PennyLaneAI / PennyLaneAI/catalyst

Indexed assignment doesn't work with dynamically-shaped arrays

Open
#906 3 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

bug upstream
Dominant language
Python
Stars
234
Forks
84
Avg merge
2d 15h
Merged PRs (30d)
66

Description

The following program raises an error:

import jax.numpy as jnp
from catalyst import *

@qjit
def f(n: int, m: int):
    x = jnp.ones((n, m), dtype=float)
    y = jnp.ones((n, m), dtype=float)

    @for_loop(0, n, 1, experimental_preserve_dimensions=True)
    def sum_and_multiply(i, x, y):
        x[i] = x[i] + y[i]
        y[i] = x[i] * y[i]
        return x, y

    return sum_and_multiply(x, y)

f(2, 3)
File /Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/jax/_src/core.py:2072, in non_negative_dim(d)
   [2070](jax/_src/core.py:2070) if is_constant_dim(d):
   [2071](jax/_src/core.py:2071)   return max(0, d)
-> [2072](jax/_src/core.py:2072) assert is_symbolic_dim(d)
   [2073](jax/_src/core.py:2073) try:
   [2074](jax/_src/core.py:2074)   d_ge_0 = (d >= 0)

AssertionError:

It does not happen without the indexed assignment.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the supplied qjit/for_loop reproducer with dynamic n and m, then compare it with the version without indexed assignment. Trace Catalyst's indexed-assignment handling alongside JAX symbolic-shape processing; done means f(2, 3) compiles and runs without the shown AssertionError while preserving the updates.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.