| /* |
| * Copyright 2010, The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef BCC_CODEMEMORYMANAGER_H |
| #define BCC_CODEMEMORYMANAGER_H |
| |
| #include "Compiler.h" |
| |
| #include "llvm/ExecutionEngine/JITMemoryManager.h" |
| |
| #include <map> |
| #include <utility> |
| |
| #include <assert.h> |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| |
| namespace llvm { |
| // Forward Declaration |
| class Function; |
| class GlobalValue; |
| }; |
| |
| |
| namespace bcc { |
| |
| ////////////////////////////////////////////////////////////////////////////// |
| // Memory manager for the code reside in memory |
| // |
| // The memory for our code emitter is very simple and is conforming to the |
| // design decisions of Android RenderScript's Exection Environment: |
| // The code, data, and symbol sizes are limited (currently 100KB.) |
| // |
| // It's very different from typical compiler, which has no limitation |
| // on the code size. How does code emitter know the size of the code |
| // it is about to emit? It does not know beforehand. We want to solve |
| // this without complicating the code emitter too much. |
| // |
| // We solve this by pre-allocating a certain amount of memory, |
| // and then start the code emission. Once the buffer overflows, the emitter |
| // simply discards all the subsequent emission but still has a counter |
| // on how many bytes have been emitted. |
| // |
| // So once the whole emission is done, if there's a buffer overflow, |
| // it re-allocates the buffer with enough size (based on the |
| // counter from previous emission) and re-emit again. |
| |
| extern const unsigned int MaxCodeSize; |
| extern const unsigned int MaxGOTSize; |
| extern const unsigned int MaxGlobalVarSize; |
| |
| |
| class CodeMemoryManager : public llvm::JITMemoryManager { |
| private: |
| typedef std::map<const llvm::Function*, |
| std::pair<void * /* start address */, |
| void * /* end address */> > FunctionMapTy; |
| |
| |
| private: |
| // |
| // Our memory layout is as follows: |
| // |
| // The direction of arrows (-> and <-) shows memory's growth direction |
| // when more space is needed. |
| // |
| // @mpCodeMem: |
| // +--------------------------------------------------------------+ |
| // | Function Memory ... -> <- ... Stub/GOT | |
| // +--------------------------------------------------------------+ |
| // |<------------------ Total: @MaxCodeSize KiB ----------------->| |
| // |
| // Where size of GOT is @MaxGOTSize KiB. |
| // |
| // @mpGVMem: |
| // +--------------------------------------------------------------+ |
| // | Global variable ... -> | |
| // +--------------------------------------------------------------+ |
| // |<--------------- Total: @MaxGlobalVarSize KiB --------------->| |
| // |
| // |
| // @mCurFuncMemIdx: The current index (starting from 0) of the last byte |
| // of function code's memory usage |
| // @mCurSGMemIdx: The current index (starting from tail) of the last byte |
| // of stub/GOT's memory usage |
| // @mCurGVMemIdx: The current index (starting from tail) of the last byte |
| // of global variable's memory usage |
| // |
| uintptr_t mCurFuncMemIdx; |
| uintptr_t mCurSGMemIdx; |
| uintptr_t mCurGVMemIdx; |
| void *mpCodeMem; |
| void *mpGVMem; |
| |
| // GOT Base |
| uint8_t *mpGOTBase; |
| |
| FunctionMapTy mFunctionMap; |
| |
| |
| public: |
| CodeMemoryManager(); |
| |
| virtual ~CodeMemoryManager(); |
| |
| uint8_t *getCodeMemBase() const { |
| return reinterpret_cast<uint8_t*>(mpCodeMem); |
| } |
| |
| // setMemoryWritable - When code generation is in progress, the code pages |
| // may need permissions changed. |
| virtual void setMemoryWritable(); |
| |
| // When code generation is done and we're ready to start execution, the |
| // code pages may need permissions changed. |
| virtual void setMemoryExecutable(); |
| |
| // Setting this flag to true makes the memory manager garbage values over |
| // freed memory. This is useful for testing and debugging, and is to be |
| // turned on by default in debug mode. |
| virtual void setPoisonMemory(bool poison); |
| |
| |
| // Global Offset Table Management |
| |
| // If the current table requires a Global Offset Table, this method is |
| // invoked to allocate it. This method is required to set HasGOT to true. |
| virtual void AllocateGOT(); |
| |
| // If this is managing a Global Offset Table, this method should return a |
| // pointer to its base. |
| virtual uint8_t *getGOTBase() const { |
| return mpGOTBase; |
| } |
| |
| // Main Allocation Functions |
| |
| // When we start JITing a function, the JIT calls this method to allocate a |
| // block of free RWX memory, which returns a pointer to it. If the JIT wants |
| // to request a block of memory of at least a certain size, it passes that |
| // value as ActualSize, and this method returns a block with at least that |
| // much space. If the JIT doesn't know ahead of time how much space it will |
| // need to emit the function, it passes 0 for the ActualSize. In either |
| // case, this method is required to pass back the size of the allocated |
| // block through ActualSize. The JIT will be careful to not write more than |
| // the returned ActualSize bytes of memory. |
| virtual uint8_t *startFunctionBody(const llvm::Function *F, |
| uintptr_t &ActualSize); |
| |
| // This method is called by the JIT to allocate space for a function stub |
| // (used to handle limited branch displacements) while it is JIT compiling a |
| // function. For example, if foo calls bar, and if bar either needs to be |
| // lazily compiled or is a native function that exists too far away from the |
| // call site to work, this method will be used to make a thunk for it. The |
| // stub should be "close" to the current function body, but should not be |
| // included in the 'actualsize' returned by startFunctionBody. |
| virtual uint8_t *allocateStub(const llvm::GlobalValue *F, |
| unsigned StubSize, |
| unsigned Alignment) { |
| return allocateSGMemory(StubSize, Alignment); |
| } |
| |
| // This method is called when the JIT is done codegen'ing the specified |
| // function. At this point we know the size of the JIT compiled function. |
| // This passes in FunctionStart (which was returned by the startFunctionBody |
| // method) and FunctionEnd which is a pointer to the actual end of the |
| // function. This method should mark the space allocated and remember where |
| // it is in case the client wants to deallocate it. |
| virtual void endFunctionBody(const llvm::Function *F, |
| uint8_t *FunctionStart, |
| uint8_t *FunctionEnd); |
| |
| // Allocate a (function code) memory block of the given size. This method |
| // cannot be called between calls to startFunctionBody and endFunctionBody. |
| virtual uint8_t *allocateSpace(intptr_t Size, unsigned Alignment); |
| |
| // Allocate memory for a global variable. |
| virtual uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment); |
| |
| // Free the specified function body. The argument must be the return value |
| // from a call to startFunctionBody() that hasn't been deallocated yet. This |
| // is never called when the JIT is currently emitting a function. |
| virtual void deallocateFunctionBody(void *Body); |
| |
| // When we finished JITing the function, if exception handling is set, we |
| // emit the exception table. |
| virtual uint8_t *startExceptionTable(const llvm::Function *F, |
| uintptr_t &ActualSize) { |
| assert(false && "Exception is not allowed in our language specification"); |
| return NULL; |
| } |
| |
| // This method is called when the JIT is done emitting the exception table. |
| virtual void endExceptionTable(const llvm::Function *F, uint8_t *TableStart, |
| uint8_t *TableEnd, uint8_t *FrameRegister) { |
| assert(false && "Exception is not allowed in our language specification"); |
| } |
| |
| // Free the specified exception table's memory. The argument must be the |
| // return value from a call to startExceptionTable() that hasn't been |
| // deallocated yet. This is never called when the JIT is currently emitting |
| // an exception table. |
| virtual void deallocateExceptionTable(void *ET) { |
| assert(false && "Exception is not allowed in our language specification"); |
| } |
| |
| // Below are the methods we create |
| void reset(); |
| |
| |
| private: |
| intptr_t getFreeCodeMemSize() const { |
| return mCurSGMemIdx - mCurFuncMemIdx; |
| } |
| |
| uint8_t *allocateSGMemory(uintptr_t Size, |
| unsigned Alignment = 1 /* no alignment */); |
| |
| uintptr_t getFreeGVMemSize() const { |
| return MaxGlobalVarSize - mCurGVMemIdx; |
| } |
| |
| uint8_t *getGVMemBase() const { |
| return reinterpret_cast<uint8_t*>(mpGVMem); |
| } |
| |
| }; |
| |
| } // namespace bcc |
| |
| #endif // BCC_CODEMEMORYMANAGER_H |