This allows cross-crate inlining which is *very* good because this is called a
lot throughout libstd (even when libstd is inlined across crates).
In one of my projects, I have a test case with the following performance characteristics
commit | optimization level | runtime (seconds)
----|------|----
before | O2 | 22s
before | O3 | 107s
after | O2 | 13s
after | O3 | 12s
I'm a bit disturbed by the 107s runtime from O3 before this commit. The performance characteristics of this test involve doing an absurd amount of small operations. A huge portion of this is creating hashmaps which involves allocating vectors.
The worst portions of the profile are:
Which as you can see looks like some *serious* problems with inlining. I would expect the hash map methods to be high up in the profile, but the top 9 callers of `cast::transmute_copy` were `Repr::repr`'s various monomorphized instances.
I wish there we a better way to detect things like this in the future, and it's unfortunate that this is required for performance in the first place. I suppose I'm not entirely sure why this is needed because all of the methods should have been generated in-crate (monomorphized versions of library functions), so they should have gotten inlined? It also could just be that by modifying LLVM's idea of the inline cost of this function it was able to inline it in many more locations.
This removes another large chunk of this odd 'clownshoes' identifier showing up
in symbol names. These all originated from external crates because the encoded
items were encoded independently of the paths calculated in ast_map. The
encoding of these paths now uses the helper function in ast_map to calculate the
"pretty name" for an impl block.
Unfortunately there is still no information about generics in the symbol name,
but it's certainly vastly better than before
hash::__extensions__::write::_version::v0.8
becomes
hash::Writer$SipState::write::hversion::v0.8
This also fixes bugs in which lots of methods would show up as `meth_XXX`, they
now only show up as `meth` and throw some extra characters onto the version
string.
The ISO 8601 standard does not mandate any specific precision for
fractional seconds, so this accepts input of any length, ignoring the
part after the nanoseconds place. It may be more correct to round with
the tenths of nanoseconds digit, but then we'd have to deal with
carrying the round through the entire Tm struct (e.g. for a time like
Dec 31 11:59.999999999999).
%f is the format specifier that Python's datetime library uses for
0-padded microseconds so it seemed appropriate here.
cc #2350
Here's a fix for issue #7588, "Overflow handling of from_str methods is broken".
The integer overflow issues are taken care of by checking to see if the multiply-by-radix-and-add-next-digit process is reversible. If it overflowed, then some information is lost and the process is irreversible, in which case, None is returned.
Floats now consistently return Some(Inf) of Some(-Inf) on overflow thanks to a call to NumStrConv::inf() and NumStrConv::neg_inf() respectively when the overflow is detected (which yields a value of None in the case of ints and uints anyway).
This is my first contribution to Rust, and my first time using the language in general, so any and all feedback is appreciated.
This is actually almost a problem, because those were my poster-child
macros for "here's how to implement a capturing macro." Following this
change, there will be no macros that use capturing; this will probably
make life unpleasant for the first person that wants to implement a
capturing macro. I should probably create a dummy_capturing macro,
just to show how it works.
