On Thu, Dec 12, 2013 at 8:19 PM, Steve Ellcey <sell...@mips.com> wrote: > I have a question about the partial pre (-ftree-partial-pre) optimization > that was added in GCC 4.8. I have noticed that this optimization is slowing > down the bitmnp01 benchmark in the EEMBC1.1 suite on MIPS. I see this with > the 4.8 GCC and with ToT GCC. Comparing "-O3 -fno-tree-partial-pre" vs. > just "-O3" on the Tot GCC with MIPS, I see almost a 50% slowdown in the > benchmark due to the partial pre optimization.
Note that partial PRE wasn't added in 4.8 but much earlier. But 4.8 got an option to disable it - which means you have a workaround at your hands now. Richard. > I was wondering if anyone else has seen a slowdown like this on other > platforms or in other benchmarks. I haven't submitted a bugzilla report > because I don't have a test case that I can include (EEMBC is licensed). > > Steve Ellcey > sell...@mips.com >
