llvm::sys::Memory Class Reference

This class provides various memory handling functions that manipulate MemoryBlock instances. More...

#include "llvm/Support/Memory.h"

Public Types
enum	ProtectionFlags {   MF_READ = 0x1000000 , MF_WRITE = 0x2000000 , MF_EXEC = 0x4000000 , MF_RWE_MASK = 0x7000000 ,   MF_HUGE_HINT = 0x0000001 }

Static Public Member Functions
static MemoryBlock	allocateMappedMemory (size_t NumBytes, const MemoryBlock *const NearBlock, unsigned Flags, std::error_code &EC)
	This method allocates a block of memory that is suitable for loading dynamically generated code (e.g.
static std::error_code	releaseMappedMemory (MemoryBlock &Block)
	This method releases a block of memory that was allocated with the allocateMappedMemory method.
static std::error_code	protectMappedMemory (const MemoryBlock &Block, unsigned Flags)
	This method sets the protection flags for a block of memory to the state specified by /p Flags.
static void	InvalidateInstructionCache (const void *Addr, size_t Len)
	InvalidateInstructionCache - Before the JIT can run a block of code that has been emitted it must invalidate the instruction cache on some platforms.

Detailed Description

This class provides various memory handling functions that manipulate MemoryBlock instances.

Since

1.4 An abstraction for memory operations.

Definition at line 52 of file Memory.h.

Member Enumeration Documentation

ProtectionFlags

enum llvm::sys::Memory::ProtectionFlags

Enumerator
MF_READ
MF_WRITE
MF_EXEC
MF_RWE_MASK
MF_HUGE_HINT	The MF_HUGE_HINT flag is used to indicate that the request for a memory block should be satisfied with large pages if possible. This is only a hint and small pages will be used as fallback. The presence or absence of this flag in the returned memory block is (at least currently) not a reliable indicator that the memory block will use or will not use large pages. On some systems a request without this flag can be backed by large pages without this flag being set, and on some other systems a request with this flag can fallback to small pages without this flag being cleared.

Definition at line 54 of file Memory.h.

Member Function Documentation

allocateMappedMemory()

static MemoryBlock llvm::sys::Memory::allocateMappedMemory ( size_t  NumBytes, const MemoryBlock *const  NearBlock, unsigned  Flags, std::error_code &  EC  )

static

This method allocates a block of memory that is suitable for loading dynamically generated code (e.g.

JIT). An attempt to allocate NumBytes bytes of virtual memory is made. NearBlock may point to an existing allocation in which case an attempt is made to allocate more memory near the existing block. The actual allocated address is not guaranteed to be near the requested address. Flags is used to set the initial protection flags for the block of the memory. EC [out] returns an object describing any error that occurs.

This method may allocate more than the number of bytes requested. The actual number of bytes allocated is indicated in the returned MemoryBlock.

The start of the allocated block must be aligned with the system allocation granularity (64K on Windows, page size on Linux). If the address following NearBlock is not so aligned, it will be rounded up to the next allocation granularity boundary.

\r a non-null MemoryBlock if the function was successful, otherwise a null MemoryBlock is with EC describing the error.

Allocate mapped memory.

Referenced by llvm::jitlink::InProcessMemoryManager::allocate(), llvm::orc::rt_bootstrap::SimpleExecutorMemoryManager::allocate(), llvm::orc::LocalIndirectStubsInfo< ORCABI >::create(), createInMemoryBuffer(), and llvm::orc::InProcessMemoryMapper::reserve().

InvalidateInstructionCache()

static void llvm::sys::Memory::InvalidateInstructionCache ( const void *  Addr, size_t  Len  )

static

InvalidateInstructionCache - Before the JIT can run a block of code that has been emitted it must invalidate the instruction cache on some platforms.

Referenced by llvm::orc::rt_bootstrap::SimpleExecutorMemoryManager::finalize(), llvm::orc::InProcessMemoryMapper::initialize(), llvm::orc::rt_bootstrap::ExecutorSharedMemoryMapperService::initialize(), and llvm::SectionMemoryManager::invalidateInstructionCache().

protectMappedMemory()

static std::error_code llvm::sys::Memory::protectMappedMemory ( const MemoryBlock &  Block, unsigned  Flags  )

static

This method sets the protection flags for a block of memory to the state specified by /p Flags.

The behavior is not specified if the memory was not allocated using the allocateMappedMemory method. Block describes the memory block to be protected. Flags specifies the new protection state to be assigned to the block.

If Flags is MF_WRITE, the actual behavior varies with the operating system (i.e. MF_READ | MF_WRITE on Windows) and the target architecture (i.e. MF_WRITE -> MF_READ | MF_WRITE on i386).

\r error_success if the function was successful, or an error_code describing the failure if an error occurred.

Set memory protection state.

Referenced by llvm::orc::LocalIndirectStubsInfo< ORCABI >::create(), llvm::orc::InProcessMemoryMapper::deinitialize(), llvm::orc::rt_bootstrap::SimpleExecutorMemoryManager::finalize(), and llvm::orc::InProcessMemoryMapper::initialize().

releaseMappedMemory()

static std::error_code llvm::sys::Memory::releaseMappedMemory ( MemoryBlock &  Block )

static

This method releases a block of memory that was allocated with the allocateMappedMemory method.

It should not be used to release any memory block allocated any other way. Block describes the memory to be released.

\r error_success if the function was successful, or an error_code describing the failure if an error occurred.

Release mapped memory.

Referenced by llvm::jitlink::InProcessMemoryManager::IPInFlightAlloc::abandon(), llvm::jitlink::InProcessMemoryManager::deallocate(), llvm::jitlink::InProcessMemoryManager::IPInFlightAlloc::finalize(), llvm::orc::rt_bootstrap::SimpleExecutorMemoryManager::finalize(), llvm::sys::OwningMemoryBlock::release(), llvm::orc::InProcessMemoryMapper::release(), and llvm::sys::OwningMemoryBlock::~OwningMemoryBlock().

---

The documentation for this class was generated from the following file:

• include/llvm/Support/Memory.h