similar to: [LLVMdev] What is "strong phi elimination"

Ask an ye shall receive. From the .cpp file: // = = =---------------------------------------------------------------------- ===// // // This pass eliminates machine instruction PHI nodes by inserting copy // instructions, using an intelligent copy-folding technique based on // dominator information. This is technique is derived from: // // Budimlic, et al. Fast copy coalescing and

Can you describe quickly (or point to references for the inclined) what this pass will do and what other stuff it might enable for LLVM? I'm just curious. -- Christopher Lamb -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20080324/46829334/attachment.html>

Ok, here are a few suggestions and comments: 1) LLVM has the capabilities to do everything that you are trying to re-implement. 2) Have you looked at the C backend? It recreates loops. It may not create "for" loops but you can hack on it to do that. 3) The way you are converting out of SSA is wrong. You will suffer from lost copies. You should look at using demotePHI(). see

Dear Prof.Adve and Bill, I deeply appreciate your comments and concerns. (Please forgive my late response. I've tried some more cases to make this issue) As Prof.Adve mentioned, I need to explain exactly what my problem is, but I have no good ability that I can explain it in this plain text space. For this reason, I made a .pdf file and linked it as follows:

I appreciate your suggestions, some follow-up questions though.... >1) LLVM has the capabilities to do everything that you are trying to >re-implement. >2) Have you looked at the C backend? It recreates loops. It may not >create "for" loops but you can hack on it to do that. I wonder if you mean "goto elimination technique" by Ana Maria Erosa (

Might I suggest the following tool for setting-up/maintaining the Visual Studio project files. It makes setting them up with all the right build options and include paths much, much easier. =) http://sourceforge.net/projects/xpj -- Christopher Lamb christopher.lamb at gmail.com On Mar 28, 2007, at 3:06 AM, Morten Ofstad wrote: > Seung Jae Lee wrote: >> Is there any special reason

It's not clear it offers any real benefits. The project files already exist. To use this, I would have to throw them away and create new XML files by hand. I would have to maintain them by hand also, whereas the project files are maintainable from within Visual Studio, i.e. via an integrated GUI interface. And to comment on supporting other targets: No reason it can't be done,

I don't want to drive this too off topic, but I should be clear that I wasn't suggesting that the LLVM project adopt XPJ as it's official config file format for Visual Studio. I have found it useful to use XPJ to generate the initial VS projects for a code base that doesn't already have VS projects. I also find it nice to be able to see all of the config options in a

Hello. My name is Seung Jae Lee. I'd like to ask you onething about converting to ARM assembly code. I saved the simplest C code shown in your LLVM webpage as 'hello.c' And I made 'hello.bc' by "$ llvm-gcc hello.c -o hello". In order to make ARM assembly code, I typed "llc -march=arm hello.bc -o hello.arm" But, I met this error. llc: ARMISelDAGToDAG.cpp:73:

Xi, I just installed VS2005 pro w/ SP1 for Win Vista. Thanks, Seung ---- Original message ---- >Date: Fri, 22 Feb 2008 12:36:43 +0800 >From: "Xi Wang" <xi.wang at gmail.com> >Subject: Re: [LLVMdev] Is there someone tried LLVM 2.1 on Visual Studio 2005? >To: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu> > >I'm sorry but did you

Hi, LLVMers. I am trying to restore the original HL code from LLVM IR (kinda reverse engineering). However, I have no good idea about how to handle PHI nodes. It is quite tricky for me to deal with the PHI nodes in LLVM IR in order to restore the original-like code. I read some reverse engineering thesis but they are a little bit old so don't handle SSA form. Could you shed some lights on

Hello, I am implementing a code transformation that would heavily benefit from the CodeGen/StrongPHIElimination pass, but on the two bytecode files I've tested it on so far llc segfaults on both. I see there have been no substantive changes to this code since the middle of last year. Could someone please tell me what the status of this pass is? Thank you. Marc -------------- next part

On Jun 8, 2012, at 9:02 AM, Hal Finkel <hfinkel at anl.gov> wrote: > On Fri, 8 Jun 2012 08:49:32 -0700 > Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote: >> When machine code is still in SSA form, there are restrictions on >> what can be done with physical registers, which by their nature can't >> be in SSA form. Lang and I have been trying to come up

On Fri, 08 Jun 2012 09:24:16 -0700 Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote: > > On Jun 8, 2012, at 9:02 AM, Hal Finkel <hfinkel at anl.gov> wrote: > > > On Fri, 8 Jun 2012 08:49:32 -0700 > > Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote: > > >> When machine code is still in SSA form, there are restrictions on > >> what can

On the document about writing an LLVM backend, I became to wonder what the 'virtual register' is in the following statement. "You also need to define register classes to contain these registers, such as the integer register class and floating-point register class, so that you can allocate virtual registers to instructions from these sets, and let the target-independent register

I'm the person who wrote it, and it's not really maintained, as we decided we wanted to go in a different direction long-term by having fewer passes making independent coalescing decisions rather than more. At the time I stopped working on it, it worked fine on x86 but caused problems with armv7 NEON code. If you file a PR with a test case, I am happy to take a quick look and try to fix

I've started using the strong PHI elimination pass, and it seems to work beautifully (producing much better placement of copy instructions) - though I'm seeing that it triggers an assert in debug+assert builds. The assertion is on line 1388 of RegisterCoalescer.C. Attached is the -debug output from the machine optimization part of the optimizer, for the simplest test case I could

I will try to make a standalone test case but the one that is failing uses a custom back end, so it's not really portable. So is the plan to have the strong PHI elimination behavior rolled into other passes? Andrew On 06/20/2012 06:54 PM, Cameron Zwarich wrote: > I'm the person who wrote it, and it's not really maintained, as we decided we wanted to go in a different direction

Is there any special reason only x86 code is implemented in win32 folder unlike lib\Target folder which contains codes for other architectures? Thank you. Seung Jae Lee

On Jun 7, 2012, at 10:54 PM, Hal Finkel wrote: > For example, sometimes LiveIntervals asserts with: > register: > %CTR8 > clang: /llvm-trunk/lib/CodeGen/LiveIntervalAnalysis.cpp:446: > void llvm::LiveInterval > s::handlePhysicalRegisterDef(llvm::MachineBasicBlock*, > llvm::MachineBasicBlock::iterator, llvm::SlotIndex, > llvm::MachineOperand&,