[LLVMdev] LLVM2.2 x64 JIT trouble on VStudio build
Chuck Rose III
cfr at adobe.com
Fri Feb 15 11:00:34 PST 2008
Hey Evan,
At the point of the instructions you suggested I step through, X86ISelLowering has this state:
- this 0x00000000005fe728 {VarArgsFrameIndex=-842150451 RegSaveFrameIndex=-842150451 VarArgsGPOffset=3452816845 ...} llvm::X86TargetLowering * const
+ llvm::TargetLowering {TM={...} TD=0x00000000008edac0 IsLittleEndian=true ...} llvm::TargetLowering
VarArgsFrameIndex -842150451 int
RegSaveFrameIndex -842150451 int
VarArgsGPOffset 3452816845 unsigned int
VarArgsFPOffset 3452816845 unsigned int
BytesToPopOnReturn 0 int
BytesCallerReserves 0 int
- Subtarget 0x00000000008eda90 {AsmFlavor=Intel PICStyle=None X86SSELevel=SSE2 ...} const llvm::X86Subtarget *
+ llvm::TargetSubtarget {...} llvm::TargetSubtarget
AsmFlavor Intel llvm::X86Subtarget::AsmWriterFlavorTy
PICStyle None llvm::PICStyle::Style
X86SSELevel SSE2 llvm::X86Subtarget::X86SSEEnum
X863DNowLevel -842150451 llvm::X86Subtarget::X863DNowEnum
HasX86_64 true bool
DarwinVers 0 unsigned char
stackAlignment 8 unsigned int
MaxInlineSizeThreshold 128 unsigned int
Is64Bit true bool
HasLow4GUserAddress true bool
TargetType isWindows llvm::X86Subtarget::<unnamed-tag>
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
// We should use extra load for direct calls to dllimported functions in
// non-JIT mode.
// it get's into here
if ((IsTailCall || !Is64Bit || // both these are false
getTargetMachine().getCodeModel() != CodeModel::Large) // this is false
&& !Subtarget->GVRequiresExtraLoad(G->getGlobal(), // this is short circuited away
getTargetMachine(), true))
Callee = DAG.getTargetGlobalAddress(G->getGlobal(), getPointerTy()); // this is passed over because the test is false
// since it made it through the if (Global...., it skips down to
// Returns a chain & a flag for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Flag);
Thanks!
Chuck.
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Evan Cheng
Sent: Friday, February 15, 2008 9:35 AM
To: LLVM Developers Mailing List
Subject: Re: [LLVMdev] LLVM2.2 x64 JIT trouble on VStudio build
On Feb 12, 2008, at 5:26 PM, Chuck Rose III wrote:
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?
What is the triplet of the target? x86_64-win32?
2. Why is the call to bar a pointer to a jump. I.e. why didn't it resolve the address in foo?
Not sure. I can't reproduce this. Can you step through the code in X86ISelLowering.cpp::LowerCALL()? Around
// If the callee is a GlobalAddress node (quite common, every direct call is)
// turn it into a TargetGlobalAddress node so that legalize doesn't hack it.
Evan
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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