Run LLVM pass with opt

问题:

I have just started to work with LLVM. I have wrote my own Hello pass, which worked fine.

Now I want to run opt with the stack protector pass, from StackProtector.cpp, but I am having trouble with that. When I look at the source code, it looks like I should use the flag -stack-protector:

INITIALIZE_PASS(StackProtector, "stack-protector", "Insert stack protectors", false, false) 

But this flag is not recognized by opt.

I am not sure which file to "load", as it is not as simple as loading my own LLVMHello.so file and I could not find a StackProtector.so file; I believe this might be the problem.

Edit:

I finally got an answer from LLVMDev. Actually, the pass I wanted to run is performed by llc, not opt. I could not find the option -stack-protector, though, with

llc --help 

because this option is hidden. If instead I do

llc --help-hidden 

it is shown that the pass is there, and I just need to run

llc -print-before=stack-protector <input> 

回答1:

First you add in your pass :

static RegisterPass<StackProtector> X("StackProtector", "Insert stack protectors", false, false); 

Second, in the terminal when you run the pass on a target file, after you run make, you have something like:

//home/YOURNAME/llvm/Release+Asserts/bin/opt -load //home/YOURNAME/llvm/Release+Asserts/lib/StackProtector.so -StackProtector //home/YOURNAME/llvm/tools/clang/woRKSPACE/Test.bc 

where Test.bc is your target code. Also, be aware: in your Makefile, don't forget to add LIBRARYNAME = StackProtector.

Also, be aware if the pass in not already registered (if so, you will get a segfault error)

文章来源: Run LLVM pass with opt