forked from OSchip/llvm-project
164 lines
5.3 KiB
C++
164 lines
5.3 KiB
C++
//===- Win32/Memory.cpp - Win32 Memory Implementation -----------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file provides the Win32 specific implementation of various Memory
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// management utilities
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/Process.h"
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#include "llvm/Support/WindowsError.h"
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// The Windows.h header must be the last one included.
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#include "WindowsSupport.h"
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namespace {
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DWORD getWindowsProtectionFlags(unsigned Flags) {
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switch (Flags) {
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// Contrary to what you might expect, the Windows page protection flags
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// are not a bitwise combination of RWX values
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case llvm::sys::Memory::MF_READ:
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return PAGE_READONLY;
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case llvm::sys::Memory::MF_WRITE:
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// Note: PAGE_WRITE is not supported by VirtualProtect
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return PAGE_READWRITE;
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case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
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return PAGE_READWRITE;
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case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
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return PAGE_EXECUTE_READ;
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case llvm::sys::Memory::MF_READ |
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llvm::sys::Memory::MF_WRITE |
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llvm::sys::Memory::MF_EXEC:
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return PAGE_EXECUTE_READWRITE;
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case llvm::sys::Memory::MF_EXEC:
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return PAGE_EXECUTE;
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default:
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llvm_unreachable("Illegal memory protection flag specified!");
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}
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// Provide a default return value as required by some compilers.
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return PAGE_NOACCESS;
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}
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size_t getAllocationGranularity() {
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SYSTEM_INFO Info;
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::GetSystemInfo(&Info);
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if (Info.dwPageSize > Info.dwAllocationGranularity)
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return Info.dwPageSize;
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else
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return Info.dwAllocationGranularity;
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}
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} // namespace
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namespace llvm {
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namespace sys {
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//===----------------------------------------------------------------------===//
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//=== WARNING: Implementation here must contain only Win32 specific code
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//=== and must not be UNIX code
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//===----------------------------------------------------------------------===//
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MemoryBlock Memory::allocateMappedMemory(size_t NumBytes,
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const MemoryBlock *const NearBlock,
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unsigned Flags,
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std::error_code &EC) {
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EC = std::error_code();
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if (NumBytes == 0)
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return MemoryBlock();
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// While we'd be happy to allocate single pages, the Windows allocation
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// granularity may be larger than a single page (in practice, it is 64K)
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// so mapping less than that will create an unreachable fragment of memory.
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// Avoid using one-time initialization of static locals here, since they
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// aren't thread safe with MSVC.
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static volatile size_t GranularityCached;
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size_t Granularity = GranularityCached;
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if (Granularity == 0) {
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Granularity = getAllocationGranularity();
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GranularityCached = Granularity;
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}
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const size_t NumBlocks = (NumBytes+Granularity-1)/Granularity;
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uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
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NearBlock->size()
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: 0;
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// If the requested address is not aligned to the allocation granularity,
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// round up to get beyond NearBlock. VirtualAlloc would have rounded down.
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if (Start && Start % Granularity != 0)
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Start += Granularity - Start % Granularity;
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DWORD Protect = getWindowsProtectionFlags(Flags);
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void *PA = ::VirtualAlloc(reinterpret_cast<void*>(Start),
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NumBlocks*Granularity,
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MEM_RESERVE | MEM_COMMIT, Protect);
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if (PA == NULL) {
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if (NearBlock) {
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// Try again without the NearBlock hint
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return allocateMappedMemory(NumBytes, NULL, Flags, EC);
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}
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EC = mapWindowsError(::GetLastError());
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return MemoryBlock();
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}
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MemoryBlock Result;
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Result.Address = PA;
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Result.Size = NumBlocks*Granularity;
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if (Flags & MF_EXEC)
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Memory::InvalidateInstructionCache(Result.Address, Result.Size);
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return Result;
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}
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std::error_code Memory::releaseMappedMemory(MemoryBlock &M) {
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if (M.Address == 0 || M.Size == 0)
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return std::error_code();
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if (!VirtualFree(M.Address, 0, MEM_RELEASE))
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return mapWindowsError(::GetLastError());
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M.Address = 0;
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M.Size = 0;
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return std::error_code();
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}
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std::error_code Memory::protectMappedMemory(const MemoryBlock &M,
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unsigned Flags) {
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if (M.Address == 0 || M.Size == 0)
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return std::error_code();
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DWORD Protect = getWindowsProtectionFlags(Flags);
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DWORD OldFlags;
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if (!VirtualProtect(M.Address, M.Size, Protect, &OldFlags))
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return mapWindowsError(::GetLastError());
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if (Flags & MF_EXEC)
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Memory::InvalidateInstructionCache(M.Address, M.Size);
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return std::error_code();
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}
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/// InvalidateInstructionCache - Before the JIT can run a block of code
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/// that has been emitted it must invalidate the instruction cache on some
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/// platforms.
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void Memory::InvalidateInstructionCache(
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const void *Addr, size_t Len) {
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FlushInstructionCache(GetCurrentProcess(), Addr, Len);
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}
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} // namespace sys
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} // namespace llvm
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