Andreas Kling e486ad2c0c AsmIntGen: Use platform-optimal codegen for NaN-boxing operations ...

Convert extract_tag, unbox_int32, unbox_object, box_int32, and
box_int32_clean from DSL macros into codegen instructions, allowing
each backend to emit optimal platform-specific code.

On aarch64, this produces significant improvements:

- extract_tag: single `lsr xD, xS, #48` instead of `mov` + `lsr`
  (3-operand shifts are free on ARM). Saves 1 instruction at 57
  call sites.

- unbox_object: single `and xD, xS, #0xffffffffffff` instead of
  `mov` + `shl` + `shr`. The 48-bit mask is a valid ARM64 logical
  immediate. Saves 2 instructions at 6 call sites.

- box_int32: `mov wD, wS` + `movk xD, #tag, lsl #48` instead of
  `mov` + `and 0xFFFFFFFF` + `movabs tag` + `or`. The w-register
  mov zero-extends, and movk overwrites just the top 16 bits.
  Saves 2 instructions and no longer clobbers t0 (rax).

- box_int32_clean: `movk xD, #tag, lsl #48` (1 instruction) instead
  of `mov` + `movabs tag` + `or` (saves 2 instructions, no t0
  clobber).

On x86_64, the generated code is equivalent to the old macros.

2026-03-07 22:18:22 +01:00

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src

AsmIntGen: Use platform-optimal codegen for NaN-boxing operations

2026-03-07 22:18:22 +01:00

Cargo.lock

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Cargo.toml

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