fix(ops): fix convolve padRight for even kernels in same mode

[shubhransh-gupta]

Proposed Changes

Resolves #466.

Fixes right-side padding calculation in convolve(_:_:mode:stream:) (Source/MLX/Ops.swift) for .same mode when the kernel length is even.

Root Cause

Previously, when the weight size was even, padRight was computed as max(0, padLeft / 2 - 1) instead of max(0, padLeft - 1). For example, with padLeft = 2 (kernel size 4), padRight incorrectly evaluated to 0 instead of 1, causing the input to be under-padded and the output length for .same mode to be truncated by 1 element.

This change aligns the calculation with the MLX C++ / Python implementation (int pad_r = std::max(0, pad_l - 1)).

Tests

Added testConvolve() in Tests/MLXTests/OpsTests.swift testing .full, .valid, and .same mode outputs with both even and odd kernel sizes.

Checklist

• I have read the CONTRIBUTING document
• I have added tests that prove my fix is effective or that my feature works
• I have updated the necessary documentation (if needed)

[simeetnayan81]

LGTM

[shubhransh-gupta]

Hi @davidkoski — Friendly ping on this PR when you get a chance. It fixes convolution right-padding calculation for even kernel sizes under 'same' mode. Tests pass cleanly. Thanks!

[davidkoski]

Nice! I realized I just found the same issue in #478

Just waiting on CI.