1 //===-- BrainF.cpp - BrainF compiler example ----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===--------------------------------------------------------------------===//
10 // This class compiles the BrainF language into LLVM assembly.
12 // The BrainF language has 8 commands:
13 // Command Equivalent C Action
14 // ------- ------------ ------
15 // , *h=getchar(); Read a character from stdin, 255 on EOF
16 // . putchar(*h); Write a character to stdout
17 // - --*h; Decrement tape
18 // + ++*h; Increment tape
19 // < --h; Move head left
20 // > ++h; Move head right
21 // [ while(*h) { Start loop
24 //===--------------------------------------------------------------------===//
27 #include "llvm/Constants.h"
28 #include "llvm/Instructions.h"
29 #include "llvm/Intrinsics.h"
30 #include "llvm/ADT/STLExtras.h"
34 //Set the constants for naming
35 const char *BrainF::tapereg = "tape";
36 const char *BrainF::headreg = "head";
37 const char *BrainF::label = "brainf";
38 const char *BrainF::testreg = "test";
40 Module *BrainF::parse(std::istream *in1, int mem, CompileFlags cf,
41 LLVMContext& Context) {
47 readloop(0, 0, 0, Context);
52 void BrainF::header(LLVMContext& C) {
53 module = new Module("BrainF", C);
57 //declare void @llvm.memset.i32(i8 *, i8, i32, i32)
58 const Type *Tys[] = { Type::getInt32Ty(C) };
59 Function *memset_func = Intrinsic::getDeclaration(module, Intrinsic::memset,
62 //declare i32 @getchar()
63 getchar_func = cast<Function>(module->
64 getOrInsertFunction("getchar", IntegerType::getInt32Ty(C), NULL));
66 //declare i32 @putchar(i32)
67 putchar_func = cast<Function>(module->
68 getOrInsertFunction("putchar", IntegerType::getInt32Ty(C),
69 IntegerType::getInt32Ty(C), NULL));
74 //define void @brainf()
75 brainf_func = cast<Function>(module->
76 getOrInsertFunction("brainf", Type::getVoidTy(C), NULL));
78 builder = new IRBuilder<>(BasicBlock::Create(C, label, brainf_func));
80 //%arr = malloc i8, i32 %d
81 ConstantInt *val_mem = ConstantInt::get(C, APInt(32, memtotal));
82 BasicBlock* BB = builder->GetInsertBlock();
83 const Type* IntPtrTy = IntegerType::getInt32Ty(C);
84 ptr_arr = CallInst::CreateMalloc(BB, IntPtrTy, IntegerType::getInt8Ty(C),
85 val_mem, NULL, "arr");
86 BB->getInstList().push_back(cast<Instruction>(ptr_arr));
88 //call void @llvm.memset.i32(i8 *%arr, i8 0, i32 %d, i32 1)
90 Value *memset_params[] = {
92 ConstantInt::get(C, APInt(8, 0)),
94 ConstantInt::get(C, APInt(32, 1))
97 CallInst *memset_call = builder->
98 CreateCall(memset_func, memset_params, array_endof(memset_params));
99 memset_call->setTailCall(false);
102 //%arrmax = getelementptr i8 *%arr, i32 %d
103 if (comflag & flag_arraybounds) {
104 ptr_arrmax = builder->
105 CreateGEP(ptr_arr, ConstantInt::get(C, APInt(32, memtotal)), "arrmax");
108 //%head.%d = getelementptr i8 *%arr, i32 %d
109 curhead = builder->CreateGEP(ptr_arr,
110 ConstantInt::get(C, APInt(32, memtotal/2)),
118 endbb = BasicBlock::Create(C, label, brainf_func);
121 new FreeInst(ptr_arr, endbb);
124 ReturnInst::Create(C, endbb);
128 //Error block for array out of bounds
129 if (comflag & flag_arraybounds)
131 //@aberrormsg = internal constant [%d x i8] c"\00"
133 ConstantArray::get(C, "Error: The head has left the tape.", true);
135 GlobalVariable *aberrormsg = new GlobalVariable(
139 GlobalValue::InternalLinkage,
143 //declare i32 @puts(i8 *)
144 Function *puts_func = cast<Function>(module->
145 getOrInsertFunction("puts", IntegerType::getInt32Ty(C),
146 PointerType::getUnqual(IntegerType::getInt8Ty(C)), NULL));
149 aberrorbb = BasicBlock::Create(C, label, brainf_func);
151 //call i32 @puts(i8 *getelementptr([%d x i8] *@aberrormsg, i32 0, i32 0))
153 Constant *zero_32 = Constant::getNullValue(IntegerType::getInt32Ty(C));
155 Constant *gep_params[] = {
160 Constant *msgptr = ConstantExpr::
161 getGetElementPtr(aberrormsg, gep_params,
162 array_lengthof(gep_params));
164 Value *puts_params[] = {
168 CallInst *puts_call =
169 CallInst::Create(puts_func,
170 puts_params, array_endof(puts_params),
172 puts_call->setTailCall(false);
175 //br label %brainf.end
176 BranchInst::Create(endbb, aberrorbb);
180 void BrainF::readloop(PHINode *phi, BasicBlock *oldbb, BasicBlock *testbb,
182 Symbol cursym = SYM_NONE;
184 Symbol nextsym = SYM_NONE;
190 while(cursym != SYM_EOF && cursym != SYM_ENDLOOP) {
191 // Write out commands
199 //%tape.%d = call i32 @getchar()
200 CallInst *getchar_call = builder->CreateCall(getchar_func, tapereg);
201 getchar_call->setTailCall(false);
202 Value *tape_0 = getchar_call;
204 //%tape.%d = trunc i32 %tape.%d to i8
205 Value *tape_1 = builder->
206 CreateTrunc(tape_0, IntegerType::getInt8Ty(C), tapereg);
208 //store i8 %tape.%d, i8 *%head.%d
209 builder->CreateStore(tape_1, curhead);
215 //%tape.%d = load i8 *%head.%d
216 LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
218 //%tape.%d = sext i8 %tape.%d to i32
219 Value *tape_1 = builder->
220 CreateSExt(tape_0, IntegerType::getInt32Ty(C), tapereg);
222 //call i32 @putchar(i32 %tape.%d)
223 Value *putchar_params[] = {
226 CallInst *putchar_call = builder->
227 CreateCall(putchar_func,
228 putchar_params, array_endof(putchar_params));
229 putchar_call->setTailCall(false);
235 //%head.%d = getelementptr i8 *%head.%d, i32 %d
237 CreateGEP(curhead, ConstantInt::get(C, APInt(32, curvalue)),
240 //Error block for array out of bounds
241 if (comflag & flag_arraybounds)
243 //%test.%d = icmp uge i8 *%head.%d, %arrmax
244 Value *test_0 = builder->
245 CreateICmpUGE(curhead, ptr_arrmax, testreg);
247 //%test.%d = icmp ult i8 *%head.%d, %arr
248 Value *test_1 = builder->
249 CreateICmpULT(curhead, ptr_arr, testreg);
251 //%test.%d = or i1 %test.%d, %test.%d
252 Value *test_2 = builder->
253 CreateOr(test_0, test_1, testreg);
255 //br i1 %test.%d, label %main.%d, label %main.%d
256 BasicBlock *nextbb = BasicBlock::Create(C, label, brainf_func);
257 builder->CreateCondBr(test_2, aberrorbb, nextbb);
260 builder->SetInsertPoint(nextbb);
267 //%tape.%d = load i8 *%head.%d
268 LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
270 //%tape.%d = add i8 %tape.%d, %d
271 Value *tape_1 = builder->
272 CreateAdd(tape_0, ConstantInt::get(C, APInt(8, curvalue)), tapereg);
274 //store i8 %tape.%d, i8 *%head.%d\n"
275 builder->CreateStore(tape_1, curhead);
282 BasicBlock *testbb = BasicBlock::Create(C, label, brainf_func);
283 builder->CreateBr(testbb);
286 BasicBlock *bb_0 = builder->GetInsertBlock();
287 BasicBlock *bb_1 = BasicBlock::Create(C, label, brainf_func);
288 builder->SetInsertPoint(bb_1);
290 // Make part of PHI instruction now, wait until end of loop to finish
292 PHINode::Create(PointerType::getUnqual(IntegerType::getInt8Ty(C)),
294 phi_0->reserveOperandSpace(2);
295 phi_0->addIncoming(curhead, bb_0);
298 readloop(phi_0, bb_1, testbb, C);
303 std::cerr << "Error: Unknown symbol.\n";
309 curvalue = nextvalue;
312 // Reading stdin loop
313 loop = (cursym == SYM_NONE)
314 || (cursym == SYM_MOVE)
315 || (cursym == SYM_CHANGE);
319 if (cursym == SYM_NONE) {
333 if (cursym == SYM_CHANGE) {
334 curvalue += direction;
337 if (cursym == SYM_NONE) {
339 curvalue = direction;
342 nextsym = SYM_CHANGE;
343 nextvalue = direction;
354 if (cursym == SYM_MOVE) {
355 curvalue += direction;
358 if (cursym == SYM_NONE) {
360 curvalue = direction;
364 nextvalue = direction;
371 if (cursym == SYM_NONE) {
380 if (cursym == SYM_NONE) {
389 if (cursym == SYM_NONE) {
398 if (cursym == SYM_NONE) {
399 cursym = SYM_ENDLOOP;
401 nextsym = SYM_ENDLOOP;
406 // Ignore other characters
414 if (cursym == SYM_ENDLOOP) {
416 std::cerr << "Error: Extra ']'\n";
423 builder->CreateBr(testbb);
427 //%head.%d = phi i8 *[%head.%d, %main.%d], [%head.%d, %main.%d]
428 //Finish phi made at beginning of loop
429 phi->addIncoming(curhead, builder->GetInsertBlock());
432 //%tape.%d = load i8 *%head.%d
433 LoadInst *tape_0 = new LoadInst(head_0, tapereg, testbb);
435 //%test.%d = icmp eq i8 %tape.%d, 0
436 ICmpInst *test_0 = new ICmpInst(*testbb, ICmpInst::ICMP_EQ, tape_0,
437 ConstantInt::get(C, APInt(8, 0)), testreg);
439 //br i1 %test.%d, label %main.%d, label %main.%d
440 BasicBlock *bb_0 = BasicBlock::Create(C, label, brainf_func);
441 BranchInst::Create(bb_0, oldbb, test_0, testbb);
444 builder->SetInsertPoint(bb_0);
446 //%head.%d = phi i8 *[%head.%d, %main.%d]
447 PHINode *phi_1 = builder->
448 CreatePHI(PointerType::getUnqual(IntegerType::getInt8Ty(C)), headreg);
449 phi_1->reserveOperandSpace(1);
450 phi_1->addIncoming(head_0, testbb);
457 //End of the program, so go to return block
458 builder->CreateBr(endbb);
461 std::cerr << "Error: Missing ']'\n";