Hi Jakub As per the discussions, I have a created a bug report for the possible regression this may cause. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82454
Sudi From: Wilco Dijkstra Sent: Tuesday, September 26, 2017 2:20 PM To: Sudi Das; Jakub Jelinek Cc: Richard Biener; GCC Patches; nd; Richard Earnshaw; James Greenhalgh Subject: Re: [PATCH][GCC] Simplification of 1U << (31 - x) Jakub Jelinek wrote: > Well, we don't want to regress performance wise on one of the most important > primary targets. I don't care that much if the RTL/backend work is done > together with the patch, or as a follow-up during stage1/3, but it should be > done, the testcases I've posted can be used as a basis of a P1 runtime > performance regression. It should be sufficient to file a bug about inefficient 64-bit constant expansions on x64. I didn't see a significant difference in my benchmarking of it on x64, so I'd say it's only a performance regression if large benchmarks regress measurably (quite unlikely). Wilco
