[LLVMdev] LLVM2.2 x64 JIT trouble on VStudio build

[Chuck Rose III]

Hola LLVMers, 

 

I'm debugging through some strangeness that I'm seeing on X64 on windows with LLVM2.2.  I had to change the code so that it would engage the x64 target machine on windows builds, but I've otherwise left LLVM 2.2 alone.  The basic idea is that I've got a function bar which is compiled by VStudio and I'm creating another function foo via LLVM JIT which is going to call into bar.  This has been working for me for a long time on win32 and also under xcode of course.  I've included the code that generates the situation at the bottom.  Some questions (which may be really brain dead) are:

 

1.       Why isn't the stack getting set up in foo prior to the call down into bar?

2.       Why is the call to bar a pointer to a jump.  I.e. why didn't it resolve the address in foo?

3.       What are some good places for me to be looking to try and drill down further on what's happening?  I've tried switching calling conventions and have watched it create machine instructions for adjusting the stack up and down, but they seem to be removed by the time it actually gets down to execution time. 

 

Any suggestions would be appreciated.

 

Thanks,

Chuck.

 

Call into function (foo)

0000000000980030  mov         rax,140001591h 

000000000098003A  call        rax                   ß this is calling to bar via a jump table

000000000098003C  ret              

 

Leads to 

0000000140001591  jmp         bar (1400064E0h) 

 

Leads to

void bar(int i)

{

00000001400064E0  mov         dword ptr [rsp+8],ecx 

00000001400064E4  push        rdi  

00000001400064E5  sub         rsp,20h 

00000001400064E9  mov         rdi,rsp 

00000001400064EC  mov         rcx,8 

00000001400064F6  mov         eax,0CCCCCCCCh 

00000001400064FB  rep stos    dword ptr [rdi] 

00000001400064FD  mov         ecx,dword ptr [rsp+30h] 

    printf("the int is %i\n",i);

0000000140006501  mov         edx,dword ptr [i] 

0000000140006505  lea         rcx,[string "the int is %i\n" (140C1A240h)] 

000000014000650C  call        qword ptr [__imp_printf (141145920h)] 

}

0000000140006512  add         rsp,20h 

0000000140006516  pop         rdi  

0000000140006517  ret              

 

At this point, we seem to be jumping back up but the stack is no longer in order, so 

000000000098003C  ret              

 

Takes us into wonderland

0000000100000003  ???              

 

But unfortunately not through the looking glass.

 

Here's the modification of the Fibonacci program which got me the above:

#include "llvm/Module.h"

#include "llvm/DerivedTypes.h"

#include "llvm/Constants.h"

#include "llvm/Instructions.h"

#include "llvm/ModuleProvider.h"

#include "llvm/Analysis/Verifier.h"

#include "llvm/ExecutionEngine/JIT.h"

#include "llvm/ExecutionEngine/Interpreter.h"

#include "llvm/ExecutionEngine/GenericValue.h"

#include "llvm/System/DynamicLibrary.h"

#include "llvm/CallingConv.h"

#include <iostream>

#include <stdio.h>

using namespace llvm;

 

void bar(int i)

{

    printf("the int is %i\n",i);

}

 

Function* createBarFunction(Module* M)

{

    Function* pBarF = cast<Function>(M->getOrInsertFunction("bar", Type::VoidTy, Type::Int32Ty, NULL));

    return pBarF;

}

 

Function* createFooFunction(Module* M)

{

    Function* pBarF = createBarFunction(M),

            * pFooF;

 

    pFooF = cast<Function>(M->getOrInsertFunction("foo", Type::VoidTy, Type::Int32Ty, NULL));

    BasicBlock* pBody = new BasicBlock("body",pFooF);

    Argument* pArg = pFooF->arg_begin();

    pArg->setName("i");

    std::vector<Value*> barArgs;

    barArgs.push_back(pArg);

    new CallInst(pBarF, barArgs.begin(), barArgs.end(), "", pBody);

    new ReturnInst(NULL, pBody);

    return pFooF;

}

 

int main(int argc, char **argv) {

    // Create some module to put our function into it.

    Module *M = new Module("test");

 

    M->setDataLayout("e-p:64:64:64-i1:8:8:8-i8:8:8:8-i32:32:32:32-f32:32:32:32");

    Function* pFooF = createFooFunction(M);

    M->print(std::cout);

 

    // Now we going to create JIT

    ExistingModuleProvider *MP = new ExistingModuleProvider(M);

    ExecutionEngine *EE = ExecutionEngine::create(MP, false);

 

    sys::DynamicLibrary::AddSymbol("bar", (void*) bar);

    llvm::Module::FunctionListType& funcList = MP->getModule()->getFunctionList();

 

    for (llvm::Module::FunctionListType::iterator i = funcList.begin() ; i != funcList.end() ; ++i)

    {

        EE->getPointerToFunction(i);

    }

 

    EE->recompileAndRelinkFunction(pFooF);

 

    std::vector<GenericValue> Args(1);

    Args[0].IntVal = APInt(32, 3);

    GenericValue GV = EE->runFunction(pFooF, Args);

 

    return 0;

}

 

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