CODEWITHSUNDEEP
c++google-nativeclient
dsign
dsign

Reputation: 12700

Google pnacl: how to use the compiler/linker

I want to compile the hello_world driver using PNacl; the only problem is that I don't know which options to pass to the compiler.

To recap, the intention here is to go from .cc (C++ file) to .bc (some llvm format I don't know much about) and from there to .pexe.

Here is what I try:

 $ TC_PATH=/opt/nacl/pepper_26/toolchain/linux_x86_pnacl/host_x86_64/bin
 $ $(TC_PATH)/clang++ hello_world.cc -o hello_world.bc -I/opt/nacl/pepper_26/include

That much works. Now, the linking step fails:

 $ $(TC_PATH)/clang++ hello_world.bc -o hello_world
 /tmp/hello_world-l8UCWM.o: file not recognized: File format not recognized

If I do 

 $ $(TC_PATH)/clang++ hello_world.bc -o hello_world.pexe --verbose

I see that the driver is trying to link with my system linker, which of course won't work:

 ...
 "/usr/bin/ld" --eh-frame-hdr "
 ...

I've tried to dig some Makefiles using the thing,but so far I have only found this one and seems outdated. Which flags should I pass to the tools?

Upvotes: 1

Views: 1406

Answers (2)

dsign
dsign

Reputation: 12700

Ok, here is what I found. First the new Makefiles distributed with the SDK know exactly how to do the whole build.... I had not found those. Basically the clang++ invoked is $(SDK_ROOT)/toolchain/linux_x86_pnacl/newlib/bin/pnacl-clang++ instead of the one at host_x86_64.

Upvotes: 0

Derek
Derek

Reputation: 793

As you mentioned in your answer, the Makefiles in the SDK have support for invoking the pnacl compiler. All of the user-facing tools are in $(SDK_ROOT)/toolchain/linux_x86_pnacl/newlib/bin or its equivalent on Windows or Mac. When used like a normal compiler/linker driver pnacl-clang (and pnacl-clang++) will generate portable object files when compiling and portable executables (called .pexe files) when linking. You can use the pnacl-translate tool to translate the pexe to an x86-64, x86-32 or arm native client executable (nexe), which is usable in the same way as nexe files generated by nacl-gcc. There will also soon be support for direct use of pexe files for in-browser translation.

Upvotes: 3

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