similar to: [LLVMdev] Register allocation questions

On Aug 15, 2010, at 5:12 PM, Silvio Ricardo Cordeiro wrote: > Is there a way for me to collect statistics about the number of loads/stores added by the "linearscan" register allocator (just like can be done with the "local" allocator)? I still haven't grokked very well the interaction between RALinScan and Spiller... Should I add those two statistics to the

Spiller::Spill( LiveInterval *li, SmallVectorImpl<LiveInterval*> &newIntervals, const SmallVectorImpl<LiveInterval*> &spillIs ); has two reference vectors which contain a small list of Live Intervals. What is the register allocator's job to do with these intervals other than analysis. What more needed other than to know

Jeff Kunkel <jdkunk3 at gmail.com> writes: > Spiller::Spill( LiveInterval *li, >                           SmallVectorImpl<LiveInterval*> &newIntervals, >                           const SmallVectorImpl<LiveInterval*> &spillIs ); > > has two reference vectors which contain a small list of Live > Intervals. What is the register allocator's job to do

Hi, Is there a way for me to collect statistics about the number of loads/stores added by the "linearscan" register allocator (just like can be done with the "local" allocator)? I still haven't grokked very well the interaction between RALinScan and Spiller... Should I add those two statistics to the spiller's class? Thanks, -- Silvio Ricardo Cordeiro --------------

On 8/7/07, David Greene <dag at cray.com> wrote: > > On Monday 06 August 2007 12:15, Anton Vayvod wrote: > > > Spill intervals must be precolored because they can't be spilled once > more. > > They are the shortest intervals precisely over each def/use of the > original > > interval. That is why they also have their weights set to #INF. > > Yes,

On Sun, Aug 15, 2010 at 10:04 PM, Jakob Stoklund Olesen <stoklund at 2pi.dk>wrote: > > On Aug 15, 2010, at 5:12 PM, Silvio Ricardo Cordeiro wrote: > > > Is there a way for me to collect statistics about the number of > loads/stores added by the "linearscan" register allocator (just like can be > done with the "local" allocator)? I still haven't

Hi, I'm working on the implementation of Extended Linear Scan register allocator as described by Sarkar & Bodik. One of the interesting features of their algorithm is the possibility to allocate different physical registers to different live-ranges of the same LiveInterval. Of course, it may require some glue code to be inserted in cases, where different physical regs were assigned to

Hi, It looks like LiveIntervals::addIntervalsForSpills does not update all of the LiveIntervals infos quite correctly. In particular, if a live interval L is defined by Reg<-Reg copy instructions whose srcReg is later spilled by the addIntervalsForSpills() function, its VNInfo information is not updated in a proper way. It still points to the same MachineInstr as before, even though the

Can someone explain the theory behind the spillers in VirtRegMap.cpp? It seems as though the spillers do triple duty: - Insert load/store operations and/or fold instructions as necessary to carry out spills - Rewrite the spilled virtual registers to use machine registers (mapping given by the caller in the VRM). - Rewrite machine code to change virtual registers to physical registers

On Feb 27, 2009, at 7:20 AM, Roman Levenstein wrote: > Hi, > > I'm working on the implementation of Extended Linear Scan register > allocator as described by Sarkar & Bodik. > One of the interesting features of their algorithm is the possibility > to allocate different physical registers to different live-ranges of > the same LiveInterval. Of course, it may require

On Wednesday 23 January 2008 02:01, Evan Cheng wrote: > On Jan 22, 2008, at 12:23 PM, David Greene wrote: > > Evan, > > > > Can you explain the basic mechanics of the live interval splitting > > code? > > Is it all in LiveIntervalAnalysis.cpp under addIntervalsForSpills > > and child > > routines? What is it trying to do? > > It's splitting

Hi Evan, Thanks a lot for your reply! 2009/2/27 Evan Cheng <evan.cheng at apple.com>: > > On Feb 27, 2009, at 7:20 AM, Roman Levenstein wrote: > >> Hi, >> >> I'm working on the implementation of Extended Linear Scan register >> allocator as described by Sarkar & Bodik. >> One of the interesting features of their algorithm is the possibility

Hi Evan, I have a few questions about current implementation of live intervals spilling, which is required for the implementation of Extended Linear Scan algorithm. --- Evan Cheng <evan.cheng at apple.com> wrote: > > On Wednesday 23 January 2008 02:01, Evan Cheng wrote: > >> On Jan 22, 2008, at 12:23 PM, David Greene wrote: > >>> Evan, > >>> >

On Monday 06 August 2007 12:15, Anton Vayvod wrote: > Spill intervals must be precolored because they can't be spilled once more. > They are the shortest intervals precisely over each def/use of the original > interval. That is why they also have their weights set to #INF. Yes, that's true. But I wonder if we shouldn't be smarter about which register we pick to color it.

On Jan 23, 2008, at 2:40 PM, David Greene <dag at cray.com> wrote: > On Wednesday 23 January 2008 02:01, Evan Cheng wrote: >> On Jan 22, 2008, at 12:23 PM, David Greene wrote: >>> Evan, >>> >>> Can you explain the basic mechanics of the live interval splitting >>> code? >>> Is it all in LiveIntervalAnalysis.cpp under

Evan, Can you explain the basic mechanics of the live interval splitting code? Is it all in LiveIntervalAnalysis.cpp under addIntervalsForSpills and child routines? What is it trying to do? Also, in the ancient subregister coalescing code, there used to be an update of the SSARegMap to point subregisters to the superregister they were coalesced to (IIRC). That has since gone away. I used to

Hi, Sorry for the delay. I was trying to wrap my head around some live interval analysis code and have forgotten about emails. :-) On Aug 6, 2007, at 9:20 AM, David Greene wrote: > Can someone explain the theory behind the spillers in VirtRegMap.cpp? > > It seems as though the spillers do triple duty: > > - Insert load/store operations and/or fold instructions as >

On Jan 22, 2008, at 12:23 PM, David Greene wrote: > Evan, > > Can you explain the basic mechanics of the live interval splitting > code? > Is it all in LiveIntervalAnalysis.cpp under addIntervalsForSpills > and child > routines? What is it trying to do? It's splitting live intervals that span multiple basic blocks. That is, when an interval is spilled, it

Hi, Roman, maybe I can try to answer this. I think that all boils down to having register to reload spilled values. Once a register is spilled, its live range is split into smaller pieces. These pieces most be contained into registers, and it is the task of the allocator to find these registers. Imagine that you have something like: Before After allocation: allocation: a

On Tuesday 07 August 2007 05:00, Anton Vayvod wrote: > > Yes, that's true. But I wonder if we shouldn't be smarter about which > > register we pick to color it. In Bill W's implementation, it was > > essentially random. What was your solution to this? > > I allocated spill intervals at the beginning of each iteration so all the > rest intervals (except of