[all-commits] [llvm/llvm-project] 2a9afd: [clang] Reduce the size of ParsedAttributesView an...

[Haojian Wu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2a9afdb7937710a4af5ebe5ab3a4fdd235fbf08e
      https://github.com/llvm/llvm-project/commit/2a9afdb7937710a4af5ebe5ab3a4fdd235fbf08e
  Author: Haojian Wu <hokein.wu at gmail.com>
  Date:   2025-07-15 (Tue, 15 Jul 2025)

  Changed paths:
    M clang/include/clang/Sema/ParsedAttr.h

  Log Message:
  -----------
  [clang] Reduce the size of ParsedAttributesView and AttributePool (#148726)

These objects are used as local stack variables during parsing, and they
are not small. This patch reduces their sizes:

* `ParsedAttributesView`: 72 → 40 bytes
* `AttributePool`: 72 → 40 bytes

No negative performance impact has been
[observed](https://llvm-compile-time-tracker.com/compare.php?from=a709621cd545b061782b03136286227867b452a6&to=f50500b3c178e97c0c861301e853e6d5b859040b&stat=instructions:u).

**Context:**
We have some verilator-generated code with extremely deep nesting of
parenthesized expressions, e.g.:

```cpp
bool s = 
(...(bool)(i[0])
 |(bool)(i[1]))
 |(bool)(i[2]))
 | ...
 |(bool)(i[n]));
```

Before this patch, on my local machine, Clang begins emitting
`-Wstack-exhausted` when `n` is 715. After the patch, that threshold
increases to `950`.



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