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.
11 //! # Compilation of match statements
13 //! I will endeavor to explain the code as best I can. I have only a loose
14 //! understanding of some parts of it.
18 //! The basic state of the code is maintained in an array `m` of `Match`
19 //! objects. Each `Match` describes some list of patterns, all of which must
20 //! match against the current list of values. If those patterns match, then
21 //! the arm listed in the match is the correct arm. A given arm may have
22 //! multiple corresponding match entries, one for each alternative that
23 //! remains. As we proceed these sets of matches are adjusted by the various
24 //! `enter_XXX()` functions, each of which adjusts the set of options given
25 //! some information about the value which has been matched.
27 //! So, initially, there is one value and N matches, each of which have one
28 //! constituent pattern. N here is usually the number of arms but may be
29 //! greater, if some arms have multiple alternatives. For example, here:
31 //! enum Foo { A, B(int), C(uint, uint) }
39 //! The value would be `foo`. There would be four matches, each of which
40 //! contains one pattern (and, in one case, a guard). We could collect the
41 //! various options and then compile the code for the case where `foo` is an
42 //! `A`, a `B`, and a `C`. When we generate the code for `C`, we would (1)
43 //! drop the two matches that do not match a `C` and (2) expand the other two
44 //! into two patterns each. In the first case, the two patterns would be `1`
45 //! and `2`, and the in the second case the _ pattern would be expanded into
46 //! `_` and `_`. The two values are of course the arguments to `C`.
48 //! Here is a quick guide to the various functions:
50 //! - `compile_submatch()`: The main workhouse. It takes a list of values and
51 //! a list of matches and finds the various possibilities that could occur.
53 //! - `enter_XXX()`: modifies the list of matches based on some information
54 //! about the value that has been matched. For example,
55 //! `enter_rec_or_struct()` adjusts the values given that a record or struct
56 //! has been matched. This is an infallible pattern, so *all* of the matches
57 //! must be either wildcards or record/struct patterns. `enter_opt()`
58 //! handles the fallible cases, and it is correspondingly more complex.
62 //! We store information about the bound variables for each arm as part of the
63 //! per-arm `ArmData` struct. There is a mapping from identifiers to
64 //! `BindingInfo` structs. These structs contain the mode/id/type of the
65 //! binding, but they also contain an LLVM value which points at an alloca
66 //! called `llmatch`. For by value bindings that are Copy, we also create
67 //! an extra alloca that we copy the matched value to so that any changes
68 //! we do to our copy is not reflected in the original and vice-versa.
69 //! We don't do this if it's a move since the original value can't be used
70 //! and thus allowing us to cheat in not creating an extra alloca.
72 //! The `llmatch` binding always stores a pointer into the value being matched
73 //! which points at the data for the binding. If the value being matched has
74 //! type `T`, then, `llmatch` will point at an alloca of type `T*` (and hence
75 //! `llmatch` has type `T**`). So, if you have a pattern like:
79 //! match (a, b) { (ref c, d) => { ... } }
81 //! For `c` and `d`, we would generate allocas of type `C*` and `D*`
82 //! respectively. These are called the `llmatch`. As we match, when we come
83 //! up against an identifier, we store the current pointer into the
84 //! corresponding alloca.
86 //! Once a pattern is completely matched, and assuming that there is no guard
87 //! pattern, we will branch to a block that leads to the body itself. For any
88 //! by-value bindings, this block will first load the ptr from `llmatch` (the
89 //! one of type `D*`) and then load a second time to get the actual value (the
90 //! one of type `D`). For by ref bindings, the value of the local variable is
91 //! simply the first alloca.
93 //! So, for the example above, we would generate a setup kind of like this:
99 //! +--------------------------------------------+
100 //! | llmatch_c = (addr of first half of tuple) |
101 //! | llmatch_d = (addr of second half of tuple) |
102 //! +--------------------------------------------+
104 //! +--------------------------------------+
105 //! | *llbinding_d = **llmatch_d |
106 //! +--------------------------------------+
108 //! If there is a guard, the situation is slightly different, because we must
109 //! execute the guard code. Moreover, we need to do so once for each of the
110 //! alternatives that lead to the arm, because if the guard fails, they may
111 //! have different points from which to continue the search. Therefore, in that
112 //! case, we generate code that looks more like:
118 //! +-------------------------------------------+
119 //! | llmatch_c = (addr of first half of tuple) |
120 //! | llmatch_d = (addr of first half of tuple) |
121 //! +-------------------------------------------+
123 //! +-------------------------------------------------+
124 //! | *llbinding_d = **llmatch_d |
125 //! | check condition |
126 //! | if false { goto next case } |
127 //! | if true { goto body } |
128 //! +-------------------------------------------------+
130 //! The handling for the cleanups is a bit... sensitive. Basically, the body
131 //! is the one that invokes `add_clean()` for each binding. During the guard
132 //! evaluation, we add temporary cleanups and revoke them after the guard is
133 //! evaluated (it could fail, after all). Note that guards and moves are
134 //! just plain incompatible.
136 //! Some relevant helper functions that manage bindings:
137 //! - `create_bindings_map()`
138 //! - `insert_lllocals()`
141 //! ## Notes on vector pattern matching.
143 //! Vector pattern matching is surprisingly tricky. The problem is that
144 //! the structure of the vector isn't fully known, and slice matches
145 //! can be done on subparts of it.
147 //! The way that vector pattern matches are dealt with, then, is as
148 //! follows. First, we make the actual condition associated with a
149 //! vector pattern simply a vector length comparison. So the pattern
150 //! [1, .. x] gets the condition "vec len >= 1", and the pattern
151 //! [.. x] gets the condition "vec len >= 0". The problem here is that
152 //! having the condition "vec len >= 1" hold clearly does not mean that
153 //! only a pattern that has exactly that condition will match. This
154 //! means that it may well be the case that a condition holds, but none
155 //! of the patterns matching that condition match; to deal with this,
156 //! when doing vector length matches, we have match failures proceed to
157 //! the next condition to check.
159 //! There are a couple more subtleties to deal with. While the "actual"
160 //! condition associated with vector length tests is simply a test on
161 //! the vector length, the actual vec_len Opt entry contains more
162 //! information used to restrict which matches are associated with it.
163 //! So that all matches in a submatch are matching against the same
164 //! values from inside the vector, they are split up by how many
165 //! elements they match at the front and at the back of the vector. In
166 //! order to make sure that arms are properly checked in order, even
167 //! with the overmatching conditions, each vec_len Opt entry is
168 //! associated with a range of matches.
169 //! Consider the following:
171 //! match &[1, 2, 3] {
172 //! [1, 1, .. _] => 0,
173 //! [1, 2, 2, .. _] => 1,
174 //! [1, 2, 3, .. _] => 2,
175 //! [1, 2, .. _] => 3,
178 //! The proper arm to match is arm 2, but arms 0 and 3 both have the
179 //! condition "len >= 2". If arm 3 was lumped in with arm 0, then the
180 //! wrong branch would be taken. Instead, vec_len Opts are associated
181 //! with a contiguous range of matches that have the same "shape".
182 //! This is sort of ugly and requires a bunch of special handling of
185 pub use self::BranchKind::*;
186 pub use self::OptResult::*;
187 pub use self::TransBindingMode::*;
189 use self::FailureHandler::*;
192 use llvm::{ValueRef, BasicBlockRef};
193 use middle::check_match::StaticInliner;
194 use middle::check_match;
195 use middle::const_eval;
196 use middle::def::{self, DefMap};
197 use middle::expr_use_visitor as euv;
198 use middle::lang_items::StrEqFnLangItem;
199 use middle::mem_categorization as mc;
200 use middle::pat_util::*;
203 use trans::build::{AddCase, And, BitCast, Br, CondBr, GEPi, InBoundsGEP, Load};
204 use trans::build::{Not, Store, Sub, add_comment};
207 use trans::cleanup::{self, CleanupMethods};
208 use trans::common::*;
211 use trans::debuginfo::{self, DebugLoc, ToDebugLoc};
212 use trans::expr::{self, Dest};
215 use middle::ty::{self, Ty};
216 use session::config::{NoDebugInfo, FullDebugInfo};
217 use util::common::indenter;
218 use util::nodemap::FnvHashMap;
219 use util::ppaux::{Repr, vec_map_to_string};
222 use std::cmp::Ordering;
223 use std::iter::AdditiveIterator;
226 use syntax::ast::{DUMMY_NODE_ID, Ident, NodeId};
227 use syntax::codemap::Span;
228 use syntax::fold::Folder;
231 #[derive(Copy, Debug)]
232 struct ConstantExpr<'a>(&'a ast::Expr);
234 impl<'a> ConstantExpr<'a> {
235 fn eq(self, other: ConstantExpr<'a>, tcx: &ty::ctxt) -> bool {
236 match const_eval::compare_lit_exprs(tcx, self.0, other.0, None) {
237 Some(result) => result == Ordering::Equal,
238 None => panic!("compare_list_exprs: type mismatch"),
243 // An option identifying a branch (either a literal, an enum variant or a range)
246 ConstantValue(ConstantExpr<'a>, DebugLoc),
247 ConstantRange(ConstantExpr<'a>, ConstantExpr<'a>, DebugLoc),
248 Variant(ty::Disr, Rc<adt::Repr<'tcx>>, ast::DefId, DebugLoc),
249 SliceLengthEqual(uint, DebugLoc),
250 SliceLengthGreaterOrEqual(/* prefix length */ uint,
251 /* suffix length */ uint,
255 impl<'a, 'tcx> Opt<'a, 'tcx> {
256 fn eq(&self, other: &Opt<'a, 'tcx>, tcx: &ty::ctxt<'tcx>) -> bool {
257 match (self, other) {
258 (&ConstantValue(a, _), &ConstantValue(b, _)) => a.eq(b, tcx),
259 (&ConstantRange(a1, a2, _), &ConstantRange(b1, b2, _)) => {
260 a1.eq(b1, tcx) && a2.eq(b2, tcx)
262 (&Variant(a_disr, ref a_repr, a_def, _),
263 &Variant(b_disr, ref b_repr, b_def, _)) => {
264 a_disr == b_disr && *a_repr == *b_repr && a_def == b_def
266 (&SliceLengthEqual(a, _), &SliceLengthEqual(b, _)) => a == b,
267 (&SliceLengthGreaterOrEqual(a1, a2, _),
268 &SliceLengthGreaterOrEqual(b1, b2, _)) => {
275 fn trans<'blk>(&self, mut bcx: Block<'blk, 'tcx>) -> OptResult<'blk, 'tcx> {
276 let _icx = push_ctxt("match::trans_opt");
279 ConstantValue(ConstantExpr(lit_expr), _) => {
280 let lit_ty = ty::node_id_to_type(bcx.tcx(), lit_expr.id);
281 let (llval, _) = consts::const_expr(ccx, &*lit_expr, bcx.fcx.param_substs);
282 let lit_datum = immediate_rvalue(llval, lit_ty);
283 let lit_datum = unpack_datum!(bcx, lit_datum.to_appropriate_datum(bcx));
284 SingleResult(Result::new(bcx, lit_datum.val))
286 ConstantRange(ConstantExpr(ref l1), ConstantExpr(ref l2), _) => {
287 let (l1, _) = consts::const_expr(ccx, &**l1, bcx.fcx.param_substs);
288 let (l2, _) = consts::const_expr(ccx, &**l2, bcx.fcx.param_substs);
289 RangeResult(Result::new(bcx, l1), Result::new(bcx, l2))
291 Variant(disr_val, ref repr, _, _) => {
292 adt::trans_case(bcx, &**repr, disr_val)
294 SliceLengthEqual(length, _) => {
295 SingleResult(Result::new(bcx, C_uint(ccx, length)))
297 SliceLengthGreaterOrEqual(prefix, suffix, _) => {
298 LowerBound(Result::new(bcx, C_uint(ccx, prefix + suffix)))
303 fn debug_loc(&self) -> DebugLoc {
305 ConstantValue(_,debug_loc) |
306 ConstantRange(_, _, debug_loc) |
307 Variant(_, _, _, debug_loc) |
308 SliceLengthEqual(_, debug_loc) |
309 SliceLengthGreaterOrEqual(_, _, debug_loc) => debug_loc
314 #[derive(Copy, PartialEq)]
315 pub enum BranchKind {
323 pub enum OptResult<'blk, 'tcx: 'blk> {
324 SingleResult(Result<'blk, 'tcx>),
325 RangeResult(Result<'blk, 'tcx>, Result<'blk, 'tcx>),
326 LowerBound(Result<'blk, 'tcx>)
329 #[derive(Clone, Copy)]
330 pub enum TransBindingMode {
331 TrByCopy(/* llbinding */ ValueRef),
336 /// Information about a pattern binding:
337 /// - `llmatch` is a pointer to a stack slot. The stack slot contains a
338 /// pointer into the value being matched. Hence, llmatch has type `T**`
339 /// where `T` is the value being matched.
340 /// - `trmode` is the trans binding mode
341 /// - `id` is the node id of the binding
342 /// - `ty` is the Rust type of the binding
343 #[derive(Clone, Copy)]
344 pub struct BindingInfo<'tcx> {
345 pub llmatch: ValueRef,
346 pub trmode: TransBindingMode,
352 type BindingsMap<'tcx> = FnvHashMap<Ident, BindingInfo<'tcx>>;
354 struct ArmData<'p, 'blk, 'tcx: 'blk> {
355 bodycx: Block<'blk, 'tcx>,
357 bindings_map: BindingsMap<'tcx>
360 /// Info about Match.
361 /// If all `pats` are matched then arm `data` will be executed.
362 /// As we proceed `bound_ptrs` are filled with pointers to values to be bound,
363 /// these pointers are stored in llmatch variables just before executing `data` arm.
364 struct Match<'a, 'p: 'a, 'blk: 'a, 'tcx: 'blk> {
365 pats: Vec<&'p ast::Pat>,
366 data: &'a ArmData<'p, 'blk, 'tcx>,
367 bound_ptrs: Vec<(Ident, ValueRef)>,
368 // Thread along renamings done by the check_match::StaticInliner, so we can
369 // map back to original NodeIds
370 pat_renaming_map: Option<&'a FnvHashMap<(NodeId, Span), NodeId>>
373 impl<'a, 'p, 'blk, 'tcx> Repr<'tcx> for Match<'a, 'p, 'blk, 'tcx> {
374 fn repr(&self, tcx: &ty::ctxt) -> String {
375 if tcx.sess.verbose() {
376 // for many programs, this just take too long to serialize
379 format!("{} pats", self.pats.len())
384 fn has_nested_bindings(m: &[Match], col: uint) -> bool {
386 match br.pats[col].node {
387 ast::PatIdent(_, _, Some(_)) => return true,
394 fn expand_nested_bindings<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
395 m: &[Match<'a, 'p, 'blk, 'tcx>],
398 -> Vec<Match<'a, 'p, 'blk, 'tcx>> {
399 debug!("expand_nested_bindings(bcx={}, m={}, col={}, val={})",
403 bcx.val_to_string(val));
404 let _indenter = indenter();
407 let mut bound_ptrs = br.bound_ptrs.clone();
408 let mut pat = br.pats[col];
410 pat = match pat.node {
411 ast::PatIdent(_, ref path, Some(ref inner)) => {
412 bound_ptrs.push((path.node, val));
419 let mut pats = br.pats.clone();
424 bound_ptrs: bound_ptrs,
425 pat_renaming_map: br.pat_renaming_map,
430 fn enter_match<'a, 'b, 'p, 'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
432 m: &[Match<'a, 'p, 'blk, 'tcx>],
436 -> Vec<Match<'a, 'p, 'blk, 'tcx>> where
437 F: FnMut(&[&'p ast::Pat]) -> Option<Vec<&'p ast::Pat>>,
439 debug!("enter_match(bcx={}, m={}, col={}, val={})",
443 bcx.val_to_string(val));
444 let _indenter = indenter();
446 m.iter().filter_map(|br| {
447 e(&br.pats[]).map(|pats| {
448 let this = br.pats[col];
449 let mut bound_ptrs = br.bound_ptrs.clone();
451 ast::PatIdent(_, ref path, None) => {
452 if pat_is_binding(dm, &*this) {
453 bound_ptrs.push((path.node, val));
456 ast::PatVec(ref before, Some(ref slice), ref after) => {
457 if let ast::PatIdent(_, ref path, None) = slice.node {
458 let subslice_val = bind_subslice_pat(
460 before.len(), after.len());
461 bound_ptrs.push((path.node, subslice_val));
469 bound_ptrs: bound_ptrs,
470 pat_renaming_map: br.pat_renaming_map,
476 fn enter_default<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
478 m: &[Match<'a, 'p, 'blk, 'tcx>],
481 -> Vec<Match<'a, 'p, 'blk, 'tcx>> {
482 debug!("enter_default(bcx={}, m={}, col={}, val={})",
486 bcx.val_to_string(val));
487 let _indenter = indenter();
489 // Collect all of the matches that can match against anything.
490 enter_match(bcx, dm, m, col, val, |pats| {
491 if pat_is_binding_or_wild(dm, &*pats[col]) {
492 let mut r = pats[..col].to_vec();
493 r.push_all(&pats[col + 1..]);
501 // <pcwalton> nmatsakis: what does enter_opt do?
502 // <pcwalton> in trans/match
503 // <pcwalton> trans/match.rs is like stumbling around in a dark cave
504 // <nmatsakis> pcwalton: the enter family of functions adjust the set of
505 // patterns as needed
506 // <nmatsakis> yeah, at some point I kind of achieved some level of
508 // <nmatsakis> anyhow, they adjust the patterns given that something of that
509 // kind has been found
510 // <nmatsakis> pcwalton: ok, right, so enter_XXX() adjusts the patterns, as I
512 // <nmatsakis> enter_match() kind of embodies the generic code
513 // <nmatsakis> it is provided with a function that tests each pattern to see
514 // if it might possibly apply and so forth
515 // <nmatsakis> so, if you have a pattern like {a: _, b: _, _} and one like _
516 // <nmatsakis> then _ would be expanded to (_, _)
517 // <nmatsakis> one spot for each of the sub-patterns
518 // <nmatsakis> enter_opt() is one of the more complex; it covers the fallible
520 // <nmatsakis> enter_rec_or_struct() or enter_tuple() are simpler, since they
521 // are infallible patterns
522 // <nmatsakis> so all patterns must either be records (resp. tuples) or
525 /// The above is now outdated in that enter_match() now takes a function that
526 /// takes the complete row of patterns rather than just the first one.
527 /// Also, most of the enter_() family functions have been unified with
528 /// the check_match specialization step.
529 fn enter_opt<'a, 'p, 'blk, 'tcx>(
530 bcx: Block<'blk, 'tcx>,
533 m: &[Match<'a, 'p, 'blk, 'tcx>],
538 -> Vec<Match<'a, 'p, 'blk, 'tcx>> {
539 debug!("enter_opt(bcx={}, m={}, opt={:?}, col={}, val={})",
544 bcx.val_to_string(val));
545 let _indenter = indenter();
547 let ctor = match opt {
548 &ConstantValue(ConstantExpr(expr), _) => check_match::ConstantValue(
549 const_eval::eval_const_expr(bcx.tcx(), &*expr)
551 &ConstantRange(ConstantExpr(lo), ConstantExpr(hi), _) => check_match::ConstantRange(
552 const_eval::eval_const_expr(bcx.tcx(), &*lo),
553 const_eval::eval_const_expr(bcx.tcx(), &*hi)
555 &SliceLengthEqual(n, _) =>
556 check_match::Slice(n),
557 &SliceLengthGreaterOrEqual(before, after, _) =>
558 check_match::SliceWithSubslice(before, after),
559 &Variant(_, _, def_id, _) =>
560 check_match::Constructor::Variant(def_id)
563 let param_env = ty::empty_parameter_environment(bcx.tcx());
564 let mcx = check_match::MatchCheckCtxt {
566 param_env: param_env,
568 enter_match(bcx, dm, m, col, val, |pats|
569 check_match::specialize(&mcx, &pats[..], &ctor, col, variant_size)
573 // Returns the options in one column of matches. An option is something that
574 // needs to be conditionally matched at runtime; for example, the discriminant
575 // on a set of enum variants or a literal.
576 fn get_branches<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
577 m: &[Match<'a, 'p, 'blk, 'tcx>],
579 -> Vec<Opt<'p, 'tcx>> {
582 let mut found: Vec<Opt> = vec![];
584 let cur = br.pats[col];
585 let debug_loc = match br.pat_renaming_map {
586 Some(pat_renaming_map) => {
587 match pat_renaming_map.get(&(cur.id, cur.span)) {
588 Some(&id) => DebugLoc::At(id, cur.span),
589 None => DebugLoc::At(cur.id, cur.span),
592 None => DebugLoc::None
595 let opt = match cur.node {
596 ast::PatLit(ref l) => {
597 ConstantValue(ConstantExpr(&**l), debug_loc)
599 ast::PatIdent(..) | ast::PatEnum(..) | ast::PatStruct(..) => {
600 // This is either an enum variant or a variable binding.
601 let opt_def = tcx.def_map.borrow().get(&cur.id).cloned();
603 Some(def::DefVariant(enum_id, var_id, _)) => {
604 let variant = ty::enum_variant_with_id(tcx, enum_id, var_id);
605 Variant(variant.disr_val,
606 adt::represent_node(bcx, cur.id),
613 ast::PatRange(ref l1, ref l2) => {
614 ConstantRange(ConstantExpr(&**l1), ConstantExpr(&**l2), debug_loc)
616 ast::PatVec(ref before, None, ref after) => {
617 SliceLengthEqual(before.len() + after.len(), debug_loc)
619 ast::PatVec(ref before, Some(_), ref after) => {
620 SliceLengthGreaterOrEqual(before.len(), after.len(), debug_loc)
625 if !found.iter().any(|x| x.eq(&opt, tcx)) {
632 struct ExtractedBlock<'blk, 'tcx: 'blk> {
634 bcx: Block<'blk, 'tcx>,
637 fn extract_variant_args<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
638 repr: &adt::Repr<'tcx>,
641 -> ExtractedBlock<'blk, 'tcx> {
642 let _icx = push_ctxt("match::extract_variant_args");
643 let args = (0..adt::num_args(repr, disr_val)).map(|i| {
644 adt::trans_field_ptr(bcx, repr, val, disr_val, i)
647 ExtractedBlock { vals: args, bcx: bcx }
650 /// Helper for converting from the ValueRef that we pass around in the match code, which is always
651 /// an lvalue, into a Datum. Eventually we should just pass around a Datum and be done with it.
652 fn match_datum<'tcx>(val: ValueRef, left_ty: Ty<'tcx>) -> Datum<'tcx, Lvalue> {
653 Datum::new(val, left_ty, Lvalue)
656 fn bind_subslice_pat(bcx: Block,
660 offset_right: uint) -> ValueRef {
661 let _icx = push_ctxt("match::bind_subslice_pat");
662 let vec_ty = node_id_type(bcx, pat_id);
663 let vt = tvec::vec_types(bcx, ty::sequence_element_type(bcx.tcx(), ty::type_content(vec_ty)));
664 let vec_datum = match_datum(val, vec_ty);
665 let (base, len) = vec_datum.get_vec_base_and_len(bcx);
667 let slice_begin = InBoundsGEP(bcx, base, &[C_uint(bcx.ccx(), offset_left)]);
668 let slice_len_offset = C_uint(bcx.ccx(), offset_left + offset_right);
669 let slice_len = Sub(bcx, len, slice_len_offset, DebugLoc::None);
670 let slice_ty = ty::mk_slice(bcx.tcx(),
671 bcx.tcx().mk_region(ty::ReStatic),
672 ty::mt {ty: vt.unit_ty, mutbl: ast::MutImmutable});
673 let scratch = rvalue_scratch_datum(bcx, slice_ty, "");
674 Store(bcx, slice_begin,
675 GEPi(bcx, scratch.val, &[0, abi::FAT_PTR_ADDR]));
676 Store(bcx, slice_len, GEPi(bcx, scratch.val, &[0, abi::FAT_PTR_EXTRA]));
680 fn extract_vec_elems<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
685 -> ExtractedBlock<'blk, 'tcx> {
686 let _icx = push_ctxt("match::extract_vec_elems");
687 let vec_datum = match_datum(val, left_ty);
688 let (base, len) = vec_datum.get_vec_base_and_len(bcx);
689 let mut elems = vec![];
690 elems.extend((0..before).map(|i| GEPi(bcx, base, &[i])));
691 elems.extend((0..after).rev().map(|i| {
692 InBoundsGEP(bcx, base, &[
693 Sub(bcx, len, C_uint(bcx.ccx(), i + 1), DebugLoc::None)
696 ExtractedBlock { vals: elems, bcx: bcx }
699 // Macro for deciding whether any of the remaining matches fit a given kind of
700 // pattern. Note that, because the macro is well-typed, either ALL of the
701 // matches should fit that sort of pattern or NONE (however, some of the
702 // matches may be wildcards like _ or identifiers).
703 macro_rules! any_pat {
704 ($m:expr, $col:expr, $pattern:pat) => (
705 ($m).iter().any(|br| {
706 match br.pats[$col].node {
714 fn any_uniq_pat(m: &[Match], col: uint) -> bool {
715 any_pat!(m, col, ast::PatBox(_))
718 fn any_region_pat(m: &[Match], col: uint) -> bool {
719 any_pat!(m, col, ast::PatRegion(..))
722 fn any_irrefutable_adt_pat(tcx: &ty::ctxt, m: &[Match], col: uint) -> bool {
724 let pat = br.pats[col];
726 ast::PatTup(_) => true,
727 ast::PatStruct(..) => {
728 match tcx.def_map.borrow().get(&pat.id) {
729 Some(&def::DefVariant(..)) => false,
733 ast::PatEnum(..) | ast::PatIdent(_, _, None) => {
734 match tcx.def_map.borrow().get(&pat.id) {
735 Some(&def::DefStruct(..)) => true,
744 /// What to do when the pattern match fails.
745 enum FailureHandler {
747 JumpToBasicBlock(BasicBlockRef),
751 impl FailureHandler {
752 fn is_fallible(&self) -> bool {
759 fn is_infallible(&self) -> bool {
763 fn handle_fail(&self, bcx: Block) {
766 panic!("attempted to panic in a non-panicking panic handler!"),
767 JumpToBasicBlock(basic_block) =>
768 Br(bcx, basic_block, DebugLoc::None),
770 build::Unreachable(bcx)
775 fn pick_column_to_specialize(def_map: &DefMap, m: &[Match]) -> Option<uint> {
776 fn pat_score(def_map: &DefMap, pat: &ast::Pat) -> uint {
778 ast::PatIdent(_, _, Some(ref inner)) => pat_score(def_map, &**inner),
779 _ if pat_is_refutable(def_map, pat) => 1,
784 let column_score = |m: &[Match], col: uint| -> uint {
785 let total_score = m.iter()
786 .map(|row| row.pats[col])
787 .map(|pat| pat_score(def_map, pat))
790 // Irrefutable columns always go first, they'd only be duplicated in the branches.
791 if total_score == 0 {
798 let column_contains_any_nonwild_patterns = |&col: &uint| -> bool {
799 m.iter().any(|row| match row.pats[col].node {
800 ast::PatWild(_) => false,
806 .filter(column_contains_any_nonwild_patterns)
807 .map(|col| (col, column_score(m, col)))
808 .max_by(|&(_, score)| score)
812 // Compiles a comparison between two things.
813 fn compare_values<'blk, 'tcx>(cx: Block<'blk, 'tcx>,
818 -> Result<'blk, 'tcx> {
819 fn compare_str<'blk, 'tcx>(cx: Block<'blk, 'tcx>,
824 -> Result<'blk, 'tcx> {
825 let did = langcall(cx,
827 &format!("comparison of `{}`",
828 cx.ty_to_string(rhs_t))[],
830 let t = ty::mk_str_slice(cx.tcx(), cx.tcx().mk_region(ty::ReStatic), ast::MutImmutable);
831 // The comparison function gets the slices by value, so we have to make copies here. Even
832 // if the function doesn't write through the pointer, things like lifetime intrinsics
833 // require that we do this properly
834 let lhs_arg = alloc_ty(cx, t, "lhs");
835 let rhs_arg = alloc_ty(cx, t, "rhs");
836 memcpy_ty(cx, lhs_arg, lhs, t);
837 memcpy_ty(cx, rhs_arg, rhs, t);
838 let res = callee::trans_lang_call(cx, did, &[lhs_arg, rhs_arg], None, debug_loc);
839 call_lifetime_end(res.bcx, lhs_arg);
840 call_lifetime_end(res.bcx, rhs_arg);
845 let _icx = push_ctxt("compare_values");
846 if ty::type_is_scalar(rhs_t) {
847 let cmp = compare_scalar_types(cx, lhs, rhs, rhs_t, ast::BiEq, debug_loc);
848 return Result::new(cx, cmp);
852 ty::ty_rptr(_, mt) => match mt.ty.sty {
853 ty::ty_str => compare_str(cx, lhs, rhs, rhs_t, debug_loc),
854 ty::ty_vec(ty, _) => match ty.sty {
855 ty::ty_uint(ast::TyU8) => {
856 // NOTE: cast &[u8] to &str and abuse the str_eq lang item,
857 // which calls memcmp().
858 let t = ty::mk_str_slice(cx.tcx(),
859 cx.tcx().mk_region(ty::ReStatic),
861 let lhs = BitCast(cx, lhs, type_of::type_of(cx.ccx(), t).ptr_to());
862 let rhs = BitCast(cx, rhs, type_of::type_of(cx.ccx(), t).ptr_to());
863 compare_str(cx, lhs, rhs, rhs_t, debug_loc)
865 _ => cx.sess().bug("only byte strings supported in compare_values"),
867 _ => cx.sess().bug("only string and byte strings supported in compare_values"),
869 _ => cx.sess().bug("only scalars, byte strings, and strings supported in compare_values"),
873 /// For each binding in `data.bindings_map`, adds an appropriate entry into the `fcx.lllocals` map
874 fn insert_lllocals<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
875 bindings_map: &BindingsMap<'tcx>,
876 cs: Option<cleanup::ScopeId>)
877 -> Block<'blk, 'tcx> {
878 for (&ident, &binding_info) in bindings_map {
879 let llval = match binding_info.trmode {
880 // By value mut binding for a copy type: load from the ptr
881 // into the matched value and copy to our alloca
882 TrByCopy(llbinding) => {
883 let llval = Load(bcx, binding_info.llmatch);
884 let datum = Datum::new(llval, binding_info.ty, Lvalue);
885 call_lifetime_start(bcx, llbinding);
886 bcx = datum.store_to(bcx, llbinding);
887 if let Some(cs) = cs {
888 bcx.fcx.schedule_lifetime_end(cs, llbinding);
894 // By value move bindings: load from the ptr into the matched value
895 TrByMove => Load(bcx, binding_info.llmatch),
897 // By ref binding: use the ptr into the matched value
898 TrByRef => binding_info.llmatch
901 let datum = Datum::new(llval, binding_info.ty, Lvalue);
902 if let Some(cs) = cs {
903 bcx.fcx.schedule_drop_and_zero_mem(cs, llval, binding_info.ty);
904 bcx.fcx.schedule_lifetime_end(cs, binding_info.llmatch);
907 debug!("binding {} to {}", binding_info.id, bcx.val_to_string(llval));
908 bcx.fcx.lllocals.borrow_mut().insert(binding_info.id, datum);
909 debuginfo::create_match_binding_metadata(bcx, ident, binding_info);
914 fn compile_guard<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
915 guard_expr: &ast::Expr,
916 data: &ArmData<'p, 'blk, 'tcx>,
917 m: &[Match<'a, 'p, 'blk, 'tcx>],
919 chk: &FailureHandler,
920 has_genuine_default: bool)
921 -> Block<'blk, 'tcx> {
922 debug!("compile_guard(bcx={}, guard_expr={}, m={}, vals={})",
924 bcx.expr_to_string(guard_expr),
926 vec_map_to_string(vals, |v| bcx.val_to_string(*v)));
927 let _indenter = indenter();
929 let mut bcx = insert_lllocals(bcx, &data.bindings_map, None);
931 let val = unpack_datum!(bcx, expr::trans(bcx, guard_expr));
932 let val = val.to_llbool(bcx);
934 for (_, &binding_info) in &data.bindings_map {
935 if let TrByCopy(llbinding) = binding_info.trmode {
936 call_lifetime_end(bcx, llbinding);
940 for (_, &binding_info) in &data.bindings_map {
941 bcx.fcx.lllocals.borrow_mut().remove(&binding_info.id);
944 with_cond(bcx, Not(bcx, val, guard_expr.debug_loc()), |bcx| {
945 for (_, &binding_info) in &data.bindings_map {
946 call_lifetime_end(bcx, binding_info.llmatch);
949 // If the default arm is the only one left, move on to the next
950 // condition explicitly rather than (possibly) falling back to
952 &JumpToBasicBlock(_) if m.len() == 1 && has_genuine_default => {
953 chk.handle_fail(bcx);
956 compile_submatch(bcx, m, vals, chk, has_genuine_default);
963 fn compile_submatch<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
964 m: &[Match<'a, 'p, 'blk, 'tcx>],
966 chk: &FailureHandler,
967 has_genuine_default: bool) {
968 debug!("compile_submatch(bcx={}, m={}, vals={})",
971 vec_map_to_string(vals, |v| bcx.val_to_string(*v)));
972 let _indenter = indenter();
973 let _icx = push_ctxt("match::compile_submatch");
976 if chk.is_fallible() {
977 chk.handle_fail(bcx);
983 let def_map = &tcx.def_map;
984 match pick_column_to_specialize(def_map, m) {
987 if has_nested_bindings(m, col) {
988 let expanded = expand_nested_bindings(bcx, m, col, val);
989 compile_submatch_continue(bcx,
997 compile_submatch_continue(bcx, m, vals, chk, col, val, has_genuine_default)
1001 let data = &m[0].data;
1002 for &(ref ident, ref value_ptr) in &m[0].bound_ptrs {
1003 let llmatch = data.bindings_map[*ident].llmatch;
1004 call_lifetime_start(bcx, llmatch);
1005 Store(bcx, *value_ptr, llmatch);
1007 match data.arm.guard {
1008 Some(ref guard_expr) => {
1009 bcx = compile_guard(bcx,
1015 has_genuine_default);
1019 Br(bcx, data.bodycx.llbb, DebugLoc::None);
1024 fn compile_submatch_continue<'a, 'p, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1025 m: &[Match<'a, 'p, 'blk, 'tcx>],
1027 chk: &FailureHandler,
1030 has_genuine_default: bool) {
1032 let tcx = bcx.tcx();
1033 let dm = &tcx.def_map;
1035 let mut vals_left = vals[0..col].to_vec();
1036 vals_left.push_all(&vals[col + 1..]);
1037 let ccx = bcx.fcx.ccx;
1039 // Find a real id (we're adding placeholder wildcard patterns, but
1040 // each column is guaranteed to have at least one real pattern)
1041 let pat_id = m.iter().map(|br| br.pats[col].id)
1042 .find(|&id| id != DUMMY_NODE_ID)
1043 .unwrap_or(DUMMY_NODE_ID);
1045 let left_ty = if pat_id == DUMMY_NODE_ID {
1048 node_id_type(bcx, pat_id)
1051 let mcx = check_match::MatchCheckCtxt {
1053 param_env: ty::empty_parameter_environment(bcx.tcx()),
1055 let adt_vals = if any_irrefutable_adt_pat(bcx.tcx(), m, col) {
1056 let repr = adt::represent_type(bcx.ccx(), left_ty);
1057 let arg_count = adt::num_args(&*repr, 0);
1058 let field_vals: Vec<ValueRef> = (0..arg_count).map(|ix|
1059 adt::trans_field_ptr(bcx, &*repr, val, 0, ix)
1062 } else if any_uniq_pat(m, col) || any_region_pat(m, col) {
1063 Some(vec!(Load(bcx, val)))
1066 ty::ty_vec(_, Some(n)) => {
1067 let args = extract_vec_elems(bcx, left_ty, n, 0, val);
1075 Some(field_vals) => {
1076 let pats = enter_match(bcx, dm, m, col, val, |pats|
1077 check_match::specialize(&mcx, pats,
1078 &check_match::Single, col,
1081 let mut vals = field_vals;
1082 vals.push_all(&vals_left);
1083 compile_submatch(bcx, &pats, &vals, chk, has_genuine_default);
1089 // Decide what kind of branch we need
1090 let opts = get_branches(bcx, m, col);
1091 debug!("options={:?}", opts);
1092 let mut kind = NoBranch;
1093 let mut test_val = val;
1094 debug!("test_val={}", bcx.val_to_string(test_val));
1097 ConstantValue(..) | ConstantRange(..) => {
1098 test_val = load_if_immediate(bcx, val, left_ty);
1099 kind = if ty::type_is_integral(left_ty) {
1105 Variant(_, ref repr, _, _) => {
1106 let (the_kind, val_opt) = adt::trans_switch(bcx, &**repr, val);
1108 if let Some(tval) = val_opt { test_val = tval; }
1110 SliceLengthEqual(..) | SliceLengthGreaterOrEqual(..) => {
1111 let (_, len) = tvec::get_base_and_len(bcx, val, left_ty);
1119 ConstantRange(..) => { kind = Compare; break },
1120 SliceLengthGreaterOrEqual(..) => { kind = CompareSliceLength; break },
1124 let else_cx = match kind {
1125 NoBranch | Single => bcx,
1126 _ => bcx.fcx.new_temp_block("match_else")
1128 let sw = if kind == Switch {
1129 build::Switch(bcx, test_val, else_cx.llbb, opts.len())
1131 C_int(ccx, 0) // Placeholder for when not using a switch
1134 let defaults = enter_default(else_cx, dm, m, col, val);
1135 let exhaustive = chk.is_infallible() && defaults.len() == 0;
1136 let len = opts.len();
1138 // Compile subtrees for each option
1139 for (i, opt) in opts.iter().enumerate() {
1140 // In some cases of range and vector pattern matching, we need to
1141 // override the failure case so that instead of failing, it proceeds
1142 // to try more matching. branch_chk, then, is the proper failure case
1143 // for the current conditional branch.
1144 let mut branch_chk = None;
1145 let mut opt_cx = else_cx;
1146 let debug_loc = opt.debug_loc();
1148 if !exhaustive || i + 1 < len {
1149 opt_cx = bcx.fcx.new_temp_block("match_case");
1151 Single => Br(bcx, opt_cx.llbb, debug_loc),
1153 match opt.trans(bcx) {
1154 SingleResult(r) => {
1155 AddCase(sw, r.val, opt_cx.llbb);
1160 "in compile_submatch, expected \
1161 opt.trans() to return a SingleResult")
1165 Compare | CompareSliceLength => {
1166 let t = if kind == Compare {
1169 tcx.types.uint // vector length
1171 let Result { bcx: after_cx, val: matches } = {
1172 match opt.trans(bcx) {
1173 SingleResult(Result { bcx, val }) => {
1174 compare_values(bcx, test_val, val, t, debug_loc)
1176 RangeResult(Result { val: vbegin, .. },
1177 Result { bcx, val: vend }) => {
1178 let llge = compare_scalar_types(bcx, test_val, vbegin,
1179 t, ast::BiGe, debug_loc);
1180 let llle = compare_scalar_types(bcx, test_val, vend,
1181 t, ast::BiLe, debug_loc);
1182 Result::new(bcx, And(bcx, llge, llle, DebugLoc::None))
1184 LowerBound(Result { bcx, val }) => {
1185 Result::new(bcx, compare_scalar_types(bcx, test_val,
1191 bcx = fcx.new_temp_block("compare_next");
1193 // If none of the sub-cases match, and the current condition
1194 // is guarded or has multiple patterns, move on to the next
1195 // condition, if there is any, rather than falling back to
1197 let guarded = m[i].data.arm.guard.is_some();
1198 let multi_pats = m[i].pats.len() > 1;
1199 if i + 1 < len && (guarded || multi_pats || kind == CompareSliceLength) {
1200 branch_chk = Some(JumpToBasicBlock(bcx.llbb));
1202 CondBr(after_cx, matches, opt_cx.llbb, bcx.llbb, debug_loc);
1206 } else if kind == Compare || kind == CompareSliceLength {
1207 Br(bcx, else_cx.llbb, debug_loc);
1211 let mut unpacked = Vec::new();
1213 Variant(disr_val, ref repr, _, _) => {
1214 let ExtractedBlock {vals: argvals, bcx: new_bcx} =
1215 extract_variant_args(opt_cx, &**repr, disr_val, val);
1216 size = argvals.len();
1220 SliceLengthEqual(len, _) => {
1221 let args = extract_vec_elems(opt_cx, left_ty, len, 0, val);
1222 size = args.vals.len();
1223 unpacked = args.vals.clone();
1226 SliceLengthGreaterOrEqual(before, after, _) => {
1227 let args = extract_vec_elems(opt_cx, left_ty, before, after, val);
1228 size = args.vals.len();
1229 unpacked = args.vals.clone();
1232 ConstantValue(..) | ConstantRange(..) => ()
1234 let opt_ms = enter_opt(opt_cx, pat_id, dm, m, opt, col, size, val);
1235 let mut opt_vals = unpacked;
1236 opt_vals.push_all(&vals_left[..]);
1237 compile_submatch(opt_cx,
1240 branch_chk.as_ref().unwrap_or(chk),
1241 has_genuine_default);
1244 // Compile the fall-through case, if any
1245 if !exhaustive && kind != Single {
1246 if kind == Compare || kind == CompareSliceLength {
1247 Br(bcx, else_cx.llbb, DebugLoc::None);
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,
1261 has_genuine_default);
1267 pub fn trans_match<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1268 match_expr: &ast::Expr,
1269 discr_expr: &ast::Expr,
1272 -> Block<'blk, 'tcx> {
1273 let _icx = push_ctxt("match::trans_match");
1274 trans_match_inner(bcx, match_expr.id, discr_expr, arms, dest)
1277 /// Checks whether the binding in `discr` is assigned to anywhere in the expression `body`
1278 fn is_discr_reassigned(bcx: Block, discr: &ast::Expr, body: &ast::Expr) -> bool {
1279 let (vid, field) = match discr.node {
1280 ast::ExprPath(_) | ast::ExprQPath(_) => match bcx.def(discr.id) {
1281 def::DefLocal(vid) | def::DefUpvar(vid, _) => (vid, None),
1284 ast::ExprField(ref base, field) => {
1285 let vid = match bcx.tcx().def_map.borrow().get(&base.id) {
1286 Some(&def::DefLocal(vid)) | Some(&def::DefUpvar(vid, _)) => vid,
1289 (vid, Some(mc::NamedField(field.node.name)))
1291 ast::ExprTupField(ref base, field) => {
1292 let vid = match bcx.tcx().def_map.borrow().get(&base.id) {
1293 Some(&def::DefLocal(vid)) | Some(&def::DefUpvar(vid, _)) => vid,
1296 (vid, Some(mc::PositionalField(field.node)))
1301 let mut rc = ReassignmentChecker {
1307 let mut visitor = euv::ExprUseVisitor::new(&mut rc, bcx);
1308 visitor.walk_expr(body);
1313 struct ReassignmentChecker {
1315 field: Option<mc::FieldName>,
1319 // Determine if the expression we're matching on is reassigned to within
1320 // the body of the match's arm.
1321 // We only care for the `mutate` callback since this check only matters
1322 // for cases where the matched value is moved.
1323 impl<'tcx> euv::Delegate<'tcx> for ReassignmentChecker {
1324 fn consume(&mut self, _: ast::NodeId, _: Span, _: mc::cmt, _: euv::ConsumeMode) {}
1325 fn matched_pat(&mut self, _: &ast::Pat, _: mc::cmt, _: euv::MatchMode) {}
1326 fn consume_pat(&mut self, _: &ast::Pat, _: mc::cmt, _: euv::ConsumeMode) {}
1327 fn borrow(&mut self, _: ast::NodeId, _: Span, _: mc::cmt, _: ty::Region,
1328 _: ty::BorrowKind, _: euv::LoanCause) {}
1329 fn decl_without_init(&mut self, _: ast::NodeId, _: Span) {}
1331 fn mutate(&mut self, _: ast::NodeId, _: Span, cmt: mc::cmt, _: euv::MutateMode) {
1333 mc::cat_upvar(mc::Upvar { id: ty::UpvarId { var_id: vid, .. }, .. }) |
1334 mc::cat_local(vid) => self.reassigned = self.node == vid,
1335 mc::cat_interior(ref base_cmt, mc::InteriorField(field)) => {
1336 match base_cmt.cat {
1337 mc::cat_upvar(mc::Upvar { id: ty::UpvarId { var_id: vid, .. }, .. }) |
1338 mc::cat_local(vid) => {
1339 self.reassigned = self.node == vid && Some(field) == self.field
1349 fn create_bindings_map<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, pat: &ast::Pat,
1350 discr: &ast::Expr, body: &ast::Expr)
1351 -> BindingsMap<'tcx> {
1352 // Create the bindings map, which is a mapping from each binding name
1353 // to an alloca() that will be the value for that local variable.
1354 // Note that we use the names because each binding will have many ids
1355 // from the various alternatives.
1356 let ccx = bcx.ccx();
1357 let tcx = bcx.tcx();
1358 let reassigned = is_discr_reassigned(bcx, discr, body);
1359 let mut bindings_map = FnvHashMap();
1360 pat_bindings(&tcx.def_map, &*pat, |bm, p_id, span, path1| {
1361 let ident = path1.node;
1362 let variable_ty = node_id_type(bcx, p_id);
1363 let llvariable_ty = type_of::type_of(ccx, variable_ty);
1364 let tcx = bcx.tcx();
1365 let param_env = ty::empty_parameter_environment(tcx);
1371 if !ty::type_moves_by_default(¶m_env, span, variable_ty) || reassigned =>
1373 llmatch = alloca_no_lifetime(bcx,
1374 llvariable_ty.ptr_to(),
1376 trmode = TrByCopy(alloca_no_lifetime(bcx,
1378 &bcx.ident(ident)[]));
1380 ast::BindByValue(_) => {
1381 // in this case, the final type of the variable will be T,
1382 // but during matching we need to store a *T as explained
1384 llmatch = alloca_no_lifetime(bcx,
1385 llvariable_ty.ptr_to(),
1386 &bcx.ident(ident)[]);
1389 ast::BindByRef(_) => {
1390 llmatch = alloca_no_lifetime(bcx,
1392 &bcx.ident(ident)[]);
1396 bindings_map.insert(ident, BindingInfo {
1404 return bindings_map;
1407 fn trans_match_inner<'blk, 'tcx>(scope_cx: Block<'blk, 'tcx>,
1408 match_id: ast::NodeId,
1409 discr_expr: &ast::Expr,
1411 dest: Dest) -> Block<'blk, 'tcx> {
1412 let _icx = push_ctxt("match::trans_match_inner");
1413 let fcx = scope_cx.fcx;
1414 let mut bcx = scope_cx;
1415 let tcx = bcx.tcx();
1417 let discr_datum = unpack_datum!(bcx, expr::trans_to_lvalue(bcx, discr_expr,
1419 if bcx.unreachable.get() {
1423 let t = node_id_type(bcx, discr_expr.id);
1424 let chk = if ty::type_is_empty(tcx, t) {
1430 let arm_datas: Vec<ArmData> = arms.iter().map(|arm| ArmData {
1431 bodycx: fcx.new_id_block("case_body", arm.body.id),
1433 bindings_map: create_bindings_map(bcx, &*arm.pats[0], discr_expr, &*arm.body)
1436 let mut pat_renaming_map = if scope_cx.sess().opts.debuginfo != NoDebugInfo {
1442 let arm_pats: Vec<Vec<P<ast::Pat>>> = {
1443 let mut static_inliner = StaticInliner::new(scope_cx.tcx(),
1444 pat_renaming_map.as_mut());
1445 arm_datas.iter().map(|arm_data| {
1446 arm_data.arm.pats.iter().map(|p| static_inliner.fold_pat((*p).clone())).collect()
1450 let mut matches = Vec::new();
1451 for (arm_data, pats) in arm_datas.iter().zip(arm_pats.iter()) {
1452 matches.extend(pats.iter().map(|p| Match {
1455 bound_ptrs: Vec::new(),
1456 pat_renaming_map: pat_renaming_map.as_ref()
1460 // `compile_submatch` works one column of arm patterns a time and
1461 // then peels that column off. So as we progress, it may become
1462 // impossible to tell whether we have a genuine default arm, i.e.
1463 // `_ => foo` or not. Sometimes it is important to know that in order
1464 // to decide whether moving on to the next condition or falling back
1465 // to the default arm.
1466 let has_default = arms.last().map_or(false, |arm| {
1468 && arm.pats.last().unwrap().node == ast::PatWild(ast::PatWildSingle)
1471 compile_submatch(bcx, &matches[..], &[discr_datum.val], &chk, has_default);
1473 let mut arm_cxs = Vec::new();
1474 for arm_data in &arm_datas {
1475 let mut bcx = arm_data.bodycx;
1477 // insert bindings into the lllocals map and add cleanups
1478 let cs = fcx.push_custom_cleanup_scope();
1479 bcx = insert_lllocals(bcx, &arm_data.bindings_map, Some(cleanup::CustomScope(cs)));
1480 bcx = expr::trans_into(bcx, &*arm_data.arm.body, dest);
1481 bcx = fcx.pop_and_trans_custom_cleanup_scope(bcx, cs);
1485 bcx = scope_cx.fcx.join_blocks(match_id, &arm_cxs[..]);
1489 /// Generates code for a local variable declaration like `let <pat>;` or `let <pat> =
1490 /// <opt_init_expr>`.
1491 pub fn store_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1493 -> Block<'blk, 'tcx> {
1494 let _icx = push_ctxt("match::store_local");
1496 let tcx = bcx.tcx();
1497 let pat = &*local.pat;
1499 fn create_dummy_locals<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1501 -> Block<'blk, 'tcx> {
1502 // create dummy memory for the variables if we have no
1503 // value to store into them immediately
1504 let tcx = bcx.tcx();
1505 pat_bindings(&tcx.def_map, pat, |_, p_id, _, path1| {
1506 let scope = cleanup::var_scope(tcx, p_id);
1507 bcx = mk_binding_alloca(
1508 bcx, p_id, &path1.node, scope, (),
1509 |(), bcx, llval, ty| { zero_mem(bcx, llval, ty); bcx });
1515 Some(ref init_expr) => {
1516 // Optimize the "let x = expr" case. This just writes
1517 // the result of evaluating `expr` directly into the alloca
1518 // for `x`. Often the general path results in similar or the
1519 // same code post-optimization, but not always. In particular,
1520 // in unsafe code, you can have expressions like
1522 // let x = intrinsics::uninit();
1524 // In such cases, the more general path is unsafe, because
1525 // it assumes it is matching against a valid value.
1526 match simple_identifier(&*pat) {
1528 let var_scope = cleanup::var_scope(tcx, local.id);
1529 return mk_binding_alloca(
1530 bcx, pat.id, ident, var_scope, (),
1531 |(), bcx, v, _| expr::trans_into(bcx, &**init_expr,
1540 unpack_datum!(bcx, expr::trans_to_lvalue(bcx, &**init_expr, "let"));
1541 if bcx.sess().asm_comments() {
1542 add_comment(bcx, "creating zeroable ref llval");
1544 let var_scope = cleanup::var_scope(tcx, local.id);
1545 bind_irrefutable_pat(bcx, pat, init_datum.val, var_scope)
1548 create_dummy_locals(bcx, pat)
1553 /// Generates code for argument patterns like `fn foo(<pat>: T)`.
1554 /// Creates entries in the `lllocals` map for each of the bindings
1559 /// - `pat` is the argument pattern
1560 /// - `llval` is a pointer to the argument value (in other words,
1561 /// if the argument type is `T`, then `llval` is a `T*`). In some
1562 /// cases, this code may zero out the memory `llval` points at.
1563 pub fn store_arg<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1565 arg: Datum<'tcx, Rvalue>,
1566 arg_scope: cleanup::ScopeId)
1567 -> Block<'blk, 'tcx> {
1568 let _icx = push_ctxt("match::store_arg");
1570 match simple_identifier(&*pat) {
1572 // Generate nicer LLVM for the common case of fn a pattern
1574 let arg_ty = node_id_type(bcx, pat.id);
1575 if type_of::arg_is_indirect(bcx.ccx(), arg_ty)
1576 && bcx.sess().opts.debuginfo != FullDebugInfo {
1577 // Don't copy an indirect argument to an alloca, the caller
1578 // already put it in a temporary alloca and gave it up, unless
1579 // we emit extra-debug-info, which requires local allocas :(.
1580 let arg_val = arg.add_clean(bcx.fcx, arg_scope);
1581 bcx.fcx.lllocals.borrow_mut()
1582 .insert(pat.id, Datum::new(arg_val, arg_ty, Lvalue));
1586 bcx, pat.id, ident, arg_scope, arg,
1587 |arg, bcx, llval, _| arg.store_to(bcx, llval))
1592 // General path. Copy out the values that are used in the
1594 let arg = unpack_datum!(
1595 bcx, arg.to_lvalue_datum_in_scope(bcx, "__arg", arg_scope));
1596 bind_irrefutable_pat(bcx, pat, arg.val, arg_scope)
1601 fn mk_binding_alloca<'blk, 'tcx, A, F>(bcx: Block<'blk, 'tcx>,
1604 cleanup_scope: cleanup::ScopeId,
1607 -> Block<'blk, 'tcx> where
1608 F: FnOnce(A, Block<'blk, 'tcx>, ValueRef, Ty<'tcx>) -> Block<'blk, 'tcx>,
1610 let var_ty = node_id_type(bcx, p_id);
1612 // Allocate memory on stack for the binding.
1613 let llval = alloc_ty(bcx, var_ty, &bcx.ident(*ident)[]);
1615 // Subtle: be sure that we *populate* the memory *before*
1616 // we schedule the cleanup.
1617 let bcx = populate(arg, bcx, llval, var_ty);
1618 bcx.fcx.schedule_lifetime_end(cleanup_scope, llval);
1619 bcx.fcx.schedule_drop_mem(cleanup_scope, llval, var_ty);
1621 // Now that memory is initialized and has cleanup scheduled,
1622 // create the datum and insert into the local variable map.
1623 let datum = Datum::new(llval, var_ty, Lvalue);
1624 bcx.fcx.lllocals.borrow_mut().insert(p_id, datum);
1628 /// A simple version of the pattern matching code that only handles
1629 /// irrefutable patterns. This is used in let/argument patterns,
1630 /// not in match statements. Unifying this code with the code above
1631 /// sounds nice, but in practice it produces very inefficient code,
1632 /// since the match code is so much more general. In most cases,
1633 /// LLVM is able to optimize the code, but it causes longer compile
1634 /// times and makes the generated code nigh impossible to read.
1637 /// - bcx: starting basic block context
1638 /// - pat: the irrefutable pattern being matched.
1639 /// - val: the value being matched -- must be an lvalue (by ref, with cleanup)
1640 fn bind_irrefutable_pat<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1643 cleanup_scope: cleanup::ScopeId)
1644 -> Block<'blk, 'tcx> {
1645 debug!("bind_irrefutable_pat(bcx={}, pat={})",
1647 pat.repr(bcx.tcx()));
1649 if bcx.sess().asm_comments() {
1650 add_comment(bcx, &format!("bind_irrefutable_pat(pat={})",
1651 pat.repr(bcx.tcx()))[]);
1654 let _indenter = indenter();
1656 let _icx = push_ctxt("match::bind_irrefutable_pat");
1658 let tcx = bcx.tcx();
1659 let ccx = bcx.ccx();
1661 ast::PatIdent(pat_binding_mode, ref path1, ref inner) => {
1662 if pat_is_binding(&tcx.def_map, &*pat) {
1663 // Allocate the stack slot where the value of this
1664 // binding will live and place it into the appropriate
1666 bcx = mk_binding_alloca(
1667 bcx, pat.id, &path1.node, cleanup_scope, (),
1668 |(), bcx, llval, ty| {
1669 match pat_binding_mode {
1670 ast::BindByValue(_) => {
1671 // By value binding: move the value that `val`
1672 // points at into the binding's stack slot.
1673 let d = Datum::new(val, ty, Lvalue);
1674 d.store_to(bcx, llval)
1677 ast::BindByRef(_) => {
1678 // By ref binding: the value of the variable
1679 // is the pointer `val` itself.
1680 Store(bcx, val, llval);
1687 if let Some(ref inner_pat) = *inner {
1688 bcx = bind_irrefutable_pat(bcx, &**inner_pat, val, cleanup_scope);
1691 ast::PatEnum(_, ref sub_pats) => {
1692 let opt_def = bcx.tcx().def_map.borrow().get(&pat.id).cloned();
1694 Some(def::DefVariant(enum_id, var_id, _)) => {
1695 let repr = adt::represent_node(bcx, pat.id);
1696 let vinfo = ty::enum_variant_with_id(ccx.tcx(),
1699 let args = extract_variant_args(bcx,
1703 if let Some(ref sub_pat) = *sub_pats {
1704 for (i, &argval) in args.vals.iter().enumerate() {
1705 bcx = bind_irrefutable_pat(bcx, &*sub_pat[i],
1706 argval, cleanup_scope);
1710 Some(def::DefStruct(..)) => {
1713 // This is a unit-like struct. Nothing to do here.
1715 Some(ref elems) => {
1716 // This is the tuple struct case.
1717 let repr = adt::represent_node(bcx, pat.id);
1718 for (i, elem) in elems.iter().enumerate() {
1719 let fldptr = adt::trans_field_ptr(bcx, &*repr,
1721 bcx = bind_irrefutable_pat(bcx, &**elem,
1722 fldptr, cleanup_scope);
1728 // Nothing to do here.
1732 ast::PatStruct(_, ref fields, _) => {
1733 let tcx = bcx.tcx();
1734 let pat_ty = node_id_type(bcx, pat.id);
1735 let pat_repr = adt::represent_type(bcx.ccx(), pat_ty);
1736 expr::with_field_tys(tcx, pat_ty, Some(pat.id), |discr, field_tys| {
1738 let ix = ty::field_idx_strict(tcx, f.node.ident.name, field_tys);
1739 let fldptr = adt::trans_field_ptr(bcx, &*pat_repr, val,
1741 bcx = bind_irrefutable_pat(bcx, &*f.node.pat, fldptr, cleanup_scope);
1745 ast::PatTup(ref elems) => {
1746 let repr = adt::represent_node(bcx, pat.id);
1747 for (i, elem) in elems.iter().enumerate() {
1748 let fldptr = adt::trans_field_ptr(bcx, &*repr, val, 0, i);
1749 bcx = bind_irrefutable_pat(bcx, &**elem, fldptr, cleanup_scope);
1752 ast::PatBox(ref inner) => {
1753 let llbox = Load(bcx, val);
1754 bcx = bind_irrefutable_pat(bcx, &**inner, llbox, cleanup_scope);
1756 ast::PatRegion(ref inner, _) => {
1757 let loaded_val = Load(bcx, val);
1758 bcx = bind_irrefutable_pat(bcx, &**inner, loaded_val, cleanup_scope);
1760 ast::PatVec(ref before, ref slice, ref after) => {
1761 let pat_ty = node_id_type(bcx, pat.id);
1762 let mut extracted = extract_vec_elems(bcx, pat_ty, before.len(), after.len(), val);
1765 extracted.vals.insert(
1767 bind_subslice_pat(bcx, pat.id, val, before.len(), after.len())
1774 .chain(slice.iter())
1775 .chain(after.iter())
1776 .zip(extracted.vals.into_iter())
1777 .fold(bcx, |bcx, (inner, elem)|
1778 bind_irrefutable_pat(bcx, &**inner, elem, cleanup_scope)
1781 ast::PatMac(..) => {
1782 bcx.sess().span_bug(pat.span, "unexpanded macro");
1784 ast::PatWild(_) | ast::PatLit(_) | ast::PatRange(_, _) => ()