On 28 February 2018 at 19:28, Christopher Li <sparse@xxxxxxxxxxx> wrote: > On Wed, Feb 28, 2018 at 10:59 AM, Dibyendu Majumdar > <mobile@xxxxxxxxxxxxxxx> wrote: >> >> Okay, so I am trying to understand where in the simplification phase >> the size of the value pseudo used. This was the only place I could >> find. Although now multiple value pseudos are created - I guess the >> actual value is still the same, and if the size of the value pseudo >> does not play a part in simplification then sure this change cannot >> cause a change in the simplification process? Or am I missing >> something? > > It is in theory possible in the following case, you have two instruction all the > same except two operand size: > > %r10 <- op.32 %r11, $10 (size 8) > %r13 <- op.32 %r11, $10 (size 32) > > In that case, CSE will not able to see the $10 as the same, because they > have size difference and reference by two different pseudo value. > > If that ever happen, that is a strange situation to get into in the first place. > We might want to look a closer look if that ever happen. How can same size > instruction have different size operand. > > The fix I think just need to change the first $10(size 8) into the $10(size 32) > version. It is a lot simpler than change the type. I am not sure this example > is actually trigger able yet. Not big deal. > Okay thank you for the explanation - might be worth trying to create a test case that triggers this scenario. Regards Dibyendu -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
