rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Added clarification regarding rust_try_inner.

Browse Source
This commit is contained in:
Vadim Chugunov
2014-08-05 19:07:38 -07:00
parent cb55279f23
commit cd2003ffd8
3 changed files with 16 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
src/librustrt/unwind.rs
View File

@@ -220,12 +220,19 @@ fn rust_exception_class() -> uw::_Unwind_Exception_Class {
// //
// This is pretty close to Rust's exception handling approach, except that Rust // This is pretty close to Rust's exception handling approach, except that Rust
// does have a single "catch-all" handler at the bottom of each task's stack. // does have a single "catch-all" handler at the bottom of each task's stack.
// So we have two versions: // So we have two versions of the personality routine:
// - rust_eh_personality, used by all cleanup landing pads, which never catches, // - rust_eh_personality, used by all cleanup landing pads, which never catches,
// so the behavior of __gcc_personality_v0 is perfectly adequate there, and // so the behavior of __gcc_personality_v0 is perfectly adequate there, and
// - rust_eh_personality_catch, used only by rust_try(), which always catches. // - rust_eh_personality_catch, used only by rust_try(), which always catches.
// This is achieved by overriding the return value in search phase to always //
// say "catch!". // Note, however, that for implementation simplicity, rust_eh_personality_catch
// lacks code to install a landing pad, so in order to obtain exception object
// pointer (which it needs to return upstream), rust_try() employs another trick:
// it calls into the nested rust_try_inner(), whose landing pad does not resume
// unwinds. Instead, it extracts the exception pointer and performs a "normal"
// return.
//
// See also: rt/rust_try.ll
#[cfg(not(target_arch = "arm"), not(windows, target_arch = "x86_64"), not(test))] #[cfg(not(target_arch = "arm"), not(windows, target_arch = "x86_64"), not(test))]
#[doc(hidden)] #[doc(hidden)]
@@ -334,7 +341,8 @@ pub mod eabi {
// ARM EHABI uses a slightly different personality routine signature, // ARM EHABI uses a slightly different personality routine signature,
// but otherwise works the same. // but otherwise works the same.
#[cfg(target_arch = "arm", not(target_os = "ios", not(test)))] #[cfg(target_arch = "arm", not(target_os = "ios"), not(test))]
#[doc(hidden)]
#[allow(visible_private_types)] #[allow(visible_private_types)]
pub mod eabi { pub mod eabi {
use uw = libunwind; use uw = libunwind;
@@ -384,10 +392,9 @@ pub mod eabi {
// with an "API translator" layer (_GCC_specific_handler). // with an "API translator" layer (_GCC_specific_handler).
#[cfg(windows, target_arch = "x86_64", not(test))] #[cfg(windows, target_arch = "x86_64", not(test))]
#[doc(hidden)]
#[allow(visible_private_types)] #[allow(visible_private_types)]
#[allow(non_camel_case_types)] #[allow(non_camel_case_types)]
#[allow(unused_variable)]
#[allow(uppercase_variables)]
pub mod eabi { pub mod eabi {
use uw = libunwind; use uw = libunwind;
use libc::{c_void, c_int}; use libc::{c_void, c_int};

3
src/rt/rust_try.ll
View File

@@ -11,6 +11,7 @@
; Rust's try-catch ; Rust's try-catch
; When f(...) returns normally, the return value is null. ; When f(...) returns normally, the return value is null.
; When f(...) throws, the return value is a pointer to the caught exception object. ; When f(...) throws, the return value is a pointer to the caught exception object.
; See also: librustrt/unwind.rs ; See also: librustrt/unwind.rs
define i8* @rust_try(void (i8*,i8*)* %f, i8* %fptr, i8* %env) { define i8* @rust_try(void (i8*,i8*)* %f, i8* %fptr, i8* %env) {
@@ -25,7 +26,7 @@ normal:
catch: catch:
landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @rust_eh_personality_catch to i8*) landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @rust_eh_personality_catch to i8*)
catch i8* null catch i8* null
; execution will never reach here because rust_try_inner's landing pad does not resume unwinds ; rust_try_inner's landing pad does not resume unwinds, so execution will never reach here
ret i8* null ret i8* null
} }

2
src/rustllvm/llvm-auto-clean-trigger
View File

@@ -1,4 +1,4 @@
# If this file is modified, then llvm will be forcibly cleaned and then rebuilt. # If this file is modified, then llvm will be forcibly cleaned and then rebuilt.
# The actual contents of this file do not matter, but to trigger a change on the # The actual contents of this file do not matter, but to trigger a change on the
# build bots then the contents should be changed so git updates the mtime. # build bots then the contents should be changed so git updates the mtime.
2014-08-24 2014-08-05