Improve the slice iterator's searching methods
Improve all, any, find, position, rposition by explicitly unrolling the loop for the slice iterators.
- Introduce a few extension methods and functions for raw pointers make the new code easy to express
- Introduce helper methods `search_while, rsearch_while` that generalize all the searching methods
LLVM doesn't unroll the loop in `.find()` by default (clang is the same), so performance benefits a lot from explicit unrolling here. An iterator method without conditional exits (like `.fold()`) does not need this on the other hand.
One of the raw pointer extension methods is `fn post_inc(&mut self) -> Self` which is the rustic equivalent of “`ptr++`”, and it is a nice way to express the raw pointer loop (see commit 3).
Specific development notes about `search_while`: I tried both computing an end pointer "rounded" to 4, as well as the `ptrdistance >= 4` loop condition, ptrdistance was better. I tried handling the last 0-3 elements unrolled or with a while loop, the loop was better.
expect_err for Result.
This adds an `expect_err` method to `Result`. Considering how `unwrap_err` already exists, this seems to make sense. Inconsistency noted in Manishearth/rust-clippy#1435.
Clarify Extend behaviour wrt existing keys
This seems to be consistent with all the Extend implementations I found, and isn't documented anywhere else afaik.
Implement Display for char Escape*, To*case.
See: rust-lang/rfcs#1848.
A good example of where this is useful would be in the example `print!("{}", 'ß'.to_uppercase())`.
Not sure if this requires a formal RFC, but I decided to write the code for it anyway regardless.
UTF-8 validation: Compute block end upfront
Simplify the conditional used for ensuring that the whole word loop is
only used if there are at least two whole words left to read.
This makes the function slightly smaller and simpler, a 0-5% reduction
in runtime for various test cases.
Remove not(stage0) from deny(warnings)
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
Use more specific panic message for &str slicing errors
Separate out of bounds errors from character boundary errors, and print
more details for character boundary errors.
It reports the first error it finds in:
1. begin out of bounds
2. end out of bounds
3. begin <= end violated
3. begin not char boundary
5. end not char boundary.
Example:
&"abcαβγ"[..4]
thread 'str::test_slice_fail_boundary_1' panicked at 'byte index 4 is not
a char boundary; it is inside 'α' (bytes 3..5) of `abcαβγ`'
Fixes#38052
Add links to methods on all slice iterator struct docs
In the same style as `std::slice::Iter` to help people find how to create iterators.
r? @steveklabnik
This commit introduces 128-bit integers. Stage 2 builds and produces a working compiler which
understands and supports 128-bit integers throughout.
The general strategy used is to have rustc_i128 module which provides aliases for iu128, equal to
iu64 in stage9 and iu128 later. Since nowhere in rustc we rely on large numbers being supported,
this strategy is good enough to get past the first bootstrap stages to end up with a fully working
128-bit capable compiler.
In order for this strategy to work, number of locations had to be changed to use associated
max_value/min_value instead of MAX/MIN constants as well as the min_value (or was it max_value?)
had to be changed to use xor instead of shift so both 64-bit and 128-bit based consteval works
(former not necessarily producing the right results in stage1).
This commit includes manual merge conflict resolution changes from a rebase by @est31.
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
