On Tue, Jan 12, 2016 at 5:10 PM, Kugan <kugan.vivekanandara...@linaro.org> wrote: > Yes, making PROMOTE_MODE to work the same way as in > promote_function_mode in arm will fix this. Can you please point me to > the test cases that are regressing so that I can also start looking at them.
The info is in here https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65932 See the comments on gcc.target/arm/wmul-[123].c which no longer generate smulbb etc instructions, which are 16x16=32 expanding multiplies which are faster on some older parts that have them. They are present in armv5e and higher architecture versions. Kyrylo looked at this in November, but the situation looks even worse now, as some of the redundant sign extends are gone even before the first rtl pass. That may make it harder to get the smulbb instructions back. Jim