os-rust/compiler/rustc_llvm
bors e2a3c9b3f0 Auto merge of #117962 - weihanglo:debug-name-table, r=wesleywiser
fix: stop emitting `.debug_pubnames` and `.debug_pubtypes`

A continuation of #94181.
Fixes #48762
MCP can be found in <https://github.com/rust-lang/compiler-team/issues/688>.

`.debug_pubnames` and `.debug_pubtypes` are poorly designed and people
seldom use them. However, they take a considerable portion of size in
the final binary. This tells LLVM stop emitting those sections on
DWARFv4 or lower. DWARFv5 use `.debug_names` which is more concise
in size and performant for name lookup.

Some other no-really-useful personal notes:

<details><summary>Details</summary>
<p>

## Pepole saying they are not useful

* https://github.com/rust-lang/rust/issues/48762
* https://rust-lang.zulipchat.com/#narrow/stream/317568-t-compiler.2Fwg-debugging/topic/investigating.20debuginfo.20size/near/342713604
* `DwarfCompileUnit::hasDwarfPubSections()` — f633f325a1/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp (L1477-L1494)
* clang default to no debug name table when no option provided — f633f325a1/clang/lib/Frontend/CompilerInvocation.cpp (L1819-L1824)
* GCC explicitly says GDB doesn't use pub sections (`TARGET_WANT_DEBUG_PUB_SECTIONS` only be true on Darwin) — 5d2a360f0a/gcc/target.def (L6985-L6990) and 319b460545/gold/dwarf_reader.h (L424-L427)
* Probably the only place that makes use of pub section in lldb — 725115d7bb/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp (L2117-L2135)

* "The -gsplit-dwarf option requires -ggnu-pubnames." — 5d2a360f0a/gcc/opts.cc (L1205)

* LLVM: Always emit `.debug_names` with dwarf 5 for Apple platforms — https://reviews.llvm.org/D118754

</p>
</details>
2023-12-11 22:32:08 +00:00
..
llvm-wrapper Auto merge of #117962 - weihanglo:debug-name-table, r=wesleywiser 2023-12-11 22:32:08 +00:00
src Bump cfg(bootstrap)s 2023-11-15 19:41:28 -05:00
build.rs Use new check-cfg syntax in rustc_llvm build script 2023-12-05 13:25:11 +01:00
Cargo.toml Clean up rustc_*/Cargo.toml. 2023-10-30 08:46:02 +11:00