rust-lang / rust-lang/rust

Should debuginfo special-case vectors?

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A-debuginfo C-discussion T-compiler WG-debugging
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Rust
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Description

In #129403 I'm seeing that using array-based SIMD types changes the debug info you get from them, and thus #128866 has in fact already changed the debuginfo you get from platform types like __m256.

 // gdb-command:print vi8x16
-// gdb-check:$1 = simd::i8x16 (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
+// gdb-check:$1 = simd::i8x16 ([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])

Should debug-info notice the Vector ABI and emit something that doesn't get double-braced? Or does it not matter and the ([1, 2]) is completely fine so it's not worth changing?

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Research direction

Start by reading issues #129403 and #128866 to understand the existing debuginfo changes for array-based SIMD and platform vector types. Reproduce the shown gdb-command for vi8x16 and compare the gdb-check output. Done means reaching a decision on whether Vector ABI types should receive special handling and documenting the expected output or implementing the agreed change.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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