similar to: [LLVMdev] undefs in phis

On Thursday 29 January 2009 18:04, Eli Friedman wrote: > On Thu, Jan 29, 2009 at 2:47 PM, David Greene <dag at cray.com> wrote: > > After phi elimination we have: > > > > bb134: > > %reg1645 = 1.0 > > > > bb74: > > %reg1176 = MOVAPS %reg1645 > > %reg1177 = MOVAPS %reg1646 > > [...] > > > > bb108: > > %reg1645 =

On Jan 29, 2009, at 5:29 PM, David Greene wrote: > On Thursday 29 January 2009 18:04, Eli Friedman wrote: >> On Thu, Jan 29, 2009 at 2:47 PM, David Greene <dag at cray.com> wrote: >>> After phi elimination we have: >>> >>> bb134: >>> %reg1645 = 1.0 >>> >>> bb74: >>> %reg1176 = MOVAPS %reg1645 >>> %reg1177 =

On Thu, Jan 29, 2009 at 2:47 PM, David Greene <dag at cray.com> wrote: > After phi elimination we have: > > bb134: > %reg1645 = 1.0 > > bb74: > %reg1176 = MOVAPS %reg1645 > %reg1177 = MOVAPS %reg1646 > [...] > > bb108: > %reg1645 = <expr> > %reg1646 = %reg1176 I find it a little strange that the IMPLICIT_DEF disappears. Besides that, it

On Friday 30 January 2009 01:41, Evan Cheng wrote: > >> I find it a little strange that the IMPLICIT_DEF disappears. Besides > >> that, it looks okay up to here. > > > > I just verified that it does disappear. > > It's intentional. We don't want a live interval defined by an > implicit_def. It unnecessarily increases register pressure. Ah, I see.

On Friday 30 January 2009 16:54, Evan Cheng wrote: > I don't have the whole context to understand why you think this is a > bug. An implicit_def doesn't actually define any value. So we don't > care if a live interval overlaps live ranges defined by an implicit_def. It's a bug because the coalerscer does illegal coaescing. Our last episode left us here: bb134: 2696

On Jan 30, 2009, at 1:52 PM, David Greene wrote: > On Friday 30 January 2009 15:10, David Greene wrote: > >> This still looks correct. The coalescer then says: >> >> 4360 %reg1177<def> = FsMOVAPSrr %reg1176<kill> ; srcLine 0 >> Inspecting %reg1176,0 = [2702,4362:0) 0 at 2702-(4362) and >> %reg1177,0 = >>

On Feb 2, 2009, at 10:08 AM, David Greene wrote: > On Friday 30 January 2009 16:54, Evan Cheng wrote: > >> I don't have the whole context to understand why you think this is a >> bug. An implicit_def doesn't actually define any value. So we don't >> care if a live interval overlaps live ranges defined by an >> implicit_def. > > It's a bug

On Friday 30 January 2009 15:10, David Greene wrote: > This still looks correct. The coalescer then says: > > 4360 %reg1177<def> = FsMOVAPSrr %reg1176<kill> ; srcLine 0 > Inspecting %reg1176,0 = [2702,4362:0) 0 at 2702-(4362) and %reg1177,0 = > [2700,3712:0)[3768,3878:0)[4362,4372:0) 0 at 4362-(3878): > Joined. Result = %reg1177,0 = [2700,4372:0) 0 at

On Monday 02 February 2009 23:55, Evan Cheng wrote: > >> Think about what will happen the 2nd iteration.  %v1177 will have > >> the value of > >> %v1645 which is wrong.  This is because %v1176 in bb74 will be > >> replaced with > >> %v1177.  That's incorrect. > > > > Ok, right. The trick to fixing is to make sure the valno of the def of

On Feb 5, 2009, at 5:30 PM, David Greene wrote: > On Monday 02 February 2009 23:55, Evan Cheng wrote: > >>>> Think about what will happen the 2nd iteration. %v1177 will have >>>> the value of >>>> %v1645 which is wrong. This is because %v1176 in bb74 will be >>>> replaced with >>>> %v1177. That's incorrect. >>>

On Feb 2, 2009, at 3:54 PM, Evan Cheng wrote: > > On Feb 2, 2009, at 1:05 PM, David Greene wrote: > >> On Monday 02 February 2009 14:29, Evan Cheng wrote: >>> On Feb 2, 2009, at 12:12 PM, David Greene wrote: >>>> On Monday 02 February 2009 13:14, Evan Cheng wrote: >>>>> I am sorry I don't really follow it. Is this what you are

On Feb 2, 2009, at 1:05 PM, David Greene wrote: > On Monday 02 February 2009 14:29, Evan Cheng wrote: >> On Feb 2, 2009, at 12:12 PM, David Greene wrote: >>> On Monday 02 February 2009 13:14, Evan Cheng wrote: >>>> I am sorry I don't really follow it. Is this what you are >>>> describing? >>>> >>>> %v1177 = undef

On Monday 02 February 2009 14:29, Evan Cheng wrote: > On Feb 2, 2009, at 12:12 PM, David Greene wrote: > > On Monday 02 February 2009 13:14, Evan Cheng wrote: > >> I am sorry I don't really follow it. Is this what you are describing? > >> > >> %v1177 = undef > >> ... > >> loop: > >> ... > >> %v1176 = op ... > >>

On Feb 2, 2009, at 12:12 PM, David Greene wrote: > On Monday 02 February 2009 13:14, Evan Cheng wrote: > >> I am sorry I don't really follow it. Is this what you are describing? >> >> %v1177 = undef >> ... >> loop: >> ... >> %v1176 = op ... >> = %v1177 >> %v1177 = %v1176 >> jmp loop >> >> Why is not