[llvm-dev] Confused on how to do a machinefunction pass
fateme Hoseini via llvm-dev
llvm-dev at lists.llvm.org
Tue Nov 17 08:48:46 PST 2015
I noticed something else, I just made a change to my x86 wawanalyzer and
make it again. And I can't see the change in my output. So the problem is
with all my targets.
After I ran my first sunctionpass in x86, I needed to crosscopmpile LLVM so
I ran the following instructions a couple of days ago:
$ cd <llvm_build_dir>
$ <PATH_TO_SOURCE>/configure --enable-targets=arm --disable-optimized
--prefix=/usr/local/llvm-arm --target=armv7a-unknown-linux-gnueabi
$ make && sudo make install
Does my problem have to do something with these instructions?
On Tue, Nov 17, 2015 at 11:29 AM, fateme Hoseini <hoseini.f at gmail.com>
wrote:
> Yes, I have done exactly the same. The wawanalyzer is the same. I changed
> ARM.h and ARMTargetMachine.cpp in the tager/arm folder. then I make
> tool/llc and lib folder.
>
> On Tue, Nov 17, 2015 at 10:55 AM, John Criswell <jtcriswel at gmail.com>
> wrote:
>
>> On 11/17/15 12:16 AM, fateme Hoseini via llvm-dev wrote:
>>
>> Hi,
>> So, I run my pass in X86 target with llc command and it printed out
>> "hello****". Now I am trying to do the same pass for ARM target. So I did
>> exactly what I did for X86 as mentioned in my previous posts. When I run
>> the following command:
>>
>>
>> Have you modified the ARM code generator to run your pass (the same way
>> that you modified the X86 code generator to run your pass)?
>>
>> Each backend has code that configures the set of MachineFunctionPass'es
>> to run when that code generator is used. For each backend, you must modify
>> that code to run your MachineFunctionPass.
>>
>> Regards,
>>
>> John Criswell
>>
>>
>> llc -march=arm test.ll -o test
>> nothing prints out. I did the same for MIPS target too and I got no
>> result. Can anyone tell me what I'm doing wrong. Is there any difference
>> between writing machinefunction passes in x86 and other targets?
>> Thank you,
>> Fami
>>
>> On Fri, Nov 6, 2015 at 10:56 AM, fateme Hoseini <hoseini.f at gmail.com>
>> wrote:
>>
>>> Hi
>>> So I m trying to write my first backend pass. I created a file in
>>> target\x86\wawanalyzer.cpp based on hexagonHardwareLoops.cpp file. Now it's
>>> just a simple file that prints hello to the output. I have attached the
>>> file to this post.
>>>
>>> Then I did the following:
>>>
>>> 1. add "FunctionPass *createwawAnalyzer();" line to x86.h
>>> 2. add file name to CMakelist.txt.
>>> 3. This is going to run after postRAscheduler and before code emission
>>> so I changed the x86TrgetMachine.cpp as follow:
>>> void X86PassConfig::addPreEmitPass() {
>>> /////////////add mypass here///////
>>> addPass(createwawAnalyzer());
>>> //////////////////////////////////
>>> if (getOptLevel() != CodeGenOpt::None)
>>> addPass(createExecutionDependencyFixPass(&X86::VR128RegClass));
>>>
>>> if (UseVZeroUpper)
>>> addPass(createX86IssueVZeroUpperPass());
>>>
>>> if (getOptLevel() != CodeGenOpt::None) {
>>> addPass(createX86PadShortFunctions());
>>> addPass(createX86FixupLEAs());
>>> }
>>> then I run make on mypass and remake llvm3.7\lib and llvm3.7\tool\llc.
>>> but when I run llc -help it doesn't show my pass. Did I miss some steps
>>> or did something wrong? What's the correct way to run the pass with llc
>>> command?
>>>
>>> I appreciate any help,
>>> Regards
>>> Fami
>>>
>>> On Wed, Nov 4, 2015 at 1:02 PM, fateme Hoseini < <hoseini.f at gmail.com>
>>> hoseini.f at gmail.com> wrote:
>>>
>>>> Thank you so much.
>>>> That helped alot.
>>>>
>>>> Fami
>>>>
>>>> On Wed, Nov 4, 2015 at 9:40 AM, John Criswell < <jtcriswel at gmail.com>
>>>> jtcriswel at gmail.com> wrote:
>>>>
>>>>> On 11/3/15 7:54 PM, fateme Hoseini wrote:
>>>>>
>>>>> Dear John,
>>>>> Thank you so much for your help. I looked at those documents. Could
>>>>> you kindly answer the following questions:
>>>>>
>>>>> Does it mean that I have to make my own backend target in order to
>>>>> write a machine pass even if I want to run a simple machinefunction pass?
>>>>> for example,if I want my pass to get MIPS instructions as an input, I have
>>>>> to copy all the files from mips target and add a file to it which
>>>>> implements my pass. and there should be a way to connect the pass to other
>>>>> MIPS backend files?
>>>>>
>>>>>
>>>>> No, you do not need to create a new backend. All you need to do is to
>>>>> add your pass to the list of passes that are run when the MIPS code
>>>>> generator is used.
>>>>>
>>>>> In LLVM 3.3, there was a file in the X86 backend that had code to
>>>>> schedule all the MachineFunctionPass'es when the X86 code generator was
>>>>> used. That was in lib/Target/X86/X86TargetMachine.cpp. You can probably
>>>>> find a similar file for LLVM 3.7 for the MIPS backend.
>>>>>
>>>>> So, to summarize, you'll add your source file to the MIPS backend, add
>>>>> a line somewhere to run your pass when the MIPS code generator is used, and
>>>>> then recompile llvm/lib and llvm/tools/llc.
>>>>>
>>>>>
>>>>>
>>>>> As a result, is the way that I described in my first post completely
>>>>> wrong because I cannot run a stand alone machine function pass like a
>>>>> frontend function pass?
>>>>>
>>>>>
>>>>> As far as I know, there is no way to load a MachineFunctionPass and
>>>>> run it using llc, opt, or clang. I believe you need to compile it into the
>>>>> MIPS backend code.
>>>>>
>>>>>
>>>>> Also another question, I'm a PhD student and I'm completely new to the
>>>>> llvm backend process. I want to estimate my project time. How long
>>>>> approximately do you think it will take to be get familiar with backend and
>>>>> be able to write machinefunction pass? for further steps I have to
>>>>> implement a register allocation algorithm.
>>>>>
>>>>>
>>>>> It's difficult to estimate (especially since I haven't implemented
>>>>> anything as complicated as a register allocator). Your profiling pass may
>>>>> take anywhere from 1 week to 1 month depending on how complicated it is. I
>>>>> think a register allocator would take anywhere from 1 month up to 6 months
>>>>> depending on how robust you need it to be, but since I've never built one,
>>>>> I can't say for certain.
>>>>>
>>>>> Regards,
>>>>>
>>>>> John Criswell
>>>>>
>>>>>
>>>>>
>>>>> Regards,
>>>>> Fami
>>>>>
>>>>>
>>>>> On Tue, Nov 3, 2015 at 3:52 PM, John Criswell < <jtcriswel at gmail.com>
>>>>> jtcriswel at gmail.com> wrote:
>>>>>
>>>>>> Dear Fami,
>>>>>>
>>>>>> A MachineFunctionPass is run by the code generator, so you can only
>>>>>> use it in tools like llc, clang, and libLTO. The opt program only
>>>>>> manipulates LLVM IR and therefore does not run MachineFunctionPass'es.
>>>>>>
>>>>>> Regarding documentation, have you looked at the following?
>>>>>>
>>>>>> <http://llvm.org/docs/WritingAnLLVMBackend.html>
>>>>>> http://llvm.org/docs/WritingAnLLVMBackend.html
>>>>>> <http://llvm.org/docs/CodeGenerator.html>
>>>>>> http://llvm.org/docs/CodeGenerator.html
>>>>>> <http://llvm.org/docs/MIRLangRef.html>
>>>>>> http://llvm.org/docs/MIRLangRef.html
>>>>>>
>>>>>> Regards,
>>>>>>
>>>>>> John Criswell
>>>>>>
>>>>>>
>>>>>> On 11/3/15 3:47 PM, fateme Hoseini via llvm-dev wrote:
>>>>>>
>>>>>> Hi everyone,
>>>>>> I am a LLVM newbie. I need to write a machinefunction pass for my
>>>>>> project. This should be an analyzer of the machine code to do some
>>>>>> profiling. I have written a couple of function passes for front end, but it
>>>>>> seems they are completely different. I searched through forum and llvm
>>>>>> documents, but couldn't find anything useful or questions were unanswered.
>>>>>> Can anyone reference me to any material on how to do that or help me with
>>>>>> my roblem.
>>>>>>
>>>>>> I have created a folder in: lib/Transform and put my pass in it.
>>>>>> I am writing a simple pass like this:
>>>>>>
>>>>>> using namespace llvm;
>>>>>>
>>>>>> namespace {
>>>>>> struct analyzer : public MachineFunctionPass {
>>>>>> static char ID;
>>>>>> analyzer() : MachineFunctionPass(ID) {}
>>>>>> virtual bool runOnMachineFunction(MachineFunction &MF) {
>>>>>> errs() << "hello " ;
>>>>>> return false;
>>>>>> }
>>>>>> };
>>>>>> }
>>>>>> char analyzer::ID = 0;
>>>>>> static RegisterPass<analyzer> X("analyzer", "WAW analyzer");
>>>>>>
>>>>>> I make it successfully. But when I load it for my test code I get
>>>>>> this error:
>>>>>>
>>>>>> Pass 'WAW analyzer' is not initialized.
>>>>>> Verify if there is a pass dependency cycle.
>>>>>> Required Passes:
>>>>>> opt: /llvm/llvm-3.7/lib/IR/LegacyPassManager.cpp:635: void
>>>>>> llvm::PMTopLevelManager::schedulePass(llvm::Pass*): Assertion `PI &&
>>>>>> "Expected required passes to be initialized"' failed.
>>>>>> .....
>>>>>>
>>>>>> I don't know how to solve it? Do we have to run machinefunction
>>>>>> passes with OPT command? Is this correct to put machinefunction pass in an
>>>>>> external folder or do we have to change some llvm built-in files?
>>>>>>
>>>>>> Regards,
>>>>>> Fami
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> LLVM Developers mailing listllvm-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> John Criswell
>>>>>> Assistant Professor
>>>>>> Department of Computer Science, University of Rochesterhttp://www.cs.rochester.edu/u/criswell
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> John Criswell
>>>>> Assistant Professor
>>>>> Department of Computer Science, University of Rochesterhttp://www.cs.rochester.edu/u/criswell
>>>>>
>>>>>
>>>>
>>>
>>
>>
>> _______________________________________________
>> LLVM Developers mailing listllvm-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
>>
>> --
>> John Criswell
>> Assistant Professor
>> Department of Computer Science, University of Rochesterhttp://www.cs.rochester.edu/u/criswell
>>
>>
>
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