Hi! On 11/19/21 8:49 AM, Michael Meissner wrote: > The next set of 3 patches add zero cycle move support to the Power10. Zero > cycle moves are where the move to LR/CTR/TAR register that is adjacent to the > jump to LR/CTR/TAR register can be fused together. > > At the moment, these set of three patches add support for zero cycle moves for > indirect jumps and switch tables using the CTR register. Potential zero cycle > moves for doing returns are not currently handled. > > In looking at the code, I discovered that just using zero cycle moves isn't as > helpful unless we can eliminate the add instruction before doing the jump. I > also noticed that the various power10 fusion options are only done if > -mcpu=power10. I added a patch to do the fusion for -mtune=power10 as well. > > I have done bootstraps and make check with these patches installed on both > little endian power9 and little endian power10 systems. Can I install these > patches? > > The following patches will be posted: > > 1) Patch to add zero cycle move for indirect jumps and switches. > > 2) Patch to enable p10 fusion for -mtune=power10 in addition to -mcpu=power10. > > 3) Patch to use absolute addresses for switch tables instead of relative > addresses if zero cycle fusion is enabled. > For this last point, I had thought that the plan was to always switch over to absolute addresses for switch tables, following the work that Hao Chen did in this area. Am I misremembering? Hao Chen, can you please remind me where we ended up here?
Thanks! Bill
