[llvm-dev] How to add NOP?

Volkan Keles via llvm-dev
Sun, 11 Oct 2015 18:15:32 -0000

Can you send the IR you are using?

Volkan

On Thu, Oct 8, 2015 at 6:28 AM Erdem Derebaşoğlu <
erdemderebasoglu at hotmail.com> wrote:

> Thanks. I enabled my pass. I have one resolved issue though:
> MachineMemOperand::getAddrSpace() always returns zero. How can I use it to
> distinguish private memory accesses?
>
> Erdem
>
> ------------------------------
> From: vlknkls at gmail.com
> Date: Sun, 4 Oct 2015 01:51:29 +0000
>
> Subject: Re: [llvm-dev] How to add NOP?
> To: erdemderebasoglu at hotmail.com; llvm-dev at lists.llvm.org
>
> Hi Erdem,
>
> Since it is a target specific pass, you should put your pass inside the
> target's folder (e.g. lib/Target/X86/) and declare your pass in
Target.h.
> Then you need to modify the target's TargetPassConfig (
> http://llvm.org/docs/doxygen/html/classllvm_1_1TargetPassConfig.html) to
> enable your pass.
>
> You can check out the existing MachineFunction passes
> (e.g. X86ExpandPseudo.cpp) to get an idea.
>
> Volkan
>
> On Sat, Oct 3, 2015 at 7:21 AM Erdem Derebaşoğlu <
> erdemderebasoglu at hotmail.com> wrote:
>
> I wrote the pass but when I try to build LLVM, I get this error:
> "/home/erdem/llvm/lib/CodeGen/CodeGen.cpp:80: error: undefined
reference
> to 'llvm::initializeNoopInserterPass(llvm::PassRegistry&).
> I need to modify Passes.h, InitializePasses.h, and Codegen.cpp files to
> register my pass, right?
>
> Erdem
> ------------------------------
> From: erdemderebasoglu at hotmail.com
> To: vlknkls at gmail.com; llvm-dev at lists.llvm.org
> Subject: RE: [llvm-dev] How to add NOP?
> Date: Thu, 17 Sep 2015 16:38:36 +0300
>
>
> This seems to be what I am looking for. That was very helpful. Thank you.
>
> Erdem
>
> ------------------------------
> From: vlknkls at gmail.com
> Date: Wed, 16 Sep 2015 16:25:29 +0000
> Subject: Re: [llvm-dev] How to add NOP?
> To: erdemderebasoglu at hotmail.com; llvm-dev at lists.llvm.org
>
> Use MachineInstr::memoperands() function to get memory operands then you
> can get the address space by using MachineMemOperand::getAddrSpace().
>
> Volkan
>
> On Tue, Sep 15, 2015 at 11:40 PM Erdem Derebaşoğlu <
> erdemderebasoglu at hotmail.com> wrote:
>
> Thanks for the response. How can I find out if an instruction uses a
> private memory access?
>
> Erdem
> ------------------------------
> From: vlknkls at gmail.com
> Date: Tue, 15 Sep 2015 14:38:16 +0000
> Subject: Re: [llvm-dev] How to add NOP?
> To: erdemderebasoglu at hotmail.com; llvm-dev at lists.llvm.org
>
>
> Hi Erdem,
>
> I would write a MachineFunction pass. You can check each load instruction
> to see if it is a private memory access and insert what you want by using
> BuildMI(...) function.
>
> Volkan
>
> On Tue, Sep 15, 2015 at 4:16 AM Erdem Derebaşoğlu <llvm-dev at
lists.llvm.org>
> wrote:
>
> I would like to convert a C file that uses OpenMP library to X86 code with
> a condition: I want to insert a NOP before each instruction that does a
> private memory access.
> I have written an optimization pass that inserts an inline assembly call
> (NOP) but it is applied at IR level, and I cannot determine where to insert
> it. How can I use LLVM to add NOPs accordingly?
>
> Thanks.
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> llvm-dev at lists.llvm.org
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>
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