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Matthew O'Connor

2014-Apr-24 23:38 UTC

[LLVMdev] writing an alias analysis pass?

Hi,

I'm attempting to do some alias analysis & other memory inspection.
I've
written a pointless AliasAnalysis pass (that says everything must alias) to
attempt to verify that my pass is getting picked up & run by opt.

I run opt with: opt -load ~/Applications/llvm/lib/MustAA.so -must-aa
-aa-eval -debug < trace0.ll

I see my pass being initialized, but never being called (I see only may
alias results).

Any ideas as to what to do to debug this? Or what I'm missing? I've read
through http://llvm.org/docs/AliasAnalysis.html and don't see anything that
I'm missing.

Thanks,
Matthew

P.S. Here's the full source code of my pass:

#define DEBUG_TYPE "must-aa"
#include "llvm/Pass.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Debug.h"
using namespace llvm;

namespace {
struct EverythingMustAlias : public ImmutablePass, public AliasAnalysis {
  static char ID;
  EverythingMustAlias() : ImmutablePass(ID) {}

  virtual void initializePass() {
    DEBUG(dbgs() << "Initializing everything-must-alias\n");
    InitializeAliasAnalysis(this);
  }

  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
    AliasAnalysis::getAnalysisUsage(AU);
    AU.setPreservesAll();
  }

  virtual AliasResult alias(const Location &LocA, const Location &LocB)
{
    DEBUG(dbgs() << "Everything must alias!\n");
    return AliasAnalysis::MustAlias;
  }
};
}

namespace llvm {
void initializeEverythingMustAliasPass(PassRegistry &Registry);
}

char EverythingMustAlias::ID = 0;
static RegisterPass<EverythingMustAlias> A("must-aa",
"Everything must
alias");
INITIALIZE_AG_PASS(EverythingMustAlias, AliasAnalysis, "must-aa",
                   "Everything must alias", false, true, false)
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Nick Lewycky

2014-Apr-26 22:59 UTC

head link

[LLVMdev] writing an alias analysis pass?

Matthew O'Connor wrote:> Hi,
>
> I'm attempting to do some alias analysis & other memory inspection.
I've
> written a pointless AliasAnalysis pass (that says everything must alias)
> to attempt to verify that my pass is getting picked up & run by opt.
>
> I run opt with: opt -load ~/Applications/llvm/lib/MustAA.so -must-aa
> -aa-eval -debug < trace0.ll
>
> I see my pass being initialized, but never being called (I see only may
> alias results).
>
> Any ideas as to what to do to debug this? Or what I'm missing? I've
read
> through http://llvm.org/docs/AliasAnalysis.html and don't see anything
> that I'm missing.
>
> Thanks,
> Matthew
>
> P.S. Here's the full source code of my pass:
>
> #define DEBUG_TYPE "must-aa"
> #include "llvm/Pass.h"
> #include "llvm/Analysis/AliasAnalysis.h"
> #include "llvm/Support/raw_ostream.h"
> #include "llvm/Support/Debug.h"
> using namespace llvm;
>
> namespace {
> struct EverythingMustAlias : public ImmutablePass, public AliasAnalysis {
Because you have multiple inheritance on a Pass, you'll need this:

     /// getAdjustedAnalysisPointer - This method is used when a pass 
implements
     /// an analysis interface through multiple inheritance.  If needed, it
     /// should override this to adjust the this pointer as needed for the
     /// specified pass info.
     void *getAdjustedAnalysisPointer(const void *ID) override {
       if (ID == &AliasAnalysis::ID)
         return (AliasAnalysis*)this;
       return this;
     }

There may be another issue beyond that, I haven't tried it.

Nick
>    static char ID;
>    EverythingMustAlias() : ImmutablePass(ID) {}
>
>    virtual void initializePass() {
>      DEBUG(dbgs() << "Initializing
everything-must-alias\n");
>      InitializeAliasAnalysis(this);
>    }
>
>    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
>      AliasAnalysis::getAnalysisUsage(AU);
>      AU.setPreservesAll();
>    }
>
>    virtual AliasResult alias(const Location &LocA, const Location
&LocB) {
>      DEBUG(dbgs() << "Everything must alias!\n");
>      return AliasAnalysis::MustAlias;
>    }
> };
> }
>
> namespace llvm {
> void initializeEverythingMustAliasPass(PassRegistry &Registry);
> }
>
> char EverythingMustAlias::ID = 0;
> static RegisterPass<EverythingMustAlias> A("must-aa",
"Everything must
> alias");
> INITIALIZE_AG_PASS(EverythingMustAlias, AliasAnalysis, "must-aa",
> "Everything must alias", false, true, false)
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

Matthew O'Connor

2014-Apr-28 17:08 UTC

head link

[LLVMdev] writing an alias analysis pass?

On Sat, Apr 26, 2014 at 4:59 PM, Nick Lewycky <nicholas at mxc.ca> wrote:
> Matthew O'Connor wrote:
>
>> Hi,
>>
>> I'm attempting to do some alias analysis & other memory
inspection. I've
>> written a pointless AliasAnalysis pass (that says everything must
alias)
>> to attempt to verify that my pass is getting picked up & run by
opt.
>>
>> I run opt with: opt -load ~/Applications/llvm/lib/MustAA.so -must-aa
>> -aa-eval -debug < trace0.ll
>>
>> I see my pass being initialized, but never being called (I see only may
>> alias results).
>>
>> Any ideas as to what to do to debug this? Or what I'm missing?
I've read
>> through http://llvm.org/docs/AliasAnalysis.html and don't see
anything
>> that I'm missing.
>>
>> Thanks,
>> Matthew
>>
>> P.S. Here's the full source code of my pass:
>>
>> #define DEBUG_TYPE "must-aa"
>> #include "llvm/Pass.h"
>> #include "llvm/Analysis/AliasAnalysis.h"
>> #include "llvm/Support/raw_ostream.h"
>> #include "llvm/Support/Debug.h"
>> using namespace llvm;
>>
>> namespace {
>> struct EverythingMustAlias : public ImmutablePass, public AliasAnalysis
{
>>
>
> Because you have multiple inheritance on a Pass, you'll need this:
>
>     /// getAdjustedAnalysisPointer - This method is used when a pass
> implements
>     /// an analysis interface through multiple inheritance.  If needed, it
>     /// should override this to adjust the this pointer as needed for the
>     /// specified pass info.
>     void *getAdjustedAnalysisPointer(const void *ID) override {
>       if (ID == &AliasAnalysis::ID)
>         return (AliasAnalysis*)this;
>       return this;
>     }
>
> There may be another issue beyond that, I haven't tried it.
>
> Nick
>
I overrode Pass's member function:
    virtual void *getAdjustedAnalysisPointer(AnalysisID ID);

I'm not seeing getAdjustedAnalysisPointer being called.

Any other ideas?

>
>     static char ID;
>>    EverythingMustAlias() : ImmutablePass(ID) {}
>>
>>    virtual void initializePass() {
>>      DEBUG(dbgs() << "Initializing
everything-must-alias\n");
>>      InitializeAliasAnalysis(this);
>>    }
>>
>>    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
>>      AliasAnalysis::getAnalysisUsage(AU);
>>      AU.setPreservesAll();
>>    }
>>
>>    virtual AliasResult alias(const Location &LocA, const Location
&LocB) {
>>      DEBUG(dbgs() << "Everything must alias!\n");
>>      return AliasAnalysis::MustAlias;
>>    }
>> };
>> }
>>
>> namespace llvm {
>> void initializeEverythingMustAliasPass(PassRegistry &Registry);
>> }
>>
>> char EverythingMustAlias::ID = 0;
>> static RegisterPass<EverythingMustAlias> A("must-aa",
"Everything must
>> alias");
>> INITIALIZE_AG_PASS(EverythingMustAlias, AliasAnalysis,
"must-aa",
>> "Everything must alias", false, true, false)
>>
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>
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Jingyue Wu

2014-Apr-29 03:43 UTC

head link

[LLVMdev] writing an alias analysis pass?

On Thu, Apr 24, 2014 at 4:38 PM, Matthew O'Connor
<thegreendragon at gmail.com>wrote:
> Hi,
>
> I'm attempting to do some alias analysis & other memory inspection.
I've
> written a pointless AliasAnalysis pass (that says everything must alias) to
> attempt to verify that my pass is getting picked up & run by opt.
>
> I run opt with: opt -load ~/Applications/llvm/lib/MustAA.so -must-aa
> -aa-eval -debug < trace0.ll
>
> I see my pass being initialized, but never being called (I see only may
> alias results).
>
> Any ideas as to what to do to debug this? Or what I'm missing? I've
read
> through http://llvm.org/docs/AliasAnalysis.html and don't see anything
> that I'm missing.
>
> Thanks,
> Matthew
>
> P.S. Here's the full source code of my pass:
>
> #define DEBUG_TYPE "must-aa"
> #include "llvm/Pass.h"
> #include "llvm/Analysis/AliasAnalysis.h"
> #include "llvm/Support/raw_ostream.h"
> #include "llvm/Support/Debug.h"
> using namespace llvm;
>
> namespace {
> struct EverythingMustAlias : public ImmutablePass, public AliasAnalysis {
>   static char ID;
>   EverythingMustAlias() : ImmutablePass(ID) {}
>
>   virtual void initializePass() {
>     DEBUG(dbgs() << "Initializing
everything-must-alias\n");
>     InitializeAliasAnalysis(this);
>   }
>
>   virtual void getAnalysisUsage(AnalysisUsage &AU) const {
>     AliasAnalysis::getAnalysisUsage(AU);
>     AU.setPreservesAll();
>   }
>
>   virtual AliasResult alias(const Location &LocA, const Location
&LocB) {
>     DEBUG(dbgs() << "Everything must alias!\n");
>     return AliasAnalysis::MustAlias;
>   }
> };
> }
>
> namespace llvm {
> void initializeEverythingMustAliasPass(PassRegistry &Registry);
> }
>
> char EverythingMustAlias::ID = 0;
> static RegisterPass<EverythingMustAlias> A("must-aa",
"Everything must
> alias");
>
static RegisterPass<EverythingMustAlias> A("must-aa",
"Everything must
alias", false, true);

Can you try this?

> INITIALIZE_AG_PASS(EverythingMustAlias, AliasAnalysis, "must-aa",
>                    "Everything must alias", false, true, false)
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Chen Li

2014-Apr-29 04:46 UTC

head link

[LLVMdev] writing an alias analysis pass?

Hi Matthew,

Did you add your alias analysis pass initializeEverythingMustAliasPass() into
llvm::initializeAnalysis(PassRegistry &Registry) {} ?
This will initialize it linked into the Analysis library.

thanks,
chen
 
On Apr 28, 2014, at 8:43 PM, Jingyue Wu <jingyue at google.com> wrote:
> 
> 
> 
> On Thu, Apr 24, 2014 at 4:38 PM, Matthew O'Connor <thegreendragon at
gmail.com> wrote:
> Hi,
> 
> I'm attempting to do some alias analysis & other memory inspection.
I've written a pointless AliasAnalysis pass (that says everything must
alias) to attempt to verify that my pass is getting picked up & run by opt.
> 
> I run opt with: opt -load ~/Applications/llvm/lib/MustAA.so -must-aa
-aa-eval -debug < trace0.ll
> 
> I see my pass being initialized, but never being called (I see only may
alias results).
> 
> Any ideas as to what to do to debug this? Or what I'm missing? I've
read through http://llvm.org/docs/AliasAnalysis.html and don't see anything
that I'm missing.
> 
> Thanks,
> Matthew
> 
> P.S. Here's the full source code of my pass:
> 
> #define DEBUG_TYPE "must-aa"
> #include "llvm/Pass.h"
> #include "llvm/Analysis/AliasAnalysis.h"
> #include "llvm/Support/raw_ostream.h"
> #include "llvm/Support/Debug.h"
> using namespace llvm;
> 
> namespace {
> struct EverythingMustAlias : public ImmutablePass, public AliasAnalysis {
>   static char ID;
>   EverythingMustAlias() : ImmutablePass(ID) {}
> 
>   virtual void initializePass() {
>     DEBUG(dbgs() << "Initializing
everything-must-alias\n");
>     InitializeAliasAnalysis(this);
>   }
> 
>   virtual void getAnalysisUsage(AnalysisUsage &AU) const {
>     AliasAnalysis::getAnalysisUsage(AU);
>     AU.setPreservesAll();
>   }
> 
>   virtual AliasResult alias(const Location &LocA, const Location
&LocB) {
>     DEBUG(dbgs() << "Everything must alias!\n");
>     return AliasAnalysis::MustAlias;
>   }
> };
> }
> 
> namespace llvm {
> void initializeEverythingMustAliasPass(PassRegistry &Registry);
> }
> 
> char EverythingMustAlias::ID = 0;
> static RegisterPass<EverythingMustAlias> A("must-aa",
"Everything must alias");
>  
> static RegisterPass<EverythingMustAlias> A("must-aa",
"Everything must alias", false, true);
> 
> Can you try this? 
>  
> INITIALIZE_AG_PASS(EverythingMustAlias, AliasAnalysis, "must-aa",
>                    "Everything must alias", false, true, false)
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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