92d1f155da
Lifetime intrinsics help to reduce stack usage, because LLVM can apply
stack coloring to reuse the stack slots of dead allocas for new ones.
For example these functions now both use the same amount of stack, while
previous `bar()` used five times as much as `foo()`:
````rust
fn foo() {
println("{}", 5);
}
fn bar() {
println("{}", 5);
println("{}", 5);
println("{}", 5);
println("{}", 5);
println("{}", 5);
}
````
On top of that, LLVM can also optimize out certain operations when it
knows that memory is dead after a certain point. For example, it can
sometimes remove the zeroing used to cancel the drop glue. This is
possible when the glue drop itself was already removed because the
zeroing dominated the drop glue call. For example in:
````rust
pub fn bar(x: (Box<int>, int)) -> (Box<int>, int) {
x
}
````
With optimizations, this currently results in:
````llvm
define void @_ZN3bar20h330fa42547df8179niaE({ i64*, i64 }* noalias nocapture nonnull sret, { i64*, i64 }* noalias nocapture nonnull) unnamed_addr #0 {
"_ZN29_$LP$Box$LT$int$GT$$C$int$RP$39glue_drop.$x22glue_drop$x22$LP$1347$RP$17h88cf42702e5a322aE.exit":
%2 = bitcast { i64*, i64 }* %1 to i8*
%3 = bitcast { i64*, i64 }* %0 to i8*
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %3, i8* %2, i64 16, i32 8, i1 false)
tail call void @llvm.memset.p0i8.i64(i8* %2, i8 0, i64 16, i32 8, i1 false)
ret void
}
````
But with lifetime intrinsics we get:
````llvm
define void @_ZN3bar20h330fa42547df8179niaE({ i64*, i64 }* noalias nocapture nonnull sret, { i64*, i64 }* noalias nocapture nonnull) unnamed_addr #0 {
"_ZN29_$LP$Box$LT$int$GT$$C$int$RP$39glue_drop.$x22glue_drop$x22$LP$1347$RP$17h88cf42702e5a322aE.exit":
%2 = bitcast { i64*, i64 }* %1 to i8*
%3 = bitcast { i64*, i64 }* %0 to i8*
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %3, i8* %2, i64 16, i32 8, i1 false)
tail call void @llvm.lifetime.end(i64 16, i8* %2)
ret void
}
````
Fixes #15665
This is a preliminary version of the Rust compiler, libraries and tools.
Source layout:
| Path | Description |
|---|---|
librustc/ |
The self-hosted compiler |
liballoc/ |
Rust's core allocation library |
libcore/ |
The Rust core library |
libdebug/ |
Debugging utilities |
libstd/ |
The standard library (imported and linked by default) |
libgreen/ |
The M:N runtime library |
libnative/ |
The 1:1 runtime library |
libsyntax/ |
The Rust parser and pretty-printer |
libtest/ |
Rust's test-runner code |
| ------------------- | --------------------------------------------------------- |
libarena/ |
The arena (a fast but limited) memory allocator |
libbacktrace/ |
The libbacktrace library |
libcollections/ |
A collection of useful data structures and containers |
libflate/ |
Simple compression library |
libfmt_macros/ |
Macro support for format strings |
libfourcc/ |
Data format identifier library |
libgetopts/ |
Get command-line-options library |
libglob/ |
Unix glob patterns library |
libgraphviz/ |
Generating files for Graphviz |
libhexfloat/ |
Hexadecimal floating-point literals |
liblibc/ |
Bindings for the C standard library |
liblog/ |
Utilities for program-wide and customizable logging |
libnum/ |
Extended number support library (complex, rational, etc) |
librand/ |
Random numbers and distributions |
libregex/ |
Regular expressions |
libregex_macros/ |
The regex! syntax extension |
libsemver/ |
Rust's semantic versioning library |
libserialize/ |
Encode-Decode types library |
libsync/ |
Concurrency mechanisms and primitives |
libterm/ |
ANSI color library for terminals |
libtime/ |
Time operations library |
liburl/ |
URL handling lirary |
libuuid/ |
UUID's handling code |
| ------------------- | --------------------------------------------------------- |
rt/ |
The runtime system |
rt/rust_*.c |
- Some of the runtime services |
rt/vg |
- Valgrind headers |
rt/msvc |
- MSVC support |
rt/sundown |
- The Markdown library used by rustdoc |
| ------------------- | --------------------------------------------------------- |
compiletest/ |
The test runner |
test/ |
Testsuite |
test/codegen |
- Tests for the LLVM IR infrastructure |
test/compile-fail |
- Tests that should fail to compile |
test/debug-info |
- Tests for the debuginfo tool |
test/run-fail |
- Tests that should compile, run and fail |
test/run-make |
- Tests that depend on a Makefile infrastructure |
test/run-pass |
- Tests that should compile, run and succeed |
test/bench |
- Benchmarks and miscellaneous |
test/pretty |
- Pretty-printer tests |
test/auxiliary |
- Dependencies of tests |
| ------------------- | --------------------------------------------------------- |
librustdoc/ |
The Rust API documentation tool |
libuv/ |
The libuv submodule |
librustuv/ |
Rust libuv support code |
| ------------------- | --------------------------------------------------------- |
llvm/ |
The LLVM submodule |
rustllvm/ |
LLVM support code |
| ------------------- | --------------------------------------------------------- |
etc/ |
Scripts, editors support, misc |
NOTE: This list (especially the second part of the table which contains modules and libraries) is highly volatile and subject to change.