Two unfortunate allocations were wrapping a proc() in a proc() with
GreenTask::build_start_wrapper, and then boxing this proc in a ~proc() inside of
Context::new(). Both of these allocations were a direct result from two
conditions:
1. The Context::new() function has a nice api of taking a procedure argument to
start up a new context with. This inherently required an allocation by
build_start_wrapper because extra code needed to be run around the edges of a
user-provided proc() for a new task.
2. The initial bootstrap code only understood how to pass one argument to the
next function. By modifying the assembly and entry points to understand more
than one argument, more information is passed through in registers instead of
allocating a pointer-sized context.
This is sadly where I end up throwing mips under a bus because I have no idea
what's going on in the mips context switching code and don't know how to modify
it.
Closes#7767
cc #11389
This also drops support for the managed pointer POISON_ON_FREE feature
as it's not worth adding back the support for it. After a snapshot, the
leftovers can be removed.
- `begin_unwind` is now generic over any `T: Any + Send`.
- Every value you fail with gets boxed as an `~Any`.
- Because of implementation details, `&'static str` and `~str` are still
handled specially behind the scenes.
- Changed the big macro source string in libsyntax to a raw string
literal, and enabled doc comments there.
This drops more of the old C++ runtime to rather be written in rust. A few
features were lost along the way, but hopefully not too many. The main loss is
that there are no longer backtraces associated with allocations (rust doesn't
have a way of acquiring those just yet). Other than that though, I believe that
the rest of the debugging utilities made their way over into rust.
Closes#8704
Beforehand, it was unclear whether rust was performing the "recommended set" of
optimizations provided by LLVM for code. This commit changes the way we run
passes to closely mirror that of clang, which in theory does it correctly. The
notable changes include:
* Passes are no longer explicitly added one by one. This would be difficult to
keep up with as LLVM changes and we don't guaranteed always know the best
order in which to run passes
* Passes are now managed by LLVM's PassManagerBuilder object. This is then used
to populate the various pass managers run.
* We now run both a FunctionPassManager and a module-wide PassManager. This is
what clang does, and I presume that we *may* see a speed boost from the
module-wide passes just having to do less work. I have no measured this.
* The codegen pass manager has been extracted to its own separate pass manager
to not get mixed up with the other passes
* All pass managers now include passes for target-specific data layout and
analysis passes
Some new features include:
* You can now print all passes being run with `-Z print-llvm-passes`
* When specifying passes via `--passes`, the passes are now appended to the
default list of passes instead of overwriting them.
* The output of `--passes list` is now generated by LLVM instead of maintaining
a list of passes ourselves
* Loop vectorization is turned on by default as an optimization pass and can be
disabled with `-Z no-vectorize-loops`
This moves the raw struct layout of closures, vectors, boxes, and strings into a
new `unstable::raw` module. This is meant to be a centralized location to find
information for the layout of these values.
As safe method, `repr`, is provided to convert a rust value to its raw
representation. Unsafe methods to convert back are not provided because they are
rarely used and too numerous to write an implementation for each (not much of a
common pattern).
