JuliaLang / julia / 746

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Commit Message

core: Fix more odd-width primitive bugs (#63408)

Primitive types whose width is not a multiple of 8, supported since
#61359, still hit several bugs:

- runtime intrinsics left the bits above a result's width set:
  `sext_int` filled them with the sign, and `flipsign_int` and
  out-of-range `fptoui`/`fptosi` kept them. `===` ignores those bits,
  but constants folded by inference carried them into package images;
- the runtime shifts counted the bits above an amount's width;
- the runtime shifts took an amount modulo 2^N for an N-bit value,
  where codegen shifts everything out, at standard widths too;
- redefining a primitive type with another width of the same size kept
  the old type;
- `@enum`, `Core.check_top_bit` and the multiplicative inverses took
  the width from `8 * sizeof`, and `Core.check_top_bit` threw on types
  narrower than 8 bits;
- a runtime `replacefield!` on a 1- or 2-byte primitive with padding
  bits failed spuriously, and asserted in debug builds.

The shifts get their own runtime wrapper, and the other integer
intrinsics pass their operands as they are: since #61359 no op reads
the sign-filled bytes they were extended with.

Fixes #63460

Co-authored-by: Cody Tapscott <topolarity@tapscott.me>
Assisted-by: Claude Code (Opus 5.5)
Assisted-by: Claude Code (Fable 5.1)

Coverage Stats

9 of 9 new or added lines in 3 files covered. (100.0%)

159 existing lines in 7 files now uncovered.

92120 of 104474 relevant lines covered (88.18%)

353.03 hits per line