├── .gitignore
├── Makefile
├── README.md
└── hello_llvm.swift


/.gitignore:
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1 | build
2 | llvm
3 | hello_llvm
4 | 


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/Makefile:
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 1 | all:
 2 | 	xcrun -sdk macosx swiftc hello_llvm.swift \
 3 | 					-module-link-name LLVM_C \
 4 | 					`./build/bin/llvm-config --libs mcjit native` \
 5 | 					-L ./build/lib \
 6 | 					-lc++ -lcurses -lz \
 7 | 					-I ./llvm/include -I ./build/include \
 8 | 					-Xcc -D__STDC_CONSTANT_MACROS \
 9 | 					-Xcc -D__STDC_LIMIT_MACROS \
10 | 					-Xcc -D__STDC_FORMAT_MACROS
11 | 
12 | 


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/README.md:
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1 | # Using LLVM C API with Swift
2 | 
3 | Example code for corresponding article - [How to use LLVM with Swift](http://lowlevelbits.com/how-to-use-llvm-api-with-swift/)
4 | 
5 | How to use LLVM MCJIT execution engine - [How to use LLVM with Swift. Addendum](http://lowlevelbits.com/how-to-use-llvm-api-with-swift-addendum/)
6 | 
7 | 


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/hello_llvm.swift:
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 1 | import LLVM_C
 2 | 
 3 | let module = LLVMModuleCreateWithName("Hello")
 4 | 
 5 | let int32 = LLVMInt32Type()
 6 | 
 7 | let paramTypes = [int32, int32]
 8 | 
 9 | // need to convert paramTypes into UnsafeMutablePointer because of API requirements
10 | var paramTypesRef = UnsafeMutablePointer<LLVMTypeRef>.alloc(paramTypes.count)
11 | paramTypesRef.initializeFrom(paramTypes)
12 | 
13 | let returnType = int32
14 | let functionType = LLVMFunctionType(returnType, paramTypesRef, UInt32(paramTypes.count), 0)
15 | 
16 | let sumFunction = LLVMAddFunction(module, "sum", functionType)
17 | 
18 | let entryBlock = LLVMAppendBasicBlock(sumFunction, "entry")
19 | 
20 | let builder = LLVMCreateBuilder()
21 | LLVMPositionBuilderAtEnd(builder, entryBlock)
22 | 
23 | let a = LLVMGetParam(sumFunction, 0)
24 | let b = LLVMGetParam(sumFunction, 1)
25 | let temp = LLVMBuildAdd(builder, a, b, "temp")
26 | LLVMBuildRet(builder, temp)
27 | 
28 | LLVMLinkInMCJIT()
29 | LLVMInitializeNativeTarget()
30 | LLVMInitializeNativeAsmPrinter()
31 | 
32 | func runSumFunction(a: Int, _ b: Int) -> Int {
33 |   let functionType = LLVMFunctionType(returnType, nil, 0, 0)
34 |   let wrapperFunction = LLVMAddFunction(module, "", functionType)
35 |   defer {
36 |     LLVMDeleteFunction(wrapperFunction)
37 |   }
38 | 
39 |   let entryBlock = LLVMAppendBasicBlock(wrapperFunction, "entry")
40 | 
41 |   let builder = LLVMCreateBuilder()
42 |   LLVMPositionBuilderAtEnd(builder, entryBlock)
43 | 
44 |   let argumentsCount = 2
45 |   var argumentValues = [LLVMValueRef]()
46 |   
47 |   argumentValues.append(LLVMConstInt(int32, UInt64(a), 0))
48 |   argumentValues.append(LLVMConstInt(int32, UInt64(b), 0))
49 | 
50 |   let argumentsPointer = UnsafeMutablePointer<LLVMValueRef>.alloc(strideof(LLVMValueRef) * argumentsCount)
51 |   defer {
52 |     argumentsPointer.dealloc(strideof(LLVMValueRef) * argumentsCount)
53 |   }
54 |   argumentsPointer.initializeFrom(argumentValues)
55 | 
56 |   let callTemp = LLVMBuildCall(builder, 
57 |                                sumFunction,
58 |                                argumentsPointer,
59 |                                UInt32(argumentsCount), "sum_temp")
60 |   LLVMBuildRet(builder, callTemp)
61 | 
62 |   let executionEngine = UnsafeMutablePointer<LLVMExecutionEngineRef>.alloc(strideof(LLVMExecutionEngineRef))
63 |   let error = UnsafeMutablePointer<UnsafeMutablePointer<Int8>>.alloc(strideof(UnsafeMutablePointer<Int8>))
64 | 
65 |   defer {
66 |     error.dealloc(strideof(UnsafeMutablePointer<Int8>))
67 |     executionEngine.dealloc(strideof(LLVMExecutionEngineRef))
68 |   }
69 | 
70 |   let res = LLVMCreateExecutionEngineForModule(executionEngine, module, error)
71 |   if res != 0 {
72 |     let msg = String.fromCString(error.memory)
73 |     print("\(msg)")
74 |     exit(1)
75 |   }
76 | 
77 |   let value = LLVMRunFunction(executionEngine.memory, wrapperFunction, 0, nil)
78 |   let result = LLVMGenericValueToInt(value, 0)
79 |   return Int(result)
80 | }
81 | 
82 | print("\(runFunction(5, 6))")
83 | print("\(runFunction(7, 142))")
84 | print("\(runFunction(557, 1024))")
85 | 
86 | LLVMDisposeModule(module)
87 | 
88 | 


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