"Illegal instruction" from oxipng on old CPU (i5-650)

[vkcz]

I was trying to run oxipng (PNG optimization software in Rust), but it did not finish correctly; it terminated with the message Illegal instruction.

The computer I was using was running Windows 7 on the x86_64 Intel Core i5-650, and I installed and ran oxipng through Cygwin bash.

I installed oxipng with cargo install oxipng and invoked oxipng with oxipng example.png (in a directory containing a valid example.png).

oxipng gave this output:

Processing: example.png
    2048x2048 pixels, PNG format
    4x8 bits/pixel, RGBA
    IDAT size = 183755 bytes
    File size = 183812 bytes
Illegal instruction

There were no errors when I was installing oxipng, nor when I ran oxipng --help. I have tried oxipng on other images with similar results.

(I understand this seems focused on oxipng, but someone I talked to outside of Github had oxipng working on their device and said the issue should be here.)

I was using rustc stable version 1.45.2 and cargo 1.45.1.

[Nicholas-Baron]

What is the output of lscpu, specifically the 'flags' category? There may be some flag that the compiler assumes is enabled, when it is not truly enabled.

Is there a way you could use gdb or some other tool to determine what instruction causing the issue or even what function it is in?

[ollie27]

This is a bit of a guess but cloudflare-zlib which is a dependency of oxipng is compiled with AVX enabled on Windows MSVC: https://gitlab.com/kornelski/cloudflare-zlib-sys/-/blob/c70f245e7c9533984aac95a28caed78df39e500a/sys/build.rs#L37. The i5-650 doesn't support AVX which would explain the illegal instruction. It would be worth checking if this also reproduces with the x86_64-pc-windows-gnu target assuming the issue is with x86_64-pc-windows-msvc.

If that's correct then this should be reported to oxipng and/or cloudflare-zlib instead.

[mati865]

I don't think cloudflare-zlib does support MinGW.

[LeSeulArtichaut]

@rustbot ping windows
Maybe someone can look into this? In particular, I think checking @ollie27's hypothesis would be great

[rustbot]

Hey Windows Group! This bug has been identified as a good "Windows candidate".
In case it's useful, here are some instructions for tackling these sorts of
bugs. Maybe take a look?
Thanks! <3

cc @arlosi @danielframpton @gdr-at-ms @kennykerr @luqmana @lzybkr @retep998 @rylev @sivadeilra

[vkcz]

I don't think cloudflare-zlib does support MinGW.

I was using Cygwin.

It would be worth checking if this also reproduces with the x86_64-pc-windows-gnu target assuming the issue is with x86_64-pc-windows-msvc.

I'll try that soon. (EDIT: couldn't)

[retep998]

cc.flag_if_supported("/arch:AVX"); is definitely flat out wrong if intending to run the software on CPUs without AVX support. What is the current recommended approach to identifying the CPU target features for the target from the build script?

[ollie27]

@vkcz could you try a different deflate implementation (i.e. passing --zopfli or --libdeflater to oxipng)? If they work it would suggest the issue is with cloudflare-zlib.

[vkcz]

(i.e. passing --zopfli or --libdeflater to oxipng)

Both of these also give Illegal instruction.

[shssoichiro]

My initial guess was also that this was related to cloudflare-zlib, but that shouldn't be triggering with zopfli or libdeflater. Unfortunately, I lack a non-AVX CPU to test this on.