[llvm-dev] llvm pass is very slow

[Muhui Jiang via llvm-dev]

Hi John

Thanks for your suggestions. I forget to send the last response to llvm
community.

I will try your idea and it would be great if you can give me some comments
on the code below, many thanks

namespace {
// Hello - The first implementation, without getAnalysisUsage.
struct Hello : public FunctionPass {
static char ID; // Pass identification, replacement for typeid
Hello() : FunctionPass(ID) {}
std::error_code error;
enum sys::fs::OpenFlags of;
bool runOnFunction(Function &F) override {

raw_fd_ostream file(StringRef(F.getName().str()+".info"), error, of);
for (BasicBlock &BB : F){
std::string bb_name = BB.getName().str();
BlockAddress* bb_addr = BlockAddress::get(&BB);
file <<"This is the Block Node"<< bb_addr<<"\n";
for(Instruction &I: BB){
int split = 0;
int indirect_call = 0;
std:: string split_func = "";
if(const SwitchInst* switchinst = dyn_cast<SwitchInst>(&I)){
file<<"SwitchInst";
}
DILocation* Loc = I.getDebugLoc().get();
if(Loc){
unsigned Line = Loc->getLine();
unsigned Column = Loc->getColumn();
StringRef File = Loc->getFilename();
StringRef Dir = Loc->getDirectory();
if (indirect_call){file<<"|IndirectCall";}
file <<"|Instruction:|Source Line:"<< Line<<"|Column:"<<Column<<"|File:"<<
File;
file <<"|IR:"<<I<<"\n";
}
}
for (BasicBlock * SuccBB : successors(&BB)){
BlockAddress * succBB_addr = BlockAddress::get(SuccBB);
file <<bb_addr<<"-->"<<succBB_addr<<"\n";
}
file<<"==============\n";
}
file.close();
return false;
}
};
}

char Hello::ID = 0;
static RegisterPass<Hello> X("hello", "Hello World Pass");


I run it using the command "opt -load /path/to/LLVMHello.so -hello
target.bc".

If you need the bitcode file that takes me so much time, please tell me.

Regards
Muhui

John Criswell <jtcriswel at gmail.com>于2018年7月16日 周一下午11:30写道：

> On 7/14/18 9:21 PM, Muhui Jiang via llvm-dev wrote:
>
> Hi
>
> I write a LLVM function pass. The pass will loop the basicblock in the
> function, check the instruction's type with dyn_cast<switchinst>, print the
> instruction and the basicblock's successors. I think it is not very complex.
>
> My bitcode file is about 30M. My CPU is i7-7700(3.6GHz). It has been
> running for 60 hours but it is still running. I am not sure whether this is
> a normal behavior. If so, any options or suggestions to help me speed up
> the analysis. Many Thanks
>
>
> The first thing you should check is whether you've written the loop
> properly.  It's possible that you've somehow written an infinite loop.  If
> your pass is adding instructions, be careful that you're not invalidating
> the iterator that you're using to loop over the instructions.  That might
> cause a non-obvious error.
>
> The second thing to consider is to use the InstVisitor class instead of
> writing a loop.  Look at InstVisitor.h in the LLVM source code; it has
> comments that show you how to use it.  In a nutshell, your FunctionPass
> will be a subclass of InstVisitor.  You then implement the
> visitSwitchInst() method and call visit() on the function in runOnFunction,
> and you're done.
>
> http://llvm.org/doxygen/classllvm_1_1InstVisitor.html
>
> Regards,
>
> John Criswell
>
>
>
> Regards
> Muhui
>
>
> _______________________________________________
> 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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