On Mon, Aug 12, 2019 at 09:20:18PM +0000, Joseph Myers wrote: > On Mon, 12 Aug 2019, Segher Boessenkool wrote: > > > (define_insn "add_truncdfsf3" > > [(set (match_operand:SF 0 "gpc_reg_operand" "=f,wa") > > (float_truncate:SF > > (plus:DF (match_operand:DF 1 "gpc_reg_operand" "%d,wa") > > (match_operand:DF 2 "gpc_reg_operand" "d,wa"))))] > > That sort of pattern is incorrect for a fused operation such as fadd, > because combine could match it for code that is supposed to do separate > addition and narrowing conversion. The RTL needs to be something that > does *not* match the combination of separate operations (just as fma has > its own RTL, and a separate pass is responsible for converting separate > operations to fused ones in the -ffp-contract=fast case where it's > permitted).
Ugh, we allow disabling contraction, I forgot. Rats. Segher
