Chris Tate 640001b260 Generate code concurrently for optimized executables that stay one partition ...

Optimized executables with at most 1 MiB of LLVM text were compiled as one
module on one thread. With more than 128 KiB of LLVM text they now pass
several outputs and `--split codegen` to the LLVM helper. The helper
optimizes the module whole, as for a single output, then divides its
functions in module order into runs of about the same instruction count and
generates code for each run on its own thread.

- The output count is 4 or 8 and depends only on the module's size
  (nativeCodegenParts), so artifacts never vary with the host. Node and
  native compiler builds pass the same outputs.
- The helper writes the optimized module to bitcode once with its use-list
  order. Every output after the first parses it and turns the other
  outputs' definitions into declarations; the first output does the same to
  the optimized module in place. Each function's machine code matches a
  single-output build except for jumps to a definition that another output
  also uses.
- Only local definitions that another output uses become hidden. Dead
  constant users are dropped before unused declarations are removed, so no
  output names a thread-local variable it does not use.
- When one run would hold more than three quarters of the instructions, the
  first output is generated from the optimized module as for a single
  output and the others are empty objects.
- Dev builds, partitioned builds and program-object validation are
  unchanged.

2026-10-27 00:22:17 -05:00

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llvm-codegen

Generate code concurrently for optimized executables that stay one partition

2026-10-27 00:22:17 -05:00