, cleanup_scope);
1630 ast::PatEnum(_, ref sub_pats) => {
1631 let opt_def = bcx.tcx().def_map.borrow().find_copy(&pat.id);
1633 Some(def::DefVariant(enum_id, var_id, _)) => {
1634 let repr = adt::represent_node(bcx, pat.id);
1635 let vinfo = ty::enum_variant_with_id(ccx.tcx(),
1638 let args = extract_variant_args(bcx,
1642 for sub_pat in sub_pats.iter() {
1643 for (i, argval) in args.vals.iter().enumerate() {
1644 bcx = bind_irrefutable_pat(bcx, *sub_pat.get(i),
1645 *argval, binding_mode,
1650 Some(def::DefFn(..)) |
1651 Some(def::DefStruct(..)) => {
1654 // This is a unit-like struct. Nothing to do here.
1656 Some(ref elems) => {
1657 // This is the tuple struct case.
1658 let repr = adt::represent_node(bcx, pat.id);
1659 for (i, elem) in elems.iter().enumerate() {
1660 let fldptr = adt::trans_field_ptr(bcx, &*repr,
1662 bcx = bind_irrefutable_pat(bcx, *elem,
1663 fldptr, binding_mode,
1670 // Nothing to do here.
1674 ast::PatStruct(_, ref fields, _) => {
1675 let tcx = bcx.tcx();
1676 let pat_ty = node_id_type(bcx, pat.id);
1677 let pat_repr = adt::represent_type(bcx.ccx(), pat_ty);
1678 expr::with_field_tys(tcx, pat_ty, Some(pat.id), |discr, field_tys| {
1679 for f in fields.iter() {
1680 let ix = ty::field_idx_strict(tcx, f.ident.name, field_tys);
1681 let fldptr = adt::trans_field_ptr(bcx, &*pat_repr, val,
1683 bcx = bind_irrefutable_pat(bcx, f.pat, fldptr,
1684 binding_mode, cleanup_scope);
1688 ast::PatTup(ref elems) => {
1689 let repr = adt::represent_node(bcx, pat.id);
1690 for (i, elem) in elems.iter().enumerate() {
1691 let fldptr = adt::trans_field_ptr(bcx, &*repr, val, 0, i);
1692 bcx = bind_irrefutable_pat(bcx, *elem, fldptr,
1693 binding_mode, cleanup_scope);
1696 ast::PatBox(inner) => {
1697 let llbox = Load(bcx, val);
1698 bcx = bind_irrefutable_pat(bcx, inner, llbox, binding_mode, cleanup_scope);
1700 ast::PatRegion(inner) => {
1701 let loaded_val = Load(bcx, val);
1702 bcx = bind_irrefutable_pat(bcx, inner, loaded_val, binding_mode, cleanup_scope);
1704 ast::PatVec(ref before, ref slice, ref after) => {
1705 let extracted = extract_vec_elems(
1706 bcx, pat.id, before.len() + 1u + after.len(),
1707 slice.map(|_| before.len()), val
1710 .iter().map(|v| Some(*v))
1711 .chain(Some(*slice).move_iter())
1712 .chain(after.iter().map(|v| Some(*v)))
1713 .zip(extracted.vals.iter())
1714 .fold(bcx, |bcx, (inner, elem)| {
1715 inner.map_or(bcx, |inner| {
1716 bind_irrefutable_pat(bcx, inner, *elem, binding_mode, cleanup_scope)
1720 ast::PatMac(..) => {
1721 bcx.sess().span_bug(pat.span, "unexpanded macro");
1723 ast::PatWild | ast::PatWildMulti | ast::PatLit(_) | ast::PatRange(_, _) => ()