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OrcV2CBindingsMCJITLikeMemoryManager.c
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OrcV2CBindingsMCJITLikeMemoryManager.c
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//=== OrcV2CBindingsMemoryManager.c - OrcV2 Memory Manager C Bindings Demo ===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This demo illustrates the C-API bindings for custom memory managers in
// ORCv2. They are used here to place generated code into manually allocated
// buffers that are subsequently marked as executable.
//
//===----------------------------------------------------------------------===//
#include "llvm-c/Core.h"
#include "llvm-c/Error.h"
#include "llvm-c/LLJIT.h"
#include "llvm-c/OrcEE.h"
#include "llvm-c/Support.h"
#include "llvm-c/Target.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#if defined(_WIN32)
#include <windows.h>
#else
#include <dlfcn.h>
#include <sys/mman.h>
#endif
struct Section {
void *Ptr;
size_t Size;
LLVMBool IsCode;
};
char CtxCtxPlaceholder;
char CtxPlaceholder;
#define MaxSections 16
static size_t SectionCount = 0;
static struct Section Sections[MaxSections];
void *addSection(size_t Size, LLVMBool IsCode) {
if (SectionCount >= MaxSections) {
fprintf(stderr, "addSection(): Too many sections!\n");
abort();
}
#if defined(_WIN32)
void *Ptr =
VirtualAlloc(NULL, Size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
if (!Ptr) {
fprintf(stderr, "addSection(): Memory allocation failed!\n");
abort();
}
#else
void *Ptr = mmap(NULL, Size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (Ptr == MAP_FAILED) {
fprintf(stderr, "addSection(): Memory allocation failed!\n");
abort();
}
#endif
Sections[SectionCount].Ptr = Ptr;
Sections[SectionCount].Size = Size;
Sections[SectionCount].IsCode = IsCode;
SectionCount++;
return Ptr;
}
// Callbacks to create the context for the subsequent functions (not used in
// this example)
void *memCreateContext(void *CtxCtx) {
assert(CtxCtx == &CtxCtxPlaceholder && "Unexpected CtxCtx value");
return &CtxPlaceholder;
}
void memNotifyTerminating(void *CtxCtx) {
assert(CtxCtx == &CtxCtxPlaceholder && "Unexpected CtxCtx value");
}
uint8_t *memAllocate(void *Opaque, uintptr_t Size, unsigned Align, unsigned Id,
const char *Name) {
printf("Allocated code section \"%s\"\n", Name);
return addSection(Size, 1);
}
uint8_t *memAllocateData(void *Opaque, uintptr_t Size, unsigned Align,
unsigned Id, const char *Name, LLVMBool ReadOnly) {
printf("Allocated data section \"%s\"\n", Name);
return addSection(Size, 0);
}
LLVMBool memFinalize(void *Opaque, char **Err) {
printf("Marking code sections as executable ..\n");
for (size_t i = 0; i < SectionCount; ++i) {
if (Sections[i].IsCode) {
LLVMBool fail;
#if defined(_WIN32)
DWORD unused;
fail = VirtualProtect(Sections[i].Ptr, Sections[i].Size,
PAGE_EXECUTE_READ, &unused) == 0;
#else
fail = mprotect(Sections[i].Ptr, Sections[i].Size,
PROT_READ | PROT_EXEC) == -1;
#endif
if (fail) {
fprintf(stderr, "Could not mark code section as executable!\n");
abort();
}
}
}
return 0;
}
void memDestroy(void *Opaque) {
assert(Opaque == &CtxPlaceholder && "Unexpected Ctx value");
printf("Releasing section memory ..\n");
for (size_t i = 0; i < SectionCount; ++i) {
LLVMBool fail;
#if defined(_WIN32)
fail = VirtualFree(Sections[i].Ptr, 0, MEM_RELEASE) == 0;
#else
fail = munmap(Sections[i].Ptr, Sections[i].Size) == -1;
#endif
if (fail) {
fprintf(stderr, "Could not release memory for section!");
abort();
}
}
}
LLVMOrcObjectLayerRef objectLinkingLayerCreator(void *Opaque,
LLVMOrcExecutionSessionRef ES,
const char *Triple) {
return LLVMOrcCreateRTDyldObjectLinkingLayerWithMCJITMemoryManagerLikeCallbacks(
ES, &CtxCtxPlaceholder, memCreateContext, memNotifyTerminating,
memAllocate, memAllocateData, memFinalize, memDestroy);
}
int handleError(LLVMErrorRef Err) {
char *ErrMsg = LLVMGetErrorMessage(Err);
fprintf(stderr, "Error: %s\n", ErrMsg);
LLVMDisposeErrorMessage(ErrMsg);
return 1;
}
LLVMOrcThreadSafeModuleRef createDemoModule(void) {
// Create a new ThreadSafeContext and underlying LLVMContext.
LLVMOrcThreadSafeContextRef TSCtx = LLVMOrcCreateNewThreadSafeContext();
// Get a reference to the underlying LLVMContext.
LLVMContextRef Ctx = LLVMOrcThreadSafeContextGetContext(TSCtx);
// Create a new LLVM module.
LLVMModuleRef M = LLVMModuleCreateWithNameInContext("demo", Ctx);
// Add a "sum" function":
// - Create the function type and function instance.
LLVMTypeRef ParamTypes[] = {LLVMInt32Type(), LLVMInt32Type()};
LLVMTypeRef SumFunctionType =
LLVMFunctionType(LLVMInt32Type(), ParamTypes, 2, 0);
LLVMValueRef SumFunction = LLVMAddFunction(M, "sum", SumFunctionType);
// - Add a basic block to the function.
LLVMBasicBlockRef EntryBB = LLVMAppendBasicBlock(SumFunction, "entry");
// - Add an IR builder and point it at the end of the basic block.
LLVMBuilderRef Builder = LLVMCreateBuilder();
LLVMPositionBuilderAtEnd(Builder, EntryBB);
// - Get the two function arguments and use them co construct an "add"
// instruction.
LLVMValueRef SumArg0 = LLVMGetParam(SumFunction, 0);
LLVMValueRef SumArg1 = LLVMGetParam(SumFunction, 1);
LLVMValueRef Result = LLVMBuildAdd(Builder, SumArg0, SumArg1, "result");
// - Build the return instruction.
LLVMBuildRet(Builder, Result);
// Our demo module is now complete. Wrap it and our ThreadSafeContext in a
// ThreadSafeModule.
LLVMOrcThreadSafeModuleRef TSM = LLVMOrcCreateNewThreadSafeModule(M, TSCtx);
// Dispose of our local ThreadSafeContext value. The underlying LLVMContext
// will be kept alive by our ThreadSafeModule, TSM.
LLVMOrcDisposeThreadSafeContext(TSCtx);
// Return the result.
return TSM;
}
int main(int argc, char *argv[]) {
int MainResult = 0;
// Parse command line arguments and initialize LLVM Core.
LLVMParseCommandLineOptions(argc, (const char **)argv, "");
// Initialize native target codegen and asm printer.
LLVMInitializeNativeTarget();
LLVMInitializeNativeAsmPrinter();
// Create the JIT instance.
LLVMOrcLLJITRef J;
{
LLVMErrorRef Err;
LLVMOrcLLJITBuilderRef Builder = LLVMOrcCreateLLJITBuilder();
LLVMOrcLLJITBuilderSetObjectLinkingLayerCreator(
Builder, objectLinkingLayerCreator, NULL);
if ((Err = LLVMOrcCreateLLJIT(&J, Builder))) {
MainResult = handleError(Err);
goto llvm_shutdown;
}
}
// Create our demo module.
LLVMOrcThreadSafeModuleRef TSM = createDemoModule();
// Add our demo module to the JIT.
{
LLVMOrcJITDylibRef MainJD = LLVMOrcLLJITGetMainJITDylib(J);
LLVMErrorRef Err;
if ((Err = LLVMOrcLLJITAddLLVMIRModule(J, MainJD, TSM))) {
// If adding the ThreadSafeModule fails then we need to clean it up
// ourselves. If adding it succeeds the JIT will manage the memory.
LLVMOrcDisposeThreadSafeModule(TSM);
MainResult = handleError(Err);
goto jit_cleanup;
}
}
// Look up the address of our demo entry point.
LLVMOrcJITTargetAddress SumAddr;
{
LLVMErrorRef Err;
if ((Err = LLVMOrcLLJITLookup(J, &SumAddr, "sum"))) {
MainResult = handleError(Err);
goto jit_cleanup;
}
}
// If we made it here then everything succeeded. Execute our JIT'd code.
int32_t (*Sum)(int32_t, int32_t) = (int32_t(*)(int32_t, int32_t))SumAddr;
int32_t Result = Sum(1, 2);
// Print the result.
printf("1 + 2 = %i\n", Result);
jit_cleanup:
// Destroy our JIT instance. This will clean up any memory that the JIT has
// taken ownership of. This operation is non-trivial (e.g. it may need to
// JIT static destructors) and may also fail. In that case we want to render
// the error to stderr, but not overwrite any existing return value.
{
LLVMErrorRef Err;
if ((Err = LLVMOrcDisposeLLJIT(J))) {
int NewFailureResult = handleError(Err);
if (MainResult == 0)
MainResult = NewFailureResult;
}
}
llvm_shutdown:
// Shut down LLVM.
LLVMShutdown();
return MainResult;
}