Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M

2020-05-15 Thread Herbert Xu
On Tue, May 05, 2020 at 03:53:45PM +0200, Arnd Bergmann wrote: > When building for ARMv7-M, clang-9 or higher tries to unroll some loops, > which ends up confusing the register allocator to the point of generating > rather bad code and using more than the warning limit for stack frames: > >

Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M

2020-05-08 Thread Nathan Chancellor
On Fri, May 08, 2020 at 11:31:07PM +0200, Arnd Bergmann wrote: > On Wed, May 6, 2020 at 7:12 AM Nathan Chancellor > wrote: > > > - > > > +#ifdef CONFIG_CC_IS_CLANG > > > > Given your comment in the bug: > > > > "The code is written to assume no loops are unrolled" > > > > Does it make sense to

Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M

2020-05-08 Thread Arnd Bergmann
On Wed, May 6, 2020 at 7:12 AM Nathan Chancellor wrote: > > - > > +#ifdef CONFIG_CC_IS_CLANG > > Given your comment in the bug: > > "The code is written to assume no loops are unrolled" > > Does it make sense to make this unconditional and take compiler > heuristics out of it? > > > +#pragma

Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M

2020-05-05 Thread Nathan Chancellor
On Tue, May 05, 2020 at 03:53:45PM +0200, Arnd Bergmann wrote: > When building for ARMv7-M, clang-9 or higher tries to unroll some loops, > which ends up confusing the register allocator to the point of generating > rather bad code and using more than the warning limit for stack frames: > >