Richard Sandiford <richard.sandif...@arm.com> writes: > "Kewen.Lin" <li...@linux.ibm.com> writes: >> @@ -626,6 +645,12 @@ public: >> /* True if have decided to use a fully-masked loop. */ >> bool fully_masked_p; >> >> + /* Records whether we still have the option of using a length access >> loop. */ >> + bool can_with_length_p; >> + >> + /* True if have decided to use length access for the loop fully. */ >> + bool fully_with_length_p; > > Rather than duplicate the flags like this, I think we should have > three bits of information: > > (1) Can the loop operate on partial vectors? Starts off optimistically > assuming "yes", gets set to "no" when we find a counter-example. > > (2) If we do decide to use partial vectors, will we need loop masks? > > (3) If we do decide to use partial vectors, will we need lengths? > > Vectorisation using partial vectors succeeds if (1) && ((2) != (3)) > > LOOP_VINFO_CAN_FULLY_MASK_P currently tracks (1) and > LOOP_VINFO_MASKS currently tracks (2). In pathological cases it's > already possible to have (1) && !(2), see r9-6240 for an example.
Oops, I meant r8-6240.
