The previous code erroneously assumed that 'steals > cnt' was always true, but
that was a false assumption. The code was altered to decrement steals to a
minimum of 0 instead of taking all of cnt into account.
I didn't include the exact test from #12295 because it could run for quite
awhile, and instead set the threshold for MAX_STEALS to much lower during
testing. I found that this triggered the old bug quite frequently when running
without this fix.
Closes#12295
This is useful in contexts like this:
```rust
let size = rdr.read_be_i32() as uint;
let mut limit = LimitReader::new(rdr.by_ref(), size);
let thing = read_a_thing(&mut limit);
assert!(limit.limit() == 0);
```
The previous code erroneously assumed that 'steals > cnt' was always true, but
that was a false assumption. The code was altered to decrement steals to a
minimum of 0 instead of taking all of cnt into account.
I didn't include the exact test from #12295 because it could run for quite
awhile, and instead set the threshold for MAX_STEALS to much lower during
testing. I found that this triggered the old bug quite frequently when running
without this fix.
Closes#12295
- adds a `LockGuard` type returned by `.lock` and `.trylock` that unlocks the mutex in the destructor
- renames `mutex::Mutex` to `StaticNativeMutex`
- adds a `NativeMutex` type with a destructor
- removes `LittleLock`
- adds `#[must_use]` to `sync::mutex::Guard` to remind people to use it
This is useful in contexts like this:
let size = rdr.read_be_i32() as uint;
let mut limit = LimitReader::new(rdr.by_ref(), size);
let thing = read_a_thing(&mut limit);
assert!(limit.limit() == 0);
Function parameters that are to be passed by value but don't fit into a
single register are currently passed by creating a copy on the stack and
passing a pointer to that copy to the callee. Since the copy is made
just for the function call, there are no aliases.
For example, this sometimes allows LLVM to eliminate unnecessary calls
to drop glue. Given
````rust
struct Foo {
a: int,
b: Option<~str>,
}
extern {
fn eat(eat: Option<~str>);
}
pub fn foo(v: Foo) {
match v {
Foo { a: _, b } => unsafe { eat(b) }
}
}
````
LLVM currently can't eliminate the drop call for the string, because it
only sees a _pointer_ to Foo, for which it has to expect an alias. So we
get:
````llvm
; Function Attrs: uwtable
define void @_ZN3foo20h9f32c90ae7201edbxaa4v0.0E(%struct.Foo* nocapture) unnamed_addr #0 {
"_ZN34std..option..Option$LT$$UP$str$GT$9glue_drop17hc39b3015f3b9c69dE.exit":
%1 = getelementptr inbounds %struct.Foo* %0, i64 0, i32 1, i32 0
%2 = load { i64, i64, [0 x i8] }** %1, align 8
store { i64, i64, [0 x i8] }* null, { i64, i64, [0 x i8] }** %1, align 8
%3 = ptrtoint { i64, i64, [0 x i8] }* %2 to i64
%.fca.0.insert = insertvalue { i64 } undef, i64 %3, 0
tail call void @eat({ i64 } %.fca.0.insert)
%4 = load { i64, i64, [0 x i8] }** %1, align 8
%5 = icmp eq { i64, i64, [0 x i8] }* %4, null
br i1 %5, label %_ZN3Foo9glue_drop17hf611996539d3036fE.exit, label %"_ZN8_$UP$str9glue_drop17h15dbdbe2b8897a98E.exit.i.i"
"_ZN8_$UP$str9glue_drop17h15dbdbe2b8897a98E.exit.i.i": ; preds = %"_ZN34std..option..Option$LT$$UP$str$GT$9glue_drop17hc39b3015f3b9c69dE.exit"
%6 = bitcast { i64, i64, [0 x i8] }* %4 to i8*
tail call void @free(i8* %6) #1
br label %_ZN3Foo9glue_drop17hf611996539d3036fE.exit
_ZN3Foo9glue_drop17hf611996539d3036fE.exit: ; preds = %"_ZN34std..option..Option$LT$$UP$str$GT$9glue_drop17hc39b3015f3b9c69dE.exit", %"_ZN8_$UP$str9glue_drop17h15dbdbe2b8897a98E.exit.i.i"
ret void
}
````
But with the `noalias` attribute, it can safely optimize that to:
````llvm
define void @_ZN3foo20hd28431f929f0d6c4xaa4v0.0E(%struct.Foo* noalias nocapture) unnamed_addr #0 {
_ZN3Foo9glue_drop17he9afbc09d4e9c851E.exit:
%1 = getelementptr inbounds %struct.Foo* %0, i64 0, i32 1, i32 0
%2 = load { i64, i64, [0 x i8] }** %1, align 8
store { i64, i64, [0 x i8] }* null, { i64, i64, [0 x i8] }** %1, align 8
%3 = ptrtoint { i64, i64, [0 x i8] }* %2 to i64
%.fca.0.insert = insertvalue { i64 } undef, i64 %3, 0
tail call void @eat({ i64 } %.fca.0.insert)
ret void
}
````
Function parameters that are to be passed by value but don't fit into a
single register are currently passed by creating a copy on the stack and
passing a pointer to that copy to the callee. Since the copy is made
just for the function call, there are no aliases.
For example, this sometimes allows LLVM to eliminate unnecessary calls
to drop glue. Given
````rust
struct Foo {
a: int,
b: Option<~str>,
}
extern {
fn eat(eat: Option<~str>);
}
pub fn foo(v: Foo) {
match v {
Foo { a: _, b } => unsafe { eat(b) }
}
}
````
LLVM currently can't eliminate the drop call for the string, because it
only sees a _pointer_ to Foo, for which it has to expect an alias. So we
get:
````llvm
; Function Attrs: uwtable
define void @_ZN3foo20h9f32c90ae7201edbxaa4v0.0E(%struct.Foo* nocapture) unnamed_addr #0 {
"_ZN34std..option..Option$LT$$UP$str$GT$9glue_drop17hc39b3015f3b9c69dE.exit":
%1 = getelementptr inbounds %struct.Foo* %0, i64 0, i32 1, i32 0
%2 = load { i64, i64, [0 x i8] }** %1, align 8
store { i64, i64, [0 x i8] }* null, { i64, i64, [0 x i8] }** %1, align 8
%3 = ptrtoint { i64, i64, [0 x i8] }* %2 to i64
%.fca.0.insert = insertvalue { i64 } undef, i64 %3, 0
tail call void @eat({ i64 } %.fca.0.insert)
%4 = load { i64, i64, [0 x i8] }** %1, align 8
%5 = icmp eq { i64, i64, [0 x i8] }* %4, null
br i1 %5, label %_ZN3Foo9glue_drop17hf611996539d3036fE.exit, label %"_ZN8_$UP$str9glue_drop17h15dbdbe2b8897a98E.exit.i.i"
"_ZN8_$UP$str9glue_drop17h15dbdbe2b8897a98E.exit.i.i": ; preds = %"_ZN34std..option..Option$LT$$UP$str$GT$9glue_drop17hc39b3015f3b9c69dE.exit"
%6 = bitcast { i64, i64, [0 x i8] }* %4 to i8*
tail call void @free(i8* %6) #1
br label %_ZN3Foo9glue_drop17hf611996539d3036fE.exit
_ZN3Foo9glue_drop17hf611996539d3036fE.exit: ; preds = %"_ZN34std..option..Option$LT$$UP$str$GT$9glue_drop17hc39b3015f3b9c69dE.exit", %"_ZN8_$UP$str9glue_drop17h15dbdbe2b8897a98E.exit.i.i"
ret void
}
````
But with the `noalias` attribute, it can safely optimize that to:
````llvm
define void @_ZN3foo20hd28431f929f0d6c4xaa4v0.0E(%struct.Foo* noalias nocapture) unnamed_addr #0 {
_ZN3Foo9glue_drop17he9afbc09d4e9c851E.exit:
%1 = getelementptr inbounds %struct.Foo* %0, i64 0, i32 1, i32 0
%2 = load { i64, i64, [0 x i8] }** %1, align 8
store { i64, i64, [0 x i8] }* null, { i64, i64, [0 x i8] }** %1, align 8
%3 = ptrtoint { i64, i64, [0 x i8] }* %2 to i64
%.fca.0.insert = insertvalue { i64 } undef, i64 %3, 0
tail call void @eat({ i64 } %.fca.0.insert)
ret void
}
````
Change `os::args()` and `os::env()` to use `str::from_utf8_lossy()`.
Add new functions `os::args_as_bytes()` and `os::env_as_bytes()` to retrieve the args/env as byte vectors instead.
The existing methods were left returning strings because I expect that the common use-case is to want string handling.
Fixes#7188.
It's too easy to forget the `rust` tag to have a code example tested, and it's
far more common to have testable code than untestable code.
This alters rustdoc to have only two directives, `ignore` and `should_fail`. The
`ignore` directive ignores the code block entirely, and the `should_fail`
directive has been fixed to only fail the test if the code execution fails, not
also compilation.
Parse the environment by default with from_utf8_lossy. Also provide
byte-vector equivalents (e.g. os::env_as_bytes()).
Unfortunately, setenv() can't have a byte-vector equivalent because of
Windows support, unless we want to define a setenv_bytes() that fails
under Windows for non-UTF8 (or non-UTF16).
os::args() was using str::raw::from_c_str(), which would assert if the
C-string wasn't valid UTF-8. Switch to using from_utf8_lossy() instead,
and add a separate function os::args_as_bytes() that returns the ~[u8]
byte-vectors instead.
The std macros used to be injected with a filename of "<std-macros>", but macros
are now injected with a filename of "<{} macros>" where `{}` is filled in with
the crate name. This updates rustdoc to understand this new system so it'll
render source more frequently.
Strip trait impls for types that are stripped either due to the strip-hidden or strip-private passes.
This fixes the search index including trait methods on stripped structs (which breaks searching), and it also removes private types from the implementors list of a trait.
Fixes#9981 and #11439.
The std macros used to be injected with a filename of "<std-macros>", but macros
are now injected with a filename of "<{} macros>" where `{}` is filled in with
the crate name. This updates rustdoc to understand this new system so it'll
render source more frequently.
