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 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)
Thanks, Tejas On Thu, 15 Aug 2019 at 02:30, Segher Boessenkool <seg...@kernel.crashing.org> wrote: > > On Wed, Aug 14, 2019 at 08:23:27PM +0000, Joseph Myers wrote: > > On Wed, 14 Aug 2019, Segher Boessenkool wrote: > > > > > Does something like > > > float d; double a, b, x; > > > ... > > > d = fadd (a + x, b - x); > > > work as wanted, with such a representation? It would simplify (does it?) > > > to > > > d = fadd (a, b); > > > but is that allowed? > > > > It's not allowed, but neither is simplifying (a + x) + (b - x) into (a + > > b), when contraction isn't allowed. > > Ah of course. And we already should not do such simplification on RTL, > when contraction is disallowed. > > So yeah it should work fine I think. A new RTL code would be best (it > would be silly to have to make an unspec for it in every port separately), > but an unspec is of course easiest for now. > > > Segher
