fatal error: error in backend: Cannot select: 0x77

Question

This is the error message when I use the following command:

clang++ test.cpp -mypass -fno-use-cxa-atexit

to compile my test.cpp source file directly with my transform pass.

Error message:
fatal error: error in backend: Cannot select: 0x7793fa0: f64 = xor 0x74291b0,
      Constant:i8<-3>
  0x74291b0: f64,ch = load<LD8[%1064](align=1)> 0x732b440, 0x74317d0, undef:i64
    0x74317d0: i64 = add 0x7794390, 0x7428f10
      0x7794390: i64 = shl 0x7464360, Constant:i8<3>
        0x7464360: i64 = sign_extend 0x7430d50
          0x7430d50: i32,ch = CopyFromReg 0x732b440, Register:i32 %vreg212
            0x77949b0: i32 = Register %vreg212
        0x77bbd40: i8 = Constant<3>
      0x7428f10: i64 = X86ISD::Wrapper TargetGlobalAddress:i64<[27 x double]* @_ZZ9test_mainiPPcE5valsA.291> 0
        0x77904a0: i64 = TargetGlobalAddress<[27 x double]* @_ZZ9test_mainiPPcE5valsA.291> 0
    0x7431990: i64 = undef
  0x77bbdb0: i8 = Constant<-3>
In function: .datadiv_decode15430557481081536446
clang-3.9: error: clang frontend command failed with exit code 70 (use -v to see invocation)
clang version 3.9.1 (tags/RELEASE_391/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/oubotong/obf/bin
clang-3.9: note: diagnostic msg: PLEASE submit a bug report to http://llvm.org/bugs/ and include the crash backtrace, preprocessed source, and associated run script.
clang-3.9: note: diagnostic msg: 
********************

However, when I use the following command to compile seperately:

clang++ -emit-llvm -S test.cpp -mypass -fno-use-cxa-atexit

This command generate test.ll and then use:

llvm-as test.ll -o test.bc

to generate test.bc and finally use:

lli test.bc

to run the program. There are no errors and my program works well. Then why the error came when I compile the test.cpp directly? Here is part of my source code in pass:

LoadInst *Load=builder.CreateLoad(gvar);
Load->setAlignment(8);
Value* indexList[2] = {ConstantInt::get(variable->getType(), 0), variable};                                 
Value *const_key=builder.getInt8(key);
Value *GEP=builder.CreateGEP(gvar,ArrayRef<Value*>(indexList, 2),"arrayIdx");
LoadInst *loadElement=builder.CreateLoad(GEP);
loadElement->setAlignment(1);
Value *Xor = builder.CreateXor(loadElement,const_key,"xor");
StoreInst *Store = builder.CreateStore(Xor, GEP);
Store->setAlignment(1);

Answer 1

Pretty late answer but actually, when you have the .ll file, the llc command can give you some meaningful hints on why things aren't compiling.

The Cannot select error is way more cryptic.