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1//=== OrcV2CBindingsMemoryManager.c - OrcV2 Memory Manager C Bindings Demo ===//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-exception6//7//===----------------------------------------------------------------------===//8//9// This demo illustrates the C-API bindings for custom memory managers in10// ORCv2. They are used here to place generated code into manually allocated11// buffers that are subsequently marked as executable.12//13//===----------------------------------------------------------------------===//14 15#include "llvm-c/Core.h"16#include "llvm-c/Error.h"17#include "llvm-c/LLJIT.h"18#include "llvm-c/OrcEE.h"19#include "llvm-c/Support.h"20#include "llvm-c/Target.h"21 22#include <assert.h>23#include <stdio.h>24#include <stdlib.h>25 26#if defined(_WIN32)27#include <windows.h>28#else29#include <dlfcn.h>30#include <sys/mman.h>31#endif32 33struct Section {34 void *Ptr;35 size_t Size;36 LLVMBool IsCode;37};38 39char CtxCtxPlaceholder;40char CtxPlaceholder;41 42#define MaxSections 1643static size_t SectionCount = 0;44static struct Section Sections[MaxSections];45 46void *addSection(size_t Size, LLVMBool IsCode) {47 if (SectionCount >= MaxSections) {48 fprintf(stderr, "addSection(): Too many sections!\n");49 abort();50 }51 52#if defined(_WIN32)53 void *Ptr =54 VirtualAlloc(NULL, Size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);55 if (!Ptr) {56 fprintf(stderr, "addSection(): Memory allocation failed!\n");57 abort();58 }59#else60 void *Ptr = mmap(NULL, Size, PROT_READ | PROT_WRITE,61 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);62 if (Ptr == MAP_FAILED) {63 fprintf(stderr, "addSection(): Memory allocation failed!\n");64 abort();65 }66#endif67 68 Sections[SectionCount].Ptr = Ptr;69 Sections[SectionCount].Size = Size;70 Sections[SectionCount].IsCode = IsCode;71 SectionCount++;72 return Ptr;73}74 75// Callbacks to create the context for the subsequent functions (not used in76// this example)77void *memCreateContext(void *CtxCtx) {78 assert(CtxCtx == &CtxCtxPlaceholder && "Unexpected CtxCtx value");79 return &CtxPlaceholder;80}81 82void memNotifyTerminating(void *CtxCtx) {83 assert(CtxCtx == &CtxCtxPlaceholder && "Unexpected CtxCtx value");84}85 86uint8_t *memAllocate(void *Opaque, uintptr_t Size, unsigned Align, unsigned Id,87 const char *Name) {88 printf("Allocated code section \"%s\"\n", Name);89 return addSection(Size, 1);90}91 92uint8_t *memAllocateData(void *Opaque, uintptr_t Size, unsigned Align,93 unsigned Id, const char *Name, LLVMBool ReadOnly) {94 printf("Allocated data section \"%s\"\n", Name);95 return addSection(Size, 0);96}97 98LLVMBool memFinalize(void *Opaque, char **Err) {99 printf("Marking code sections as executable ..\n");100 for (size_t i = 0; i < SectionCount; ++i) {101 if (Sections[i].IsCode) {102 LLVMBool fail;103#if defined(_WIN32)104 DWORD unused;105 fail = VirtualProtect(Sections[i].Ptr, Sections[i].Size,106 PAGE_EXECUTE_READ, &unused) == 0;107#else108 fail = mprotect(Sections[i].Ptr, Sections[i].Size,109 PROT_READ | PROT_EXEC) == -1;110#endif111 if (fail) {112 fprintf(stderr, "Could not mark code section as executable!\n");113 abort();114 }115 }116 }117 return 0;118}119 120void memDestroy(void *Opaque) {121 assert(Opaque == &CtxPlaceholder && "Unexpected Ctx value");122 printf("Releasing section memory ..\n");123 for (size_t i = 0; i < SectionCount; ++i) {124 LLVMBool fail;125#if defined(_WIN32)126 fail = VirtualFree(Sections[i].Ptr, 0, MEM_RELEASE) == 0;127#else128 fail = munmap(Sections[i].Ptr, Sections[i].Size) == -1;129#endif130 if (fail) {131 fprintf(stderr, "Could not release memory for section!");132 abort();133 }134 }135}136 137LLVMOrcObjectLayerRef objectLinkingLayerCreator(void *Opaque,138 LLVMOrcExecutionSessionRef ES,139 const char *Triple) {140 return LLVMOrcCreateRTDyldObjectLinkingLayerWithMCJITMemoryManagerLikeCallbacks(141 ES, &CtxCtxPlaceholder, memCreateContext, memNotifyTerminating,142 memAllocate, memAllocateData, memFinalize, memDestroy);143}144 145int handleError(LLVMErrorRef Err) {146 char *ErrMsg = LLVMGetErrorMessage(Err);147 fprintf(stderr, "Error: %s\n", ErrMsg);148 LLVMDisposeErrorMessage(ErrMsg);149 return 1;150}151 152LLVMOrcThreadSafeModuleRef createDemoModule(void) {153 // Create an LLVMContext.154 LLVMContextRef Ctx = LLVMContextCreate();155 156 // Create a new LLVM module.157 LLVMModuleRef M = LLVMModuleCreateWithNameInContext("demo", Ctx);158 159 // Add a "sum" function":160 // - Create the function type and function instance.161 LLVMTypeRef ParamTypes[] = {LLVMInt32Type(), LLVMInt32Type()};162 LLVMTypeRef SumFunctionType =163 LLVMFunctionType(LLVMInt32Type(), ParamTypes, 2, 0);164 LLVMValueRef SumFunction = LLVMAddFunction(M, "sum", SumFunctionType);165 166 // - Add a basic block to the function.167 LLVMBasicBlockRef EntryBB = LLVMAppendBasicBlock(SumFunction, "entry");168 169 // - Add an IR builder and point it at the end of the basic block.170 LLVMBuilderRef Builder = LLVMCreateBuilder();171 LLVMPositionBuilderAtEnd(Builder, EntryBB);172 173 // - Get the two function arguments and use them co construct an "add"174 // instruction.175 LLVMValueRef SumArg0 = LLVMGetParam(SumFunction, 0);176 LLVMValueRef SumArg1 = LLVMGetParam(SumFunction, 1);177 LLVMValueRef Result = LLVMBuildAdd(Builder, SumArg0, SumArg1, "result");178 179 // - Build the return instruction.180 LLVMBuildRet(Builder, Result);181 182 // Create a new ThreadSafeContext to hold the context.183 LLVMOrcThreadSafeContextRef TSCtx =184 LLVMOrcCreateNewThreadSafeContextFromLLVMContext(Ctx);185 186 // Our demo module is now complete. Wrap it and our ThreadSafeContext in a187 // ThreadSafeModule.188 LLVMOrcThreadSafeModuleRef TSM = LLVMOrcCreateNewThreadSafeModule(M, TSCtx);189 190 // Dispose of our local ThreadSafeContext value. The underlying LLVMContext191 // will be kept alive by our ThreadSafeModule, TSM.192 LLVMOrcDisposeThreadSafeContext(TSCtx);193 194 // Return the result.195 return TSM;196}197 198int main(int argc, const char *argv[]) {199 200 int MainResult = 0;201 202 // Parse command line arguments and initialize LLVM Core.203 LLVMParseCommandLineOptions(argc, argv, "");204 205 // Initialize native target codegen and asm printer.206 LLVMInitializeNativeTarget();207 LLVMInitializeNativeAsmPrinter();208 209 // Create the JIT instance.210 LLVMOrcLLJITRef J;211 {212 LLVMErrorRef Err;213 214 LLVMOrcLLJITBuilderRef Builder = LLVMOrcCreateLLJITBuilder();215 LLVMOrcLLJITBuilderSetObjectLinkingLayerCreator(216 Builder, objectLinkingLayerCreator, NULL);217 218 if ((Err = LLVMOrcCreateLLJIT(&J, Builder))) {219 MainResult = handleError(Err);220 goto llvm_shutdown;221 }222 }223 224 // Create our demo module.225 LLVMOrcThreadSafeModuleRef TSM = createDemoModule();226 227 // Add our demo module to the JIT.228 {229 LLVMOrcJITDylibRef MainJD = LLVMOrcLLJITGetMainJITDylib(J);230 LLVMErrorRef Err;231 if ((Err = LLVMOrcLLJITAddLLVMIRModule(J, MainJD, TSM))) {232 // If adding the ThreadSafeModule fails then we need to clean it up233 // ourselves. If adding it succeeds the JIT will manage the memory.234 LLVMOrcDisposeThreadSafeModule(TSM);235 MainResult = handleError(Err);236 goto jit_cleanup;237 }238 }239 240 // Look up the address of our demo entry point.241 LLVMOrcJITTargetAddress SumAddr;242 {243 LLVMErrorRef Err;244 if ((Err = LLVMOrcLLJITLookup(J, &SumAddr, "sum"))) {245 MainResult = handleError(Err);246 goto jit_cleanup;247 }248 }249 250 // If we made it here then everything succeeded. Execute our JIT'd code.251 int32_t (*Sum)(int32_t, int32_t) = (int32_t(*)(int32_t, int32_t))SumAddr;252 int32_t Result = Sum(1, 2);253 254 // Print the result.255 printf("1 + 2 = %i\n", Result);256 257jit_cleanup:258 // Destroy our JIT instance. This will clean up any memory that the JIT has259 // taken ownership of. This operation is non-trivial (e.g. it may need to260 // JIT static destructors) and may also fail. In that case we want to render261 // the error to stderr, but not overwrite any existing return value.262 {263 LLVMErrorRef Err;264 if ((Err = LLVMOrcDisposeLLJIT(J))) {265 int NewFailureResult = handleError(Err);266 if (MainResult == 0)267 MainResult = NewFailureResult;268 }269 }270 271llvm_shutdown:272 // Shut down LLVM.273 LLVMShutdown();274 275 return MainResult;276}277