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() {
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 }
177