llvm/examples/OrcV2Examples/OrcV2CBindingsRemovableCode/OrcV2CBindingsRemovableCode.c

   1 //===-------- BasicOrcV2CBindings.c - Basic OrcV2 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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm-c/Core.h"
  10 #include "llvm-c/Error.h"
  11 #include "llvm-c/Initialization.h"
  12 #include "llvm-c/LLJIT.h"
  13 #include "llvm-c/Support.h"
  14 #include "llvm-c/Target.h"
  15
  16 #include <stdio.h>
  17
  18 int handleError(LLVMErrorRef Err) {
  19   char *ErrMsg = LLVMGetErrorMessage(Err);
  20   fprintf(stderr, "Error: %s\n", ErrMsg);
  21   LLVMDisposeErrorMessage(ErrMsg);
  22   return 1;
  23 }
  24
  25 LLVMOrcThreadSafeModuleRef createDemoModule(void) {
  26   // Create a new ThreadSafeContext and underlying LLVMContext.
  27   LLVMOrcThreadSafeContextRef TSCtx = LLVMOrcCreateNewThreadSafeContext();
  28
  29   // Get a reference to the underlying LLVMContext.
  30   LLVMContextRef Ctx = LLVMOrcThreadSafeContextGetContext(TSCtx);
  31
  32   // Create a new LLVM module.
  33   LLVMModuleRef M = LLVMModuleCreateWithNameInContext("demo", Ctx);
  34
  35   // Add a "sum" function":
  36   //  - Create the function type and function instance.
  37   LLVMTypeRef ParamTypes[] = {LLVMInt32Type(), LLVMInt32Type()};
  38   LLVMTypeRef SumFunctionType =
  39       LLVMFunctionType(LLVMInt32Type(), ParamTypes, 2, 0);
  40   LLVMValueRef SumFunction = LLVMAddFunction(M, "sum", SumFunctionType);
  41
  42   //  - Add a basic block to the function.
  43   LLVMBasicBlockRef EntryBB = LLVMAppendBasicBlock(SumFunction, "entry");
  44
  45   //  - Add an IR builder and point it at the end of the basic block.
  46   LLVMBuilderRef Builder = LLVMCreateBuilder();
  47   LLVMPositionBuilderAtEnd(Builder, EntryBB);
  48
  49   //  - Get the two function arguments and use them co construct an "add"
  50   //    instruction.
  51   LLVMValueRef SumArg0 = LLVMGetParam(SumFunction, 0);
  52   LLVMValueRef SumArg1 = LLVMGetParam(SumFunction, 1);
  53   LLVMValueRef Result = LLVMBuildAdd(Builder, SumArg0, SumArg1, "result");
  54
  55   //  - Build the return instruction.
  56   LLVMBuildRet(Builder, Result);
  57
  58   // Our demo module is now complete. Wrap it and our ThreadSafeContext in a
  59   // ThreadSafeModule.
  60   LLVMOrcThreadSafeModuleRef TSM = LLVMOrcCreateNewThreadSafeModule(M, TSCtx);
  61
  62   // Dispose of our local ThreadSafeContext value. The underlying LLVMContext
  63   // will be kept alive by our ThreadSafeModule, TSM.
  64   LLVMOrcDisposeThreadSafeContext(TSCtx);
  65
  66   // Return the result.
  67   return TSM;
  68 }
  69
  70 int main(int argc, char *argv[]) {
  71
  72   int MainResult = 0;
  73
  74   // Parse command line arguments and initialize LLVM Core.
  75   LLVMParseCommandLineOptions(argc, (const char **)argv, "");
  76   LLVMInitializeCore(LLVMGetGlobalPassRegistry());
  77
  78   // Initialize native target codegen and asm printer.
  79   LLVMInitializeNativeTarget();
  80   LLVMInitializeNativeAsmPrinter();
  81
  82   // Create the JIT instance.
  83   LLVMOrcLLJITRef J;
  84   {
  85     LLVMErrorRef Err;
  86     if ((Err = LLVMOrcCreateLLJIT(&J, 0))) {
  87       MainResult = handleError(Err);
  88       goto llvm_shutdown;
  89     }
  90   }
  91
  92   // Create our demo module.
  93   LLVMOrcThreadSafeModuleRef TSM = createDemoModule();
  94   LLVMOrcResourceTrackerRef RT;
  95
  96   // Add our demo module to the JIT.
  97   {
  98     LLVMOrcJITDylibRef MainJD = LLVMOrcLLJITGetMainJITDylib(J);
  99     RT = LLVMOrcJITDylibCreateResourceTracker(MainJD);
 100     LLVMErrorRef Err;
 101     if ((Err = LLVMOrcLLJITAddLLVMIRModuleWithRT(J, RT, TSM))) {
 102       // If adding the ThreadSafeModule fails then we need to clean it up
 103       // ourselves. If adding it succeeds the JIT will manage the memory.
 104       LLVMOrcDisposeThreadSafeModule(TSM);
 105       MainResult = handleError(Err);
 106       goto jit_cleanup;
 107     }
 108   }
 109
 110   // Look up the address of our demo entry point.
 111   printf("Looking up before removal...\n");
 112   LLVMOrcJITTargetAddress SumAddr;
 113   {
 114     LLVMErrorRef Err;
 115     if ((Err = LLVMOrcLLJITLookup(J, &SumAddr, "sum"))) {
 116       MainResult = handleError(Err);
 117       goto jit_cleanup;
 118     }
 119   }
 120
 121   // If we made it here then everything succeeded. Execute our JIT'd code.
 122   int32_t (*Sum)(int32_t, int32_t) = (int32_t(*)(int32_t, int32_t))SumAddr;
 123   int32_t Result = Sum(1, 2);
 124
 125   // Print the result.
 126   printf("1 + 2 = %i\n", Result);
 127
 128   // Remove the code.
 129   {
 130     LLVMErrorRef Err;
 131     if ((Err = LLVMOrcResourceTrackerRemove(RT))) {
 132       MainResult = handleError(Err);
 133       goto jit_cleanup;
 134     }
 135   }
 136
 137   // Attempt a second lookup. Here we expect an error as the code and symbols
 138   // should have been removed.
 139   printf("Attempting to remove code / symbols...\n");
 140   {
 141     LLVMOrcJITTargetAddress ThrowAwayAddress;
 142     LLVMErrorRef Err = LLVMOrcLLJITLookup(J, &ThrowAwayAddress, "sum");
 143     if (Err) {
 144       printf("Received error as expected:\n");
 145       handleError(Err);
 146     } else {
 147       printf("Failure: Second lookup should have generated an error.\n");
 148       MainResult = 1;
 149     }
 150   }
 151
 152 jit_cleanup:
 153   // Destroy our JIT instance. This will clean up any memory that the JIT has
 154   // taken ownership of. This operation is non-trivial (e.g. it may need to
 155   // JIT static destructors) and may also fail. In that case we want to render
 156   // the error to stderr, but not overwrite any existing return value.
 157
 158   printf("Releasing resource tracker...\n");
 159   LLVMOrcReleaseResourceTracker(RT);
 160
 161   printf("Destroying LLJIT instance and exiting.\n");
 162   {
 163     LLVMErrorRef Err;
 164     if ((Err = LLVMOrcDisposeLLJIT(J))) {
 165       int NewFailureResult = handleError(Err);
 166       if (MainResult == 0)
 167         MainResult = NewFailureResult;
 168     }
 169   }
 170
 171 llvm_shutdown:
 172   // Shut down LLVM.
 173   LLVMShutdown();
 174
 175   return MainResult;
 176 }