Running LLVM passes on Windows 10 gives no output in terminal?

问题

I've the sample pass code from LLVM.org:

#include "llvm/Pass.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

namespace {
    struct Hello : public FunctionPass {
        static char ID;
        Hello() : FunctionPass(ID) {}

        bool runOnFunction(Function &F) override {
            errs() << "Hello: ";
            errs().write_escaped(F.getName()) << '\n';
            return false;
        }
    }; // end of struct Hello
}  // end of anonymous namespace

char Hello::ID = 0;
static RegisterPass<Hello> X("hello", "Hello World Pass",
    false /* Only looks at CFG */,
    false /* Analysis Pass */);

The project builds fine and creates a SkeletonPass.dll.

When I execute the command:

C:\Users\nlykkei\Projects\llvm-pass-tutorial\build>opt -load skeleton\Debug\SkeletonPass.dll -hello foo.bc
opt: Unknown command line argument '-hello'.  Try: 'opt -help'
opt: Did you mean '-help'?

opt doesn't recognize -hello option, even thus everything works fine on Ubuntu 16.04.

In addition, if I execute:

clang -Xclang -load -Xclang skeleton\Debug\SkeletonPass.dll foo.bc

nothing is printed out on Visual Studio terminal (Native Tools Command Prompt x86). On Linux, the function names are printed nicely for the same bitcode file.

What can be the reason for my experience? I do exactly the same on Windows 10 as I do on Ubuntu, but very different results.

回答1:

Plugins are special beasts on Windows, because the latter does not support proper dynamic linking, so, your pass simply does not register itself in the PassRegistry. So you'd either need to compile all the LLVM into .dll or link your pass statically into opt / clang.

来源：https://stackoverflow.com/questions/41943353/running-llvm-passes-on-windows-10-gives-no-output-in-terminal

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