[InstCombine] fold min/max tree with common operand (PR35717)
There is precedence for factorization transforms in instcombine for FP ops with fast-math.
We also have similar logic in foldSPFofSPF().
It would take more work to add this to reassociate because that's specialized for binops,
and min/max are not binops (or even single instructions). Also, I don't have evidence that
larger min/max trees than this exist in real code, but if we find that's true, we might
want to reorganize where/how we do this optimization.
In the motivating example from https://bugs.llvm.org/show_bug.cgi?id=35717 , we have:
int test(int xc, int xm, int xy) {
int xk;
if (xc < xm)
xk = xc < xy ? xc : xy;
else
xk = xm < xy ? xm : xy;
return xk;
}
This patch solves that problem because we recognize more min/max patterns after rL321672
https://rise4fun.com/Alive/Qjne
https://rise4fun.com/Alive/3yg
Differential Revision: https://reviews.llvm.org/D41603
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321998 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed