similar to: [LLVMdev] Debugger for Register Allocation

On Aug 17, 2007, at 4:17 PM, Fernando Magno Quintao Pereira wrote: > > Hi guys, > > I have been using a debugger for my register allocator. The > debugger > happened to be very useful at catching register assignment errors. > I've > put the debugger on-line, if anyone who is working with register > allocation wants to use. The debugger itself has nothing to

On 11/23/07, Fernando Magno Quintao Pereira <fernando at cs.ucla.edu> wrote: > > > Hi, Sanjiv, > > those passes operate on the whole machine function. Each machine > function contains many basic blocks. If a program has many functions, the > register allocator will be called as many times, i.e it does not do > interprocedural allocation. > > best, > >

Thank you Chris. I will try to implement the TwoAddress pass to run on machine code. Why it has not been originally implemented to run on machine code? Is there anything that makes it troublesome after RA has been performed? Could you tell me if the transformations below are correct? 1) a := b op c --> a := b --> a := b a := a op c a

Hi, again, I think you can do it in the same way that the other allocators have been coded, i.e extend RA, register the pass and so forth. I am not sure about the best way to pass information among a run of RegAlloc to the other, maybe the other guys in the list could suggest something. Yet, you can always dump it into a file, and read it again, everytime it is necessary. Remember that

Thanks again. One more question here: Since the regalloc works once per function, do I stil have access to the Call graph? Just saving information between regalloc passes for different functions may not be enough for my case. I will need to maintain the regalloc info of various passes in the call graph order. Anyways thanks for your inputs. I will get back if I need to learn more. Sanjiv On Nov

Fernando Magno Quintao Pereira wrote: >> I'm not sure about one thing: you assign stack slot to each new register you >> replace the spilled one with. And then you need to allocate physical >> registers to them. Is it possible to assign physical register to the virtual >> one which has a stack slot already? >> > > Yes. The stack slot is the place where the

Dear guys, I am in need of more of your help. I'm implementing a register allocator, and I am having problems to make it produce correct code. Consider this program here: int main(int argc, char ** argv) { int i, j, sum; i = argv[0][0]; j = argv[0][1]; sum = (i + j) * j; printf("Sum = %d\n", sum); } that maps to this llvm bytecode: entry (0xa785590, LLVM

On Mon, 26 Jun 2006, Fernando Magno Quintao Pereira wrote: > The problem is that, after the TwoAddressInstructionPass is used, the > code is no longer in SSA form, and my register allocator rely on > some SSA properties. I am using the Spiller in VirtRegMap.* to generate > the code, but the incorrect mapping still happens when I invoke the > setReg() method directly on machine

Hi Fernando, --- Fernando Magno Quintao Pereira <fernando at cs.ucla.edu> wrote: > > Hi, Roman, > > maybe I can try to answer this. I think that all boils down to > having register to reload spilled values. Ok. That I can follow. > Once a register is spilled, its live range is split into smaller > pieces. These pieces most be contained into registers, and

I'm not sure about one thing: you assign stack slot to each new register you replace the spilled one with. And then you need to allocate physical registers to them. Is it possible to assign physical register to the virtual one which has a stack slot already? On 8/21/06, Fernando Magno Quintao Pereira <fernando at cs.ucla.edu> wrote: > > > > So what addIntervalsToSpills

> I'm not sure about one thing: you assign stack slot to each new register you > replace the spilled one with. And then you need to allocate physical > registers to them. Is it possible to assign physical register to the virtual > one which has a stack slot already? > Yes. The stack slot is the place where the value will be stored in memory, but, when that value is effectively

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

>> And I have a quite fast algo that I believe is simpler than [Budimlic02] >> and I can share it with you :) > > Do you have a paper on this? I'd be interested in seeing it. > Yes, I have a tech report on this page: http://compilers/fernando/projects/soc/ and I have submitted a paper to SAS, and now I am waiting for the review. The coalescing algorithm is described in

> And I have a quite fast algo that I believe is simpler than [Budimlic02] > and I can share it with you :) Do you have a paper on this? I'd be interested in seeing it. -Tanya > > Fernando > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >

As far as I understand , the regalloc passes provided operate on basic block level? Is there anything that operate on the whole Module? Thx, Sanjiv -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20071122/0b24c954/attachment.html>

Hi, Sanjiv, those passes operate on the whole machine function. Each machine function contains many basic blocks. If a program has many functions, the register allocator will be called as many times, i.e it does not do interprocedural allocation. best, Fernando > As far as I understand , the regalloc passes provided operate on basic block > level? > Is there anything that

On 8/7/06, Chris Lattner <sabre at nondot.org> wrote: > > On Sun, 6 Aug 2006, Anton Vayvod wrote: > > I'm developing a register allocator that works iteratively. It spills > some > > virtual registers on each iteration until all the rest have physical > ones > > assigned. > > Take a look at the linear scan allocator. It is also iterative: it uses >

Dear guys, what is the best way to implement a swap of floating point registers in X86? For the integer registers, I am using xchg. Is there a similar instruction for floating point? My function to insert swaps is like: void X86RegisterInfo::swapRegs( MachineBasicBlock & mbb, MachineBasicBlock::iterator mi, unsigned r1, unsigned r2, const TargetRegisterClass

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, > >>> >

Guys, I need advice in how to handle a problem. The problem: In X86_64, pointers are 64-bit variables, and are stored into 64-bit registers. However, some pointers are small enough that they can be represented as 32-bit values. Is there some way, in LLVM, to recognize which pointers can be stored into 32-bit registers, and so modify their class accordingly? Any ideas or hints would