similar to: [LLVMdev] Still Another LiveInterval Question

On Thursday 17 January 2008 13:03, Evan Cheng wrote: > > So why does the live range extend throughout the entire basic block? > > > > %reg1055 doesn't appear anywhere else in the program so it shouldn't > > be > > live-in to the block. > > It could be a bug. Can you get me a test case? I'll see if I can whittle it down. It's a pretty huge

Post-phi-elimination, when can a LiveInterval VNInfo have a ~1 or ~0 def value? I've seen ~0 on intervals created for spills. Can it happen anywhere else? -Dave

On Jan 16, 2008, at 11:49 AM, David Greene wrote: > I had been assuming that give a LiveRange a, a.valno->def, if > valid, would be the same as a.start. But this is apparently not > always the case. For example: > > Predecessors according to CFG: 0x839d130 (#3) 0x8462780 (#35) > 308 %reg1051 = MOV64rr %reg1227<kill> > 312 %reg1052 = MOV64rr %reg1228<kill>

Hi, I insert a new machine basic block(MBB) before Greedy Register Allocation, after Simple Register Coalescing. But I encounter a fatal error "regalloc = ... not currently supported with -O0". I use command line with opt level O2, not O0. The probable reason of this error is that no LiveInterval information for newly MBB which is used by Register Allocation. And, LiveIntervals depend

I had been assuming that give a LiveRange a, a.valno->def, if valid, would be the same as a.start. But this is apparently not always the case. For example: Predecessors according to CFG: 0x839d130 (#3) 0x8462780 (#35) 308 %reg1051 = MOV64rr %reg1227<kill> 312 %reg1052 = MOV64rr %reg1228<kill> 316 %reg1053 = MOV64rr %reg1229<kill> 320 %reg1054 = MOV64rr

At 2014-01-01 04:36:21,"Andrew Trick" <atrick at apple.com> wrote: On Dec 31, 2013, at 3:52 AM, Haishan <hndxvon at 163.com> wrote: Hi, I insert a new machine basic block(MBB) before Greedy Register Allocation, after Simple Register Coalescing. But I encounter a fatal error "regalloc = ... not currently supported with -O0". I use command line with opt level

On Jan 17, 2008, at 1:49 PM, David Greene wrote: > Post-phi-elimination, when can a LiveInterval VNInfo have a ~1 or ~0 > def > value? I've seen ~0 on intervals created for spills. Can it happen > anywhere > else? They can be created during coalescing. Evan > > > -Dave >

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

On Wednesday 23 January 2008 02:01, Evan Cheng wrote: > > Can you explain the basic mechanics of the live interval splitting > > code? > It's splitting live intervals that span multiple basic blocks. That > is, when an interval is spilled, it introduce a single reload per > basic block and retarget all the uses to use the result of the single > reload. It does not

Hi all, As I work toward improving LLVM register allocation, I've come across the need to do some refactoring. Specifically, I would like to separate register coalescing from live interval analysis. Right now LiveIntervals handles both. The reason I want to separate them is that other types of register allocators might like to do coalescing differently (e.g. graph coloring does it by

Andy, Jacob, I have ported Hexagon MI scheduler to use the new scheduler infrastructure, but one of my tests triggers an assert in LiveInterval update. On the surface it does not make much sense to me, so I wonder if this is something you readily recognize, before I try to prop it open... The assert is: lib/CodeGen/LiveInterval.cpp:266: llvm::LiveRange*

I though LiveVariables may be invalidated by LiveIntervals, but it's declared not: void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const { AU.addPreserved<LiveVariables>(); AU.addRequired<LiveVariables>(); ... LiveInterval may coalesce virtual registers and remove identity moves instructions: bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {

I just ran into a problem here. I'm in SimpleRegisterCoalescing at the point where EXTRACT_SUBREG coalescing updates live ranges of aliased registers (around line 473 of SimpleRegisterCoalescing.cpp). There's a call to MergeValueInAsValue at line 50. MergeValueInAsValue has this code: void LiveInterval::MergeValueInAsValue(const LiveInterval &RHS,

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

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

On May 24, 2011, at 8:22 AM, Jonas Paulsson wrote: > Hi (Jakob), > > in reference to the prior message below, I have the following follow-up questions, as I also need a scheduling pass > prior to regalloc. I need to do this in order to set VLIW-flags, so that the RA is aware of several MI's > per cycle with a redefined LiveRange::overlap-function. On a multiple-issue cycle, a

Hi (Jakob), in reference to the prior message below, I have the following follow-up questions, as I also need a scheduling pass prior to regalloc. I need to do this in order to set VLIW-flags, so that the RA is aware of several MI's per cycle with a redefined LiveRange::overlap-function. On a multiple-issue cycle, a register that gets killed can be reused by another MI - these live ranges do

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

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

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