On Thu, Aug 15, 2019 at 01:47:47PM +0100, Richard Sandiford wrote: > Tejas Joshi <tejasjoshi9...@gmail.com> writes: > > Hello. > > I just wanted to make sure that I am looking at the correct code here. > > Except for rtl.def where I should be introducing something like > > float_contract (or float_narrow?) and also simplify-rtx.c, breakpoints
I like that "float_narrow" name :-) > > set on functions around expr.c, cfgexpand.c where I grep for > > float_truncate/FLOAT_TRUNCATE did not hit. > > Also, in what manner should float_contract/narrow be different from > > float_truncate as both are trying to do similar things? (truncation > > from DF to SF) > > I think the code should instead be a fused addition and truncation, > a bit like FMA is a fused addition and multiplication. Describing it as > a DFmode addition followed by some conversion to SF would still involve > double rounding. How so? It would *mean* there is only single rounding, even! That's the whole point of it. > simplify-rtx.c is probably the most important place to handle it. > It would be easiest to test using the selftests at the end of the file. Segher
