On 25 May 2015 at 12:49, hwang4 <hui.wang at canonical.com> wrote: > > > On 2015å¹´05æ??25æ?¥ 14:40, David Henningsson wrote: >> >> >> >> On 2015-05-25 06:49, Hui Wang wrote: >>> >>> On 32bits OS, this test case fails. The reason is when rewinding to >>> the middle of a block, some of float parameters in the saved_state >>> are stored in the memory from FPU registers, and those parameters will >>> be used for next time to process data with lfe. Here if FPU register >>> is over 32bits, the storing from FPU register to memory will introduce >>> some variation, and this small variation will introduce small >>> variation to the rewinding result. >> >> >> Very interesting finding. I didn't know that storing things back and forth >> to memory could change the computation result. >> >> And the fact that it only happens on 32-bit platforms and only with >> optimisations makes it even stranger. Makes me wonder if this is actually an >> gcc optimisation bug. >> > Probably. Did I misunderstand something here? Fixing a problem with the compiler in our test seems to be incorrect. -- Arun
