[InstCombine] Signed saturation patterns
[llvm-core.git] / lib / ExecutionEngine / SectionMemoryManager.cpp
blob925049b2a1b4fccfb789bfb6d971dad78cb48192
1 //===- SectionMemoryManager.cpp - Memory manager for MCJIT/RtDyld *- C++ -*-==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the section-based memory manager used by the MCJIT
10 // execution engine and RuntimeDyld
12 //===----------------------------------------------------------------------===//
14 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
15 #include "llvm/Config/config.h"
16 #include "llvm/Support/MathExtras.h"
17 #include "llvm/Support/Process.h"
19 namespace llvm {
21 uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size,
22 unsigned Alignment,
23 unsigned SectionID,
24 StringRef SectionName,
25 bool IsReadOnly) {
26 if (IsReadOnly)
27 return allocateSection(SectionMemoryManager::AllocationPurpose::ROData,
28 Size, Alignment);
29 return allocateSection(SectionMemoryManager::AllocationPurpose::RWData, Size,
30 Alignment);
33 uint8_t *SectionMemoryManager::allocateCodeSection(uintptr_t Size,
34 unsigned Alignment,
35 unsigned SectionID,
36 StringRef SectionName) {
37 return allocateSection(SectionMemoryManager::AllocationPurpose::Code, Size,
38 Alignment);
41 uint8_t *SectionMemoryManager::allocateSection(
42 SectionMemoryManager::AllocationPurpose Purpose, uintptr_t Size,
43 unsigned Alignment) {
44 if (!Alignment)
45 Alignment = 16;
47 assert(!(Alignment & (Alignment - 1)) && "Alignment must be a power of two.");
49 uintptr_t RequiredSize = Alignment * ((Size + Alignment - 1) / Alignment + 1);
50 uintptr_t Addr = 0;
52 MemoryGroup &MemGroup = [&]() -> MemoryGroup & {
53 switch (Purpose) {
54 case AllocationPurpose::Code:
55 return CodeMem;
56 case AllocationPurpose::ROData:
57 return RODataMem;
58 case AllocationPurpose::RWData:
59 return RWDataMem;
61 llvm_unreachable("Unknown SectionMemoryManager::AllocationPurpose");
62 }();
64 // Look in the list of free memory regions and use a block there if one
65 // is available.
66 for (FreeMemBlock &FreeMB : MemGroup.FreeMem) {
67 if (FreeMB.Free.allocatedSize() >= RequiredSize) {
68 Addr = (uintptr_t)FreeMB.Free.base();
69 uintptr_t EndOfBlock = Addr + FreeMB.Free.allocatedSize();
70 // Align the address.
71 Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1);
73 if (FreeMB.PendingPrefixIndex == (unsigned)-1) {
74 // The part of the block we're giving out to the user is now pending
75 MemGroup.PendingMem.push_back(sys::MemoryBlock((void *)Addr, Size));
77 // Remember this pending block, such that future allocations can just
78 // modify it rather than creating a new one
79 FreeMB.PendingPrefixIndex = MemGroup.PendingMem.size() - 1;
80 } else {
81 sys::MemoryBlock &PendingMB =
82 MemGroup.PendingMem[FreeMB.PendingPrefixIndex];
83 PendingMB = sys::MemoryBlock(PendingMB.base(),
84 Addr + Size - (uintptr_t)PendingMB.base());
87 // Remember how much free space is now left in this block
88 FreeMB.Free =
89 sys::MemoryBlock((void *)(Addr + Size), EndOfBlock - Addr - Size);
90 return (uint8_t *)Addr;
94 // No pre-allocated free block was large enough. Allocate a new memory region.
95 // Note that all sections get allocated as read-write. The permissions will
96 // be updated later based on memory group.
98 // FIXME: It would be useful to define a default allocation size (or add
99 // it as a constructor parameter) to minimize the number of allocations.
101 // FIXME: Initialize the Near member for each memory group to avoid
102 // interleaving.
103 std::error_code ec;
104 sys::MemoryBlock MB = MMapper.allocateMappedMemory(
105 Purpose, RequiredSize, &MemGroup.Near,
106 sys::Memory::MF_READ | sys::Memory::MF_WRITE, ec);
107 if (ec) {
108 // FIXME: Add error propagation to the interface.
109 return nullptr;
112 // Save this address as the basis for our next request
113 MemGroup.Near = MB;
115 // Remember that we allocated this memory
116 MemGroup.AllocatedMem.push_back(MB);
117 Addr = (uintptr_t)MB.base();
118 uintptr_t EndOfBlock = Addr + MB.allocatedSize();
120 // Align the address.
121 Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1);
123 // The part of the block we're giving out to the user is now pending
124 MemGroup.PendingMem.push_back(sys::MemoryBlock((void *)Addr, Size));
126 // The allocateMappedMemory may allocate much more memory than we need. In
127 // this case, we store the unused memory as a free memory block.
128 unsigned FreeSize = EndOfBlock - Addr - Size;
129 if (FreeSize > 16) {
130 FreeMemBlock FreeMB;
131 FreeMB.Free = sys::MemoryBlock((void *)(Addr + Size), FreeSize);
132 FreeMB.PendingPrefixIndex = (unsigned)-1;
133 MemGroup.FreeMem.push_back(FreeMB);
136 // Return aligned address
137 return (uint8_t *)Addr;
140 bool SectionMemoryManager::finalizeMemory(std::string *ErrMsg) {
141 // FIXME: Should in-progress permissions be reverted if an error occurs?
142 std::error_code ec;
144 // Make code memory executable.
145 ec = applyMemoryGroupPermissions(CodeMem,
146 sys::Memory::MF_READ | sys::Memory::MF_EXEC);
147 if (ec) {
148 if (ErrMsg) {
149 *ErrMsg = ec.message();
151 return true;
154 // Make read-only data memory read-only.
155 ec = applyMemoryGroupPermissions(RODataMem,
156 sys::Memory::MF_READ | sys::Memory::MF_EXEC);
157 if (ec) {
158 if (ErrMsg) {
159 *ErrMsg = ec.message();
161 return true;
164 // Read-write data memory already has the correct permissions
166 // Some platforms with separate data cache and instruction cache require
167 // explicit cache flush, otherwise JIT code manipulations (like resolved
168 // relocations) will get to the data cache but not to the instruction cache.
169 invalidateInstructionCache();
171 return false;
174 static sys::MemoryBlock trimBlockToPageSize(sys::MemoryBlock M) {
175 static const size_t PageSize = sys::Process::getPageSizeEstimate();
177 size_t StartOverlap =
178 (PageSize - ((uintptr_t)M.base() % PageSize)) % PageSize;
180 size_t TrimmedSize = M.allocatedSize();
181 TrimmedSize -= StartOverlap;
182 TrimmedSize -= TrimmedSize % PageSize;
184 sys::MemoryBlock Trimmed((void *)((uintptr_t)M.base() + StartOverlap),
185 TrimmedSize);
187 assert(((uintptr_t)Trimmed.base() % PageSize) == 0);
188 assert((Trimmed.allocatedSize() % PageSize) == 0);
189 assert(M.base() <= Trimmed.base() &&
190 Trimmed.allocatedSize() <= M.allocatedSize());
192 return Trimmed;
195 std::error_code
196 SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup,
197 unsigned Permissions) {
198 for (sys::MemoryBlock &MB : MemGroup.PendingMem)
199 if (std::error_code EC = MMapper.protectMappedMemory(MB, Permissions))
200 return EC;
202 MemGroup.PendingMem.clear();
204 // Now go through free blocks and trim any of them that don't span the entire
205 // page because one of the pending blocks may have overlapped it.
206 for (FreeMemBlock &FreeMB : MemGroup.FreeMem) {
207 FreeMB.Free = trimBlockToPageSize(FreeMB.Free);
208 // We cleared the PendingMem list, so all these pointers are now invalid
209 FreeMB.PendingPrefixIndex = (unsigned)-1;
212 // Remove all blocks which are now empty
213 MemGroup.FreeMem.erase(remove_if(MemGroup.FreeMem,
214 [](FreeMemBlock &FreeMB) {
215 return FreeMB.Free.allocatedSize() == 0;
217 MemGroup.FreeMem.end());
219 return std::error_code();
222 void SectionMemoryManager::invalidateInstructionCache() {
223 for (sys::MemoryBlock &Block : CodeMem.PendingMem)
224 sys::Memory::InvalidateInstructionCache(Block.base(),
225 Block.allocatedSize());
228 SectionMemoryManager::~SectionMemoryManager() {
229 for (MemoryGroup *Group : {&CodeMem, &RWDataMem, &RODataMem}) {
230 for (sys::MemoryBlock &Block : Group->AllocatedMem)
231 MMapper.releaseMappedMemory(Block);
235 SectionMemoryManager::MemoryMapper::~MemoryMapper() {}
237 void SectionMemoryManager::anchor() {}
239 namespace {
240 // Trivial implementation of SectionMemoryManager::MemoryMapper that just calls
241 // into sys::Memory.
242 class DefaultMMapper final : public SectionMemoryManager::MemoryMapper {
243 public:
244 sys::MemoryBlock
245 allocateMappedMemory(SectionMemoryManager::AllocationPurpose Purpose,
246 size_t NumBytes, const sys::MemoryBlock *const NearBlock,
247 unsigned Flags, std::error_code &EC) override {
248 return sys::Memory::allocateMappedMemory(NumBytes, NearBlock, Flags, EC);
251 std::error_code protectMappedMemory(const sys::MemoryBlock &Block,
252 unsigned Flags) override {
253 return sys::Memory::protectMappedMemory(Block, Flags);
256 std::error_code releaseMappedMemory(sys::MemoryBlock &M) override {
257 return sys::Memory::releaseMappedMemory(M);
261 DefaultMMapper DefaultMMapperInstance;
262 } // namespace
264 SectionMemoryManager::SectionMemoryManager(MemoryMapper *MM)
265 : MMapper(MM ? *MM : DefaultMMapperInstance) {}
267 } // namespace llvm