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/Intrinsics.h"
29 #include "llvm/ADT/STLExtras.h"
33 //Set the constants for naming
34 const char *BrainF::tapereg = "tape";
35 const char *BrainF::headreg = "head";
36 const char *BrainF::label = "brainf";
37 const char *BrainF::testreg = "test";
39 Module *BrainF::parse(std::istream *in1, int mem, CompileFlags cf) {
50 void BrainF::header() {
51 module = new Module("BrainF");
55 //declare void @llvm.memset.i32(i8 *, i8, i32, i32)
56 const Type *Tys[] = { Type::Int32Ty };
57 Function *memset_func = Intrinsic::getDeclaration(module, Intrinsic::memset,
60 //declare i32 @getchar()
61 getchar_func = cast<Function>(module->
62 getOrInsertFunction("getchar", IntegerType::Int32Ty, NULL));
64 //declare i32 @putchar(i32)
65 putchar_func = cast<Function>(module->
66 getOrInsertFunction("putchar", IntegerType::Int32Ty,
67 IntegerType::Int32Ty, NULL));
72 //define void @brainf()
73 brainf_func = cast<Function>(module->
74 getOrInsertFunction("brainf", Type::VoidTy, NULL));
76 builder = new IRBuilder<>(BasicBlock::Create(label, brainf_func));
78 //%arr = malloc i8, i32 %d
79 ConstantInt *val_mem = ConstantInt::get(APInt(32, memtotal));
80 ptr_arr = builder->CreateMalloc(IntegerType::Int8Ty, val_mem, "arr");
82 //call void @llvm.memset.i32(i8 *%arr, i8 0, i32 %d, i32 1)
84 Value *memset_params[] = {
86 ConstantInt::get(APInt(8, 0)),
88 ConstantInt::get(APInt(32, 1))
91 CallInst *memset_call = builder->
92 CreateCall(memset_func, memset_params, array_endof(memset_params));
93 memset_call->setTailCall(false);
96 //%arrmax = getelementptr i8 *%arr, i32 %d
97 if (comflag & flag_arraybounds) {
98 ptr_arrmax = builder->
99 CreateGEP(ptr_arr, ConstantInt::get(APInt(32, memtotal)), "arrmax");
102 //%head.%d = getelementptr i8 *%arr, i32 %d
103 curhead = builder->CreateGEP(ptr_arr,
104 ConstantInt::get(APInt(32, memtotal/2)),
112 endbb = BasicBlock::Create(label, brainf_func);
115 new FreeInst(ptr_arr, endbb);
118 ReturnInst::Create(endbb);
122 //Error block for array out of bounds
123 if (comflag & flag_arraybounds)
125 //@aberrormsg = internal constant [%d x i8] c"\00"
126 Constant *msg_0 = ConstantArray::
127 get("Error: The head has left the tape.", true);
129 GlobalVariable *aberrormsg = new GlobalVariable(
132 GlobalValue::InternalLinkage,
137 //declare i32 @puts(i8 *)
138 Function *puts_func = cast<Function>(module->
139 getOrInsertFunction("puts", IntegerType::Int32Ty,
140 PointerType::getUnqual(IntegerType::Int8Ty), NULL));
143 aberrorbb = BasicBlock::Create(label, brainf_func);
145 //call i32 @puts(i8 *getelementptr([%d x i8] *@aberrormsg, i32 0, i32 0))
147 Constant *zero_32 = Constant::getNullValue(IntegerType::Int32Ty);
149 Constant *gep_params[] = {
154 Constant *msgptr = ConstantExpr::
155 getGetElementPtr(aberrormsg, gep_params,
156 array_lengthof(gep_params));
158 Value *puts_params[] = {
162 CallInst *puts_call =
163 CallInst::Create(puts_func,
164 puts_params, array_endof(puts_params),
166 puts_call->setTailCall(false);
169 //br label %brainf.end
170 BranchInst::Create(endbb, aberrorbb);
174 void BrainF::readloop(PHINode *phi, BasicBlock *oldbb, BasicBlock *testbb) {
175 Symbol cursym = SYM_NONE;
177 Symbol nextsym = SYM_NONE;
183 while(cursym != SYM_EOF && cursym != SYM_ENDLOOP) {
184 // Write out commands
192 //%tape.%d = call i32 @getchar()
193 CallInst *getchar_call = builder->CreateCall(getchar_func, tapereg);
194 getchar_call->setTailCall(false);
195 Value *tape_0 = getchar_call;
197 //%tape.%d = trunc i32 %tape.%d to i8
198 Value *tape_1 = builder->
199 CreateTrunc(tape_0, IntegerType::Int8Ty, tapereg);
201 //store i8 %tape.%d, i8 *%head.%d
202 builder->CreateStore(tape_1, curhead);
208 //%tape.%d = load i8 *%head.%d
209 LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
211 //%tape.%d = sext i8 %tape.%d to i32
212 Value *tape_1 = builder->
213 CreateSExt(tape_0, IntegerType::Int32Ty, tapereg);
215 //call i32 @putchar(i32 %tape.%d)
216 Value *putchar_params[] = {
219 CallInst *putchar_call = builder->
220 CreateCall(putchar_func,
221 putchar_params, array_endof(putchar_params));
222 putchar_call->setTailCall(false);
228 //%head.%d = getelementptr i8 *%head.%d, i32 %d
230 CreateGEP(curhead, ConstantInt::get(APInt(32, curvalue)),
233 //Error block for array out of bounds
234 if (comflag & flag_arraybounds)
236 //%test.%d = icmp uge i8 *%head.%d, %arrmax
237 Value *test_0 = builder->
238 CreateICmpUGE(curhead, ptr_arrmax, testreg);
240 //%test.%d = icmp ult i8 *%head.%d, %arr
241 Value *test_1 = builder->
242 CreateICmpULT(curhead, ptr_arr, testreg);
244 //%test.%d = or i1 %test.%d, %test.%d
245 Value *test_2 = builder->
246 CreateOr(test_0, test_1, testreg);
248 //br i1 %test.%d, label %main.%d, label %main.%d
249 BasicBlock *nextbb = BasicBlock::Create(label, brainf_func);
250 builder->CreateCondBr(test_2, aberrorbb, nextbb);
253 builder->SetInsertPoint(nextbb);
260 //%tape.%d = load i8 *%head.%d
261 LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
263 //%tape.%d = add i8 %tape.%d, %d
264 Value *tape_1 = builder->
265 CreateAdd(tape_0, ConstantInt::get(APInt(8, curvalue)), tapereg);
267 //store i8 %tape.%d, i8 *%head.%d\n"
268 builder->CreateStore(tape_1, curhead);
275 BasicBlock *testbb = BasicBlock::Create(label, brainf_func);
276 builder->CreateBr(testbb);
279 BasicBlock *bb_0 = builder->GetInsertBlock();
280 BasicBlock *bb_1 = BasicBlock::Create(label, brainf_func);
281 builder->SetInsertPoint(bb_1);
283 // Make part of PHI instruction now, wait until end of loop to finish
285 PHINode::Create(PointerType::getUnqual(IntegerType::Int8Ty),
287 phi_0->reserveOperandSpace(2);
288 phi_0->addIncoming(curhead, bb_0);
291 readloop(phi_0, bb_1, testbb);
296 std::cerr << "Error: Unknown symbol.\n";
302 curvalue = nextvalue;
305 // Reading stdin loop
306 loop = (cursym == SYM_NONE)
307 || (cursym == SYM_MOVE)
308 || (cursym == SYM_CHANGE);
312 if (cursym == SYM_NONE) {
326 if (cursym == SYM_CHANGE) {
327 curvalue += direction;
330 if (cursym == SYM_NONE) {
332 curvalue = direction;
335 nextsym = SYM_CHANGE;
336 nextvalue = direction;
347 if (cursym == SYM_MOVE) {
348 curvalue += direction;
351 if (cursym == SYM_NONE) {
353 curvalue = direction;
357 nextvalue = direction;
364 if (cursym == SYM_NONE) {
373 if (cursym == SYM_NONE) {
382 if (cursym == SYM_NONE) {
391 if (cursym == SYM_NONE) {
392 cursym = SYM_ENDLOOP;
394 nextsym = SYM_ENDLOOP;
399 // Ignore other characters
407 if (cursym == SYM_ENDLOOP) {
409 std::cerr << "Error: Extra ']'\n";
416 builder->CreateBr(testbb);
420 //%head.%d = phi i8 *[%head.%d, %main.%d], [%head.%d, %main.%d]
421 //Finish phi made at beginning of loop
422 phi->addIncoming(curhead, builder->GetInsertBlock());
425 //%tape.%d = load i8 *%head.%d
426 LoadInst *tape_0 = new LoadInst(head_0, tapereg, testbb);
428 //%test.%d = icmp eq i8 %tape.%d, 0
429 ICmpInst *test_0 = new ICmpInst(ICmpInst::ICMP_EQ, tape_0,
430 ConstantInt::get(APInt(8, 0)), testreg,
433 //br i1 %test.%d, label %main.%d, label %main.%d
434 BasicBlock *bb_0 = BasicBlock::Create(label, brainf_func);
435 BranchInst::Create(bb_0, oldbb, test_0, testbb);
438 builder->SetInsertPoint(bb_0);
440 //%head.%d = phi i8 *[%head.%d, %main.%d]
441 PHINode *phi_1 = builder->
442 CreatePHI(PointerType::getUnqual(IntegerType::Int8Ty), headreg);
443 phi_1->reserveOperandSpace(1);
444 phi_1->addIncoming(head_0, testbb);
451 //End of the program, so go to return block
452 builder->CreateBr(endbb);
455 std::cerr << "Error: Missing ']'\n";