1726 lines
67 KiB
Rust
1726 lines
67 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/*!
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*
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* # Compilation of match statements
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*
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* I will endeavor to explain the code as best I can. I have only a loose
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* understanding of some parts of it.
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*
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* ## Matching
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*
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* The basic state of the code is maintained in an array `m` of `Match`
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* objects. Each `Match` describes some list of patterns, all of which must
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* match against the current list of values. If those patterns match, then
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* the arm listed in the match is the correct arm. A given arm may have
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* multiple corresponding match entries, one for each alternative that
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* remains. As we proceed these sets of matches are adjusted by the various
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* `enter_XXX()` functions, each of which adjusts the set of options given
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* some information about the value which has been matched.
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*
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* So, initially, there is one value and N matches, each of which have one
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* constituent pattern. N here is usually the number of arms but may be
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* greater, if some arms have multiple alternatives. For example, here:
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*
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* enum Foo { A, B(int), C(uint, uint) }
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* match foo {
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* A => ...,
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* B(x) => ...,
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* C(1u, 2) => ...,
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* C(_) => ...
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* }
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*
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* The value would be `foo`. There would be four matches, each of which
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* contains one pattern (and, in one case, a guard). We could collect the
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* various options and then compile the code for the case where `foo` is an
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* `A`, a `B`, and a `C`. When we generate the code for `C`, we would (1)
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* drop the two matches that do not match a `C` and (2) expand the other two
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* into two patterns each. In the first case, the two patterns would be `1u`
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* and `2`, and the in the second case the _ pattern would be expanded into
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* `_` and `_`. The two values are of course the arguments to `C`.
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*
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* Here is a quick guide to the various functions:
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*
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* - `compile_submatch()`: The main workhouse. It takes a list of values and
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* a list of matches and finds the various possibilities that could occur.
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*
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* - `enter_XXX()`: modifies the list of matches based on some information
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* about the value that has been matched. For example,
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* `enter_rec_or_struct()` adjusts the values given that a record or struct
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* has been matched. This is an infallible pattern, so *all* of the matches
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* must be either wildcards or record/struct patterns. `enter_opt()`
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* handles the fallible cases, and it is correspondingly more complex.
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*
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* ## Bindings
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*
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* We store information about the bound variables for each arm as part of the
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* per-arm `ArmData` struct. There is a mapping from identifiers to
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* `BindingInfo` structs. These structs contain the mode/id/type of the
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* binding, but they also contain an LLVM value which points at an alloca
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* called `llmatch`. For by value bindings that are Copy, we also create
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* an extra alloca that we copy the matched value to so that any changes
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* we do to our copy is not reflected in the original and vice-versa.
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* We don't do this if it's a move since the original value can't be used
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* and thus allowing us to cheat in not creating an extra alloca.
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*
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* The `llmatch` binding always stores a pointer into the value being matched
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* which points at the data for the binding. If the value being matched has
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* type `T`, then, `llmatch` will point at an alloca of type `T*` (and hence
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* `llmatch` has type `T**`). So, if you have a pattern like:
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*
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* let a: A = ...;
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* let b: B = ...;
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* match (a, b) { (ref c, d) => { ... } }
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*
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* For `c` and `d`, we would generate allocas of type `C*` and `D*`
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* respectively. These are called the `llmatch`. As we match, when we come
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* up against an identifier, we store the current pointer into the
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* corresponding alloca.
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*
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* Once a pattern is completely matched, and assuming that there is no guard
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* pattern, we will branch to a block that leads to the body itself. For any
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* by-value bindings, this block will first load the ptr from `llmatch` (the
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* one of type `D*`) and then load a second time to get the actual value (the
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* one of type `D`). For by ref bindings, the value of the local variable is
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* simply the first alloca.
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*
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* So, for the example above, we would generate a setup kind of like this:
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*
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* +-------+
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* | Entry |
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* +-------+
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* |
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* +--------------------------------------------+
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* | llmatch_c = (addr of first half of tuple) |
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* | llmatch_d = (addr of second half of tuple) |
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* +--------------------------------------------+
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* |
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* +--------------------------------------+
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* | *llbinding_d = **llmatch_d |
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* +--------------------------------------+
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*
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* If there is a guard, the situation is slightly different, because we must
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* execute the guard code. Moreover, we need to do so once for each of the
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* alternatives that lead to the arm, because if the guard fails, they may
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* have different points from which to continue the search. Therefore, in that
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* case, we generate code that looks more like:
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*
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* +-------+
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* | Entry |
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* +-------+
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* |
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* +-------------------------------------------+
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* | llmatch_c = (addr of first half of tuple) |
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* | llmatch_d = (addr of first half of tuple) |
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* +-------------------------------------------+
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* |
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* +-------------------------------------------------+
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* | *llbinding_d = **llmatch_d |
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* | check condition |
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* | if false { goto next case } |
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* | if true { goto body } |
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* +-------------------------------------------------+
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*
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* The handling for the cleanups is a bit... sensitive. Basically, the body
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* is the one that invokes `add_clean()` for each binding. During the guard
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* evaluation, we add temporary cleanups and revoke them after the guard is
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* evaluated (it could fail, after all). Note that guards and moves are
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* just plain incompatible.
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*
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* Some relevant helper functions that manage bindings:
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* - `create_bindings_map()`
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* - `insert_lllocals()`
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*
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*
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* ## Notes on vector pattern matching.
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*
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* Vector pattern matching is surprisingly tricky. The problem is that
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* the structure of the vector isn't fully known, and slice matches
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* can be done on subparts of it.
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*
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* The way that vector pattern matches are dealt with, then, is as
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* follows. First, we make the actual condition associated with a
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* vector pattern simply a vector length comparison. So the pattern
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* [1, .. x] gets the condition "vec len >= 1", and the pattern
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* [.. x] gets the condition "vec len >= 0". The problem here is that
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* having the condition "vec len >= 1" hold clearly does not mean that
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* only a pattern that has exactly that condition will match. This
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* means that it may well be the case that a condition holds, but none
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* of the patterns matching that condition match; to deal with this,
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* when doing vector length matches, we have match failures proceed to
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* the next condition to check.
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*
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* There are a couple more subtleties to deal with. While the "actual"
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* condition associated with vector length tests is simply a test on
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* the vector length, the actual vec_len Opt entry contains more
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* information used to restrict which matches are associated with it.
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* So that all matches in a submatch are matching against the same
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* values from inside the vector, they are split up by how many
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* elements they match at the front and at the back of the vector. In
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* order to make sure that arms are properly checked in order, even
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* with the overmatching conditions, each vec_len Opt entry is
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* associated with a range of matches.
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* Consider the following:
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*
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* match &[1, 2, 3] {
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* [1, 1, .. _] => 0,
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* [1, 2, 2, .. _] => 1,
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* [1, 2, 3, .. _] => 2,
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* [1, 2, .. _] => 3,
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* _ => 4
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* }
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* The proper arm to match is arm 2, but arms 0 and 3 both have the
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* condition "len >= 2". If arm 3 was lumped in with arm 0, then the
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* wrong branch would be taken. Instead, vec_len Opts are associated
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* with a contiguous range of matches that have the same "shape".
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* This is sort of ugly and requires a bunch of special handling of
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* vec_len options.
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*
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*/
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use back::abi;
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use driver::config::FullDebugInfo;
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use llvm::{ValueRef, BasicBlockRef};
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use middle::check_match::StaticInliner;
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use middle::check_match;
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use middle::const_eval;
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use middle::def;
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use middle::expr_use_visitor as euv;
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use middle::lang_items::StrEqFnLangItem;
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use middle::mem_categorization as mc;
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use middle::pat_util::*;
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use middle::resolve::DefMap;
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use middle::trans::adt;
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use middle::trans::base::*;
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use middle::trans::build::{AddCase, And, BitCast, Br, CondBr, GEPi, InBoundsGEP, Load};
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use middle::trans::build::{Mul, Not, Store, Sub, add_comment};
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use middle::trans::build;
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use middle::trans::callee;
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use middle::trans::cleanup::{mod, CleanupMethods};
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use middle::trans::common::*;
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use middle::trans::consts;
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use middle::trans::datum::*;
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use middle::trans::expr::{mod, Dest};
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use middle::trans::tvec;
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use middle::trans::type_of;
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use middle::trans::debuginfo;
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use middle::ty;
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use util::common::indenter;
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use util::ppaux::{Repr, vec_map_to_string};
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use std;
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use std::collections::HashMap;
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use std::rc::Rc;
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use syntax::ast;
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use syntax::ast::{DUMMY_NODE_ID, Ident};
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use syntax::codemap::Span;
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use syntax::fold::Folder;
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use syntax::ptr::P;
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struct ConstantExpr<'a>(&'a ast::Expr);
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impl<'a> ConstantExpr<'a> {
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fn eq(self, other: ConstantExpr<'a>, tcx: &ty::ctxt) -> bool {
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let ConstantExpr(expr) = self;
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let ConstantExpr(other_expr) = other;
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match const_eval::compare_lit_exprs(tcx, expr, other_expr) {
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Some(val1) => val1 == 0,
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None => fail!("compare_list_exprs: type mismatch"),
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}
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}
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}
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// An option identifying a branch (either a literal, an enum variant or a range)
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enum Opt<'a> {
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ConstantValue(ConstantExpr<'a>),
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ConstantRange(ConstantExpr<'a>, ConstantExpr<'a>),
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Variant(ty::Disr, Rc<adt::Repr>, ast::DefId),
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SliceLengthEqual(uint),
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SliceLengthGreaterOrEqual(/* prefix length */ uint, /* suffix length */ uint),
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}
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impl<'a> Opt<'a> {
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fn eq(&self, other: &Opt<'a>, tcx: &ty::ctxt) -> bool {
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match (self, other) {
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(&ConstantValue(a), &ConstantValue(b)) => a.eq(b, tcx),
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(&ConstantRange(a1, a2), &ConstantRange(b1, b2)) => {
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a1.eq(b1, tcx) && a2.eq(b2, tcx)
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}
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(&Variant(a_disr, ref a_repr, a_def), &Variant(b_disr, ref b_repr, b_def)) => {
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a_disr == b_disr && *a_repr == *b_repr && a_def == b_def
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}
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(&SliceLengthEqual(a), &SliceLengthEqual(b)) => a == b,
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(&SliceLengthGreaterOrEqual(a1, a2), &SliceLengthGreaterOrEqual(b1, b2)) => {
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a1 == b1 && a2 == b2
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}
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_ => false
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}
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}
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fn trans<'blk, 'tcx>(&self, mut bcx: Block<'blk, 'tcx>) -> OptResult<'blk, 'tcx> {
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let _icx = push_ctxt("match::trans_opt");
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let ccx = bcx.ccx();
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match *self {
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ConstantValue(ConstantExpr(lit_expr)) => {
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let lit_ty = ty::node_id_to_type(bcx.tcx(), lit_expr.id);
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let (llval, _, _) = consts::const_expr(ccx, &*lit_expr, true);
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let lit_datum = immediate_rvalue(llval, lit_ty);
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let lit_datum = unpack_datum!(bcx, lit_datum.to_appropriate_datum(bcx));
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SingleResult(Result::new(bcx, lit_datum.val))
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}
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ConstantRange(ConstantExpr(ref l1), ConstantExpr(ref l2)) => {
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let (l1, _, _) = consts::const_expr(ccx, &**l1, true);
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let (l2, _, _) = consts::const_expr(ccx, &**l2, true);
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RangeResult(Result::new(bcx, l1), Result::new(bcx, l2))
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}
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Variant(disr_val, ref repr, _) => {
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adt::trans_case(bcx, &**repr, disr_val)
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}
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SliceLengthEqual(length) => {
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SingleResult(Result::new(bcx, C_uint(ccx, length)))
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}
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SliceLengthGreaterOrEqual(prefix, suffix) => {
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LowerBound(Result::new(bcx, C_uint(ccx, prefix + suffix)))
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}
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}
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}
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}
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#[deriving(PartialEq)]
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pub enum BranchKind {
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NoBranch,
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Single,
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Switch,
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Compare,
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CompareSliceLength
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}
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pub enum OptResult<'blk, 'tcx: 'blk> {
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SingleResult(Result<'blk, 'tcx>),
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RangeResult(Result<'blk, 'tcx>, Result<'blk, 'tcx>),
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LowerBound(Result<'blk, 'tcx>)
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}
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#[deriving(Clone)]
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pub enum TransBindingMode {
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TrByCopy(/* llbinding */ ValueRef),
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TrByMove,
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TrByRef,
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}
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/**
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* Information about a pattern binding:
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* - `llmatch` is a pointer to a stack slot. The stack slot contains a
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* pointer into the value being matched. Hence, llmatch has type `T**`
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* where `T` is the value being matched.
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* - `trmode` is the trans binding mode
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* - `id` is the node id of the binding
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* - `ty` is the Rust type of the binding */
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#[deriving(Clone)]
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pub struct BindingInfo {
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pub llmatch: ValueRef,
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pub trmode: TransBindingMode,
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pub id: ast::NodeId,
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pub span: Span,
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pub ty: ty::t,
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}
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type BindingsMap = HashMap<Ident, BindingInfo>;
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struct ArmData<'p, 'blk, 'tcx: 'blk> {
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bodycx: Block<'blk, 'tcx>,
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arm: &'p ast::Arm,
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bindings_map: BindingsMap
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}
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/**
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* Info about Match.
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* If all `pats` are matched then arm `data` will be executed.
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* As we proceed `bound_ptrs` are filled with pointers to values to be bound,
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* these pointers are stored in llmatch variables just before executing `data` arm.
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*/
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struct Match<'a, 'p: 'a, 'blk: 'a, 'tcx: 'blk> {
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pats: Vec<&'p ast::Pat>,
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data: &'a ArmData<'p, 'blk, 'tcx>,
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bound_ptrs: Vec<(Ident, ValueRef)>
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}
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impl<'a, 'p, 'blk, 'tcx> Repr for Match<'a, 'p, 'blk, 'tcx> {
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fn repr(&self, tcx: &ty::ctxt) -> String {
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if tcx.sess.verbose() {
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// for many programs, this just take too long to serialize
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self.pats.repr(tcx)
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} else {
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format!("{} pats", self.pats.len())
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}
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}
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}
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fn has_nested_bindings(m: &[Match], col: uint) -> bool {
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for br in m.iter() {
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match br.pats.get(col).node {
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ast::PatIdent(_, _, Some(_)) => return true,
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_ => ()
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}
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}
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return false;
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}
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fn expand_nested_bindings<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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m: &[Match<'a, 'p, 'blk, 'tcx>],
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col: uint,
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val: ValueRef)
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-> Vec<Match<'a, 'p, 'blk, 'tcx>> {
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debug!("expand_nested_bindings(bcx={}, m={}, col={}, val={})",
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bcx.to_str(),
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m.repr(bcx.tcx()),
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col,
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bcx.val_to_string(val));
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let _indenter = indenter();
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m.iter().map(|br| {
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let mut bound_ptrs = br.bound_ptrs.clone();
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let mut pat = *br.pats.get(col);
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loop {
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pat = match pat.node {
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ast::PatIdent(_, ref path, Some(ref inner)) => {
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bound_ptrs.push((path.node, val));
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&**inner
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},
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_ => break
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}
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}
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let mut pats = br.pats.clone();
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*pats.get_mut(col) = pat;
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Match {
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pats: pats,
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data: &*br.data,
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bound_ptrs: bound_ptrs
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}
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}).collect()
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}
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type EnterPatterns<'a> = <'p> |&[&'p ast::Pat]|: 'a -> Option<Vec<&'p ast::Pat>>;
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fn enter_match<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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dm: &DefMap,
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m: &[Match<'a, 'p, 'blk, 'tcx>],
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col: uint,
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val: ValueRef,
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e: EnterPatterns)
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-> Vec<Match<'a, 'p, 'blk, 'tcx>> {
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debug!("enter_match(bcx={}, m={}, col={}, val={})",
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bcx.to_str(),
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m.repr(bcx.tcx()),
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col,
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bcx.val_to_string(val));
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let _indenter = indenter();
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m.iter().filter_map(|br| {
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e(br.pats.as_slice()).map(|pats| {
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let this = *br.pats.get(col);
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let mut bound_ptrs = br.bound_ptrs.clone();
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match this.node {
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ast::PatIdent(_, ref path, None) => {
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if pat_is_binding(dm, &*this) {
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bound_ptrs.push((path.node, val));
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}
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}
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ast::PatVec(ref before, Some(ref slice), ref after) => {
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match slice.node {
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ast::PatIdent(_, ref path, None) => {
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let subslice_val = bind_subslice_pat(
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bcx, this.id, val,
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before.len(), after.len());
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bound_ptrs.push((path.node, subslice_val));
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}
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_ => {}
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}
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}
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_ => {}
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}
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Match {
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pats: pats,
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data: br.data,
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bound_ptrs: bound_ptrs
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|
}
|
|
})
|
|
}).collect()
|
|
}
|
|
|
|
fn enter_default<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
dm: &DefMap,
|
|
m: &[Match<'a, 'p, 'blk, 'tcx>],
|
|
col: uint,
|
|
val: ValueRef)
|
|
-> Vec<Match<'a, 'p, 'blk, 'tcx>> {
|
|
debug!("enter_default(bcx={}, m={}, col={}, val={})",
|
|
bcx.to_str(),
|
|
m.repr(bcx.tcx()),
|
|
col,
|
|
bcx.val_to_string(val));
|
|
let _indenter = indenter();
|
|
|
|
// Collect all of the matches that can match against anything.
|
|
enter_match(bcx, dm, m, col, val, |pats| {
|
|
if pat_is_binding_or_wild(dm, &*pats[col]) {
|
|
Some(Vec::from_slice(pats.slice_to(col)).append(pats.slice_from(col + 1)))
|
|
} else {
|
|
None
|
|
}
|
|
})
|
|
}
|
|
|
|
// <pcwalton> nmatsakis: what does enter_opt do?
|
|
// <pcwalton> in trans/match
|
|
// <pcwalton> trans/match.rs is like stumbling around in a dark cave
|
|
// <nmatsakis> pcwalton: the enter family of functions adjust the set of
|
|
// patterns as needed
|
|
// <nmatsakis> yeah, at some point I kind of achieved some level of
|
|
// understanding
|
|
// <nmatsakis> anyhow, they adjust the patterns given that something of that
|
|
// kind has been found
|
|
// <nmatsakis> pcwalton: ok, right, so enter_XXX() adjusts the patterns, as I
|
|
// said
|
|
// <nmatsakis> enter_match() kind of embodies the generic code
|
|
// <nmatsakis> it is provided with a function that tests each pattern to see
|
|
// if it might possibly apply and so forth
|
|
// <nmatsakis> so, if you have a pattern like {a: _, b: _, _} and one like _
|
|
// <nmatsakis> then _ would be expanded to (_, _)
|
|
// <nmatsakis> one spot for each of the sub-patterns
|
|
// <nmatsakis> enter_opt() is one of the more complex; it covers the fallible
|
|
// cases
|
|
// <nmatsakis> enter_rec_or_struct() or enter_tuple() are simpler, since they
|
|
// are infallible patterns
|
|
// <nmatsakis> so all patterns must either be records (resp. tuples) or
|
|
// wildcards
|
|
|
|
/// The above is now outdated in that enter_match() now takes a function that
|
|
/// takes the complete row of patterns rather than just the first one.
|
|
/// Also, most of the enter_() family functions have been unified with
|
|
/// the check_match specialization step.
|
|
fn enter_opt<'a, 'p, 'blk, 'tcx>(
|
|
bcx: Block<'blk, 'tcx>,
|
|
_: ast::NodeId,
|
|
dm: &DefMap,
|
|
m: &[Match<'a, 'p, 'blk, 'tcx>],
|
|
opt: &Opt,
|
|
col: uint,
|
|
variant_size: uint,
|
|
val: ValueRef)
|
|
-> Vec<Match<'a, 'p, 'blk, 'tcx>> {
|
|
debug!("enter_opt(bcx={}, m={}, opt={:?}, col={}, val={})",
|
|
bcx.to_str(),
|
|
m.repr(bcx.tcx()),
|
|
*opt,
|
|
col,
|
|
bcx.val_to_string(val));
|
|
let _indenter = indenter();
|
|
|
|
let ctor = match opt {
|
|
&ConstantValue(ConstantExpr(expr)) => check_match::ConstantValue(
|
|
const_eval::eval_const_expr(bcx.tcx(), &*expr)
|
|
),
|
|
&ConstantRange(ConstantExpr(lo), ConstantExpr(hi)) => check_match::ConstantRange(
|
|
const_eval::eval_const_expr(bcx.tcx(), &*lo),
|
|
const_eval::eval_const_expr(bcx.tcx(), &*hi)
|
|
),
|
|
&SliceLengthEqual(n) =>
|
|
check_match::Slice(n),
|
|
&SliceLengthGreaterOrEqual(before, after) =>
|
|
check_match::SliceWithSubslice(before, after),
|
|
&Variant(_, _, def_id) =>
|
|
check_match::Variant(def_id)
|
|
};
|
|
|
|
let mcx = check_match::MatchCheckCtxt { tcx: bcx.tcx() };
|
|
enter_match(bcx, dm, m, col, val, |pats|
|
|
check_match::specialize(&mcx, pats.as_slice(), &ctor, col, variant_size)
|
|
)
|
|
}
|
|
|
|
// Returns the options in one column of matches. An option is something that
|
|
// needs to be conditionally matched at runtime; for example, the discriminant
|
|
// on a set of enum variants or a literal.
|
|
fn get_branches<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
m: &[Match<'a, 'p, 'blk, 'tcx>], col: uint)
|
|
-> Vec<Opt<'p>> {
|
|
let tcx = bcx.tcx();
|
|
|
|
let mut found: Vec<Opt> = vec![];
|
|
for br in m.iter() {
|
|
let cur = *br.pats.get(col);
|
|
let opt = match cur.node {
|
|
ast::PatLit(ref l) => ConstantValue(ConstantExpr(&**l)),
|
|
ast::PatIdent(..) | ast::PatEnum(..) | ast::PatStruct(..) => {
|
|
// This is either an enum variant or a variable binding.
|
|
let opt_def = tcx.def_map.borrow().find_copy(&cur.id);
|
|
match opt_def {
|
|
Some(def::DefVariant(enum_id, var_id, _)) => {
|
|
let variant = ty::enum_variant_with_id(tcx, enum_id, var_id);
|
|
Variant(variant.disr_val, adt::represent_node(bcx, cur.id), var_id)
|
|
}
|
|
_ => continue
|
|
}
|
|
}
|
|
ast::PatRange(ref l1, ref l2) => {
|
|
ConstantRange(ConstantExpr(&**l1), ConstantExpr(&**l2))
|
|
}
|
|
ast::PatVec(ref before, None, ref after) => {
|
|
SliceLengthEqual(before.len() + after.len())
|
|
}
|
|
ast::PatVec(ref before, Some(_), ref after) => {
|
|
SliceLengthGreaterOrEqual(before.len(), after.len())
|
|
}
|
|
_ => continue
|
|
};
|
|
|
|
if !found.iter().any(|x| x.eq(&opt, tcx)) {
|
|
found.push(opt);
|
|
}
|
|
}
|
|
found
|
|
}
|
|
|
|
struct ExtractedBlock<'blk, 'tcx: 'blk> {
|
|
vals: Vec<ValueRef>,
|
|
bcx: Block<'blk, 'tcx>,
|
|
}
|
|
|
|
fn extract_variant_args<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
repr: &adt::Repr,
|
|
disr_val: ty::Disr,
|
|
val: ValueRef)
|
|
-> ExtractedBlock<'blk, 'tcx> {
|
|
let _icx = push_ctxt("match::extract_variant_args");
|
|
let args = Vec::from_fn(adt::num_args(repr, disr_val), |i| {
|
|
adt::trans_field_ptr(bcx, repr, val, disr_val, i)
|
|
});
|
|
|
|
ExtractedBlock { vals: args, bcx: bcx }
|
|
}
|
|
|
|
fn match_datum(val: ValueRef, left_ty: ty::t) -> Datum<Lvalue> {
|
|
/*!
|
|
* Helper for converting from the ValueRef that we pass around in
|
|
* the match code, which is always an lvalue, into a Datum. Eventually
|
|
* we should just pass around a Datum and be done with it.
|
|
*/
|
|
Datum::new(val, left_ty, Lvalue)
|
|
}
|
|
|
|
fn bind_subslice_pat(bcx: Block,
|
|
pat_id: ast::NodeId,
|
|
val: ValueRef,
|
|
offset_left: uint,
|
|
offset_right: uint) -> ValueRef {
|
|
let _icx = push_ctxt("match::bind_subslice_pat");
|
|
let vec_ty = node_id_type(bcx, pat_id);
|
|
let vt = tvec::vec_types(bcx, ty::sequence_element_type(bcx.tcx(), ty::type_content(vec_ty)));
|
|
let vec_datum = match_datum(val, vec_ty);
|
|
let (base, len) = vec_datum.get_vec_base_and_len(bcx);
|
|
|
|
let slice_byte_offset = Mul(bcx, vt.llunit_size, C_uint(bcx.ccx(), offset_left));
|
|
let slice_begin = tvec::pointer_add_byte(bcx, base, slice_byte_offset);
|
|
let slice_len_offset = C_uint(bcx.ccx(), offset_left + offset_right);
|
|
let slice_len = Sub(bcx, len, slice_len_offset);
|
|
let slice_ty = ty::mk_slice(bcx.tcx(),
|
|
ty::ReStatic,
|
|
ty::mt {ty: vt.unit_ty, mutbl: ast::MutImmutable});
|
|
let scratch = rvalue_scratch_datum(bcx, slice_ty, "");
|
|
Store(bcx, slice_begin,
|
|
GEPi(bcx, scratch.val, [0u, abi::slice_elt_base]));
|
|
Store(bcx, slice_len, GEPi(bcx, scratch.val, [0u, abi::slice_elt_len]));
|
|
scratch.val
|
|
}
|
|
|
|
fn extract_vec_elems<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
left_ty: ty::t,
|
|
before: uint,
|
|
after: uint,
|
|
val: ValueRef)
|
|
-> ExtractedBlock<'blk, 'tcx> {
|
|
let _icx = push_ctxt("match::extract_vec_elems");
|
|
let vec_datum = match_datum(val, left_ty);
|
|
let (base, len) = vec_datum.get_vec_base_and_len(bcx);
|
|
let mut elems = vec![];
|
|
elems.extend(range(0, before).map(|i| GEPi(bcx, base, [i])));
|
|
elems.extend(range(0, after).rev().map(|i| {
|
|
InBoundsGEP(bcx, base, [
|
|
Sub(bcx, len, C_uint(bcx.ccx(), i + 1))
|
|
])
|
|
}));
|
|
ExtractedBlock { vals: elems, bcx: bcx }
|
|
}
|
|
|
|
// Macro for deciding whether any of the remaining matches fit a given kind of
|
|
// pattern. Note that, because the macro is well-typed, either ALL of the
|
|
// matches should fit that sort of pattern or NONE (however, some of the
|
|
// matches may be wildcards like _ or identifiers).
|
|
macro_rules! any_pat (
|
|
($m:expr, $col:expr, $pattern:pat) => (
|
|
($m).iter().any(|br| {
|
|
match br.pats.get($col).node {
|
|
$pattern => true,
|
|
_ => false
|
|
}
|
|
})
|
|
)
|
|
)
|
|
|
|
fn any_uniq_pat(m: &[Match], col: uint) -> bool {
|
|
any_pat!(m, col, ast::PatBox(_))
|
|
}
|
|
|
|
fn any_region_pat(m: &[Match], col: uint) -> bool {
|
|
any_pat!(m, col, ast::PatRegion(_))
|
|
}
|
|
|
|
fn any_irrefutable_adt_pat(tcx: &ty::ctxt, m: &[Match], col: uint) -> bool {
|
|
m.iter().any(|br| {
|
|
let pat = *br.pats.get(col);
|
|
match pat.node {
|
|
ast::PatTup(_) => true,
|
|
ast::PatStruct(..) => {
|
|
match tcx.def_map.borrow().find(&pat.id) {
|
|
Some(&def::DefVariant(..)) => false,
|
|
_ => true,
|
|
}
|
|
}
|
|
ast::PatEnum(..) | ast::PatIdent(_, _, None) => {
|
|
match tcx.def_map.borrow().find(&pat.id) {
|
|
Some(&def::DefStruct(..)) => true,
|
|
_ => false
|
|
}
|
|
}
|
|
_ => false
|
|
}
|
|
})
|
|
}
|
|
|
|
/// What to do when the pattern match fails.
|
|
enum FailureHandler {
|
|
Infallible,
|
|
JumpToBasicBlock(BasicBlockRef),
|
|
Unreachable
|
|
}
|
|
|
|
impl FailureHandler {
|
|
fn is_fallible(&self) -> bool {
|
|
match *self {
|
|
Infallible => false,
|
|
_ => true
|
|
}
|
|
}
|
|
|
|
fn is_infallible(&self) -> bool {
|
|
!self.is_fallible()
|
|
}
|
|
|
|
fn handle_fail(&self, bcx: Block) {
|
|
match *self {
|
|
Infallible =>
|
|
fail!("attempted to fail in an infallible failure handler!"),
|
|
JumpToBasicBlock(basic_block) =>
|
|
Br(bcx, basic_block),
|
|
Unreachable =>
|
|
build::Unreachable(bcx)
|
|
}
|
|
}
|
|
}
|
|
|
|
fn pick_col(m: &[Match]) -> uint {
|
|
fn score(p: &ast::Pat) -> uint {
|
|
match p.node {
|
|
ast::PatLit(_) | ast::PatEnum(_, _) | ast::PatRange(_, _) => 1u,
|
|
ast::PatIdent(_, _, Some(ref p)) => score(&**p),
|
|
_ => 0u
|
|
}
|
|
}
|
|
let mut scores = Vec::from_elem(m[0].pats.len(), 0u);
|
|
for br in m.iter() {
|
|
for (i, ref p) in br.pats.iter().enumerate() {
|
|
*scores.get_mut(i) += score(&***p);
|
|
}
|
|
}
|
|
let mut max_score = 0u;
|
|
let mut best_col = 0u;
|
|
for (i, score) in scores.iter().enumerate() {
|
|
let score = *score;
|
|
|
|
// Irrefutable columns always go first, they'd only be duplicated in
|
|
// the branches.
|
|
if score == 0u { return i; }
|
|
// If no irrefutable ones are found, we pick the one with the biggest
|
|
// branching factor.
|
|
if score > max_score { max_score = score; best_col = i; }
|
|
}
|
|
return best_col;
|
|
}
|
|
|
|
// Compiles a comparison between two things.
|
|
fn compare_values<'blk, 'tcx>(cx: Block<'blk, 'tcx>,
|
|
lhs: ValueRef,
|
|
rhs: ValueRef,
|
|
rhs_t: ty::t)
|
|
-> Result<'blk, 'tcx> {
|
|
fn compare_str<'blk, 'tcx>(cx: Block<'blk, 'tcx>,
|
|
lhs: ValueRef,
|
|
rhs: ValueRef,
|
|
rhs_t: ty::t)
|
|
-> Result<'blk, 'tcx> {
|
|
let did = langcall(cx,
|
|
None,
|
|
format!("comparison of `{}`",
|
|
cx.ty_to_string(rhs_t)).as_slice(),
|
|
StrEqFnLangItem);
|
|
callee::trans_lang_call(cx, did, [lhs, rhs], None)
|
|
}
|
|
|
|
let _icx = push_ctxt("compare_values");
|
|
if ty::type_is_scalar(rhs_t) {
|
|
let rs = compare_scalar_types(cx, lhs, rhs, rhs_t, ast::BiEq);
|
|
return Result::new(rs.bcx, rs.val);
|
|
}
|
|
|
|
match ty::get(rhs_t).sty {
|
|
ty::ty_rptr(_, mt) => match ty::get(mt.ty).sty {
|
|
ty::ty_str => compare_str(cx, lhs, rhs, rhs_t),
|
|
ty::ty_vec(ty, _) => match ty::get(ty).sty {
|
|
ty::ty_uint(ast::TyU8) => {
|
|
// NOTE: cast &[u8] to &str and abuse the str_eq lang item,
|
|
// which calls memcmp().
|
|
let t = ty::mk_str_slice(cx.tcx(), ty::ReStatic, ast::MutImmutable);
|
|
let lhs = BitCast(cx, lhs, type_of::type_of(cx.ccx(), t).ptr_to());
|
|
let rhs = BitCast(cx, rhs, type_of::type_of(cx.ccx(), t).ptr_to());
|
|
compare_str(cx, lhs, rhs, rhs_t)
|
|
},
|
|
_ => cx.sess().bug("only byte strings supported in compare_values"),
|
|
},
|
|
_ => cx.sess().bug("only string and byte strings supported in compare_values"),
|
|
},
|
|
_ => cx.sess().bug("only scalars, byte strings, and strings supported in compare_values"),
|
|
}
|
|
}
|
|
|
|
fn insert_lllocals<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
|
|
bindings_map: &BindingsMap,
|
|
cs: Option<cleanup::ScopeId>)
|
|
-> Block<'blk, 'tcx> {
|
|
/*!
|
|
* For each binding in `data.bindings_map`, adds an appropriate entry into
|
|
* the `fcx.lllocals` map
|
|
*/
|
|
|
|
for (&ident, &binding_info) in bindings_map.iter() {
|
|
let llval = match binding_info.trmode {
|
|
// By value mut binding for a copy type: load from the ptr
|
|
// into the matched value and copy to our alloca
|
|
TrByCopy(llbinding) => {
|
|
let llval = Load(bcx, binding_info.llmatch);
|
|
let datum = Datum::new(llval, binding_info.ty, Lvalue);
|
|
call_lifetime_start(bcx, llbinding);
|
|
bcx = datum.store_to(bcx, llbinding);
|
|
match cs {
|
|
Some(cs) => bcx.fcx.schedule_lifetime_end(cs, llbinding),
|
|
_ => {}
|
|
}
|
|
|
|
llbinding
|
|
},
|
|
|
|
// By value move bindings: load from the ptr into the matched value
|
|
TrByMove => Load(bcx, binding_info.llmatch),
|
|
|
|
// By ref binding: use the ptr into the matched value
|
|
TrByRef => binding_info.llmatch
|
|
};
|
|
|
|
let datum = Datum::new(llval, binding_info.ty, Lvalue);
|
|
match cs {
|
|
Some(cs) => {
|
|
bcx.fcx.schedule_drop_and_zero_mem(cs, llval, binding_info.ty);
|
|
bcx.fcx.schedule_lifetime_end(cs, binding_info.llmatch);
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
debug!("binding {:?} to {}",
|
|
binding_info.id,
|
|
bcx.val_to_string(llval));
|
|
bcx.fcx.lllocals.borrow_mut().insert(binding_info.id, datum);
|
|
|
|
if bcx.sess().opts.debuginfo == FullDebugInfo {
|
|
debuginfo::create_match_binding_metadata(bcx,
|
|
ident,
|
|
binding_info);
|
|
}
|
|
}
|
|
bcx
|
|
}
|
|
|
|
fn compile_guard<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
guard_expr: &ast::Expr,
|
|
data: &ArmData,
|
|
m: &[Match<'a, 'p, 'blk, 'tcx>],
|
|
vals: &[ValueRef],
|
|
chk: &FailureHandler,
|
|
has_genuine_default: bool)
|
|
-> Block<'blk, 'tcx> {
|
|
debug!("compile_guard(bcx={}, guard_expr={}, m={}, vals={})",
|
|
bcx.to_str(),
|
|
bcx.expr_to_string(guard_expr),
|
|
m.repr(bcx.tcx()),
|
|
vec_map_to_string(vals, |v| bcx.val_to_string(*v)));
|
|
let _indenter = indenter();
|
|
|
|
let mut bcx = insert_lllocals(bcx, &data.bindings_map, None);
|
|
|
|
let val = unpack_datum!(bcx, expr::trans(bcx, guard_expr));
|
|
let val = val.to_llbool(bcx);
|
|
|
|
for (_, &binding_info) in data.bindings_map.iter() {
|
|
match binding_info.trmode {
|
|
TrByCopy(llbinding) => call_lifetime_end(bcx, llbinding),
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
with_cond(bcx, Not(bcx, val), |bcx| {
|
|
// Guard does not match: remove all bindings from the lllocals table
|
|
for (_, &binding_info) in data.bindings_map.iter() {
|
|
call_lifetime_end(bcx, binding_info.llmatch);
|
|
bcx.fcx.lllocals.borrow_mut().remove(&binding_info.id);
|
|
}
|
|
match chk {
|
|
// If the default arm is the only one left, move on to the next
|
|
// condition explicitly rather than (possibly) falling back to
|
|
// the default arm.
|
|
&JumpToBasicBlock(_) if m.len() == 1 && has_genuine_default => {
|
|
chk.handle_fail(bcx);
|
|
}
|
|
_ => {
|
|
compile_submatch(bcx, m, vals, chk, has_genuine_default);
|
|
}
|
|
};
|
|
bcx
|
|
})
|
|
}
|
|
|
|
fn compile_submatch<'a, 'p, 'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
m: &[Match<'a, 'p, 'blk, 'tcx>],
|
|
vals: &[ValueRef],
|
|
chk: &FailureHandler,
|
|
has_genuine_default: bool) {
|
|
debug!("compile_submatch(bcx={}, m={}, vals={})",
|
|
bcx.to_str(),
|
|
m.repr(bcx.tcx()),
|
|
vec_map_to_string(vals, |v| bcx.val_to_string(*v)));
|
|
let _indenter = indenter();
|
|
let _icx = push_ctxt("match::compile_submatch");
|
|
let mut bcx = bcx;
|
|
if m.len() == 0u {
|
|
if chk.is_fallible() {
|
|
chk.handle_fail(bcx);
|
|
}
|
|
return;
|
|
}
|
|
|
|
let col_count = m[0].pats.len();
|
|
if col_count == 0u {
|
|
let data = &m[0].data;
|
|
for &(ref ident, ref value_ptr) in m[0].bound_ptrs.iter() {
|
|
let llmatch = data.bindings_map.get(ident).llmatch;
|
|
call_lifetime_start(bcx, llmatch);
|
|
Store(bcx, *value_ptr, llmatch);
|
|
}
|
|
match data.arm.guard {
|
|
Some(ref guard_expr) => {
|
|
bcx = compile_guard(bcx,
|
|
&**guard_expr,
|
|
m[0].data,
|
|
m.slice(1, m.len()),
|
|
vals,
|
|
chk,
|
|
has_genuine_default);
|
|
}
|
|
_ => ()
|
|
}
|
|
Br(bcx, data.bodycx.llbb);
|
|
return;
|
|
}
|
|
|
|
let col = pick_col(m);
|
|
let val = vals[col];
|
|
|
|
if has_nested_bindings(m, col) {
|
|
let expanded = expand_nested_bindings(bcx, m, col, val);
|
|
compile_submatch_continue(bcx,
|
|
expanded.as_slice(),
|
|
vals,
|
|
chk,
|
|
col,
|
|
val,
|
|
has_genuine_default)
|
|
} else {
|
|
compile_submatch_continue(bcx, m, vals, chk, col, val, has_genuine_default)
|
|
}
|
|
}
|
|
|
|
fn compile_submatch_continue<'a, 'p, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
|
|
m: &[Match<'a, 'p, 'blk, 'tcx>],
|
|
vals: &[ValueRef],
|
|
chk: &FailureHandler,
|
|
col: uint,
|
|
val: ValueRef,
|
|
has_genuine_default: bool) {
|
|
let fcx = bcx.fcx;
|
|
let tcx = bcx.tcx();
|
|
let dm = &tcx.def_map;
|
|
|
|
let vals_left = Vec::from_slice(vals.slice(0u, col)).append(vals.slice(col + 1u, vals.len()));
|
|
let ccx = bcx.fcx.ccx;
|
|
|
|
// Find a real id (we're adding placeholder wildcard patterns, but
|
|
// each column is guaranteed to have at least one real pattern)
|
|
let pat_id = m.iter().map(|br| br.pats.get(col).id)
|
|
.find(|&id| id != DUMMY_NODE_ID)
|
|
.unwrap_or(DUMMY_NODE_ID);
|
|
|
|
let left_ty = if pat_id == DUMMY_NODE_ID {
|
|
ty::mk_nil()
|
|
} else {
|
|
node_id_type(bcx, pat_id)
|
|
};
|
|
|
|
let mcx = check_match::MatchCheckCtxt { tcx: bcx.tcx() };
|
|
let adt_vals = if any_irrefutable_adt_pat(bcx.tcx(), m, col) {
|
|
let repr = adt::represent_type(bcx.ccx(), left_ty);
|
|
let arg_count = adt::num_args(&*repr, 0);
|
|
let field_vals: Vec<ValueRef> = std::iter::range(0, arg_count).map(|ix|
|
|
adt::trans_field_ptr(bcx, &*repr, val, 0, ix)
|
|
).collect();
|
|
Some(field_vals)
|
|
} else if any_uniq_pat(m, col) || any_region_pat(m, col) {
|
|
Some(vec!(Load(bcx, val)))
|
|
} else {
|
|
match ty::get(left_ty).sty {
|
|
ty::ty_vec(_, Some(n)) => {
|
|
let args = extract_vec_elems(bcx, left_ty, n, 0, val);
|
|
Some(args.vals)
|
|
}
|
|
_ => None
|
|
}
|
|
};
|
|
|
|
match adt_vals {
|
|
Some(field_vals) => {
|
|
let pats = enter_match(bcx, dm, m, col, val, |pats|
|
|
check_match::specialize(&mcx, pats, &check_match::Single, col, field_vals.len())
|
|
);
|
|
let vals = field_vals.append(vals_left.as_slice());
|
|
compile_submatch(bcx, pats.as_slice(), vals.as_slice(), chk, has_genuine_default);
|
|
return;
|
|
}
|
|
_ => ()
|
|
}
|
|
|
|
// Decide what kind of branch we need
|
|
let opts = get_branches(bcx, m, col);
|
|
debug!("options={:?}", opts);
|
|
let mut kind = NoBranch;
|
|
let mut test_val = val;
|
|
debug!("test_val={}", bcx.val_to_string(test_val));
|
|
if opts.len() > 0u {
|
|
match *opts.get(0) {
|
|
ConstantValue(_) | ConstantRange(_, _) => {
|
|
test_val = load_if_immediate(bcx, val, left_ty);
|
|
kind = if ty::type_is_integral(left_ty) {
|
|
Switch
|
|
} else {
|
|
Compare
|
|
};
|
|
}
|
|
Variant(_, ref repr, _) => {
|
|
let (the_kind, val_opt) = adt::trans_switch(bcx, &**repr, val);
|
|
kind = the_kind;
|
|
for &tval in val_opt.iter() { test_val = tval; }
|
|
}
|
|
SliceLengthEqual(_) | SliceLengthGreaterOrEqual(_, _) => {
|
|
let (_, len) = tvec::get_base_and_len(bcx, val, left_ty);
|
|
test_val = len;
|
|
kind = Switch;
|
|
}
|
|
}
|
|
}
|
|
for o in opts.iter() {
|
|
match *o {
|
|
ConstantRange(_, _) => { kind = Compare; break },
|
|
SliceLengthGreaterOrEqual(_, _) => { kind = CompareSliceLength; break },
|
|
_ => ()
|
|
}
|
|
}
|
|
let else_cx = match kind {
|
|
NoBranch | Single => bcx,
|
|
_ => bcx.fcx.new_temp_block("match_else")
|
|
};
|
|
let sw = if kind == Switch {
|
|
build::Switch(bcx, test_val, else_cx.llbb, opts.len())
|
|
} else {
|
|
C_int(ccx, 0) // Placeholder for when not using a switch
|
|
};
|
|
|
|
let defaults = enter_default(else_cx, dm, m, col, val);
|
|
let exhaustive = chk.is_infallible() && defaults.len() == 0u;
|
|
let len = opts.len();
|
|
|
|
// Compile subtrees for each option
|
|
for (i, opt) in opts.iter().enumerate() {
|
|
// In some cases of range and vector pattern matching, we need to
|
|
// override the failure case so that instead of failing, it proceeds
|
|
// to try more matching. branch_chk, then, is the proper failure case
|
|
// for the current conditional branch.
|
|
let mut branch_chk = None;
|
|
let mut opt_cx = else_cx;
|
|
if !exhaustive || i + 1 < len {
|
|
opt_cx = bcx.fcx.new_temp_block("match_case");
|
|
match kind {
|
|
Single => Br(bcx, opt_cx.llbb),
|
|
Switch => {
|
|
match opt.trans(bcx) {
|
|
SingleResult(r) => {
|
|
AddCase(sw, r.val, opt_cx.llbb);
|
|
bcx = r.bcx;
|
|
}
|
|
_ => {
|
|
bcx.sess().bug(
|
|
"in compile_submatch, expected \
|
|
opt.trans() to return a SingleResult")
|
|
}
|
|
}
|
|
}
|
|
Compare | CompareSliceLength => {
|
|
let t = if kind == Compare {
|
|
left_ty
|
|
} else {
|
|
ty::mk_uint() // vector length
|
|
};
|
|
let Result { bcx: after_cx, val: matches } = {
|
|
match opt.trans(bcx) {
|
|
SingleResult(Result { bcx, val }) => {
|
|
compare_values(bcx, test_val, val, t)
|
|
}
|
|
RangeResult(Result { val: vbegin, .. },
|
|
Result { bcx, val: vend }) => {
|
|
let Result { bcx, val: llge } =
|
|
compare_scalar_types(
|
|
bcx, test_val,
|
|
vbegin, t, ast::BiGe);
|
|
let Result { bcx, val: llle } =
|
|
compare_scalar_types(
|
|
bcx, test_val, vend,
|
|
t, ast::BiLe);
|
|
Result::new(bcx, And(bcx, llge, llle))
|
|
}
|
|
LowerBound(Result { bcx, val }) => {
|
|
compare_scalar_types(bcx, test_val, val, t, ast::BiGe)
|
|
}
|
|
}
|
|
};
|
|
bcx = fcx.new_temp_block("compare_next");
|
|
|
|
// If none of the sub-cases match, and the current condition
|
|
// is guarded or has multiple patterns, move on to the next
|
|
// condition, if there is any, rather than falling back to
|
|
// the default.
|
|
let guarded = m[i].data.arm.guard.is_some();
|
|
let multi_pats = m[i].pats.len() > 1;
|
|
if i + 1 < len && (guarded || multi_pats || kind == CompareSliceLength) {
|
|
branch_chk = Some(JumpToBasicBlock(bcx.llbb));
|
|
}
|
|
CondBr(after_cx, matches, opt_cx.llbb, bcx.llbb);
|
|
}
|
|
_ => ()
|
|
}
|
|
} else if kind == Compare || kind == CompareSliceLength {
|
|
Br(bcx, else_cx.llbb);
|
|
}
|
|
|
|
let mut size = 0u;
|
|
let mut unpacked = Vec::new();
|
|
match *opt {
|
|
Variant(disr_val, ref repr, _) => {
|
|
let ExtractedBlock {vals: argvals, bcx: new_bcx} =
|
|
extract_variant_args(opt_cx, &**repr, disr_val, val);
|
|
size = argvals.len();
|
|
unpacked = argvals;
|
|
opt_cx = new_bcx;
|
|
}
|
|
SliceLengthEqual(len) => {
|
|
let args = extract_vec_elems(opt_cx, left_ty, len, 0, val);
|
|
size = args.vals.len();
|
|
unpacked = args.vals.clone();
|
|
opt_cx = args.bcx;
|
|
}
|
|
SliceLengthGreaterOrEqual(before, after) => {
|
|
let args = extract_vec_elems(opt_cx, left_ty, before, after, val);
|
|
size = args.vals.len();
|
|
unpacked = args.vals.clone();
|
|
opt_cx = args.bcx;
|
|
}
|
|
ConstantValue(_) | ConstantRange(_, _) => ()
|
|
}
|
|
let opt_ms = enter_opt(opt_cx, pat_id, dm, m, opt, col, size, val);
|
|
let opt_vals = unpacked.append(vals_left.as_slice());
|
|
compile_submatch(opt_cx,
|
|
opt_ms.as_slice(),
|
|
opt_vals.as_slice(),
|
|
branch_chk.as_ref().unwrap_or(chk),
|
|
has_genuine_default);
|
|
}
|
|
|
|
// Compile the fall-through case, if any
|
|
if !exhaustive && kind != Single {
|
|
if kind == Compare || kind == CompareSliceLength {
|
|
Br(bcx, else_cx.llbb);
|
|
}
|
|
match chk {
|
|
// If there is only one default arm left, move on to the next
|
|
// condition explicitly rather than (eventually) falling back to
|
|
// the last default arm.
|
|
&JumpToBasicBlock(_) if defaults.len() == 1 && has_genuine_default => {
|
|
chk.handle_fail(else_cx);
|
|
}
|
|
_ => {
|
|
compile_submatch(else_cx,
|
|
defaults.as_slice(),
|
|
vals_left.as_slice(),
|
|
chk,
|
|
has_genuine_default);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn trans_match<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
match_expr: &ast::Expr,
|
|
discr_expr: &ast::Expr,
|
|
arms: &[ast::Arm],
|
|
dest: Dest)
|
|
-> Block<'blk, 'tcx> {
|
|
let _icx = push_ctxt("match::trans_match");
|
|
trans_match_inner(bcx, match_expr.id, discr_expr, arms, dest)
|
|
}
|
|
|
|
/// Checks whether the binding in `discr` is assigned to anywhere in the expression `body`
|
|
fn is_discr_reassigned(bcx: Block, discr: &ast::Expr, body: &ast::Expr) -> bool {
|
|
match discr.node {
|
|
ast::ExprPath(..) => match bcx.def(discr.id) {
|
|
def::DefLocal(vid) | def::DefUpvar(vid, _, _) => {
|
|
let mut rc = ReassignmentChecker {
|
|
node: vid,
|
|
reassigned: false
|
|
};
|
|
{
|
|
let mut visitor = euv::ExprUseVisitor::new(&mut rc, bcx);
|
|
visitor.walk_expr(body);
|
|
}
|
|
rc.reassigned
|
|
}
|
|
_ => false
|
|
},
|
|
_ => false
|
|
}
|
|
}
|
|
|
|
struct ReassignmentChecker {
|
|
node: ast::NodeId,
|
|
reassigned: bool
|
|
}
|
|
|
|
impl euv::Delegate for ReassignmentChecker {
|
|
fn consume(&mut self, _: ast::NodeId, _: Span, _: mc::cmt, _: euv::ConsumeMode) {}
|
|
fn consume_pat(&mut self, _: &ast::Pat, _: mc::cmt, _: euv::ConsumeMode) {}
|
|
fn borrow(&mut self, _: ast::NodeId, _: Span, _: mc::cmt, _: ty::Region,
|
|
_: ty::BorrowKind, _: euv::LoanCause) {}
|
|
fn decl_without_init(&mut self, _: ast::NodeId, _: Span) {}
|
|
|
|
fn mutate(&mut self, _: ast::NodeId, _: Span, cmt: mc::cmt, _: euv::MutateMode) {
|
|
match cmt.cat {
|
|
mc::cat_copied_upvar(mc::CopiedUpvar { upvar_id: vid, .. }) |
|
|
mc::cat_local(vid) => self.reassigned = self.node == vid,
|
|
_ => {}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn create_bindings_map(bcx: Block, pat: &ast::Pat,
|
|
discr: &ast::Expr, body: &ast::Expr) -> BindingsMap {
|
|
// Create the bindings map, which is a mapping from each binding name
|
|
// to an alloca() that will be the value for that local variable.
|
|
// Note that we use the names because each binding will have many ids
|
|
// from the various alternatives.
|
|
let ccx = bcx.ccx();
|
|
let tcx = bcx.tcx();
|
|
let reassigned = is_discr_reassigned(bcx, discr, body);
|
|
let mut bindings_map = HashMap::new();
|
|
pat_bindings(&tcx.def_map, &*pat, |bm, p_id, span, path1| {
|
|
let ident = path1.node;
|
|
let variable_ty = node_id_type(bcx, p_id);
|
|
let llvariable_ty = type_of::type_of(ccx, variable_ty);
|
|
let tcx = bcx.tcx();
|
|
|
|
let llmatch;
|
|
let trmode;
|
|
match bm {
|
|
ast::BindByValue(_)
|
|
if !ty::type_moves_by_default(tcx, variable_ty) || reassigned => {
|
|
llmatch = alloca_no_lifetime(bcx,
|
|
llvariable_ty.ptr_to(),
|
|
"__llmatch");
|
|
trmode = TrByCopy(alloca_no_lifetime(bcx,
|
|
llvariable_ty,
|
|
bcx.ident(ident).as_slice()));
|
|
}
|
|
ast::BindByValue(_) => {
|
|
// in this case, the final type of the variable will be T,
|
|
// but during matching we need to store a *T as explained
|
|
// above
|
|
llmatch = alloca_no_lifetime(bcx,
|
|
llvariable_ty.ptr_to(),
|
|
bcx.ident(ident).as_slice());
|
|
trmode = TrByMove;
|
|
}
|
|
ast::BindByRef(_) => {
|
|
llmatch = alloca_no_lifetime(bcx,
|
|
llvariable_ty,
|
|
bcx.ident(ident).as_slice());
|
|
trmode = TrByRef;
|
|
}
|
|
};
|
|
bindings_map.insert(ident, BindingInfo {
|
|
llmatch: llmatch,
|
|
trmode: trmode,
|
|
id: p_id,
|
|
span: span,
|
|
ty: variable_ty
|
|
});
|
|
});
|
|
return bindings_map;
|
|
}
|
|
|
|
fn trans_match_inner<'blk, 'tcx>(scope_cx: Block<'blk, 'tcx>,
|
|
match_id: ast::NodeId,
|
|
discr_expr: &ast::Expr,
|
|
arms: &[ast::Arm],
|
|
dest: Dest) -> Block<'blk, 'tcx> {
|
|
let _icx = push_ctxt("match::trans_match_inner");
|
|
let fcx = scope_cx.fcx;
|
|
let mut bcx = scope_cx;
|
|
let tcx = bcx.tcx();
|
|
|
|
let discr_datum = unpack_datum!(bcx, expr::trans_to_lvalue(bcx, discr_expr,
|
|
"match"));
|
|
if bcx.unreachable.get() {
|
|
return bcx;
|
|
}
|
|
|
|
let t = node_id_type(bcx, discr_expr.id);
|
|
let chk = if ty::type_is_empty(tcx, t) {
|
|
Unreachable
|
|
} else {
|
|
Infallible
|
|
};
|
|
|
|
let arm_datas: Vec<ArmData> = arms.iter().map(|arm| ArmData {
|
|
bodycx: fcx.new_id_block("case_body", arm.body.id),
|
|
arm: arm,
|
|
bindings_map: create_bindings_map(bcx, &**arm.pats.get(0), discr_expr, &*arm.body)
|
|
}).collect();
|
|
|
|
let mut static_inliner = StaticInliner::new(scope_cx.tcx());
|
|
let arm_pats: Vec<Vec<P<ast::Pat>>> = arm_datas.iter().map(|arm_data| {
|
|
arm_data.arm.pats.iter().map(|p| static_inliner.fold_pat((*p).clone())).collect()
|
|
}).collect();
|
|
let mut matches = Vec::new();
|
|
for (arm_data, pats) in arm_datas.iter().zip(arm_pats.iter()) {
|
|
matches.extend(pats.iter().map(|p| Match {
|
|
pats: vec![&**p],
|
|
data: arm_data,
|
|
bound_ptrs: Vec::new(),
|
|
}));
|
|
}
|
|
|
|
// `compile_submatch` works one column of arm patterns a time and
|
|
// then peels that column off. So as we progress, it may become
|
|
// impossible to tell whether we have a genuine default arm, i.e.
|
|
// `_ => foo` or not. Sometimes it is important to know that in order
|
|
// to decide whether moving on to the next condition or falling back
|
|
// to the default arm.
|
|
let has_default = arms.last().map_or(false, |arm| {
|
|
arm.pats.len() == 1
|
|
&& arm.pats.last().unwrap().node == ast::PatWild(ast::PatWildSingle)
|
|
});
|
|
|
|
compile_submatch(bcx, matches.as_slice(), [discr_datum.val], &chk, has_default);
|
|
|
|
let mut arm_cxs = Vec::new();
|
|
for arm_data in arm_datas.iter() {
|
|
let mut bcx = arm_data.bodycx;
|
|
|
|
// insert bindings into the lllocals map and add cleanups
|
|
let cs = fcx.push_custom_cleanup_scope();
|
|
bcx = insert_lllocals(bcx, &arm_data.bindings_map, Some(cleanup::CustomScope(cs)));
|
|
bcx = expr::trans_into(bcx, &*arm_data.arm.body, dest);
|
|
bcx = fcx.pop_and_trans_custom_cleanup_scope(bcx, cs);
|
|
arm_cxs.push(bcx);
|
|
}
|
|
|
|
bcx = scope_cx.fcx.join_blocks(match_id, arm_cxs.as_slice());
|
|
return bcx;
|
|
}
|
|
|
|
pub fn store_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
local: &ast::Local)
|
|
-> Block<'blk, 'tcx> {
|
|
/*!
|
|
* Generates code for a local variable declaration like
|
|
* `let <pat>;` or `let <pat> = <opt_init_expr>`.
|
|
*/
|
|
let _icx = push_ctxt("match::store_local");
|
|
let mut bcx = bcx;
|
|
let tcx = bcx.tcx();
|
|
let pat = &*local.pat;
|
|
|
|
fn create_dummy_locals<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
|
|
pat: &ast::Pat)
|
|
-> Block<'blk, 'tcx> {
|
|
// create dummy memory for the variables if we have no
|
|
// value to store into them immediately
|
|
let tcx = bcx.tcx();
|
|
pat_bindings(&tcx.def_map, pat, |_, p_id, _, path1| {
|
|
let scope = cleanup::var_scope(tcx, p_id);
|
|
bcx = mk_binding_alloca(
|
|
bcx, p_id, &path1.node, scope, (),
|
|
|(), bcx, llval, ty| { zero_mem(bcx, llval, ty); bcx });
|
|
});
|
|
bcx
|
|
}
|
|
|
|
match local.init {
|
|
Some(ref init_expr) => {
|
|
// Optimize the "let x = expr" case. This just writes
|
|
// the result of evaluating `expr` directly into the alloca
|
|
// for `x`. Often the general path results in similar or the
|
|
// same code post-optimization, but not always. In particular,
|
|
// in unsafe code, you can have expressions like
|
|
//
|
|
// let x = intrinsics::uninit();
|
|
//
|
|
// In such cases, the more general path is unsafe, because
|
|
// it assumes it is matching against a valid value.
|
|
match simple_identifier(&*pat) {
|
|
Some(ident) => {
|
|
let var_scope = cleanup::var_scope(tcx, local.id);
|
|
return mk_binding_alloca(
|
|
bcx, pat.id, ident, var_scope, (),
|
|
|(), bcx, v, _| expr::trans_into(bcx, &**init_expr,
|
|
expr::SaveIn(v)));
|
|
}
|
|
|
|
None => {}
|
|
}
|
|
|
|
// General path.
|
|
let init_datum =
|
|
unpack_datum!(bcx, expr::trans_to_lvalue(bcx, &**init_expr, "let"));
|
|
if ty::type_is_bot(expr_ty(bcx, &**init_expr)) {
|
|
create_dummy_locals(bcx, pat)
|
|
} else {
|
|
if bcx.sess().asm_comments() {
|
|
add_comment(bcx, "creating zeroable ref llval");
|
|
}
|
|
let var_scope = cleanup::var_scope(tcx, local.id);
|
|
bind_irrefutable_pat(bcx, pat, init_datum.val, var_scope)
|
|
}
|
|
}
|
|
None => {
|
|
create_dummy_locals(bcx, pat)
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn store_arg<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
|
|
pat: &ast::Pat,
|
|
arg: Datum<Rvalue>,
|
|
arg_scope: cleanup::ScopeId)
|
|
-> Block<'blk, 'tcx> {
|
|
/*!
|
|
* Generates code for argument patterns like `fn foo(<pat>: T)`.
|
|
* Creates entries in the `lllocals` map for each of the bindings
|
|
* in `pat`.
|
|
*
|
|
* # Arguments
|
|
*
|
|
* - `pat` is the argument pattern
|
|
* - `llval` is a pointer to the argument value (in other words,
|
|
* if the argument type is `T`, then `llval` is a `T*`). In some
|
|
* cases, this code may zero out the memory `llval` points at.
|
|
*/
|
|
|
|
let _icx = push_ctxt("match::store_arg");
|
|
|
|
match simple_identifier(&*pat) {
|
|
Some(ident) => {
|
|
// Generate nicer LLVM for the common case of fn a pattern
|
|
// like `x: T`
|
|
let arg_ty = node_id_type(bcx, pat.id);
|
|
if type_of::arg_is_indirect(bcx.ccx(), arg_ty)
|
|
&& bcx.sess().opts.debuginfo != FullDebugInfo {
|
|
// Don't copy an indirect argument to an alloca, the caller
|
|
// already put it in a temporary alloca and gave it up, unless
|
|
// we emit extra-debug-info, which requires local allocas :(.
|
|
let arg_val = arg.add_clean(bcx.fcx, arg_scope);
|
|
bcx.fcx.lllocals.borrow_mut()
|
|
.insert(pat.id, Datum::new(arg_val, arg_ty, Lvalue));
|
|
bcx
|
|
} else {
|
|
mk_binding_alloca(
|
|
bcx, pat.id, ident, arg_scope, arg,
|
|
|arg, bcx, llval, _| arg.store_to(bcx, llval))
|
|
}
|
|
}
|
|
|
|
None => {
|
|
// General path. Copy out the values that are used in the
|
|
// pattern.
|
|
let arg = unpack_datum!(
|
|
bcx, arg.to_lvalue_datum_in_scope(bcx, "__arg", arg_scope));
|
|
bind_irrefutable_pat(bcx, pat, arg.val, arg_scope)
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Generates code for the pattern binding in a `for` loop like
|
|
/// `for <pat> in <expr> { ... }`.
|
|
pub fn store_for_loop_binding<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
pat: &ast::Pat,
|
|
llvalue: ValueRef,
|
|
body_scope: cleanup::ScopeId)
|
|
-> Block<'blk, 'tcx> {
|
|
let _icx = push_ctxt("match::store_for_loop_binding");
|
|
|
|
if simple_identifier(&*pat).is_some() {
|
|
// Generate nicer LLVM for the common case of a `for` loop pattern
|
|
// like `for x in blahblah { ... }`.
|
|
let binding_type = node_id_type(bcx, pat.id);
|
|
bcx.fcx.lllocals.borrow_mut().insert(pat.id,
|
|
Datum::new(llvalue,
|
|
binding_type,
|
|
Lvalue));
|
|
return bcx
|
|
}
|
|
|
|
// General path. Copy out the values that are used in the pattern.
|
|
bind_irrefutable_pat(bcx, pat, llvalue, body_scope)
|
|
}
|
|
|
|
fn mk_binding_alloca<'blk, 'tcx, A>(bcx: Block<'blk, 'tcx>,
|
|
p_id: ast::NodeId,
|
|
ident: &ast::Ident,
|
|
cleanup_scope: cleanup::ScopeId,
|
|
arg: A,
|
|
populate: |A, Block<'blk, 'tcx>, ValueRef, ty::t|
|
|
-> Block<'blk, 'tcx>)
|
|
-> Block<'blk, 'tcx> {
|
|
let var_ty = node_id_type(bcx, p_id);
|
|
|
|
// Allocate memory on stack for the binding.
|
|
let llval = alloc_ty(bcx, var_ty, bcx.ident(*ident).as_slice());
|
|
|
|
// Subtle: be sure that we *populate* the memory *before*
|
|
// we schedule the cleanup.
|
|
let bcx = populate(arg, bcx, llval, var_ty);
|
|
bcx.fcx.schedule_lifetime_end(cleanup_scope, llval);
|
|
bcx.fcx.schedule_drop_mem(cleanup_scope, llval, var_ty);
|
|
|
|
// Now that memory is initialized and has cleanup scheduled,
|
|
// create the datum and insert into the local variable map.
|
|
let datum = Datum::new(llval, var_ty, Lvalue);
|
|
bcx.fcx.lllocals.borrow_mut().insert(p_id, datum);
|
|
bcx
|
|
}
|
|
|
|
fn bind_irrefutable_pat<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
pat: &ast::Pat,
|
|
val: ValueRef,
|
|
cleanup_scope: cleanup::ScopeId)
|
|
-> Block<'blk, 'tcx> {
|
|
/*!
|
|
* A simple version of the pattern matching code that only handles
|
|
* irrefutable patterns. This is used in let/argument patterns,
|
|
* not in match statements. Unifying this code with the code above
|
|
* sounds nice, but in practice it produces very inefficient code,
|
|
* since the match code is so much more general. In most cases,
|
|
* LLVM is able to optimize the code, but it causes longer compile
|
|
* times and makes the generated code nigh impossible to read.
|
|
*
|
|
* # Arguments
|
|
* - bcx: starting basic block context
|
|
* - pat: the irrefutable pattern being matched.
|
|
* - val: the value being matched -- must be an lvalue (by ref, with cleanup)
|
|
*/
|
|
|
|
debug!("bind_irrefutable_pat(bcx={}, pat={})",
|
|
bcx.to_str(),
|
|
pat.repr(bcx.tcx()));
|
|
|
|
if bcx.sess().asm_comments() {
|
|
add_comment(bcx, format!("bind_irrefutable_pat(pat={})",
|
|
pat.repr(bcx.tcx())).as_slice());
|
|
}
|
|
|
|
let _indenter = indenter();
|
|
|
|
let _icx = push_ctxt("match::bind_irrefutable_pat");
|
|
let mut bcx = bcx;
|
|
let tcx = bcx.tcx();
|
|
let ccx = bcx.ccx();
|
|
match pat.node {
|
|
ast::PatIdent(pat_binding_mode, ref path1, ref inner) => {
|
|
if pat_is_binding(&tcx.def_map, &*pat) {
|
|
// Allocate the stack slot where the value of this
|
|
// binding will live and place it into the appropriate
|
|
// map.
|
|
bcx = mk_binding_alloca(
|
|
bcx, pat.id, &path1.node, cleanup_scope, (),
|
|
|(), bcx, llval, ty| {
|
|
match pat_binding_mode {
|
|
ast::BindByValue(_) => {
|
|
// By value binding: move the value that `val`
|
|
// points at into the binding's stack slot.
|
|
let d = Datum::new(val, ty, Lvalue);
|
|
d.store_to(bcx, llval)
|
|
}
|
|
|
|
ast::BindByRef(_) => {
|
|
// By ref binding: the value of the variable
|
|
// is the pointer `val` itself.
|
|
Store(bcx, val, llval);
|
|
bcx
|
|
}
|
|
}
|
|
});
|
|
}
|
|
|
|
for inner_pat in inner.iter() {
|
|
bcx = bind_irrefutable_pat(bcx, &**inner_pat, val, cleanup_scope);
|
|
}
|
|
}
|
|
ast::PatEnum(_, ref sub_pats) => {
|
|
let opt_def = bcx.tcx().def_map.borrow().find_copy(&pat.id);
|
|
match opt_def {
|
|
Some(def::DefVariant(enum_id, var_id, _)) => {
|
|
let repr = adt::represent_node(bcx, pat.id);
|
|
let vinfo = ty::enum_variant_with_id(ccx.tcx(),
|
|
enum_id,
|
|
var_id);
|
|
let args = extract_variant_args(bcx,
|
|
&*repr,
|
|
vinfo.disr_val,
|
|
val);
|
|
for sub_pat in sub_pats.iter() {
|
|
for (i, &argval) in args.vals.iter().enumerate() {
|
|
bcx = bind_irrefutable_pat(bcx, &**sub_pat.get(i),
|
|
argval, cleanup_scope);
|
|
}
|
|
}
|
|
}
|
|
Some(def::DefStruct(..)) => {
|
|
match *sub_pats {
|
|
None => {
|
|
// This is a unit-like struct. Nothing to do here.
|
|
}
|
|
Some(ref elems) => {
|
|
// This is the tuple struct case.
|
|
let repr = adt::represent_node(bcx, pat.id);
|
|
for (i, elem) in elems.iter().enumerate() {
|
|
let fldptr = adt::trans_field_ptr(bcx, &*repr,
|
|
val, 0, i);
|
|
bcx = bind_irrefutable_pat(bcx, &**elem,
|
|
fldptr, cleanup_scope);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
_ => {
|
|
// Nothing to do here.
|
|
}
|
|
}
|
|
}
|
|
ast::PatStruct(_, ref fields, _) => {
|
|
let tcx = bcx.tcx();
|
|
let pat_ty = node_id_type(bcx, pat.id);
|
|
let pat_repr = adt::represent_type(bcx.ccx(), pat_ty);
|
|
expr::with_field_tys(tcx, pat_ty, Some(pat.id), |discr, field_tys| {
|
|
for f in fields.iter() {
|
|
let ix = ty::field_idx_strict(tcx, f.ident.name, field_tys);
|
|
let fldptr = adt::trans_field_ptr(bcx, &*pat_repr, val,
|
|
discr, ix);
|
|
bcx = bind_irrefutable_pat(bcx, &*f.pat, fldptr, cleanup_scope);
|
|
}
|
|
})
|
|
}
|
|
ast::PatTup(ref elems) => {
|
|
let repr = adt::represent_node(bcx, pat.id);
|
|
for (i, elem) in elems.iter().enumerate() {
|
|
let fldptr = adt::trans_field_ptr(bcx, &*repr, val, 0, i);
|
|
bcx = bind_irrefutable_pat(bcx, &**elem, fldptr, cleanup_scope);
|
|
}
|
|
}
|
|
ast::PatBox(ref inner) => {
|
|
let llbox = Load(bcx, val);
|
|
bcx = bind_irrefutable_pat(bcx, &**inner, llbox, cleanup_scope);
|
|
}
|
|
ast::PatRegion(ref inner) => {
|
|
let loaded_val = Load(bcx, val);
|
|
bcx = bind_irrefutable_pat(bcx, &**inner, loaded_val, cleanup_scope);
|
|
}
|
|
ast::PatVec(ref before, ref slice, ref after) => {
|
|
let pat_ty = node_id_type(bcx, pat.id);
|
|
let mut extracted = extract_vec_elems(bcx, pat_ty, before.len(), after.len(), val);
|
|
match slice {
|
|
&Some(_) => {
|
|
extracted.vals.insert(
|
|
before.len(),
|
|
bind_subslice_pat(bcx, pat.id, val, before.len(), after.len())
|
|
);
|
|
}
|
|
&None => ()
|
|
}
|
|
bcx = before
|
|
.iter()
|
|
.chain(slice.iter())
|
|
.chain(after.iter())
|
|
.zip(extracted.vals.into_iter())
|
|
.fold(bcx, |bcx, (inner, elem)|
|
|
bind_irrefutable_pat(bcx, &**inner, elem, cleanup_scope)
|
|
);
|
|
}
|
|
ast::PatMac(..) => {
|
|
bcx.sess().span_bug(pat.span, "unexpanded macro");
|
|
}
|
|
ast::PatWild(_) | ast::PatLit(_) | ast::PatRange(_, _) => ()
|
|
}
|
|
return bcx;
|
|
}
|