Bisected failure

["Søren Holm" <sgh@sgh.dk>]

Hi

My application running on a stm32f7 started to behave "random" when 
compiled with gcc 10.1 - Gcc 9.x works fine.

By random I mean this.

1. Flash the application onto the target.
2. reset - the application starts up fine
2. reset again - the application somehow goes haywire during startup 
effectively starting over with out a reset. That ends up leaving 
interrups and timers enabled fireing during BSS clear.
3. Reset again - now the application starts up fine again.
4. reset again - lockup again
5. reset again - lockup again
6 .......


I have bisected and verified that whatever makes my

commit 79f1d8521882de51480866fd7037199d670316bd (HEAD, refs/bisect/bad)
Author: Jan Hubicka <hubicka@ucw.cz>
Date:   Thu Nov 14 14:30:46 2019 +0100

     * params.opt (max-inline-insns-single-O2): Set to 70 (instead of 30).

     From-SVN: r278221


Do you have any ideas to how to hunt down this bug? Besides trying to 
isolate the place where things go wrong. I'm unsure if GCC does 
something that the hardware does not like or my application is buggy. In 
any case I'd like to figure out the root cause. I do not like to be 
stuck at gcc 9 because of these kinds of issues :)

I'd appreciate any input you might have.

/Søren