llvm dev - Jan 2012 - [LLVMdev] Code crashing in CreateGlobalStringPtr, passes when I add code for main routine + entry

Hi All,

The following crashes in CreateGlobalStringPtr:
#include "llvm/Support/DataTypes.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/BasicBlock.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ExecutionEngine/GenericValue.h"
#include "llvm/Support/IRBuilder.h"

#include <vector>
#include <cstdio>
#include <string>

int main()
{
  llvm::LLVMContext & context = llvm::getGlobalContext();
  llvm::Module *module = new llvm::Module("asdf", context);
  llvm::IRBuilder<> builder(context);
  llvm::Value *helloWorld = builder.CreateGlobalStringPtr("hello
world!\n"); // crash here
}

And this one doesn't, any idea what's happening here:
#include "llvm/Support/DataTypes.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/BasicBlock.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ExecutionEngine/GenericValue.h"
#include "llvm/Support/IRBuilder.h"

#include <vector>
#include <cstdio>
#include <string>

int main()
{
  llvm::LLVMContext & context = llvm::getGlobalContext();
  llvm::Module *module = new llvm::Module("asdf", context);
  llvm::IRBuilder<> builder(context);

  // Added extra
  llvm::FunctionType *funcType llvm::FunctionType::get(builder.getVoidTy(),
false);
  llvm::Function *mainFunc = llvm::Function::Create(funcType,
llvm::Function::ExternalLinkage, "main", module);
  llvm::BasicBlock *entry = llvm::BasicBlock::Create(context, "entry",
mainFunc);
  builder.SetInsertPoint(entry);

  llvm::Value *helloWorld = builder.CreateGlobalStringPtr("hello
world!\n");
}

Not sure how creating a main routine and an entry point can remove the
crash. Thought they were unrelated. Here are my options to g++ for
compiling:
llvm-config --cxxflags --ldflags --libs
-I/usr/include  -DNDEBUG -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS
-D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -O3  -fno-exceptions -fno-rtti
-fno-common -Woverloaded-virtual -Wcast-qual
-L/usr/lib  -lpthread -lm
-lLLVMXCoreCodeGen -lLLVMTableGen -lLLVMSystemZCodeGen -lLLVMSparcCodeGen
-lLLVMPTXCodeGen -lLLVMPowerPCCodeGen -lLLVMMSP430CodeGen -lLLVMMipsCodeGen
-lLLVMMCJIT -lLLVMRuntimeDyld -lLLVMObject -lLLVMMCDisassembler
-lLLVMXCoreDesc -lLLVMXCoreInfo -lLLVMSystemZDesc -lLLVMSystemZInfo
-lLLVMSparcDesc -lLLVMSparcInfo -lLLVMPowerPCDesc -lLLVMPowerPCInfo
-lLLVMPowerPCAsmPrinter -lLLVMPTXDesc -lLLVMPTXInfo -lLLVMPTXAsmPrinter
-lLLVMMipsDesc -lLLVMMipsInfo -lLLVMMipsAsmPrinter -lLLVMMSP430Desc
-lLLVMMSP430Info -lLLVMMSP430AsmPrinter -lLLVMMBlazeDisassembler
-lLLVMMBlazeAsmParser -lLLVMMBlazeCodeGen -lLLVMMBlazeDesc
-lLLVMMBlazeAsmPrinter -lLLVMMBlazeInfo -lLLVMLinker -lLLVMipo
-lLLVMInterpreter -lLLVMInstrumentation -lLLVMJIT -lLLVMExecutionEngine
-lLLVMDebugInfo -lLLVMCppBackend -lLLVMCppBackendInfo -lLLVMCellSPUCodeGen
-lLLVMCellSPUDesc -lLLVMCellSPUInfo -lLLVMCBackend -lLLVMCBackendInfo
-lLLVMBlackfinCodeGen -lLLVMBlackfinDesc -lLLVMBlackfinInfo -lLLVMBitWriter
-lLLVMX86Disassembler -lLLVMX86AsmParser -lLLVMX86CodeGen -lLLVMX86Desc
-lLLVMX86AsmPrinter -lLLVMX86Utils -lLLVMX86Info -lLLVMAsmParser
-lLLVMARMDisassembler -lLLVMARMAsmParser -lLLVMARMCodeGen -lLLVMARMDesc
-lLLVMARMAsmPrinter -lLLVMARMInfo -lLLVMArchive -lLLVMBitReader
-lLLVMAlphaCodeGen -lLLVMSelectionDAG -lLLVMAsmPrinter -lLLVMMCParser
-lLLVMCodeGen -lLLVMScalarOpts -lLLVMInstCombine -lLLVMTransformUtils
-lLLVMipa -lLLVMAnalysis -lLLVMTarget -lLLVMCore -lLLVMAlphaDesc
-lLLVMAlphaInfo -lLLVMMC -lLLVMSupport

Thanks,
  Arpan
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Arpan Sen wrote:
> Hi All,
>
> The following crashes in CreateGlobalStringPtr:
> #include "llvm/Support/DataTypes.h"
> #include "llvm/LLVMContext.h"
> #include "llvm/Module.h"
> #include "llvm/Constants.h"
> #include "llvm/Function.h"
> #include "llvm/BasicBlock.h"
> #include "llvm/ExecutionEngine/ExecutionEngine.h"
> #include "llvm/ExecutionEngine/GenericValue.h"
> #include "llvm/Support/IRBuilder.h"
>
> #include <vector>
> #include <cstdio>
> #include <string>
>
> int main()
> {
>    llvm::LLVMContext & context = llvm::getGlobalContext();
>    llvm::Module *module = new llvm::Module("asdf", context);
>    llvm::IRBuilder<> builder(context);
>    llvm::Value *helloWorld = builder.CreateGlobalStringPtr("hello
> world!\n"); // crash here
The IRBuilder doesn't know what Module you're trying to create the 
string in, and ends up dereferencing a null pointer.

(Did your build have assertions enabled? I haven't checked whether 
there's an assert for this, but there ought to be!)

Nick