[llvm] r204076 - Use range metadata instead of introducing selects.
rafael.espindola at gmail.com
Tue Mar 25 07:24:15 PDT 2014
On 25 March 2014 09:49, Dan Gohman <dan433584 at gmail.com> wrote:
> Hi Lang,
> I can reproduce the performance regression on fourinarow, at least. With the
> patch, the code size and static instruction count of the benchmark's one
> embarassingly-hot function is lower, the dynamic instruction count is lower,
> and the stack frame is smaller, but it still runs slower. Instruction
> selection is basically the same, except that there are fewer cmovs. There
> appears to be a minor difference in instruction scheduling in the hot
> function. The regression disappeared when I experimented with non-default
> values for -pre-RA-sched. However, I'm not prepared for the adventure of
> changing the instruction scheduler's heuristics at this time, so I'll just
> let this patch go for now.
Do you have a small .ll testcase?
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