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/LLJIT.h"
  12 #include "llvm-c/Support.h"
  13 #include "llvm-c/Target.h"
  14
  15 #include <stdio.h>
  16
  17 int handleError(LLVMErrorRef Err) {
  18   char *ErrMsg = LLVMGetErrorMessage(Err);
  19   fprintf(stderr, "Error: %s\n", ErrMsg);
  20   LLVMDisposeErrorMessage(ErrMsg);
  21   return 1;
  22 }
  23
  24 LLVMOrcThreadSafeModuleRef createDemoModule(void) {
  25   // Create a new ThreadSafeContext and underlying LLVMContext.
  26   LLVMOrcThreadSafeContextRef TSCtx = LLVMOrcCreateNewThreadSafeContext();
  27
  28   // Get a reference to the underlying LLVMContext.
  29   LLVMContextRef Ctx = LLVMOrcThreadSafeContextGetContext(TSCtx);
  30
  31   // Create a new LLVM module.
  32   LLVMModuleRef M = LLVMModuleCreateWithNameInContext("demo", Ctx);
  33
  34   // Add a "sum" function":
  35   //  - Create the function type and function instance.
  36   LLVMTypeRef ParamTypes[] = {LLVMInt32Type(), LLVMInt32Type()};
  37   LLVMTypeRef SumFunctionType =
  38       LLVMFunctionType(LLVMInt32Type(), ParamTypes, 2, 0);
  39   LLVMValueRef SumFunction = LLVMAddFunction(M, "sum", SumFunctionType);
  40
  41   //  - Add a basic block to the function.
  42   LLVMBasicBlockRef EntryBB = LLVMAppendBasicBlock(SumFunction, "entry");
  43
  44   //  - Add an IR builder and point it at the end of the basic block.
  45   LLVMBuilderRef Builder = LLVMCreateBuilder();
  46   LLVMPositionBuilderAtEnd(Builder, EntryBB);
  47
  48   //  - Get the two function arguments and use them co construct an "add"
  49   //    instruction.
  50   LLVMValueRef SumArg0 = LLVMGetParam(SumFunction, 0);
  51   LLVMValueRef SumArg1 = LLVMGetParam(SumFunction, 1);
  52   LLVMValueRef Result = LLVMBuildAdd(Builder, SumArg0, SumArg1, "result");
  53
  54   //  - Build the return instruction.
  55   LLVMBuildRet(Builder, Result);
  56
  57   //  - Free the builder.
  58   LLVMDisposeBuilder(Builder);
  59
  60   // Our demo module is now complete. Wrap it and our ThreadSafeContext in a
  61   // ThreadSafeModule.
  62   LLVMOrcThreadSafeModuleRef TSM = LLVMOrcCreateNewThreadSafeModule(M, TSCtx);
  63
  64   // Dispose of our local ThreadSafeContext value. The underlying LLVMContext
  65   // will be kept alive by our ThreadSafeModule, TSM.
  66   LLVMOrcDisposeThreadSafeContext(TSCtx);
  67
  68   // Return the result.
  69   return TSM;
  70 }
  71
  72 int main(int argc, const char *argv[]) {
  73
  74   int MainResult = 0;
  75
  76   // Parse command line arguments and initialize LLVM Core.
  77   LLVMParseCommandLineOptions(argc, argv, "");
  78
  79   // Initialize native target codegen and asm printer.
  80   LLVMInitializeNativeTarget();
  81   LLVMInitializeNativeAsmPrinter();
  82
  83   // Create the JIT instance.
  84   LLVMOrcLLJITRef J;
  85   {
  86     LLVMErrorRef Err;
  87     if ((Err = LLVMOrcCreateLLJIT(&J, 0))) {
  88       MainResult = handleError(Err);
  89       goto llvm_shutdown;
  90     }
  91   }
  92
  93   // Create our demo module.
  94   LLVMOrcThreadSafeModuleRef TSM = createDemoModule();
  95   LLVMOrcResourceTrackerRef RT;
  96
  97   // Add our demo module to the JIT.
  98   {
  99     LLVMOrcJITDylibRef MainJD = LLVMOrcLLJITGetMainJITDylib(J);
 100     RT = LLVMOrcJITDylibCreateResourceTracker(MainJD);
 101     LLVMErrorRef Err;
 102     if ((Err = LLVMOrcLLJITAddLLVMIRModuleWithRT(J, RT, TSM))) {
 103       // If adding the ThreadSafeModule fails then we need to clean it up
 104       // ourselves. If adding it succeeds the JIT will manage the memory.
 105       LLVMOrcDisposeThreadSafeModule(TSM);
 106       MainResult = handleError(Err);
 107       goto jit_cleanup;
 108     }
 109   }
 110
 111   // Look up the address of our demo entry point.
 112   printf("Looking up before removal...\n");
 113   LLVMOrcJITTargetAddress SumAddr;
 114   {
 115     LLVMErrorRef Err;
 116     if ((Err = LLVMOrcLLJITLookup(J, &SumAddr, "sum"))) {
 117       MainResult = handleError(Err);
 118       goto jit_cleanup;
 119     }
 120   }
 121
 122   // If we made it here then everything succeeded. Execute our JIT'd code.
 123   int32_t (*Sum)(int32_t, int32_t) = (int32_t(*)(int32_t, int32_t))SumAddr;
 124   int32_t Result = Sum(1, 2);
 125
 126   // Print the result.
 127   printf("1 + 2 = %i\n", Result);
 128
 129   // Remove the code.
 130   {
 131     LLVMErrorRef Err;
 132     if ((Err = LLVMOrcResourceTrackerRemove(RT))) {
 133       MainResult = handleError(Err);
 134       goto jit_cleanup;
 135     }
 136   }
 137
 138   // Attempt a second lookup. Here we expect an error as the code and symbols
 139   // should have been removed.
 140   printf("Attempting to remove code / symbols...\n");
 141   {
 142     LLVMOrcJITTargetAddress ThrowAwayAddress;
 143     LLVMErrorRef Err = LLVMOrcLLJITLookup(J, &ThrowAwayAddress, "sum");
 144     if (Err) {
 145       printf("Received error as expected:\n");
 146       handleError(Err);
 147     } else {
 148       printf("Failure: Second lookup should have generated an error.\n");
 149       MainResult = 1;
 150     }
 151   }
 152
 153 jit_cleanup:
 154   // Destroy our JIT instance. This will clean up any memory that the JIT has
 155   // taken ownership of. This operation is non-trivial (e.g. it may need to
 156   // JIT static destructors) and may also fail. In that case we want to render
 157   // the error to stderr, but not overwrite any existing return value.
 158
 159   printf("Releasing resource tracker...\n");
 160   LLVMOrcReleaseResourceTracker(RT);
 161
 162   printf("Destroying LLJIT instance and exiting.\n");
 163   {
 164     LLVMErrorRef Err;
 165     if ((Err = LLVMOrcDisposeLLJIT(J))) {
 166       int NewFailureResult = handleError(Err);
 167       if (MainResult == 0)
 168         MainResult = NewFailureResult;
 169     }
 170   }
 171
 172 llvm_shutdown:
 173   // Shut down LLVM.
 174   LLVMShutdown();
 175
 176   return MainResult;
 177 }