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Nicolas Geoffray

2008-Apr-01 07:50 UTC

[LLVMdev] Being able to know the jitted code-size before emitting

Hi Evan,

Evan Cheng wrote:> 1) How are you computing size of the method being  
> jitted? 
I add a new pass with addSimpleCodeEmitter, with the emitter being a 
SizeEmitter. Since the target calls the emitter with functions such as 
writeByte, writeWord, etc.... the SizeEmitter class implements these 
function by incrementing a counter.

At the end of the pass, the code size of the function is known.
> 2) Why not simply add the functionality of allocating emission  
> buffer of specific size to MachineCodeEmitter instead?
>   
I don't understand. The MachineCodeEmitter class writes directly to a 
buffer which is remalloc'ed if necessary. I want this buffer to be 
pre-allocated and of the correct size. Hence I need a pass that runs 
before emitting code.

Nicolas> Thanks,
>
> Evan
>
> On Mar 30, 2008, at 12:05 PM, Nicolas Geoffray wrote:
>
>   
>> Hi everyone,
>>
>> vmkit requires to know the size of a jitted method before emitting  
>> the method. This allows to allocate the correct size for the method.  
>> The attached patch creates this functionality when the flag  
>> SizedMemoryCode is on.
>>
>> In order to implement this functionality, i had to virtualize some  
>> MachineCodeEmitter functions.
>>
>> Is it OK to commit the patch?
>>
>> Thanks,
>> Nicolas
>> Index: include/llvm/Target/TargetOptions.h
>>
==================================================================>> ---
include/llvm/Target/TargetOptions.h (revision 48944)
>> +++ include/llvm/Target/TargetOptions.h (working copy)
>> @@ -74,6 +74,10 @@
>>   /// be emitted.
>>   extern bool ExceptionHandling;
>>
>> +  /// SizedMemoryCode - This flags indicates that memory for code  
>> is allocated by
>> +  /// an external allocator which requires the size to allocate
>> +  extern bool SizedMemoryCode;
>> +
>>   /// PerformTailCallOpt - This flag is enabled when -tailcallopt is  
>> specified
>>   /// on the commandline. When the flag is on, the target will  
>> perform tail call
>>   /// optimization (pop the caller's stack) providing it supports
it.
>> Index: include/llvm/CodeGen/SizeEmitter.h
>>
==================================================================>> ---
include/llvm/CodeGen/SizeEmitter.h	(revision 0)
>> +++ include/llvm/CodeGen/SizeEmitter.h	(revision 0)
>> @@ -0,0 +1,116 @@
>> +//===-- llvm/CodeGen/MachineCodeEmitter.h - Code emission -------*-  
>> C++ -*-===//
>> +//
>> +//                     The LLVM Compiler Infrastructure
>> +//
>> +// This file was developed by the LLVM research group and is  
>> distributed under
>> +// the University of Illinois Open Source License. See LICENSE.TXT  
>> for details.
>> +//
>> +// 
>> = 
>> = 
>> = 
>> ----------------------------------------------------------------------=
>> ==//
>> +//
>> +// This file defines an abstract interface that is used by the  
>> machine code
>> +// emission framework to output the code.  This allows machine code  
>> emission to
>> +// be separated from concerns such as resolution of call targets,  
>> and where the
>> +// machine code will be written (memory or disk, f.e.).
>> +//
>> +// 
>> = 
>> = 
>> = 
>> ----------------------------------------------------------------------=
>> ==//
>> +
>> +#ifndef LLVM_CODEGEN_SIZEEMITTER_H
>> +#define LLVM_CODEGEN_SIZEEMITTER_H
>> +
>> +#include "llvm/CodeGen/MachineCodeEmitter.h"
>> +#include "llvm/CodeGen/MachineFunction.h"
>> +
>> +namespace llvm {
>> +  /// SizeEmitter - The JIT implementation of the  
>> MachineCodeEmitter, which is
>> +  /// used to output functions to memory for execution.
>> +class SizeEmitter : public MachineCodeEmitter {
>> +  MachineFunction * Fn;
>> +  void* ConstantPoolBase;
>> +  void* JumpTableBase;
>> +  MachineConstantPool *ConstantPool;
>> +  MachineJumpTableInfo *JumpTable;
>> +  std::vector<intptr_t> LabelLocations;
>> +  MachineCodeEmitter* MCE;
>> +
>> +public:
>> +  SizeEmitter(MachineCodeEmitter* mce) {
>> +    CurBufferPtr = 0;
>> +    BufferBegin = 0;
>> +    BufferEnd = (unsigned char*)-1;
>> +    MCE = mce;
>> +  }
>> +
>> +  SizeEmitter(std::vector<intptr_t> locations) {
>> +    LabelLocations = locations;
>> +    CurBufferPtr = 0;
>> +    BufferBegin = 0;
>> +    BufferEnd = (unsigned char*)-1;
>> +  }
>> +
>> +  void initConstantPool(MachineConstantPool *MCP);
>> +
>> +  void initJumpTableInfo(MachineJumpTableInfo *MJTI);
>> +
>> +
>> +  virtual void startFunction(MachineFunction &F) {
>> +    CurBufferPtr = 0;
>> +    Fn = &F;
>> +
>> +    // Ensure the constant pool/jump table info is at least 4-byte  
>> aligned.
>> +    emitAlignment(16);
>> +
>> +    initConstantPool(F.getConstantPool());
>> +    initJumpTableInfo(F.getJumpTableInfo());
>> +
>> +    ConstantPoolBase  = (void*)(((uintptr_t) ConstantPoolBase) +  
>> CurBufferPtr);
>> +    JumpTableBase     = (void*)(((uintptr_t) JumpTableBase) +  
>> CurBufferPtr);
>> +  }
>> +
>> +  virtual bool finishFunction(MachineFunction &F) {
>> +    MCE->setCurrentPtr(CurBufferPtr);
>> +    return false;
>> +  }
>> +  virtual void startFunctionStub(unsigned StubSize, unsigned  
>> Alignment) {}
>> +  virtual void *finishFunctionStub(const Function *F) { return 0; }
>> +  virtual void addRelocation(const llvm::MachineRelocation&) { }
>> +  virtual void emitByte(unsigned char B) {
>> +    CurBufferPtr++;
>> +  }
>> +  virtual void emitWordLE(unsigned W) {
>> +    CurBufferPtr+=4;
>> +  }
>> +  virtual void emitWordBE(unsigned W) {
>> +    CurBufferPtr+=4;
>> +  }
>> +  virtual void emitInt32(int Value) {
>> +    CurBufferPtr += 4;
>> +  }
>> +  virtual void emitInt64(uint64_t Value) {
>> +    CurBufferPtr += 8;
>> +  }
>> +  virtual void emitAt(uintptr_t *Addr, uintptr_t Value) {
>> +  }
>> +
>> +
>> +
>> +  virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) {}
>> +  virtual intptr_t getConstantPoolEntryAddress(unsigned  
>> ConstantNum) const;
>> +
>> +  virtual intptr_t getJumpTableEntryAddress(unsigned Index) const;
>> +
>> +  virtual intptr_t getMachineBasicBlockAddress(MachineBasicBlock  
>> *MBB) const {
>> +    assert(0 && "Should not be in
getMachineBasicBlockAddress of
>> SizeEmitter");
>> +  }
>> +
>> +  virtual void emitLabel(uint64_t) {}
>> +  virtual intptr_t getLabelAddress(uint64_t LabelID) const {
>> +    assert(LabelLocations.size() > (unsigned)LabelID &&
>> +             LabelLocations[LabelID] && "Label not
emitted!");
>> +      return LabelLocations[LabelID];
>> +  }
>> +  virtual void setModuleInfo(llvm::MachineModuleInfo*) {}
>> +};
>> +
>> +} // end llvm namespace
>> +
>> +#endif
>> Index: include/llvm/CodeGen/MachineCodeEmitter.h
>>
==================================================================>> ---
include/llvm/CodeGen/MachineCodeEmitter.h	(revision 48143)
>> +++ include/llvm/CodeGen/MachineCodeEmitter.h	(working copy)
>> @@ -18,6 +18,7 @@
>> #define LLVM_CODEGEN_MACHINECODEEMITTER_H
>>
>> #include "llvm/Support/DataTypes.h"
>> +#include <string>
>> #include <vector>
>>
>> namespace llvm {
>> @@ -92,7 +93,7 @@
>>   /// emitByte - This callback is invoked when a byte needs to be  
>> written to the
>>   /// output stream.
>>   ///
>> -  void emitByte(unsigned char B) {
>> +  virtual void emitByte(unsigned char B) {
>>     if (CurBufferPtr != BufferEnd)
>>       *CurBufferPtr++ = B;
>>   }
>> @@ -100,7 +101,7 @@
>>   /// emitWordLE - This callback is invoked when a 32-bit word needs  
>> to be
>>   /// written to the output stream in little-endian format.
>>   ///
>> -  void emitWordLE(unsigned W) {
>> +  virtual void emitWordLE(unsigned W) {
>>     if (CurBufferPtr+4 <= BufferEnd) {
>>       *CurBufferPtr++ = (unsigned char)(W >>  0);
>>       *CurBufferPtr++ = (unsigned char)(W >>  8);
>> @@ -114,7 +115,7 @@
>>   /// emitWordBE - This callback is invoked when a 32-bit word needs  
>> to be
>>   /// written to the output stream in big-endian format.
>>   ///
>> -  void emitWordBE(unsigned W) {
>> +  virtual void emitWordBE(unsigned W) {
>>     if (CurBufferPtr+4 <= BufferEnd) {
>>       *CurBufferPtr++ = (unsigned char)(W >> 24);
>>       *CurBufferPtr++ = (unsigned char)(W >> 16);
>> @@ -175,7 +176,7 @@
>>   }
>>
>>   /// emitInt32 - Emit a int32 directive.
>> -  void emitInt32(int Value) {
>> +  virtual void emitInt32(int Value) {
>>     if (CurBufferPtr+4 <= BufferEnd) {
>>       *((uint32_t*)CurBufferPtr) = Value;
>>       CurBufferPtr += 4;
>> @@ -185,7 +186,7 @@
>>   }
>>
>>   /// emitInt64 - Emit a int64 directive.
>> -  void emitInt64(uint64_t Value) {
>> +  virtual void emitInt64(uint64_t Value) {
>>     if (CurBufferPtr+8 <= BufferEnd) {
>>       *((uint64_t*)CurBufferPtr) = Value;
>>       CurBufferPtr += 8;
>> @@ -195,7 +196,7 @@
>>   }
>>
>>   /// emitAt - Emit Value in Addr
>> -  void emitAt(uintptr_t *Addr, uintptr_t Value) {
>> +  virtual void emitAt(uintptr_t *Addr, uintptr_t Value) {
>>     if (Addr >= (uintptr_t*)BufferBegin && Addr <  
>> (uintptr_t*)BufferEnd)
>>       (*Addr) = Value;
>>   }
>> @@ -270,6 +271,11 @@
>>   /// Specifies the MachineModuleInfo object. This is used for  
>> exception handling
>>   /// purposes.
>>   virtual void setModuleInfo(MachineModuleInfo* Info) = 0;
>> +
>> +  void setCurrentPtr(unsigned char* Ptr) {
>> +    CurBufferPtr = Ptr;
>> +  }
>> +
>> };
>>
>> } // End llvm namespace
>> Index: lib/CodeGen/LLVMTargetMachine.cpp
>>
==================================================================>> ---
lib/CodeGen/LLVMTargetMachine.cpp	(revision 48143)
>> +++ lib/CodeGen/LLVMTargetMachine.cpp	(working copy)
>> @@ -17,6 +17,7 @@
>> #include "llvm/Assembly/PrintModulePass.h"
>> #include "llvm/Analysis/LoopPass.h"
>> #include "llvm/CodeGen/Passes.h"
>> +#include "llvm/CodeGen/SizeEmitter.h"
>> #include "llvm/CodeGen/Collector.h"
>> #include "llvm/Target/TargetOptions.h"
>> #include "llvm/Transforms/Scalar.h"
>> @@ -257,7 +258,13 @@
>>
>>   if (addPreEmitPass(PM, Fast) && PrintMachineCode)
>>     PM.add(createMachineFunctionPrinterPass(cerr));
>> +
>> +  if (SizedMemoryCode) {
>> +    SizeEmitter * SE = new SizeEmitter(&MCE);
>> +    addSimpleCodeEmitter(PM, Fast, false, *SE);
>> +  }
>>
>> +
>>   addCodeEmitter(PM, Fast, PrintEmittedAsm, MCE);
>>
>>   PM.add(createCollectorMetadataDeleter());
>> Index: lib/CodeGen/SizeEmitter.cpp
>>
==================================================================>> ---
lib/CodeGen/SizeEmitter.cpp	(revision 0)
>> +++ lib/CodeGen/SizeEmitter.cpp	(revision 0)
>> @@ -0,0 +1,77 @@
>> +#include "llvm/CodeGen/SizeEmitter.h"
>> +#include "llvm/Constant.h"
>> +#include "llvm/Constants.h"
>> +#include "llvm/DerivedTypes.h"
>> +#include "llvm/Module.h"
>> +#include "llvm/Type.h"
>> +#include "llvm/CodeGen/MachineCodeEmitter.h"
>> +#include "llvm/CodeGen/MachineFunction.h"
>> +#include "llvm/CodeGen/MachineConstantPool.h"
>> +#include "llvm/CodeGen/MachineJumpTableInfo.h"
>> +#include "llvm/CodeGen/MachineRelocation.h"
>> +#include "llvm/ExecutionEngine/GenericValue.h"
>> +#include "llvm/Target/TargetData.h"
>> +#include "llvm/Target/TargetJITInfo.h"
>> +#include "llvm/Target/TargetMachine.h"
>> +#include "llvm/Target/TargetOptions.h"
>> +#include "llvm/Support/Debug.h"
>> +#include "llvm/Support/MutexGuard.h"
>> +#include "llvm/System/Disassembler.h"
>> +#include "llvm/ADT/Statistic.h"
>> +#include "llvm/System/Memory.h"
>> +#include <algorithm>
>> +using namespace llvm;
>> +
>> +
>> +void SizeEmitter::initConstantPool(MachineConstantPool *MCP) {
>> +  const std::vector<MachineConstantPoolEntry> &Constants =
MCP-
>>     
>>> getConstants();
>>>       
>> +  if (Constants.empty()) return;
>> +
>> +  MachineConstantPoolEntry CPE = Constants.back();
>> +  unsigned Size = CPE.Offset;
>> +  const Type *Ty = CPE.isMachineConstantPoolEntry()
>> +    ? CPE.Val.MachineCPVal->getType() :
CPE.Val.ConstVal->getType();
>> +  Size += Fn->getTarget().getTargetData()->getABITypeSize(Ty);
>> +  ConstantPoolBase = allocateSpace(Size, 1 << MCP- 
>>     
>>> getConstantPoolAlignment());
>>>       
>> +  ConstantPool = MCP;
>> +}
>> +
>> +void SizeEmitter::initJumpTableInfo(MachineJumpTableInfo *MJTI) {
>> +  const std::vector<MachineJumpTableEntry> &JT = MJTI- 
>>     
>>> getJumpTables();
>>>       
>> +  if (JT.empty()) return;
>> +
>> +  unsigned NumEntries = 0;
>> +  for (unsigned i = 0, e = JT.size(); i != e; ++i)
>> +    NumEntries += JT[i].MBBs.size();
>> +
>> +  unsigned EntrySize = MJTI->getEntrySize();
>> +
>> +  // Just allocate space for all the jump tables now.  We will fix  
>> up the actual
>> +  // MBB entries in the tables after we emit the code for each  
>> block, since then
>> +  // we will know the final locations of the MBBs in memory.
>> +  JumpTable = MJTI;
>> +  JumpTableBase = allocateSpace(NumEntries * EntrySize, MJTI- 
>>     
>>> getAlignment());
>>>       
>> +}
>> +
>> +intptr_t SizeEmitter::getConstantPoolEntryAddress(unsigned  
>> ConstantNum) const {
>> +  assert(ConstantNum < ConstantPool->getConstants().size()
&&
>> +         "Invalid ConstantPoolIndex!");
>> +  return (intptr_t)ConstantPoolBase +
>> +         ConstantPool->getConstants()[ConstantNum].Offset;
>> +}
>> +
>> +intptr_t SizeEmitter::getJumpTableEntryAddress(unsigned Index)  
>> const {
>> +  const std::vector<MachineJumpTableEntry> &JT = JumpTable- 
>>     
>>> getJumpTables();
>>>       
>> +  assert(Index < JT.size() && "Invalid jump table
index!");
>> +
>> +  unsigned Offset = 0;
>> +  unsigned EntrySize = JumpTable->getEntrySize();
>> +
>> +  for (unsigned i = 0; i < Index; ++i)
>> +    Offset += JT[i].MBBs.size();
>> +
>> +   Offset *= EntrySize;
>> +
>> +  return (intptr_t)((char *)JumpTableBase + Offset);
>> +}
>> +
>> Index: lib/Target/TargetMachine.cpp
>>
==================================================================>> ---
lib/Target/TargetMachine.cpp	(revision 48143)
>> +++ lib/Target/TargetMachine.cpp	(working copy)
>> @@ -31,6 +31,7 @@
>>   bool UseSoftFloat;
>>   bool NoZerosInBSS;
>>   bool ExceptionHandling;
>> +  bool SizedMemoryCode;
>>   Reloc::Model RelocationModel;
>>   CodeModel::Model CMModel;
>>   bool PerformTailCallOpt;
>> Index: lib/ExecutionEngine/JIT/JITEmitter.cpp
>>
==================================================================>> ---
lib/ExecutionEngine/JIT/JITEmitter.cpp	(revision 48143)
>> +++ lib/ExecutionEngine/JIT/JITEmitter.cpp	(working copy)
>> @@ -18,12 +18,14 @@
>> #include "llvm/Constant.h"
>> #include "llvm/Module.h"
>> #include "llvm/Type.h"
>> +#include "llvm/ADT/DenseMap.h"
>> #include "llvm/CodeGen/MachineCodeEmitter.h"
>> #include "llvm/CodeGen/MachineFunction.h"
>> #include "llvm/CodeGen/MachineConstantPool.h"
>> #include "llvm/CodeGen/MachineJumpTableInfo.h"
>> #include "llvm/CodeGen/MachineModuleInfo.h"
>> #include "llvm/CodeGen/MachineRelocation.h"
>> +#include "llvm/CodeGen/SizeEmitter.h"
>> #include "llvm/ExecutionEngine/JITMemoryManager.h"
>> #include "llvm/Target/TargetData.h"
>> #include "llvm/Target/TargetJITInfo.h"
>> @@ -370,6 +376,7 @@
>>     virtual void startFunction(MachineFunction &F);
>>     virtual bool finishFunction(MachineFunction &F);
>>
>> +    void initConstantPool(MachineConstantPool *MCP);
>>     void emitConstantPool(MachineConstantPool *MCP);
>>     void initJumpTableInfo(MachineJumpTableInfo *MJTI);
>>     void emitJumpTableInfo(MachineJumpTableInfo *MJTI);
>> @@ -469,19 +476,47 @@
>>
>>
>> void JITEmitter::startFunction(MachineFunction &F) {
>> -  uintptr_t ActualSize;
>> -  BufferBegin = CurBufferPtr = MemMgr- 
>>     
>>> startFunctionBody(F.getFunction(),
>>>       
>> -                                                         ActualSize);
>> -  BufferEnd = BufferBegin+ActualSize;
>> +  MMI->BeginFunction(&F);
>>
>> -  // Ensure the constant pool/jump table info is at least 4-byte  
>> aligned.
>> -  emitAlignment(16);
>> +  if (SizedMemoryCode) {
>> +    BufferBegin = CurBufferPtr;
>> +    BufferEnd = (unsigned char*) 0xffffffff;
>> +
>> +    // Ensure the constant pool/jump table info is at least 4-byte  
>> aligned.
>> +    emitAlignment(16);
>>
>> -  emitConstantPool(F.getConstantPool());
>> -  initJumpTableInfo(F.getJumpTableInfo());
>> +    initConstantPool(F.getConstantPool());
>> +    initJumpTableInfo(F.getJumpTableInfo());
>> +
>> +
>> +    uintptr_t ActualSize = (uintptr_t)CurBufferPtr;
>> +    CurBufferPtr = MemMgr->startFunctionBody(F.getFunction(),
>> +                                             ActualSize);
>> +
>> +    ConstantPoolBase  = (void*)(((unsigned) ConstantPoolBase) +  
>> CurBufferPtr);
>> +    JumpTableBase     = (void*)(((unsigned) JumpTableBase) +  
>> CurBufferPtr);
>>
>> -  // About to start emitting the machine code for the function.
>> -  emitAlignment(std::max(F.getFunction()->getAlignment(), 8U));
>> +    emitConstantPool(F.getConstantPool());
>> +
>> +  } else {
>> +    uintptr_t ActualSize;
>> +    BufferBegin = CurBufferPtr = MemMgr- 
>>     
>>> startFunctionBody(F.getFunction(),
>>>       
>> +                                                            
>> ActualSize);
>> +    BufferEnd = BufferBegin+ActualSize;
>> +
>> +    // Ensure the constant pool/jump table info is at least 4-byte  
>> aligned.
>> +    emitAlignment(16);
>> +
>> +    initConstantPool(F.getConstantPool());
>> +    emitConstantPool(F.getConstantPool());
>> +    initJumpTableInfo(F.getJumpTableInfo());
>> +
>> +    // About to start emitting the machine code for the function.
>> +    emitAlignment(std::max(F.getFunction()->getAlignment(), 8U));
>> +
>> +  }
>> +
>> +
>>   TheJIT->updateGlobalMapping(F.getFunction(), CurBufferPtr);
>>
>>   MBBLocations.clear();
>> @@ -579,12 +614,18 @@
>>     DOUT << "Disassembled code:\n"
>>          << sys::disassembleBuffer(FnStart, FnEnd-FnStart,  
>> (uintptr_t)FnStart);
>> #endif
>> +
>>   if (ExceptionHandling) {
>>     uintptr_t ActualSize;
>> +    if (SizedMemoryCode) {
>> +      SizeEmitter sz(LabelLocations);
>> +      DE->EmitDwarfTable(F, sz, FnStart, FnEnd);
>> +      ActualSize = sz.getCurrentPCValue();
>> +    }
>>     SavedBufferBegin = BufferBegin;
>>     SavedBufferEnd = BufferEnd;
>>     SavedCurBufferPtr = CurBufferPtr;
>> -
>> +
>>     BufferBegin = CurBufferPtr = MemMgr- 
>>     
>>> startExceptionTable(F.getFunction(),
>>>       
>>                                                               
>> ActualSize);
>>     BufferEnd = BufferBegin+ActualSize;
>> @@ -598,11 +639,10 @@
>>     TheJIT->RegisterTable(FrameRegister);
>>   }
>>   MMI->EndFunction();
>> -
>>   return false;
>> }
>>
>> -void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
>> +void JITEmitter::initConstantPool(MachineConstantPool *MCP) {
>>   const std::vector<MachineConstantPoolEntry> &Constants =
MCP-
>>     
>>> getConstants();
>>>       
>>   if (Constants.empty()) return;
>>
>> @@ -611,12 +651,15 @@
>>   const Type *Ty = CPE.isMachineConstantPoolEntry()
>>     ? CPE.Val.MachineCPVal->getType() :
CPE.Val.ConstVal->getType();
>>   Size += TheJIT->getTargetData()->getABITypeSize(Ty);
>> -
>> +
>>   ConstantPoolBase = allocateSpace(Size, 1 << MCP- 
>>     
>>> getConstantPoolAlignment());
>>>       
>>   ConstantPool = MCP;
>> +}
>>
>> +void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
>>   if (ConstantPoolBase == 0) return;  // Buffer overflow.
>>
>> +  const std::vector<MachineConstantPoolEntry> &Constants =
MCP-
>>     
>>> getConstants();
>>>       
>>   // Initialize the memory for all of the constant pool entries.
>>   for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
>>     void *CAddr = (char*)ConstantPoolBase+Constants[i].Offset;
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>     
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Evan Cheng

2008-Apr-01 17:05 UTC

head link

[LLVMdev] Being able to know the jitted code-size before emitting

On Apr 1, 2008, at 12:50 AM, Nicolas Geoffray wrote:
> Hi Evan,
>
> Evan Cheng wrote:
>> 1) How are you computing size of the method being
>> jitted?
>
> I add a new pass with addSimpleCodeEmitter, with the emitter being a
> SizeEmitter. Since the target calls the emitter with functions such as
> writeByte, writeWord, etc.... the SizeEmitter class implements these
> function by incrementing a counter.
>
> At the end of the pass, the code size of the function is known.
That's a hack. :-) Some targets already have ways to compute the exact  
size of a function. See ARM::GetFunctionSize() ARM::GetInstSize(). I'd  
like to see them standardized (all targets that have JIT support can  
accurately calculate the function / instruction sizes) and then you  
can make use of that.
>
>
>> 2) Why not simply add the functionality of allocating emission
>> buffer of specific size to MachineCodeEmitter instead?
>>
>
> I don't understand. The MachineCodeEmitter class writes directly to a
> buffer which is remalloc'ed if necessary. I want this buffer to be
> pre-allocated and of the correct size. Hence I need a pass that runs
> before emitting code.
Suppose you have the size, can't you pass the desired buffer size to  
MachineCodeEmitter and have it do the right thing? It seems like you  
can add the functionality to MachineCodeEmitter rather than add a new  
class for it.

Evan
>
>
> Nicolas
>> Thanks,
>>
>> Evan
>>
>> On Mar 30, 2008, at 12:05 PM, Nicolas Geoffray wrote:
>>
>>
>>> Hi everyone,
>>>
>>> vmkit requires to know the size of a jitted method before emitting
>>> the method. This allows to allocate the correct size for the
method.
>>> The attached patch creates this functionality when the flag
>>> SizedMemoryCode is on.
>>>
>>> In order to implement this functionality, i had to virtualize some
>>> MachineCodeEmitter functions.
>>>
>>> Is it OK to commit the patch?
>>>
>>> Thanks,
>>> Nicolas
>>> Index: include/llvm/Target/TargetOptions.h
>>>
==================================================================>>>
--- include/llvm/Target/TargetOptions.h (revision 48944)
>>> +++ include/llvm/Target/TargetOptions.h (working copy)
>>> @@ -74,6 +74,10 @@
>>>  /// be emitted.
>>>  extern bool ExceptionHandling;
>>>
>>> +  /// SizedMemoryCode - This flags indicates that memory for code
>>> is allocated by
>>> +  /// an external allocator which requires the size to allocate
>>> +  extern bool SizedMemoryCode;
>>> +
>>>  /// PerformTailCallOpt - This flag is enabled when -tailcallopt is
>>> specified
>>>  /// on the commandline. When the flag is on, the target will
>>> perform tail call
>>>  /// optimization (pop the caller's stack) providing it
supports it.
>>> Index: include/llvm/CodeGen/SizeEmitter.h
>>>
==================================================================>>>
--- include/llvm/CodeGen/SizeEmitter.h	(revision 0)
>>> +++ include/llvm/CodeGen/SizeEmitter.h	(revision 0)
>>> @@ -0,0 +1,116 @@
>>> +//===-- llvm/CodeGen/MachineCodeEmitter.h - Code emission
-------*-
>>> C++ -*-===//
>>> +//
>>> +//                     The LLVM Compiler Infrastructure
>>> +//
>>> +// This file was developed by the LLVM research group and is
>>> distributed under
>>> +// the University of Illinois Open Source License. See LICENSE.TXT
>>> for details.
>>> +//
>>> +//
>>> >>> >>> >>>
---------------------------------------------------------------------->>>
==//
>>> +//
>>> +// This file defines an abstract interface that is used by the
>>> machine code
>>> +// emission framework to output the code.  This allows machine
code
>>> emission to
>>> +// be separated from concerns such as resolution of call targets,
>>> and where the
>>> +// machine code will be written (memory or disk, f.e.).
>>> +//
>>> +//
>>> >>> >>> >>>
---------------------------------------------------------------------->>>
==//
>>> +
>>> +#ifndef LLVM_CODEGEN_SIZEEMITTER_H
>>> +#define LLVM_CODEGEN_SIZEEMITTER_H
>>> +
>>> +#include "llvm/CodeGen/MachineCodeEmitter.h"
>>> +#include "llvm/CodeGen/MachineFunction.h"
>>> +
>>> +namespace llvm {
>>> +  /// SizeEmitter - The JIT implementation of the
>>> MachineCodeEmitter, which is
>>> +  /// used to output functions to memory for execution.
>>> +class SizeEmitter : public MachineCodeEmitter {
>>> +  MachineFunction * Fn;
>>> +  void* ConstantPoolBase;
>>> +  void* JumpTableBase;
>>> +  MachineConstantPool *ConstantPool;
>>> +  MachineJumpTableInfo *JumpTable;
>>> +  std::vector<intptr_t> LabelLocations;
>>> +  MachineCodeEmitter* MCE;
>>> +
>>> +public:
>>> +  SizeEmitter(MachineCodeEmitter* mce) {
>>> +    CurBufferPtr = 0;
>>> +    BufferBegin = 0;
>>> +    BufferEnd = (unsigned char*)-1;
>>> +    MCE = mce;
>>> +  }
>>> +
>>> +  SizeEmitter(std::vector<intptr_t> locations) {
>>> +    LabelLocations = locations;
>>> +    CurBufferPtr = 0;
>>> +    BufferBegin = 0;
>>> +    BufferEnd = (unsigned char*)-1;
>>> +  }
>>> +
>>> +  void initConstantPool(MachineConstantPool *MCP);
>>> +
>>> +  void initJumpTableInfo(MachineJumpTableInfo *MJTI);
>>> +
>>> +
>>> +  virtual void startFunction(MachineFunction &F) {
>>> +    CurBufferPtr = 0;
>>> +    Fn = &F;
>>> +
>>> +    // Ensure the constant pool/jump table info is at least 4-byte
>>> aligned.
>>> +    emitAlignment(16);
>>> +
>>> +    initConstantPool(F.getConstantPool());
>>> +    initJumpTableInfo(F.getJumpTableInfo());
>>> +
>>> +    ConstantPoolBase  = (void*)(((uintptr_t) ConstantPoolBase) +
>>> CurBufferPtr);
>>> +    JumpTableBase     = (void*)(((uintptr_t) JumpTableBase) +
>>> CurBufferPtr);
>>> +  }
>>> +
>>> +  virtual bool finishFunction(MachineFunction &F) {
>>> +    MCE->setCurrentPtr(CurBufferPtr);
>>> +    return false;
>>> +  }
>>> +  virtual void startFunctionStub(unsigned StubSize, unsigned
>>> Alignment) {}
>>> +  virtual void *finishFunctionStub(const Function *F) { return 0;
}
>>> +  virtual void addRelocation(const llvm::MachineRelocation&) {
}
>>> +  virtual void emitByte(unsigned char B) {
>>> +    CurBufferPtr++;
>>> +  }
>>> +  virtual void emitWordLE(unsigned W) {
>>> +    CurBufferPtr+=4;
>>> +  }
>>> +  virtual void emitWordBE(unsigned W) {
>>> +    CurBufferPtr+=4;
>>> +  }
>>> +  virtual void emitInt32(int Value) {
>>> +    CurBufferPtr += 4;
>>> +  }
>>> +  virtual void emitInt64(uint64_t Value) {
>>> +    CurBufferPtr += 8;
>>> +  }
>>> +  virtual void emitAt(uintptr_t *Addr, uintptr_t Value) {
>>> +  }
>>> +
>>> +
>>> +
>>> +  virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) {}
>>> +  virtual intptr_t getConstantPoolEntryAddress(unsigned
>>> ConstantNum) const;
>>> +
>>> +  virtual intptr_t getJumpTableEntryAddress(unsigned Index) const;
>>> +
>>> +  virtual intptr_t getMachineBasicBlockAddress(MachineBasicBlock
>>> *MBB) const {
>>> +    assert(0 && "Should not be in
getMachineBasicBlockAddress of
>>> SizeEmitter");
>>> +  }
>>> +
>>> +  virtual void emitLabel(uint64_t) {}
>>> +  virtual intptr_t getLabelAddress(uint64_t LabelID) const {
>>> +    assert(LabelLocations.size() > (unsigned)LabelID &&
>>> +             LabelLocations[LabelID] && "Label not
emitted!");
>>> +      return LabelLocations[LabelID];
>>> +  }
>>> +  virtual void setModuleInfo(llvm::MachineModuleInfo*) {}
>>> +};
>>> +
>>> +} // end llvm namespace
>>> +
>>> +#endif
>>> Index: include/llvm/CodeGen/MachineCodeEmitter.h
>>>
==================================================================>>>
--- include/llvm/CodeGen/MachineCodeEmitter.h	(revision 48143)
>>> +++ include/llvm/CodeGen/MachineCodeEmitter.h	(working copy)
>>> @@ -18,6 +18,7 @@
>>> #define LLVM_CODEGEN_MACHINECODEEMITTER_H
>>>
>>> #include "llvm/Support/DataTypes.h"
>>> +#include <string>
>>> #include <vector>
>>>
>>> namespace llvm {
>>> @@ -92,7 +93,7 @@
>>>  /// emitByte - This callback is invoked when a byte needs to be
>>> written to the
>>>  /// output stream.
>>>  ///
>>> -  void emitByte(unsigned char B) {
>>> +  virtual void emitByte(unsigned char B) {
>>>    if (CurBufferPtr != BufferEnd)
>>>      *CurBufferPtr++ = B;
>>>  }
>>> @@ -100,7 +101,7 @@
>>>  /// emitWordLE - This callback is invoked when a 32-bit word needs
>>> to be
>>>  /// written to the output stream in little-endian format.
>>>  ///
>>> -  void emitWordLE(unsigned W) {
>>> +  virtual void emitWordLE(unsigned W) {
>>>    if (CurBufferPtr+4 <= BufferEnd) {
>>>      *CurBufferPtr++ = (unsigned char)(W >>  0);
>>>      *CurBufferPtr++ = (unsigned char)(W >>  8);
>>> @@ -114,7 +115,7 @@
>>>  /// emitWordBE - This callback is invoked when a 32-bit word needs
>>> to be
>>>  /// written to the output stream in big-endian format.
>>>  ///
>>> -  void emitWordBE(unsigned W) {
>>> +  virtual void emitWordBE(unsigned W) {
>>>    if (CurBufferPtr+4 <= BufferEnd) {
>>>      *CurBufferPtr++ = (unsigned char)(W >> 24);
>>>      *CurBufferPtr++ = (unsigned char)(W >> 16);
>>> @@ -175,7 +176,7 @@
>>>  }
>>>
>>>  /// emitInt32 - Emit a int32 directive.
>>> -  void emitInt32(int Value) {
>>> +  virtual void emitInt32(int Value) {
>>>    if (CurBufferPtr+4 <= BufferEnd) {
>>>      *((uint32_t*)CurBufferPtr) = Value;
>>>      CurBufferPtr += 4;
>>> @@ -185,7 +186,7 @@
>>>  }
>>>
>>>  /// emitInt64 - Emit a int64 directive.
>>> -  void emitInt64(uint64_t Value) {
>>> +  virtual void emitInt64(uint64_t Value) {
>>>    if (CurBufferPtr+8 <= BufferEnd) {
>>>      *((uint64_t*)CurBufferPtr) = Value;
>>>      CurBufferPtr += 8;
>>> @@ -195,7 +196,7 @@
>>>  }
>>>
>>>  /// emitAt - Emit Value in Addr
>>> -  void emitAt(uintptr_t *Addr, uintptr_t Value) {
>>> +  virtual void emitAt(uintptr_t *Addr, uintptr_t Value) {
>>>    if (Addr >= (uintptr_t*)BufferBegin && Addr <
>>> (uintptr_t*)BufferEnd)
>>>      (*Addr) = Value;
>>>  }
>>> @@ -270,6 +271,11 @@
>>>  /// Specifies the MachineModuleInfo object. This is used for
>>> exception handling
>>>  /// purposes.
>>>  virtual void setModuleInfo(MachineModuleInfo* Info) = 0;
>>> +
>>> +  void setCurrentPtr(unsigned char* Ptr) {
>>> +    CurBufferPtr = Ptr;
>>> +  }
>>> +
>>> };
>>>
>>> } // End llvm namespace
>>> Index: lib/CodeGen/LLVMTargetMachine.cpp
>>>
==================================================================>>>
--- lib/CodeGen/LLVMTargetMachine.cpp	(revision 48143)
>>> +++ lib/CodeGen/LLVMTargetMachine.cpp	(working copy)
>>> @@ -17,6 +17,7 @@
>>> #include "llvm/Assembly/PrintModulePass.h"
>>> #include "llvm/Analysis/LoopPass.h"
>>> #include "llvm/CodeGen/Passes.h"
>>> +#include "llvm/CodeGen/SizeEmitter.h"
>>> #include "llvm/CodeGen/Collector.h"
>>> #include "llvm/Target/TargetOptions.h"
>>> #include "llvm/Transforms/Scalar.h"
>>> @@ -257,7 +258,13 @@
>>>
>>>  if (addPreEmitPass(PM, Fast) && PrintMachineCode)
>>>    PM.add(createMachineFunctionPrinterPass(cerr));
>>> +
>>> +  if (SizedMemoryCode) {
>>> +    SizeEmitter * SE = new SizeEmitter(&MCE);
>>> +    addSimpleCodeEmitter(PM, Fast, false, *SE);
>>> +  }
>>>
>>> +
>>>  addCodeEmitter(PM, Fast, PrintEmittedAsm, MCE);
>>>
>>>  PM.add(createCollectorMetadataDeleter());
>>> Index: lib/CodeGen/SizeEmitter.cpp
>>>
==================================================================>>>
--- lib/CodeGen/SizeEmitter.cpp	(revision 0)
>>> +++ lib/CodeGen/SizeEmitter.cpp	(revision 0)
>>> @@ -0,0 +1,77 @@
>>> +#include "llvm/CodeGen/SizeEmitter.h"
>>> +#include "llvm/Constant.h"
>>> +#include "llvm/Constants.h"
>>> +#include "llvm/DerivedTypes.h"
>>> +#include "llvm/Module.h"
>>> +#include "llvm/Type.h"
>>> +#include "llvm/CodeGen/MachineCodeEmitter.h"
>>> +#include "llvm/CodeGen/MachineFunction.h"
>>> +#include "llvm/CodeGen/MachineConstantPool.h"
>>> +#include "llvm/CodeGen/MachineJumpTableInfo.h"
>>> +#include "llvm/CodeGen/MachineRelocation.h"
>>> +#include "llvm/ExecutionEngine/GenericValue.h"
>>> +#include "llvm/Target/TargetData.h"
>>> +#include "llvm/Target/TargetJITInfo.h"
>>> +#include "llvm/Target/TargetMachine.h"
>>> +#include "llvm/Target/TargetOptions.h"
>>> +#include "llvm/Support/Debug.h"
>>> +#include "llvm/Support/MutexGuard.h"
>>> +#include "llvm/System/Disassembler.h"
>>> +#include "llvm/ADT/Statistic.h"
>>> +#include "llvm/System/Memory.h"
>>> +#include <algorithm>
>>> +using namespace llvm;
>>> +
>>> +
>>> +void SizeEmitter::initConstantPool(MachineConstantPool *MCP) {
>>> +  const std::vector<MachineConstantPoolEntry> &Constants
= MCP-
>>>
>>>> getConstants();
>>>>
>>> +  if (Constants.empty()) return;
>>> +
>>> +  MachineConstantPoolEntry CPE = Constants.back();
>>> +  unsigned Size = CPE.Offset;
>>> +  const Type *Ty = CPE.isMachineConstantPoolEntry()
>>> +    ? CPE.Val.MachineCPVal->getType() : CPE.Val.ConstVal- 
>>> >getType();
>>> +  Size +=
Fn->getTarget().getTargetData()->getABITypeSize(Ty);
>>> +  ConstantPoolBase = allocateSpace(Size, 1 << MCP-
>>>
>>>> getConstantPoolAlignment());
>>>>
>>> +  ConstantPool = MCP;
>>> +}
>>> +
>>> +void SizeEmitter::initJumpTableInfo(MachineJumpTableInfo *MJTI) {
>>> +  const std::vector<MachineJumpTableEntry> &JT = MJTI-
>>>
>>>> getJumpTables();
>>>>
>>> +  if (JT.empty()) return;
>>> +
>>> +  unsigned NumEntries = 0;
>>> +  for (unsigned i = 0, e = JT.size(); i != e; ++i)
>>> +    NumEntries += JT[i].MBBs.size();
>>> +
>>> +  unsigned EntrySize = MJTI->getEntrySize();
>>> +
>>> +  // Just allocate space for all the jump tables now.  We will fix
>>> up the actual
>>> +  // MBB entries in the tables after we emit the code for each
>>> block, since then
>>> +  // we will know the final locations of the MBBs in memory.
>>> +  JumpTable = MJTI;
>>> +  JumpTableBase = allocateSpace(NumEntries * EntrySize, MJTI-
>>>
>>>> getAlignment());
>>>>
>>> +}
>>> +
>>> +intptr_t SizeEmitter::getConstantPoolEntryAddress(unsigned
>>> ConstantNum) const {
>>> +  assert(ConstantNum < ConstantPool->getConstants().size()
&&
>>> +         "Invalid ConstantPoolIndex!");
>>> +  return (intptr_t)ConstantPoolBase +
>>> +         ConstantPool->getConstants()[ConstantNum].Offset;
>>> +}
>>> +
>>> +intptr_t SizeEmitter::getJumpTableEntryAddress(unsigned Index)
>>> const {
>>> +  const std::vector<MachineJumpTableEntry> &JT =
JumpTable-
>>>
>>>> getJumpTables();
>>>>
>>> +  assert(Index < JT.size() && "Invalid jump table
index!");
>>> +
>>> +  unsigned Offset = 0;
>>> +  unsigned EntrySize = JumpTable->getEntrySize();
>>> +
>>> +  for (unsigned i = 0; i < Index; ++i)
>>> +    Offset += JT[i].MBBs.size();
>>> +
>>> +   Offset *= EntrySize;
>>> +
>>> +  return (intptr_t)((char *)JumpTableBase + Offset);
>>> +}
>>> +
>>> Index: lib/Target/TargetMachine.cpp
>>>
==================================================================>>>
--- lib/Target/TargetMachine.cpp	(revision 48143)
>>> +++ lib/Target/TargetMachine.cpp	(working copy)
>>> @@ -31,6 +31,7 @@
>>>  bool UseSoftFloat;
>>>  bool NoZerosInBSS;
>>>  bool ExceptionHandling;
>>> +  bool SizedMemoryCode;
>>>  Reloc::Model RelocationModel;
>>>  CodeModel::Model CMModel;
>>>  bool PerformTailCallOpt;
>>> Index: lib/ExecutionEngine/JIT/JITEmitter.cpp
>>>
==================================================================>>>
--- lib/ExecutionEngine/JIT/JITEmitter.cpp	(revision 48143)
>>> +++ lib/ExecutionEngine/JIT/JITEmitter.cpp	(working copy)
>>> @@ -18,12 +18,14 @@
>>> #include "llvm/Constant.h"
>>> #include "llvm/Module.h"
>>> #include "llvm/Type.h"
>>> +#include "llvm/ADT/DenseMap.h"
>>> #include "llvm/CodeGen/MachineCodeEmitter.h"
>>> #include "llvm/CodeGen/MachineFunction.h"
>>> #include "llvm/CodeGen/MachineConstantPool.h"
>>> #include "llvm/CodeGen/MachineJumpTableInfo.h"
>>> #include "llvm/CodeGen/MachineModuleInfo.h"
>>> #include "llvm/CodeGen/MachineRelocation.h"
>>> +#include "llvm/CodeGen/SizeEmitter.h"
>>> #include "llvm/ExecutionEngine/JITMemoryManager.h"
>>> #include "llvm/Target/TargetData.h"
>>> #include "llvm/Target/TargetJITInfo.h"
>>> @@ -370,6 +376,7 @@
>>>    virtual void startFunction(MachineFunction &F);
>>>    virtual bool finishFunction(MachineFunction &F);
>>>
>>> +    void initConstantPool(MachineConstantPool *MCP);
>>>    void emitConstantPool(MachineConstantPool *MCP);
>>>    void initJumpTableInfo(MachineJumpTableInfo *MJTI);
>>>    void emitJumpTableInfo(MachineJumpTableInfo *MJTI);
>>> @@ -469,19 +476,47 @@
>>>
>>>
>>> void JITEmitter::startFunction(MachineFunction &F) {
>>> -  uintptr_t ActualSize;
>>> -  BufferBegin = CurBufferPtr = MemMgr-
>>>
>>>> startFunctionBody(F.getFunction(),
>>>>
>>> -                                                          
>>> ActualSize);
>>> -  BufferEnd = BufferBegin+ActualSize;
>>> +  MMI->BeginFunction(&F);
>>>
>>> -  // Ensure the constant pool/jump table info is at least 4-byte
>>> aligned.
>>> -  emitAlignment(16);
>>> +  if (SizedMemoryCode) {
>>> +    BufferBegin = CurBufferPtr;
>>> +    BufferEnd = (unsigned char*) 0xffffffff;
>>> +
>>> +    // Ensure the constant pool/jump table info is at least 4-byte
>>> aligned.
>>> +    emitAlignment(16);
>>>
>>> -  emitConstantPool(F.getConstantPool());
>>> -  initJumpTableInfo(F.getJumpTableInfo());
>>> +    initConstantPool(F.getConstantPool());
>>> +    initJumpTableInfo(F.getJumpTableInfo());
>>> +
>>> +
>>> +    uintptr_t ActualSize = (uintptr_t)CurBufferPtr;
>>> +    CurBufferPtr = MemMgr->startFunctionBody(F.getFunction(),
>>> +                                             ActualSize);
>>> +
>>> +    ConstantPoolBase  = (void*)(((unsigned) ConstantPoolBase) +
>>> CurBufferPtr);
>>> +    JumpTableBase     = (void*)(((unsigned) JumpTableBase) +
>>> CurBufferPtr);
>>>
>>> -  // About to start emitting the machine code for the function.
>>> -  emitAlignment(std::max(F.getFunction()->getAlignment(), 8U));
>>> +    emitConstantPool(F.getConstantPool());
>>> +
>>> +  } else {
>>> +    uintptr_t ActualSize;
>>> +    BufferBegin = CurBufferPtr = MemMgr-
>>>
>>>> startFunctionBody(F.getFunction(),
>>>>
>>> +
>>> ActualSize);
>>> +    BufferEnd = BufferBegin+ActualSize;
>>> +
>>> +    // Ensure the constant pool/jump table info is at least 4-byte
>>> aligned.
>>> +    emitAlignment(16);
>>> +
>>> +    initConstantPool(F.getConstantPool());
>>> +    emitConstantPool(F.getConstantPool());
>>> +    initJumpTableInfo(F.getJumpTableInfo());
>>> +
>>> +    // About to start emitting the machine code for the function.
>>> +    emitAlignment(std::max(F.getFunction()->getAlignment(),
8U));
>>> +
>>> +  }
>>> +
>>> +
>>>  TheJIT->updateGlobalMapping(F.getFunction(), CurBufferPtr);
>>>
>>>  MBBLocations.clear();
>>> @@ -579,12 +614,18 @@
>>>    DOUT << "Disassembled code:\n"
>>>         << sys::disassembleBuffer(FnStart, FnEnd-FnStart,
>>> (uintptr_t)FnStart);
>>> #endif
>>> +
>>>  if (ExceptionHandling) {
>>>    uintptr_t ActualSize;
>>> +    if (SizedMemoryCode) {
>>> +      SizeEmitter sz(LabelLocations);
>>> +      DE->EmitDwarfTable(F, sz, FnStart, FnEnd);
>>> +      ActualSize = sz.getCurrentPCValue();
>>> +    }
>>>    SavedBufferBegin = BufferBegin;
>>>    SavedBufferEnd = BufferEnd;
>>>    SavedCurBufferPtr = CurBufferPtr;
>>> -
>>> +
>>>    BufferBegin = CurBufferPtr = MemMgr-
>>>
>>>> startExceptionTable(F.getFunction(),
>>>>
>>>
>>> ActualSize);
>>>    BufferEnd = BufferBegin+ActualSize;
>>> @@ -598,11 +639,10 @@
>>>    TheJIT->RegisterTable(FrameRegister);
>>>  }
>>>  MMI->EndFunction();
>>> -
>>>  return false;
>>> }
>>>
>>> -void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
>>> +void JITEmitter::initConstantPool(MachineConstantPool *MCP) {
>>>  const std::vector<MachineConstantPoolEntry> &Constants =
MCP-
>>>
>>>> getConstants();
>>>>
>>>  if (Constants.empty()) return;
>>>
>>> @@ -611,12 +651,15 @@
>>>  const Type *Ty = CPE.isMachineConstantPoolEntry()
>>>    ? CPE.Val.MachineCPVal->getType() :
CPE.Val.ConstVal->getType();
>>>  Size += TheJIT->getTargetData()->getABITypeSize(Ty);
>>> -
>>> +
>>>  ConstantPoolBase = allocateSpace(Size, 1 << MCP-
>>>
>>>> getConstantPoolAlignment());
>>>>
>>>  ConstantPool = MCP;
>>> +}
>>>
>>> +void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
>>>  if (ConstantPoolBase == 0) return;  // Buffer overflow.
>>>
>>> +  const std::vector<MachineConstantPoolEntry> &Constants
= MCP-
>>>
>>>> getConstants();
>>>>
>>>  // Initialize the memory for all of the constant pool entries.
>>>  for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
>>>    void *CAddr = (char*)ConstantPoolBase+Constants[i].Offset;
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

Nicolas Geoffray

2008-Apr-04 12:50 UTC

head link

[LLVMdev] Being able to know the jitted code-size before emitting

Evan Cheng wrote:> On Apr 1, 2008, at 12:50 AM, Nicolas Geoffray wrote:
>   
>
> That's a hack. :-) 
It is if you think that code emitter should only be used for actually 
writing somewhere the data. It is not if you find it another useful 
utility ;-)
> Some targets already have ways to compute the exact  
> size of a function. See ARM::GetFunctionSize() ARM::GetInstSize(). I'd
> like to see them standardized (all targets that have JIT support can  
> accurately calculate the function / instruction sizes) and then you  
> can make use of that.
>   
OK, I see. However this requires to do this to all targets. In my 
solution, it works for all targets, is not very intrusive and requires 
fewer code, hence introduces fewer bugs ;-)
>
> Suppose you have the size, can't you pass the desired buffer size to  
> MachineCodeEmitter and have it do the right thing? 
Sure, that's what I'm doing. The emitter with the SizeEmitter class will
give the accurate size to the MachineCodeEmitter. And the 
MachineCodeEmitter will emit the instructions in the buffer.

My solution is surely using things in a way that wasn't intended, but it 
works fine and for all targets. Is this really a stopper for integrating 
it? (You can see here my laziness on implementing the GetFunctionSize to 
every targets :)).

Nicolas
> It seems like you  
> can add the functionality to MachineCodeEmitter rather than add a new  
> class for it.
>
> Evan
>
>   
>> Nicolas
>>     
>>> Thanks,
>>>
>>> Evan
>>>
>>> On Mar 30, 2008, at 12:05 PM, Nicolas Geoffray wrote:
>>>
>>>
>>>       
>>>> Hi everyone,
>>>>
>>>> vmkit requires to know the size of a jitted method before
emitting
>>>> the method. This allows to allocate the correct size for the
method.
>>>> The attached patch creates this functionality when the flag
>>>> SizedMemoryCode is on.
>>>>
>>>> In order to implement this functionality, i had to virtualize
some
>>>> MachineCodeEmitter functions.
>>>>
>>>> Is it OK to commit the patch?
>>>>
>>>> Thanks,
>>>> Nicolas
>>>> Index: include/llvm/Target/TargetOptions.h
>>>>
==================================================================>>>>
--- include/llvm/Target/TargetOptions.h (revision 48944)
>>>> +++ include/llvm/Target/TargetOptions.h (working copy)
>>>> @@ -74,6 +74,10 @@
>>>>  /// be emitted.
>>>>  extern bool ExceptionHandling;
>>>>
>>>> +  /// SizedMemoryCode - This flags indicates that memory for
code
>>>> is allocated by
>>>> +  /// an external allocator which requires the size to
allocate
>>>> +  extern bool SizedMemoryCode;
>>>> +
>>>>  /// PerformTailCallOpt - This flag is enabled when
-tailcallopt is
>>>> specified
>>>>  /// on the commandline. When the flag is on, the target will
>>>> perform tail call
>>>>  /// optimization (pop the caller's stack) providing it
supports it.
>>>> Index: include/llvm/CodeGen/SizeEmitter.h
>>>>
==================================================================>>>>
--- include/llvm/CodeGen/SizeEmitter.h	(revision 0)
>>>> +++ include/llvm/CodeGen/SizeEmitter.h	(revision 0)
>>>> @@ -0,0 +1,116 @@
>>>> +//===-- llvm/CodeGen/MachineCodeEmitter.h - Code emission
-------*-
>>>> C++ -*-===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file was developed by the LLVM research group and is
>>>> distributed under
>>>> +// the University of Illinois Open Source License. See
LICENSE.TXT
>>>> for details.
>>>> +//
>>>> +//
>>>> >>>> >>>> >>>>
---------------------------------------------------------------------->>>>
==//
>>>> +//
>>>> +// This file defines an abstract interface that is used by the
>>>> machine code
>>>> +// emission framework to output the code.  This allows machine
code
>>>> emission to
>>>> +// be separated from concerns such as resolution of call
targets,
>>>> and where the
>>>> +// machine code will be written (memory or disk, f.e.).
>>>> +//
>>>> +//
>>>> >>>> >>>> >>>>
---------------------------------------------------------------------->>>>
==//
>>>> +
>>>> +#ifndef LLVM_CODEGEN_SIZEEMITTER_H
>>>> +#define LLVM_CODEGEN_SIZEEMITTER_H
>>>> +
>>>> +#include "llvm/CodeGen/MachineCodeEmitter.h"
>>>> +#include "llvm/CodeGen/MachineFunction.h"
>>>> +
>>>> +namespace llvm {
>>>> +  /// SizeEmitter - The JIT implementation of the
>>>> MachineCodeEmitter, which is
>>>> +  /// used to output functions to memory for execution.
>>>> +class SizeEmitter : public MachineCodeEmitter {
>>>> +  MachineFunction * Fn;
>>>> +  void* ConstantPoolBase;
>>>> +  void* JumpTableBase;
>>>> +  MachineConstantPool *ConstantPool;
>>>> +  MachineJumpTableInfo *JumpTable;
>>>> +  std::vector<intptr_t> LabelLocations;
>>>> +  MachineCodeEmitter* MCE;
>>>> +
>>>> +public:
>>>> +  SizeEmitter(MachineCodeEmitter* mce) {
>>>> +    CurBufferPtr = 0;
>>>> +    BufferBegin = 0;
>>>> +    BufferEnd = (unsigned char*)-1;
>>>> +    MCE = mce;
>>>> +  }
>>>> +
>>>> +  SizeEmitter(std::vector<intptr_t> locations) {
>>>> +    LabelLocations = locations;
>>>> +    CurBufferPtr = 0;
>>>> +    BufferBegin = 0;
>>>> +    BufferEnd = (unsigned char*)-1;
>>>> +  }
>>>> +
>>>> +  void initConstantPool(MachineConstantPool *MCP);
>>>> +
>>>> +  void initJumpTableInfo(MachineJumpTableInfo *MJTI);
>>>> +
>>>> +
>>>> +  virtual void startFunction(MachineFunction &F) {
>>>> +    CurBufferPtr = 0;
>>>> +    Fn = &F;
>>>> +
>>>> +    // Ensure the constant pool/jump table info is at least
4-byte
>>>> aligned.
>>>> +    emitAlignment(16);
>>>> +
>>>> +    initConstantPool(F.getConstantPool());
>>>> +    initJumpTableInfo(F.getJumpTableInfo());
>>>> +
>>>> +    ConstantPoolBase  = (void*)(((uintptr_t) ConstantPoolBase)
+
>>>> CurBufferPtr);
>>>> +    JumpTableBase     = (void*)(((uintptr_t) JumpTableBase) +
>>>> CurBufferPtr);
>>>> +  }
>>>> +
>>>> +  virtual bool finishFunction(MachineFunction &F) {
>>>> +    MCE->setCurrentPtr(CurBufferPtr);
>>>> +    return false;
>>>> +  }
>>>> +  virtual void startFunctionStub(unsigned StubSize, unsigned
>>>> Alignment) {}
>>>> +  virtual void *finishFunctionStub(const Function *F) { return
0; }
>>>> +  virtual void addRelocation(const
llvm::MachineRelocation&) { }
>>>> +  virtual void emitByte(unsigned char B) {
>>>> +    CurBufferPtr++;
>>>> +  }
>>>> +  virtual void emitWordLE(unsigned W) {
>>>> +    CurBufferPtr+=4;
>>>> +  }
>>>> +  virtual void emitWordBE(unsigned W) {
>>>> +    CurBufferPtr+=4;
>>>> +  }
>>>> +  virtual void emitInt32(int Value) {
>>>> +    CurBufferPtr += 4;
>>>> +  }
>>>> +  virtual void emitInt64(uint64_t Value) {
>>>> +    CurBufferPtr += 8;
>>>> +  }
>>>> +  virtual void emitAt(uintptr_t *Addr, uintptr_t Value) {
>>>> +  }
>>>> +
>>>> +
>>>> +
>>>> +  virtual void StartMachineBasicBlock(MachineBasicBlock *MBB)
{}
>>>> +  virtual intptr_t getConstantPoolEntryAddress(unsigned
>>>> ConstantNum) const;
>>>> +
>>>> +  virtual intptr_t getJumpTableEntryAddress(unsigned Index)
const;
>>>> +
>>>> +  virtual intptr_t
getMachineBasicBlockAddress(MachineBasicBlock
>>>> *MBB) const {
>>>> +    assert(0 && "Should not be in
getMachineBasicBlockAddress of
>>>> SizeEmitter");
>>>> +  }
>>>> +
>>>> +  virtual void emitLabel(uint64_t) {}
>>>> +  virtual intptr_t getLabelAddress(uint64_t LabelID) const {
>>>> +    assert(LabelLocations.size() > (unsigned)LabelID
&&
>>>> +             LabelLocations[LabelID] && "Label
not emitted!");
>>>> +      return LabelLocations[LabelID];
>>>> +  }
>>>> +  virtual void setModuleInfo(llvm::MachineModuleInfo*) {}
>>>> +};
>>>> +
>>>> +} // end llvm namespace
>>>> +
>>>> +#endif
>>>> Index: include/llvm/CodeGen/MachineCodeEmitter.h
>>>>
==================================================================>>>>
--- include/llvm/CodeGen/MachineCodeEmitter.h	(revision 48143)
>>>> +++ include/llvm/CodeGen/MachineCodeEmitter.h	(working copy)
>>>> @@ -18,6 +18,7 @@
>>>> #define LLVM_CODEGEN_MACHINECODEEMITTER_H
>>>>
>>>> #include "llvm/Support/DataTypes.h"
>>>> +#include <string>
>>>> #include <vector>
>>>>
>>>> namespace llvm {
>>>> @@ -92,7 +93,7 @@
>>>>  /// emitByte - This callback is invoked when a byte needs to
be
>>>> written to the
>>>>  /// output stream.
>>>>  ///
>>>> -  void emitByte(unsigned char B) {
>>>> +  virtual void emitByte(unsigned char B) {
>>>>    if (CurBufferPtr != BufferEnd)
>>>>      *CurBufferPtr++ = B;
>>>>  }
>>>> @@ -100,7 +101,7 @@
>>>>  /// emitWordLE - This callback is invoked when a 32-bit word
needs
>>>> to be
>>>>  /// written to the output stream in little-endian format.
>>>>  ///
>>>> -  void emitWordLE(unsigned W) {
>>>> +  virtual void emitWordLE(unsigned W) {
>>>>    if (CurBufferPtr+4 <= BufferEnd) {
>>>>      *CurBufferPtr++ = (unsigned char)(W >>  0);
>>>>      *CurBufferPtr++ = (unsigned char)(W >>  8);
>>>> @@ -114,7 +115,7 @@
>>>>  /// emitWordBE - This callback is invoked when a 32-bit word
needs
>>>> to be
>>>>  /// written to the output stream in big-endian format.
>>>>  ///
>>>> -  void emitWordBE(unsigned W) {
>>>> +  virtual void emitWordBE(unsigned W) {
>>>>    if (CurBufferPtr+4 <= BufferEnd) {
>>>>      *CurBufferPtr++ = (unsigned char)(W >> 24);
>>>>      *CurBufferPtr++ = (unsigned char)(W >> 16);
>>>> @@ -175,7 +176,7 @@
>>>>  }
>>>>
>>>>  /// emitInt32 - Emit a int32 directive.
>>>> -  void emitInt32(int Value) {
>>>> +  virtual void emitInt32(int Value) {
>>>>    if (CurBufferPtr+4 <= BufferEnd) {
>>>>      *((uint32_t*)CurBufferPtr) = Value;
>>>>      CurBufferPtr += 4;
>>>> @@ -185,7 +186,7 @@
>>>>  }
>>>>
>>>>  /// emitInt64 - Emit a int64 directive.
>>>> -  void emitInt64(uint64_t Value) {
>>>> +  virtual void emitInt64(uint64_t Value) {
>>>>    if (CurBufferPtr+8 <= BufferEnd) {
>>>>      *((uint64_t*)CurBufferPtr) = Value;
>>>>      CurBufferPtr += 8;
>>>> @@ -195,7 +196,7 @@
>>>>  }
>>>>
>>>>  /// emitAt - Emit Value in Addr
>>>> -  void emitAt(uintptr_t *Addr, uintptr_t Value) {
>>>> +  virtual void emitAt(uintptr_t *Addr, uintptr_t Value) {
>>>>    if (Addr >= (uintptr_t*)BufferBegin && Addr <
>>>> (uintptr_t*)BufferEnd)
>>>>      (*Addr) = Value;
>>>>  }
>>>> @@ -270,6 +271,11 @@
>>>>  /// Specifies the MachineModuleInfo object. This is used for
>>>> exception handling
>>>>  /// purposes.
>>>>  virtual void setModuleInfo(MachineModuleInfo* Info) = 0;
>>>> +
>>>> +  void setCurrentPtr(unsigned char* Ptr) {
>>>> +    CurBufferPtr = Ptr;
>>>> +  }
>>>> +
>>>> };
>>>>
>>>> } // End llvm namespace
>>>> Index: lib/CodeGen/LLVMTargetMachine.cpp
>>>>
==================================================================>>>>
--- lib/CodeGen/LLVMTargetMachine.cpp	(revision 48143)
>>>> +++ lib/CodeGen/LLVMTargetMachine.cpp	(working copy)
>>>> @@ -17,6 +17,7 @@
>>>> #include "llvm/Assembly/PrintModulePass.h"
>>>> #include "llvm/Analysis/LoopPass.h"
>>>> #include "llvm/CodeGen/Passes.h"
>>>> +#include "llvm/CodeGen/SizeEmitter.h"
>>>> #include "llvm/CodeGen/Collector.h"
>>>> #include "llvm/Target/TargetOptions.h"
>>>> #include "llvm/Transforms/Scalar.h"
>>>> @@ -257,7 +258,13 @@
>>>>
>>>>  if (addPreEmitPass(PM, Fast) && PrintMachineCode)
>>>>    PM.add(createMachineFunctionPrinterPass(cerr));
>>>> +
>>>> +  if (SizedMemoryCode) {
>>>> +    SizeEmitter * SE = new SizeEmitter(&MCE);
>>>> +    addSimpleCodeEmitter(PM, Fast, false, *SE);
>>>> +  }
>>>>
>>>> +
>>>>  addCodeEmitter(PM, Fast, PrintEmittedAsm, MCE);
>>>>
>>>>  PM.add(createCollectorMetadataDeleter());
>>>> Index: lib/CodeGen/SizeEmitter.cpp
>>>>
==================================================================>>>>
--- lib/CodeGen/SizeEmitter.cpp	(revision 0)
>>>> +++ lib/CodeGen/SizeEmitter.cpp	(revision 0)
>>>> @@ -0,0 +1,77 @@
>>>> +#include "llvm/CodeGen/SizeEmitter.h"
>>>> +#include "llvm/Constant.h"
>>>> +#include "llvm/Constants.h"
>>>> +#include "llvm/DerivedTypes.h"
>>>> +#include "llvm/Module.h"
>>>> +#include "llvm/Type.h"
>>>> +#include "llvm/CodeGen/MachineCodeEmitter.h"
>>>> +#include "llvm/CodeGen/MachineFunction.h"
>>>> +#include "llvm/CodeGen/MachineConstantPool.h"
>>>> +#include "llvm/CodeGen/MachineJumpTableInfo.h"
>>>> +#include "llvm/CodeGen/MachineRelocation.h"
>>>> +#include "llvm/ExecutionEngine/GenericValue.h"
>>>> +#include "llvm/Target/TargetData.h"
>>>> +#include "llvm/Target/TargetJITInfo.h"
>>>> +#include "llvm/Target/TargetMachine.h"
>>>> +#include "llvm/Target/TargetOptions.h"
>>>> +#include "llvm/Support/Debug.h"
>>>> +#include "llvm/Support/MutexGuard.h"
>>>> +#include "llvm/System/Disassembler.h"
>>>> +#include "llvm/ADT/Statistic.h"
>>>> +#include "llvm/System/Memory.h"
>>>> +#include <algorithm>
>>>> +using namespace llvm;
>>>> +
>>>> +
>>>> +void SizeEmitter::initConstantPool(MachineConstantPool *MCP) {
>>>> +  const std::vector<MachineConstantPoolEntry>
&Constants = MCP-
>>>>
>>>>         
>>>>> getConstants();
>>>>>
>>>>>           
>>>> +  if (Constants.empty()) return;
>>>> +
>>>> +  MachineConstantPoolEntry CPE = Constants.back();
>>>> +  unsigned Size = CPE.Offset;
>>>> +  const Type *Ty = CPE.isMachineConstantPoolEntry()
>>>> +    ? CPE.Val.MachineCPVal->getType() : CPE.Val.ConstVal- 
>>>>         
>>>>> getType();
>>>>>           
>>>> +  Size +=
Fn->getTarget().getTargetData()->getABITypeSize(Ty);
>>>> +  ConstantPoolBase = allocateSpace(Size, 1 << MCP-
>>>>
>>>>         
>>>>> getConstantPoolAlignment());
>>>>>
>>>>>           
>>>> +  ConstantPool = MCP;
>>>> +}
>>>> +
>>>> +void SizeEmitter::initJumpTableInfo(MachineJumpTableInfo
*MJTI) {
>>>> +  const std::vector<MachineJumpTableEntry> &JT =
MJTI-
>>>>
>>>>         
>>>>> getJumpTables();
>>>>>
>>>>>           
>>>> +  if (JT.empty()) return;
>>>> +
>>>> +  unsigned NumEntries = 0;
>>>> +  for (unsigned i = 0, e = JT.size(); i != e; ++i)
>>>> +    NumEntries += JT[i].MBBs.size();
>>>> +
>>>> +  unsigned EntrySize = MJTI->getEntrySize();
>>>> +
>>>> +  // Just allocate space for all the jump tables now.  We will
fix
>>>> up the actual
>>>> +  // MBB entries in the tables after we emit the code for each
>>>> block, since then
>>>> +  // we will know the final locations of the MBBs in memory.
>>>> +  JumpTable = MJTI;
>>>> +  JumpTableBase = allocateSpace(NumEntries * EntrySize, MJTI-
>>>>
>>>>         
>>>>> getAlignment());
>>>>>
>>>>>           
>>>> +}
>>>> +
>>>> +intptr_t SizeEmitter::getConstantPoolEntryAddress(unsigned
>>>> ConstantNum) const {
>>>> +  assert(ConstantNum <
ConstantPool->getConstants().size() &&
>>>> +         "Invalid ConstantPoolIndex!");
>>>> +  return (intptr_t)ConstantPoolBase +
>>>> +         ConstantPool->getConstants()[ConstantNum].Offset;
>>>> +}
>>>> +
>>>> +intptr_t SizeEmitter::getJumpTableEntryAddress(unsigned Index)
>>>> const {
>>>> +  const std::vector<MachineJumpTableEntry> &JT =
JumpTable-
>>>>
>>>>         
>>>>> getJumpTables();
>>>>>
>>>>>           
>>>> +  assert(Index < JT.size() && "Invalid jump
table index!");
>>>> +
>>>> +  unsigned Offset = 0;
>>>> +  unsigned EntrySize = JumpTable->getEntrySize();
>>>> +
>>>> +  for (unsigned i = 0; i < Index; ++i)
>>>> +    Offset += JT[i].MBBs.size();
>>>> +
>>>> +   Offset *= EntrySize;
>>>> +
>>>> +  return (intptr_t)((char *)JumpTableBase + Offset);
>>>> +}
>>>> +
>>>> Index: lib/Target/TargetMachine.cpp
>>>>
==================================================================>>>>
--- lib/Target/TargetMachine.cpp	(revision 48143)
>>>> +++ lib/Target/TargetMachine.cpp	(working copy)
>>>> @@ -31,6 +31,7 @@
>>>>  bool UseSoftFloat;
>>>>  bool NoZerosInBSS;
>>>>  bool ExceptionHandling;
>>>> +  bool SizedMemoryCode;
>>>>  Reloc::Model RelocationModel;
>>>>  CodeModel::Model CMModel;
>>>>  bool PerformTailCallOpt;
>>>> Index: lib/ExecutionEngine/JIT/JITEmitter.cpp
>>>>
==================================================================>>>>
--- lib/ExecutionEngine/JIT/JITEmitter.cpp	(revision 48143)
>>>> +++ lib/ExecutionEngine/JIT/JITEmitter.cpp	(working copy)
>>>> @@ -18,12 +18,14 @@
>>>> #include "llvm/Constant.h"
>>>> #include "llvm/Module.h"
>>>> #include "llvm/Type.h"
>>>> +#include "llvm/ADT/DenseMap.h"
>>>> #include "llvm/CodeGen/MachineCodeEmitter.h"
>>>> #include "llvm/CodeGen/MachineFunction.h"
>>>> #include "llvm/CodeGen/MachineConstantPool.h"
>>>> #include "llvm/CodeGen/MachineJumpTableInfo.h"
>>>> #include "llvm/CodeGen/MachineModuleInfo.h"
>>>> #include "llvm/CodeGen/MachineRelocation.h"
>>>> +#include "llvm/CodeGen/SizeEmitter.h"
>>>> #include "llvm/ExecutionEngine/JITMemoryManager.h"
>>>> #include "llvm/Target/TargetData.h"
>>>> #include "llvm/Target/TargetJITInfo.h"
>>>> @@ -370,6 +376,7 @@
>>>>    virtual void startFunction(MachineFunction &F);
>>>>    virtual bool finishFunction(MachineFunction &F);
>>>>
>>>> +    void initConstantPool(MachineConstantPool *MCP);
>>>>    void emitConstantPool(MachineConstantPool *MCP);
>>>>    void initJumpTableInfo(MachineJumpTableInfo *MJTI);
>>>>    void emitJumpTableInfo(MachineJumpTableInfo *MJTI);
>>>> @@ -469,19 +476,47 @@
>>>>
>>>>
>>>> void JITEmitter::startFunction(MachineFunction &F) {
>>>> -  uintptr_t ActualSize;
>>>> -  BufferBegin = CurBufferPtr = MemMgr-
>>>>
>>>>         
>>>>> startFunctionBody(F.getFunction(),
>>>>>
>>>>>           
>>>> -                                                          
>>>> ActualSize);
>>>> -  BufferEnd = BufferBegin+ActualSize;
>>>> +  MMI->BeginFunction(&F);
>>>>
>>>> -  // Ensure the constant pool/jump table info is at least
4-byte
>>>> aligned.
>>>> -  emitAlignment(16);
>>>> +  if (SizedMemoryCode) {
>>>> +    BufferBegin = CurBufferPtr;
>>>> +    BufferEnd = (unsigned char*) 0xffffffff;
>>>> +
>>>> +    // Ensure the constant pool/jump table info is at least
4-byte
>>>> aligned.
>>>> +    emitAlignment(16);
>>>>
>>>> -  emitConstantPool(F.getConstantPool());
>>>> -  initJumpTableInfo(F.getJumpTableInfo());
>>>> +    initConstantPool(F.getConstantPool());
>>>> +    initJumpTableInfo(F.getJumpTableInfo());
>>>> +
>>>> +
>>>> +    uintptr_t ActualSize = (uintptr_t)CurBufferPtr;
>>>> +    CurBufferPtr =
MemMgr->startFunctionBody(F.getFunction(),
>>>> +                                             ActualSize);
>>>> +
>>>> +    ConstantPoolBase  = (void*)(((unsigned) ConstantPoolBase)
+
>>>> CurBufferPtr);
>>>> +    JumpTableBase     = (void*)(((unsigned) JumpTableBase) +
>>>> CurBufferPtr);
>>>>
>>>> -  // About to start emitting the machine code for the
function.
>>>> -  emitAlignment(std::max(F.getFunction()->getAlignment(),
8U));
>>>> +    emitConstantPool(F.getConstantPool());
>>>> +
>>>> +  } else {
>>>> +    uintptr_t ActualSize;
>>>> +    BufferBegin = CurBufferPtr = MemMgr-
>>>>
>>>>         
>>>>> startFunctionBody(F.getFunction(),
>>>>>
>>>>>           
>>>> +
>>>> ActualSize);
>>>> +    BufferEnd = BufferBegin+ActualSize;
>>>> +
>>>> +    // Ensure the constant pool/jump table info is at least
4-byte
>>>> aligned.
>>>> +    emitAlignment(16);
>>>> +
>>>> +    initConstantPool(F.getConstantPool());
>>>> +    emitConstantPool(F.getConstantPool());
>>>> +    initJumpTableInfo(F.getJumpTableInfo());
>>>> +
>>>> +    // About to start emitting the machine code for the
function.
>>>> +    emitAlignment(std::max(F.getFunction()->getAlignment(),
8U));
>>>> +
>>>> +  }
>>>> +
>>>> +
>>>>  TheJIT->updateGlobalMapping(F.getFunction(), CurBufferPtr);
>>>>
>>>>  MBBLocations.clear();
>>>> @@ -579,12 +614,18 @@
>>>>    DOUT << "Disassembled code:\n"
>>>>         << sys::disassembleBuffer(FnStart, FnEnd-FnStart,
>>>> (uintptr_t)FnStart);
>>>> #endif
>>>> +
>>>>  if (ExceptionHandling) {
>>>>    uintptr_t ActualSize;
>>>> +    if (SizedMemoryCode) {
>>>> +      SizeEmitter sz(LabelLocations);
>>>> +      DE->EmitDwarfTable(F, sz, FnStart, FnEnd);
>>>> +      ActualSize = sz.getCurrentPCValue();
>>>> +    }
>>>>    SavedBufferBegin = BufferBegin;
>>>>    SavedBufferEnd = BufferEnd;
>>>>    SavedCurBufferPtr = CurBufferPtr;
>>>> -
>>>> +
>>>>    BufferBegin = CurBufferPtr = MemMgr-
>>>>
>>>>         
>>>>> startExceptionTable(F.getFunction(),
>>>>>
>>>>>           
>>>> ActualSize);
>>>>    BufferEnd = BufferBegin+ActualSize;
>>>> @@ -598,11 +639,10 @@
>>>>    TheJIT->RegisterTable(FrameRegister);
>>>>  }
>>>>  MMI->EndFunction();
>>>> -
>>>>  return false;
>>>> }
>>>>
>>>> -void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
>>>> +void JITEmitter::initConstantPool(MachineConstantPool *MCP) {
>>>>  const std::vector<MachineConstantPoolEntry>
&Constants = MCP-
>>>>
>>>>         
>>>>> getConstants();
>>>>>
>>>>>           
>>>>  if (Constants.empty()) return;
>>>>
>>>> @@ -611,12 +651,15 @@
>>>>  const Type *Ty = CPE.isMachineConstantPoolEntry()
>>>>    ? CPE.Val.MachineCPVal->getType() :
CPE.Val.ConstVal->getType();
>>>>  Size += TheJIT->getTargetData()->getABITypeSize(Ty);
>>>> -
>>>> +
>>>>  ConstantPoolBase = allocateSpace(Size, 1 << MCP-
>>>>
>>>>         
>>>>> getConstantPoolAlignment());
>>>>>
>>>>>           
>>>>  ConstantPool = MCP;
>>>> +}
>>>>
>>>> +void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
>>>>  if (ConstantPoolBase == 0) return;  // Buffer overflow.
>>>>
>>>> +  const std::vector<MachineConstantPoolEntry>
&Constants = MCP-
>>>>
>>>>         
>>>>> getConstants();
>>>>>
>>>>>           
>>>>  // Initialize the memory for all of the constant pool entries.
>>>>  for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
>>>>    void *CAddr = (char*)ConstantPoolBase+Constants[i].Offset;
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>>         
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>>       
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>     
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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