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bors 3139ff09e9 Auto merge of #128861 - khuey:mir-inlining-parameters-debuginfo, r=wesleywiser
Rework MIR inlining debuginfo so function parameters show up in debuggers.

Line numbers of multiply-inlined functions were fixed in #114643 by using a single DISubprogram. That, however, triggered assertions because parameters weren't deduplicated. The "solution" to that in #115417 was to insert a DILexicalScope below the DISubprogram and parent all of the parameters to that scope. That fixed the assertion, but debuggers (including gdb and lldb) don't recognize variables that are not parented to the subprogram itself as parameters, even if they are emitted with DW_TAG_formal_parameter.

Consider the program:

```rust
use std::env;

#[inline(always)]
fn square(n: i32) -> i32 {
    n * n
}

#[inline(never)]
fn square_no_inline(n: i32) -> i32 {
    n * n
}

fn main() {
    let x = square(env::vars().count() as i32);
    let y = square_no_inline(env::vars().count() as i32);
    println!("{x} == {y}");
}
```

When making a release build with debug=2 and rustc 1.82.0-nightly (8b3870784 2024-08-07)

```
(gdb) r
Starting program: /ephemeral/tmp/target/release/tmp [Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 1, tmp::square () at src/main.rs:5
5	    n * n
(gdb) info args
No arguments.
(gdb) info locals
n = 31
(gdb) c
Continuing.

Breakpoint 2, tmp::square_no_inline (n=31) at src/main.rs:10
10	    n * n
(gdb) info args
n = 31
(gdb) info locals
No locals.
```

This issue is particularly annoying because it removes arguments from stack traces.

The DWARF for the inlined function looks like this:

```
< 2><0x00002132 GOFF=0x00002132>      DW_TAG_subprogram
                                        DW_AT_linkage_name          _ZN3tmp6square17hc507052ff3d2a488E
                                        DW_AT_name                  square
                                        DW_AT_decl_file             0x0000000f /ephemeral/tmp/src/main.rs
                                        DW_AT_decl_line             0x00000004
                                        DW_AT_type                  0x00001a56<.debug_info+0x00001a56>
                                        DW_AT_inline                DW_INL_inlined
< 3><0x00002142 GOFF=0x00002142>        DW_TAG_lexical_block
< 4><0x00002143 GOFF=0x00002143>          DW_TAG_formal_parameter
                                            DW_AT_name                  n
                                            DW_AT_decl_file             0x0000000f /ephemeral/tmp/src/main.rs
                                            DW_AT_decl_line             0x00000004
                                            DW_AT_type                  0x00001a56<.debug_info+0x00001a56>
< 4><0x0000214e GOFF=0x0000214e>          DW_TAG_null
< 3><0x0000214f GOFF=0x0000214f>        DW_TAG_null
```

That DW_TAG_lexical_block inhibits every debugger I've tested from recognizing 'n' as a parameter.

This patch removes the additional lexical scope. Parameters can be easily deduplicated by a tuple of their scope and the argument index, at the trivial cost of taking a Hash + Eq bound on DIScope.
2024-08-15 11:42:15 +00:00
.github Fix dependencies cron job 2024-08-14 09:57:14 -07:00
compiler Auto merge of #128861 - khuey:mir-inlining-parameters-debuginfo, r=wesleywiser 2024-08-15 11:42:15 +00:00
library Rollup merge of #128946 - orlp:faster-ip-hash, r=joboet 2024-08-15 00:02:25 +02:00
LICENSES Include REUSE.toml in REUSE.toml. 2024-07-22 09:44:18 +01:00
src Auto merge of #129066 - weihanglo:update-cargo, r=weihanglo 2024-08-15 06:09:39 +00:00
tests Auto merge of #128861 - khuey:mir-inlining-parameters-debuginfo, r=wesleywiser 2024-08-15 11:42:15 +00:00
.clang-format Add .clang-format 2024-06-26 05:56:00 +08:00
.editorconfig Only use max_line_length = 100 for *.rs 2023-07-10 15:18:36 -07:00
.git-blame-ignore-revs Ignore use declaration reformatting in .git-blame-ignore-revs. 2024-08-01 14:33:17 +10:00
.gitattributes Rename config.toml.example to config.example.toml 2023-03-11 14:10:00 -08:00
.gitignore gitignore: Add Zed and Helix editors 2024-08-09 21:26:27 +01:00
.gitmodules Update to LLVM 19 2024-07-30 10:22:48 +02:00
.ignore Add .ignore file to make config.toml searchable in vscode 2024-06-24 10:15:16 +02:00
.mailmap trans her gender 2024-07-27 23:36:23 +00:00
Cargo.lock Update indexmap and use IndexMap::append 2024-08-13 16:16:57 -07:00
Cargo.toml Use -D warnings instead of deny-warnings feature. 2024-08-06 10:46:39 -04:00
CODE_OF_CONDUCT.md Remove the code of conduct; instead link https://www.rust-lang.org/conduct.html 2019-10-05 22:55:19 +02:00
config.example.toml Enable zstd for debug compression. 2024-08-09 05:55:23 -07:00
configure Ensure ./configure works when configure.py path contains spaces 2024-02-16 18:57:22 +00:00
CONTRIBUTING.md fix: Update CONTRIBUTING.md recommend -> recommended 2023-11-16 23:57:09 +05:30
COPYRIGHT Update COPYRIGHT file 2022-10-30 10:23:14 -04:00
INSTALL.md Rollup merge of #127434 - onur-ozkan:use-bootstrap-instead-of-rustbuild, r=Mark-Simulacrum 2024-07-13 20:19:45 -07:00
LICENSE-APACHE Remove appendix from LICENCE-APACHE 2019-12-30 14:25:53 +00:00
LICENSE-MIT LICENSE-MIT: Remove inaccurate (misattributed) copyright notice 2017-07-26 16:51:58 -07:00
README.md Use SVG logos in the README.md. 2024-04-03 19:48:20 +02:00
RELEASES.md Fix 1.80.0 version in RELEASES.md 2024-07-25 16:57:57 +02:00
REUSE.toml REUSE.toml: Copyright text isn't parsed as Markdown. 2024-08-06 11:04:55 +01:00
rust-bors.toml Increase timeout for new bors bot 2024-03-13 08:31:07 +01:00
rustfmt.toml Auto merge of #128083 - Mark-Simulacrum:bump-bootstrap, r=albertlarsan68 2024-07-30 17:49:08 +00:00
triagebot.toml Add mw back to review rotation 2024-08-13 20:16:14 +02:00
x Make x capable of resolving symlinks 2023-10-14 17:53:33 +03:00
x.ps1 use & instead of start-process in x.ps1 2023-12-09 09:46:16 -05:00
x.py Fix recent python linting errors 2023-08-02 04:40:28 -04:00

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