Hang on font rendering

[antoncoetzee]

So I've been setting up uGFX with ChibiOS on a STM32L152 Nucleo board. Everything works great, and as expected, except for font rendering, which seems to hang the board completely -- all threads. This happens whether or not the uGFX code is in the main thread or child threads.

I don't have onboard debugging working properly at this point, but near as I can tell it's happening within mf_bwfont.c, at line 89:

callback(x0 + x - runlen, y0 + y, runlen, 255, state);

Which seems to be related to gdisp.c around line 3158, calling drawcharline and fillcharline.

Any ideas on what could be happening? I'm tearing my hair out here.... |-(

[inmarket]

This is obviously fairly well tested code so things I would suggest trying...

1/ if you are using a custom font, try replacing it with the ui2 font. If that doesn't crash then it is likely to be your custom font has some corruption.

2/ Increase the size of the stack. Many linker scripts provide any initial stack that is just too small.

[antoncoetzee]

Thanks. Tried all of that, but no luck. Turns out I had GCC -O2 optimisation enabled in my Makefile. Removed that and it works perfectly...

Go figure.

[inmarket]

Wonderful! Another compiler optimizer bug.

We have seen a few of those. Mostly we fix these as we find them (by code rearrangement) however different versions of compilers, let alone different compilers can have different optimisation bugs.