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default to obfuscation #4

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alexcohn
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This is not a real Pull Request it has not been tested thoroughly enough, and may not be fit for everybody. I open it now as a way of discussion: what should be the right approach to resolve the limitation that was introduced by LLVM relatively recently.

This is the easiest way I found to work around -mllvm is not supported with -fembed-bitcode.

This didn't happen before, on llvm-9.0.1 (but that was not compatible with the modern Xcode).

I tried to simply remove the error check for mllvm from clang/lib/Driver/ToolChains/Clang.cpp, but this resulted in lots of suspicious warnings while compiling my iOS code, so I did not follow this path. Maybe, I did something wrong?

@ghost
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ghost commented Dec 19, 2021

@heroims please open the issue page

@heroims heroims self-requested a review December 19, 2021 13:52
@heroims heroims added good first issue Good for newcomers question Further information is requested wontfix This will not be worked on labels Dec 19, 2021
@androiddisk
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@alexcohn
你好，我按照您的修改，有以下报错。要怎样才能编译出 LLVMgold.so

Hello, according to your modification, I have the following error reports. How to compile llvmgold.so。

`

[armeabi-v7a] StaticLibrary : libkooapk.a
[armeabi-v7a] Compile++ thumb: utils <= missing.cpp
[armeabi-v7a] Compile++ thumb: utils <= new.cpp
[armeabi-v7a] Compile++ thumb: utils <= files.cpp
[armeabi-v7a] Compile++ thumb: utils <= misc.cpp
[armeabi-v7a] Compile++ thumb: utils <= selinux.cpp
[armeabi-v7a] Compile++ thumb: utils <= logging.cpp
[armeabi-v7a] Compile++ thumb: utils <= xwrap.cpp
[armeabi-v7a] Compile++ thumb: utils <= stream.cpp
[armeabi-v7a] StaticLibrary : libutils.a
[armeabi-v7a] Executable : binary
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: /root/kooapk/llvm/obfuscator_9.0.1/build/bin/../lib/LLVMgold.so: could not load plugin library: /root/kooapk/llvm/obfuscator_9.0.1/build/bin/../lib/LLVMgold.so: cannot open shared object file: No such file or directory
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/binary/binary.o:1:3: invalid character
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/binary/binary.o:1:3: syntax error, unexpected $end
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/binary/binary.o: not an object or archive
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/resetprop/persist_properties.o:1:3: invalid character
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/resetprop/persist_properties.o:1:3: syntax error, unexpected $end
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/resetprop/persist_properties.o: not an object or archive
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/resetprop/resetprop.o:1:3: invalid character
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/resetprop/resetprop.o:1:3: syntax error, unexpected $end
/root/kooapk/cmdline-tools/ndk/ollvm/toolchains/llvm/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: ./obj/local/armeabi-v7a/objs/binary/resetprop/resetprop.o: not an object or archive
/root/kooapk/cmdline-tools/ndk/ollvm/platforms/android-16/arch-arm/usr/lib/../lib/crtbegin_dynamic.o:crtbegin.c:function _start_main: error: undefined reference to 'main'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [/root/kooapk/cmdline-tools/ndk/ollvm/build/core/build-binary.mk:738: obj/local/armeabi-v7a/binary] Error 1
`

@alexcohn
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alexcohn commented Jan 1, 2022

@androiddisk This build failure does not look related to the change in PassManagerBuilder.cpp.

hudjefa pushed a commit to hudjefa/obfuscator-llvm that referenced this pull request Feb 14, 2022
@yonghong-song @tstellar
BPF: Fix a bug in peephole TRUNC elimination optimization
6564e0c 
Andrei Matei reported a llvm11 core dump for his bpf program
   https://bugs.llvm.org/show_bug.cgi?id=48578
The core dump happens in LiveVariables analysis phase.
  heroims#4 0x00007fce54356bb0 __restore_rt
  heroims#5 0x00007fce4d51785e llvm::LiveVariables::HandleVirtRegUse(unsigned int,
      llvm::MachineBasicBlock*, llvm::MachineInstr&)
  heroims#6 0x00007fce4d519abe llvm::LiveVariables::runOnInstr(llvm::MachineInstr&,
      llvm::SmallVectorImpl<unsigned int>&)
  heroims#7 0x00007fce4d519ec6 llvm::LiveVariables::runOnBlock(llvm::MachineBasicBlock*, unsigned int)
  heroims#8 0x00007fce4d51a4bf llvm::LiveVariables::runOnMachineFunction(llvm::MachineFunction&)
The bug can be reproduced with llvm12 and latest trunk as well.

Futher analysis shows that there is a bug in BPF peephole
TRUNC elimination optimization, which tries to remove
unnecessary TRUNC operations (a <<= 32; a >>= 32).
Specifically, the compiler did wrong transformation for the
following patterns:
   %1 = LDW ...
   %2 = SLL_ri %1, 32
   %3 = SRL_ri %2, 32
   ... %3 ...
   %4 = SRA_ri %2, 32
   ... %4 ...

The current transformation did not check how many uses of %2
and did transformation like
   %1 = LDW ...
   ... %1 ...
   %4 = SRL_ri %2, 32
   ... %4 ...
and pseudo register %2 is used by not defined and
caused LiveVariables analysis core dump.

To fix the issue, when traversing back from SRL_ri to SLL_ri,
check to ensure SLL_ri has only one use. Otherwise, don't
do transformation.

Differential Revision: https://reviews.llvm.org/D97792

(cherry picked from commit 51cdb780db3b9b46c783efcec672c4da272e9992)
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@alexcohn @androiddisk @heroims