Re: Change of assumptions/behavior with -ftree-vrp in gcc 4.8+?

2016-08-03 Thread Vikram Mulukutla
On 8/3/2016 12:11 PM, Andrew Pinski wrote: On Wed, Aug 3, 2016 at 12:10 PM, Andrew Pinski wrote: On Wed, Aug 3, 2016 at 12:06 PM, Vikram Mulukutla wrote: Hi, The program listed below seems to invoke optimization behavior that produces different results pre 4.8 and 4.8+ versions of gcc

Change of assumptions/behavior with -ftree-vrp in gcc 4.8+?

2016-08-03 Thread Vikram Mulukutla
Hi, The program listed below seems to invoke optimization behavior that produces different results pre 4.8 and 4.8+ versions of gcc. Using the -fno-tree-vrp option makes things consistent again. I make no claim of an understanding of what this flag really does. The program is badly written s