| Age | Commit message (Collapse) | Author | Lines |
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This commit updates our Fat LTO logic to tweak our custom wrapper around LLVM's
"link modules" functionality. Previously whenever the
`LLVMRustLinkInExternalBitcode` function was called it would call LLVM's
`Linker::linkModules` wrapper. Internally this would crate an instance of a
`Linker` which internally creates an instance of an `IRMover`. Unfortunately for
us the creation of `IRMover` is somewhat O(n) with the input module. This means
that every time we linked a module it was O(n) with respect to the entire module
we had built up!
Now the modules we build up during LTO are quite large, so this quickly started
creating an O(n^2) problem for us! Discovered in #48025 it turns out this has
always been a problem and we just haven't noticed it. It became particularly
worse recently though due to most libraries having 16x more object files than
they previously did (1 -> 16).
This commit fixes this performance issue by preserving the `Linker` instance
across all links into the main LLVM module. This means we only create one
`IRMover` and allows LTO to progress much speedier.
From the `cargo-cache` project in #48025 a **full build** locally when from
5m15s to 2m24s. Looking at the timing logs each object file was linked in in
single-digit millisecond rather than hundreds, clearly being a nice improvement!
Closes #48025
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The following submodules have been updated for a new version of LLVM:
- `src/llvm`
- `src/libcompiler_builtins` - transitively contains compiler-rt
- `src/dlmalloc`
This also updates the docker container for dist-i686-freebsd as the old 16.04
container is no longer capable of building LLVM. The
compiler-rt/compiler-builtins and dlmalloc updates are pretty routine without
much interesting happening, but the LLVM update here is of particular note.
Unlike previous updates I haven't cherry-picked all existing patches we had on
top of our LLVM branch as we have a [huge amount][patches4] and have at this
point forgotten what most of them are for. Instead I started from the current
`release_60` branch in LLVM and only applied patches that were necessary to get
our tests working and building.
The current set of custom rustc-specific patches included in this LLVM update are:
* rust-lang/llvm@1187443 - this is how we actually implement
`cfg(target_feature)` for now and continues to not be upstreamed. While a
hazard for SIMD stabilization this commit is otherwise keeping the status
quo of a small rustc-specific feature.
* rust-lang/llvm@013f2ec - this is a rustc-specific optimization that we haven't
upstreamed, notably teaching LLVM about our allocation-related routines (which
aren't malloc/free). Once we stabilize the global allocator routines we will
likely want to upstream this patch, but for now it seems reasonable to keep it
on our fork.
* rust-lang/llvm@a65bbfd - I found this necessary to fix compilation of LLVM in
our 32-bit linux container. I'm not really sure why it's necessary but my
guess is that it's because of the absolutely ancient glibc that we're using.
In any case it's only updating pieces we're not actually using in LLVM so I'm
hoping it'll turn out alright. This doesn't seem like something we'll want to
upstream.c
* rust-lang/llvm@77ab1f0 - this is what's actually enabling LLVM to build in our
i686-freebsd container, I'm not really sure what's going on but we for sure
probably don't want to upstream this and otherwise it seems not too bad for
now at least.
* rust-lang/llvm@9eb9267 - we currently suffer on MSVC from an [upstream bug]
which although diagnosed to a particular revision isn't currently fixed
upstream (and the bug itself doesn't seem too active). This commit is a
partial revert of the suspected cause of this regression (found via a
bisection). I'm sort of hoping that this eventually gets fixed upstream with a
similar fix (which we can replace in our branch), but for now I'm also hoping
it's a relatively harmless change to have.
After applying these patches (plus one [backport] which should be [backported
upstream][llvm-back]) I believe we should have all tests working on all
platforms in our current test suite. I'm like 99% sure that we'll need some more
backports as issues are reported for LLVM 6 when this propagates through
nightlies, but that's sort of just par for the course nowadays!
In any case though some extra scrutiny of the patches here would definitely be
welcome, along with scrutiny of the "missing patches" like a [change to pass
manager order](rust-lang/llvm@27174447533), [another change to pass manager
order](rust-lang/llvm@c782febb7b9), some [compile fixes for
sparc](rust-lang/llvm@1a83de63c42), and some [fixes for
solaris](rust-lang/llvm@c2bfe0abb).
[patches4]: https://github.com/rust-lang/llvm/compare/5401fdf23...rust-llvm-release-4-0-1
[backport]: https://github.com/rust-lang/llvm/commit/5c54c252db
[llvm-back]: https://bugs.llvm.org/show_bug.cgi?id=36114
[upstream bug]: https://bugs.llvm.org/show_bug.cgi?id=36096
---
The update to LLVM 6 is desirable for a number of reasons, notably:
* This'll allow us to keep up with the upstream wasm backend, picking up new
features as they start landing.
* Upstream LLVM has fixed a number of SIMD-related compilation errors,
especially around AVX-512 and such.
* There's a few assorted known bugs which are fixed in LLVM 5 and aren't fixed
in the LLVM 4 branch we're using.
* Overall it's not a great idea to stagnate with our codegen backend!
This update is mostly powered by #47730 which is allowing us to update LLVM
*independent* of the version of LLVM that Emscripten is locked to. This means
that when compiling code for Emscripten we'll still be using the old LLVM 4
backend, but when compiling code for any other target we'll be using the new
LLVM 6 target. Once Emscripten updates we may no longer need this distinction,
but we're not sure when that will happen!
Closes #43370
Closes #43418
Closes #47015
Closes #47683
Closes rust-lang-nursery/stdsimd#157
Closes rust-lang-nursery/rust-wasm#3
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First round of LLVM 6.0.0 compatibility
This includes a number of commits for the first round of upgrading to LLVM 6. There are still [lingering bugs](https://github.com/rust-lang/rust/issues/47683) but I believe all of this will nonetheless be necessary!
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Teach rustc about DW_AT_noreturn and a few more DIFlags
We achieve two small things with this PR:
1. We provide definitions for a few additional llvm debuginfo flags
1. We _use_ one of these new flags, `FlagNoReturn`, and add it to debuginfo for functions with the never return type (`!`).
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Looks like they did some refactoring of flags in the backend and this should
catch us up! The "unsafe algebra" boolean has been split into a number of
boolean flags for various operations, and this updates to use the `setFast`
function which should hopefully have the same behavior as before.
This was updated in llvm-mirror/llvm@00e900afd
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LLVM <= 4.0 used a non-standard interpretation of `DW_OP_plus`. In the
DWARF standard, this adds two items on the expressions stack. LLVM's
behavior was more like DWARF's `DW_OP_plus_uconst` -- adding a constant
that follows the op. The patch series starting with [D33892] switched
to the standard DWARF interpretation, so we need to follow.
[D33892]: https://reviews.llvm.org/D33892
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Refs #46437 as it also removes LLVMRustWriteDebugLocToString()
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Refs #46437
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The same effect can be achieved using -Cllvm-args=-debug
Refs #46437 as it removes LLVMRustSetDebug()
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Use name-discarding LLVM context
This is only applicable when neither of --emit=llvm-ir or --emit=llvm-bc are not
requested.
In case either of these outputs are wanted, but the benefits of such context are
desired as well, -Zfewer_names option provides the same functionality regardless
of the outputs requested.
Should be a viable fix for https://github.com/rust-lang/rust/issues/46449
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This is only applicable when neither of --emit=llvm-ir or --emit=llvm-bc are not
requested.
In case either of these outputs are wanted, but the benefits of such context are
desired as well, -Zfewer_names option provides the same functionality regardless
of the outputs requested.
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Refs #46437
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The function was added as a wrapper to handle compatibility with older
LLVM versions that we no longer support, so it can be removed.
Refs #46437
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`LLVMRustMetadataAsValue` would previously return `void`, despite the
corresponding Rust function expecting to return a `ValueRef`.
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We bumped the minimum LLVM to 3.9 in #45326. This just cleans up the
conditional code in the rustllvm C++ wrappers to assume at least 3.9.
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This makes it more robust when assertions are disabled,
crashing instead of causing UB.
Also introduces a tidy check to enforce this rule,
which in turn necessitated making tidy run on src/rustllvm.
Fixes #44020
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This is a big hammer, but should be effective at completely removing a
few issues, including inconsistent error messages and segfaults when
LLVM workers race to report results
LLVM_THREAD_LOCAL has been present in LLVM since 8 months before 3.7
(the earliest supported LLVM version that Rust can use)
Maybe fixes #43402 (third time lucky?)
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This commit is a refactoring of the LTO backend in Rust to support compilations
with multiple codegen units. The immediate result of this PR is to remove the
artificial error emitted by rustc about `-C lto -C codegen-units-8`, but longer
term this is intended to lay the groundwork for LTO with incremental compilation
and ultimately be the underpinning of ThinLTO support.
The problem here that needed solving is that when rustc is producing multiple
codegen units in one compilation LTO needs to merge them all together.
Previously only upstream dependencies were merged and it was inherently relied
on that there was only one local codegen unit. Supporting this involved
refactoring the optimization backend architecture for rustc, namely splitting
the `optimize_and_codegen` function into `optimize` and `codegen`. After an LLVM
module has been optimized it may be blocked and queued up for LTO, and only
after LTO are modules code generated.
Non-LTO compilations should look the same as they do today backend-wise, we'll
spin up a thread for each codegen unit and optimize/codegen in that thread. LTO
compilations will, however, send the LLVM module back to the coordinator thread
once optimizations have finished. When all LLVM modules have finished optimizing
the coordinator will invoke the LTO backend, producing a further list of LLVM
modules. Currently this is always a list of one LLVM module. The coordinator
then spawns further work to run LTO and code generation passes over each module.
In the course of this refactoring a number of other pieces were refactored:
* Management of the bytecode encoding in rlibs was centralized into one module
instead of being scattered across LTO and linking.
* Some internal refactorings on the link stage of the compiler was done to work
directly from `CompiledModule` structures instead of lists of paths.
* The trans time-graph output was tweaked a little to include a name on each
bar and inflate the size of the bars a little
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When -Z profile is passed, the GCDAProfiling LLVM pass is added
to the pipeline, which uses debug information to instrument the IR.
After compiling with -Z profile, the $(OUT_DIR)/$(CRATE_NAME).gcno
file is created, containing initial profiling information.
After running the program built, the $(OUT_DIR)/$(CRATE_NAME).gcda
file is created, containing branch counters.
The created *.gcno and *.gcda files can be processed using
the "llvm-cov gcov" and "lcov" tools. The profiling data LLVM
generates does not faithfully follow the GCC's format for *.gcno
and *.gcda files, and so it will probably not work with other tools
(such as gcov itself) that consume these files.
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[MIR] SwitchInt Everywhere
Something I've been meaning to do for a very long while. This PR essentially gets rid of 3 kinds of conditional branching and only keeps the most general one - `SwitchInt`. Primary benefits are such that dealing with MIR now does not involve dealing with 3 different ways to do conditional control flow. On the other hand, constructing a `SwitchInt` currently requires more code than what previously was necessary to build an equivalent `If` terminator. Something trivially "fixable" with some constructor methods somewhere (MIR needs stuff like that badly in general).
Some timings (tl;dr: slightly faster^1 (unexpected), but also uses slightly more memory at peak (expected)):
^1: Not sure if the speed benefits are because of LLVM liking the generated code better or the compiler itself getting compiled better. Either way, its a net benefit. The CORE and SYNTAX timings done for compilation without optimisation.
```
AFTER:
Building stage1 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 31.50 secs
Finished release [optimized] target(s) in 31.42 secs
Building stage1 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 439.56 secs
Finished release [optimized] target(s) in 435.15 secs
CORE: 99% (24.81 real, 0.13 kernel, 24.57 user); 358536k resident
CORE: 99% (24.56 real, 0.15 kernel, 24.36 user); 359168k resident
SYNTAX: 99% (49.98 real, 0.48 kernel, 49.42 user); 653416k resident
SYNTAX: 99% (50.07 real, 0.58 kernel, 49.43 user); 653604k resident
BEFORE:
Building stage1 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 31.84 secs
Building stage1 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 451.17 secs
CORE: 99% (24.66 real, 0.20 kernel, 24.38 user); 351096k resident
CORE: 99% (24.36 real, 0.17 kernel, 24.18 user); 352284k resident
SYNTAX: 99% (52.24 real, 0.56 kernel, 51.66 user); 645544k resident
SYNTAX: 99% (51.55 real, 0.48 kernel, 50.99 user); 646428k resident
```
cc @nikomatsakis @eddyb
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Emit DW_AT_main_subprogram
This changes rustc to emit DW_AT_main_subprogram on the "main" program.
This lets gdb suitably stop at the user's main in response to
"start" (rather than the library's main, which is what happens
currently).
Fixes #32620
r? michaelwoerister
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LeakSanitizer, ThreadSanitizer, AddressSanitizer and MemorySanitizer support
```
$ cargo new --bin leak && cd $_
$ edit Cargo.toml && tail -n3 $_
```
``` toml
[profile.dev]
opt-level = 1
```
```
$ edit src/main.rs && cat $_
```
``` rust
use std::mem;
fn main() {
let xs = vec![0, 1, 2, 3];
mem::forget(xs);
}
```
```
$ RUSTFLAGS="-Z sanitizer=leak" cargo run --target x86_64-unknown-linux-gnu; echo $?
Finished dev [optimized + debuginfo] target(s) in 0.0 secs
Running `target/debug/leak`
=================================================================
==10848==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 16 byte(s) in 1 object(s) allocated from:
#0 0x557c3488db1f in __interceptor_malloc /shared/rust/checkouts/lsan/src/compiler-rt/lib/lsan/lsan_interceptors.cc:55
#1 0x557c34888aaa in alloc::heap::exchange_malloc::h68f3f8b376a0da42 /shared/rust/checkouts/lsan/src/liballoc/heap.rs:138
#2 0x557c34888afc in leak::main::hc56ab767de6d653a $PWD/src/main.rs:4
#3 0x557c348c0806 in __rust_maybe_catch_panic ($PWD/target/debug/leak+0x3d806)
SUMMARY: LeakSanitizer: 16 byte(s) leaked in 1 allocation(s).
23
```
```
$ cargo new --bin racy && cd $_
$ edit src/main.rs && cat $_
```
``` rust
use std::thread;
static mut ANSWER: i32 = 0;
fn main() {
let t1 = thread::spawn(|| unsafe { ANSWER = 42 });
unsafe {
ANSWER = 24;
}
t1.join().ok();
}
```
```
$ RUSTFLAGS="-Z sanitizer=thread" cargo run --target x86_64-unknown-linux-gnu; echo $?
==================
WARNING: ThreadSanitizer: data race (pid=12019)
Write of size 4 at 0x562105989bb4 by thread T1:
#0 racy::main::_$u7b$$u7b$closure$u7d$$u7d$::hbe13ea9e8ac73f7e $PWD/src/main.rs:6 (racy+0x000000010e3f)
#1 _$LT$std..panic..AssertUnwindSafe$LT$F$GT$$u20$as$u20$core..ops..FnOnce$LT$$LP$$RP$$GT$$GT$::call_once::h2e466a92accacc78 /shared/rust/checkouts/lsan/src/libstd/panic.rs:296 (racy+0x000000010cc5)
#2 std::panicking::try::do_call::h7f4d2b38069e4042 /shared/rust/checkouts/lsan/src/libstd/panicking.rs:460 (racy+0x00000000c8f2)
#3 __rust_maybe_catch_panic <null> (racy+0x0000000b4e56)
#4 std::panic::catch_unwind::h31ca45621ad66d5a /shared/rust/checkouts/lsan/src/libstd/panic.rs:361 (racy+0x00000000b517)
#5 std::thread::Builder::spawn::_$u7b$$u7b$closure$u7d$$u7d$::hccfc37175dea0b01 /shared/rust/checkouts/lsan/src/libstd/thread/mod.rs:357 (racy+0x00000000c226)
#6 _$LT$F$u20$as$u20$alloc..boxed..FnBox$LT$A$GT$$GT$::call_box::hd880bbf91561e033 /shared/rust/checkouts/lsan/src/liballoc/boxed.rs:605 (racy+0x00000000f27e)
#7 std::sys::imp::thread::Thread::new::thread_start::hebdfc4b3d17afc85 <null> (racy+0x0000000abd40)
Previous write of size 4 at 0x562105989bb4 by main thread:
#0 racy::main::h23e6e5ca46d085c3 $PWD/src/main.rs:8 (racy+0x000000010d7c)
#1 __rust_maybe_catch_panic <null> (racy+0x0000000b4e56)
#2 __libc_start_main <null> (libc.so.6+0x000000020290)
Location is global 'racy::ANSWER::h543d2b139f819b19' of size 4 at 0x562105989bb4 (racy+0x0000002f8bb4)
Thread T1 (tid=12028, running) created by main thread at:
#0 pthread_create /shared/rust/checkouts/lsan/src/compiler-rt/lib/tsan/rtl/tsan_interceptors.cc:902 (racy+0x00000001aedb)
#1 std::sys::imp::thread::Thread::new::hce44187bf4a36222 <null> (racy+0x0000000ab9ae)
#2 std::thread::spawn::he382608373eb667e /shared/rust/checkouts/lsan/src/libstd/thread/mod.rs:412 (racy+0x00000000b5aa)
#3 racy::main::h23e6e5ca46d085c3 $PWD/src/main.rs:6 (racy+0x000000010d5c)
#4 __rust_maybe_catch_panic <null> (racy+0x0000000b4e56)
#5 __libc_start_main <null> (libc.so.6+0x000000020290)
SUMMARY: ThreadSanitizer: data race $PWD/src/main.rs:6 in racy::main::_$u7b$$u7b$closure$u7d$$u7d$::hbe13ea9e8ac73f7e
==================
ThreadSanitizer: reported 1 warnings
66
```
```
$ cargo new --bin oob && cd $_
$ edit src/main.rs && cat $_
```
``` rust
fn main() {
let xs = [0, 1, 2, 3];
let y = unsafe { *xs.as_ptr().offset(4) };
}
```
```
$ RUSTFLAGS="-Z sanitizer=address" cargo run --target x86_64-unknown-linux-gnu; echo $?
=================================================================
==13328==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fff29f3ecd0 at pc 0x55802dc6bf7e bp 0x7fff29f3ec90 sp 0x7fff29f3ec88
READ of size 4 at 0x7fff29f3ecd0 thread T0
#0 0x55802dc6bf7d in oob::main::h0adc7b67e5feb2e7 $PWD/src/main.rs:3
#1 0x55802dd60426 in __rust_maybe_catch_panic ($PWD/target/debug/oob+0xfe426)
#2 0x55802dd58dd9 in std::rt::lang_start::hb2951fc8a59d62a7 ($PWD/target/debug/oob+0xf6dd9)
#3 0x55802dc6c002 in main ($PWD/target/debug/oob+0xa002)
#4 0x7fad8c3b3290 in __libc_start_main (/usr/lib/libc.so.6+0x20290)
#5 0x55802dc6b719 in _start ($PWD/target/debug/oob+0x9719)
Address 0x7fff29f3ecd0 is located in stack of thread T0 at offset 48 in frame
#0 0x55802dc6bd5f in oob::main::h0adc7b67e5feb2e7 $PWD/src/main.rs:1
This frame has 1 object(s):
[32, 48) 'xs' <== Memory access at offset 48 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow $PWD/src/main.rs:3 in oob::main::h0adc7b67e5feb2e7
Shadow bytes around the buggy address:
0x1000653dfd40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfd50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfd60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfd70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x1000653dfd90: 00 00 00 00 f1 f1 f1 f1 00 00[f3]f3 00 00 00 00
0x1000653dfda0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfdb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfdc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfdd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000653dfde0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==13328==ABORTING
1
```
```
$ cargo new --bin uninit && cd $_
$ edit src/main.rs && cat $_
```
``` rust
use std::mem;
fn main() {
let xs: [u8; 4] = unsafe { mem::uninitialized() };
let y = xs[0] + xs[1];
}
```
```
$ RUSTFLAGS="-Z sanitizer=memory" cargo run; echo $?
==30198==WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x563f4b6867da in uninit::main::hc2731cd4f2ed48f8 $PWD/src/main.rs:5
#1 0x563f4b7033b6 in __rust_maybe_catch_panic ($PWD/target/debug/uninit+0x873b6)
#2 0x563f4b6fbd69 in std::rt::lang_start::hb2951fc8a59d62a7 ($PWD/target/debug/uninit+0x7fd69)
#3 0x563f4b6868a9 in main ($PWD/target/debug/uninit+0xa8a9)
#4 0x7fe844354290 in __libc_start_main (/usr/lib/libc.so.6+0x20290)
#5 0x563f4b6864f9 in _start ($PWD/target/debug/uninit+0xa4f9)
SUMMARY: MemorySanitizer: use-of-uninitialized-value $PWD/src/main.rs:5 in uninit::main::hc2731cd4f2ed48f8
Exiting
77
```
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[LLVM 4.0] Use 32-bits for alignment
LLVM 4.0 changes this. This change is fine to make for LLVM 3.9 as we
won't have alignments greater than 2^32-1.
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This changes rustc to emit DW_AT_main_subprogram on the "main" program.
This lets gdb suitably stop at the user's main in response to
"start" (rather than the library's main, which is what happens
currently).
Fixes #32620
r? michaelwoerister
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LLVM 4.0 changes this. This change is fine to make for LLVM 3.9 as we
won't have alignments greater than 2^32-1.
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Instead of directly creating a 'DIGlobalVariable', we now have to create
a 'DIGlobalVariableExpression' which itself contains a reference to a
'DIGlobalVariable'.
This is a straightforward change.
In the future, we should rename 'DIGlobalVariable' in the FFI
bindings, assuming we will only refer to 'DIGlobalVariableExpression'
and not 'DIGlobalVariable'.
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LLVM Core C bindings provide this function for all the versions back to what we support (3.7), and
helps to avoid this unnecessary builder->function transition every time. Also a negative diff.
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These switch statements cover all possible values, so the default case
is dead code (it contains an llvm_unreachable anyway), triggering a
-Wcovered-switch-default warning. Moving the unreachable after the
switch resolves these warnings. This keeps the build output clean.
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