1 //===-- BrainF.cpp - BrainF compiler example ----------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===--------------------------------------------------------------------===//
9 //
10 // This class compiles the BrainF language into LLVM assembly.
11 //
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
22 // ] } End loop
23 //
24 //===--------------------------------------------------------------------===//
25
26 #include "BrainF.h"
27 #include "llvm/Constants.h"
28 #include "llvm/Instructions.h"
29 #include "llvm/Intrinsics.h"
30 #include "llvm/ADT/STLExtras.h"
31 #include <iostream>
32 using namespace llvm;
33
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";
39
parse(std::istream * in1,int mem,CompileFlags cf,LLVMContext & Context)40 Module *BrainF::parse(std::istream *in1, int mem, CompileFlags cf,
41 LLVMContext& Context) {
42 in = in1;
43 memtotal = mem;
44 comflag = cf;
45
46 header(Context);
47 readloop(0, 0, 0, Context);
48 delete builder;
49 return module;
50 }
51
header(LLVMContext & C)52 void BrainF::header(LLVMContext& C) {
53 module = new Module("BrainF", C);
54
55 //Function prototypes
56
57 //declare void @llvm.memset.p0i8.i32(i8 *, i8, i32, i32, i1)
58 Type *Tys[] = { Type::getInt8PtrTy(C), Type::getInt32Ty(C) };
59 Function *memset_func = Intrinsic::getDeclaration(module, Intrinsic::memset,
60 Tys);
61
62 //declare i32 @getchar()
63 getchar_func = cast<Function>(module->
64 getOrInsertFunction("getchar", IntegerType::getInt32Ty(C), NULL));
65
66 //declare i32 @putchar(i32)
67 putchar_func = cast<Function>(module->
68 getOrInsertFunction("putchar", IntegerType::getInt32Ty(C),
69 IntegerType::getInt32Ty(C), NULL));
70
71
72 //Function header
73
74 //define void @brainf()
75 brainf_func = cast<Function>(module->
76 getOrInsertFunction("brainf", Type::getVoidTy(C), NULL));
77
78 builder = new IRBuilder<>(BasicBlock::Create(C, label, brainf_func));
79
80 //%arr = malloc i8, i32 %d
81 ConstantInt *val_mem = ConstantInt::get(C, APInt(32, memtotal));
82 BasicBlock* BB = builder->GetInsertBlock();
83 Type* IntPtrTy = IntegerType::getInt32Ty(C);
84 Type* Int8Ty = IntegerType::getInt8Ty(C);
85 Constant* allocsize = ConstantExpr::getSizeOf(Int8Ty);
86 allocsize = ConstantExpr::getTruncOrBitCast(allocsize, IntPtrTy);
87 ptr_arr = CallInst::CreateMalloc(BB, IntPtrTy, Int8Ty, allocsize, val_mem,
88 NULL, "arr");
89 BB->getInstList().push_back(cast<Instruction>(ptr_arr));
90
91 //call void @llvm.memset.p0i8.i32(i8 *%arr, i8 0, i32 %d, i32 1, i1 0)
92 {
93 Value *memset_params[] = {
94 ptr_arr,
95 ConstantInt::get(C, APInt(8, 0)),
96 val_mem,
97 ConstantInt::get(C, APInt(32, 1)),
98 ConstantInt::get(C, APInt(1, 0))
99 };
100
101 CallInst *memset_call = builder->
102 CreateCall(memset_func, memset_params);
103 memset_call->setTailCall(false);
104 }
105
106 //%arrmax = getelementptr i8 *%arr, i32 %d
107 if (comflag & flag_arraybounds) {
108 ptr_arrmax = builder->
109 CreateGEP(ptr_arr, ConstantInt::get(C, APInt(32, memtotal)), "arrmax");
110 }
111
112 //%head.%d = getelementptr i8 *%arr, i32 %d
113 curhead = builder->CreateGEP(ptr_arr,
114 ConstantInt::get(C, APInt(32, memtotal/2)),
115 headreg);
116
117
118
119 //Function footer
120
121 //brainf.end:
122 endbb = BasicBlock::Create(C, label, brainf_func);
123
124 //call free(i8 *%arr)
125 endbb->getInstList().push_back(CallInst::CreateFree(ptr_arr, endbb));
126
127 //ret void
128 ReturnInst::Create(C, endbb);
129
130
131
132 //Error block for array out of bounds
133 if (comflag & flag_arraybounds)
134 {
135 //@aberrormsg = internal constant [%d x i8] c"\00"
136 Constant *msg_0 =
137 ConstantArray::get(C, "Error: The head has left the tape.", true);
138
139 GlobalVariable *aberrormsg = new GlobalVariable(
140 *module,
141 msg_0->getType(),
142 true,
143 GlobalValue::InternalLinkage,
144 msg_0,
145 "aberrormsg");
146
147 //declare i32 @puts(i8 *)
148 Function *puts_func = cast<Function>(module->
149 getOrInsertFunction("puts", IntegerType::getInt32Ty(C),
150 PointerType::getUnqual(IntegerType::getInt8Ty(C)), NULL));
151
152 //brainf.aberror:
153 aberrorbb = BasicBlock::Create(C, label, brainf_func);
154
155 //call i32 @puts(i8 *getelementptr([%d x i8] *@aberrormsg, i32 0, i32 0))
156 {
157 Constant *zero_32 = Constant::getNullValue(IntegerType::getInt32Ty(C));
158
159 Constant *gep_params[] = {
160 zero_32,
161 zero_32
162 };
163
164 Constant *msgptr = ConstantExpr::
165 getGetElementPtr(aberrormsg, gep_params);
166
167 Value *puts_params[] = {
168 msgptr
169 };
170
171 CallInst *puts_call =
172 CallInst::Create(puts_func,
173 puts_params,
174 "", aberrorbb);
175 puts_call->setTailCall(false);
176 }
177
178 //br label %brainf.end
179 BranchInst::Create(endbb, aberrorbb);
180 }
181 }
182
readloop(PHINode * phi,BasicBlock * oldbb,BasicBlock * testbb,LLVMContext & C)183 void BrainF::readloop(PHINode *phi, BasicBlock *oldbb, BasicBlock *testbb,
184 LLVMContext &C) {
185 Symbol cursym = SYM_NONE;
186 int curvalue = 0;
187 Symbol nextsym = SYM_NONE;
188 int nextvalue = 0;
189 char c;
190 int loop;
191 int direction;
192
193 while(cursym != SYM_EOF && cursym != SYM_ENDLOOP) {
194 // Write out commands
195 switch(cursym) {
196 case SYM_NONE:
197 // Do nothing
198 break;
199
200 case SYM_READ:
201 {
202 //%tape.%d = call i32 @getchar()
203 CallInst *getchar_call = builder->CreateCall(getchar_func, tapereg);
204 getchar_call->setTailCall(false);
205 Value *tape_0 = getchar_call;
206
207 //%tape.%d = trunc i32 %tape.%d to i8
208 Value *tape_1 = builder->
209 CreateTrunc(tape_0, IntegerType::getInt8Ty(C), tapereg);
210
211 //store i8 %tape.%d, i8 *%head.%d
212 builder->CreateStore(tape_1, curhead);
213 }
214 break;
215
216 case SYM_WRITE:
217 {
218 //%tape.%d = load i8 *%head.%d
219 LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
220
221 //%tape.%d = sext i8 %tape.%d to i32
222 Value *tape_1 = builder->
223 CreateSExt(tape_0, IntegerType::getInt32Ty(C), tapereg);
224
225 //call i32 @putchar(i32 %tape.%d)
226 Value *putchar_params[] = {
227 tape_1
228 };
229 CallInst *putchar_call = builder->
230 CreateCall(putchar_func,
231 putchar_params);
232 putchar_call->setTailCall(false);
233 }
234 break;
235
236 case SYM_MOVE:
237 {
238 //%head.%d = getelementptr i8 *%head.%d, i32 %d
239 curhead = builder->
240 CreateGEP(curhead, ConstantInt::get(C, APInt(32, curvalue)),
241 headreg);
242
243 //Error block for array out of bounds
244 if (comflag & flag_arraybounds)
245 {
246 //%test.%d = icmp uge i8 *%head.%d, %arrmax
247 Value *test_0 = builder->
248 CreateICmpUGE(curhead, ptr_arrmax, testreg);
249
250 //%test.%d = icmp ult i8 *%head.%d, %arr
251 Value *test_1 = builder->
252 CreateICmpULT(curhead, ptr_arr, testreg);
253
254 //%test.%d = or i1 %test.%d, %test.%d
255 Value *test_2 = builder->
256 CreateOr(test_0, test_1, testreg);
257
258 //br i1 %test.%d, label %main.%d, label %main.%d
259 BasicBlock *nextbb = BasicBlock::Create(C, label, brainf_func);
260 builder->CreateCondBr(test_2, aberrorbb, nextbb);
261
262 //main.%d:
263 builder->SetInsertPoint(nextbb);
264 }
265 }
266 break;
267
268 case SYM_CHANGE:
269 {
270 //%tape.%d = load i8 *%head.%d
271 LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
272
273 //%tape.%d = add i8 %tape.%d, %d
274 Value *tape_1 = builder->
275 CreateAdd(tape_0, ConstantInt::get(C, APInt(8, curvalue)), tapereg);
276
277 //store i8 %tape.%d, i8 *%head.%d\n"
278 builder->CreateStore(tape_1, curhead);
279 }
280 break;
281
282 case SYM_LOOP:
283 {
284 //br label %main.%d
285 BasicBlock *testbb = BasicBlock::Create(C, label, brainf_func);
286 builder->CreateBr(testbb);
287
288 //main.%d:
289 BasicBlock *bb_0 = builder->GetInsertBlock();
290 BasicBlock *bb_1 = BasicBlock::Create(C, label, brainf_func);
291 builder->SetInsertPoint(bb_1);
292
293 // Make part of PHI instruction now, wait until end of loop to finish
294 PHINode *phi_0 =
295 PHINode::Create(PointerType::getUnqual(IntegerType::getInt8Ty(C)),
296 2, headreg, testbb);
297 phi_0->addIncoming(curhead, bb_0);
298 curhead = phi_0;
299
300 readloop(phi_0, bb_1, testbb, C);
301 }
302 break;
303
304 default:
305 std::cerr << "Error: Unknown symbol.\n";
306 abort();
307 break;
308 }
309
310 cursym = nextsym;
311 curvalue = nextvalue;
312 nextsym = SYM_NONE;
313
314 // Reading stdin loop
315 loop = (cursym == SYM_NONE)
316 || (cursym == SYM_MOVE)
317 || (cursym == SYM_CHANGE);
318 while(loop) {
319 *in>>c;
320 if (in->eof()) {
321 if (cursym == SYM_NONE) {
322 cursym = SYM_EOF;
323 } else {
324 nextsym = SYM_EOF;
325 }
326 loop = 0;
327 } else {
328 direction = 1;
329 switch(c) {
330 case '-':
331 direction = -1;
332 // Fall through
333
334 case '+':
335 if (cursym == SYM_CHANGE) {
336 curvalue += direction;
337 // loop = 1
338 } else {
339 if (cursym == SYM_NONE) {
340 cursym = SYM_CHANGE;
341 curvalue = direction;
342 // loop = 1
343 } else {
344 nextsym = SYM_CHANGE;
345 nextvalue = direction;
346 loop = 0;
347 }
348 }
349 break;
350
351 case '<':
352 direction = -1;
353 // Fall through
354
355 case '>':
356 if (cursym == SYM_MOVE) {
357 curvalue += direction;
358 // loop = 1
359 } else {
360 if (cursym == SYM_NONE) {
361 cursym = SYM_MOVE;
362 curvalue = direction;
363 // loop = 1
364 } else {
365 nextsym = SYM_MOVE;
366 nextvalue = direction;
367 loop = 0;
368 }
369 }
370 break;
371
372 case ',':
373 if (cursym == SYM_NONE) {
374 cursym = SYM_READ;
375 } else {
376 nextsym = SYM_READ;
377 }
378 loop = 0;
379 break;
380
381 case '.':
382 if (cursym == SYM_NONE) {
383 cursym = SYM_WRITE;
384 } else {
385 nextsym = SYM_WRITE;
386 }
387 loop = 0;
388 break;
389
390 case '[':
391 if (cursym == SYM_NONE) {
392 cursym = SYM_LOOP;
393 } else {
394 nextsym = SYM_LOOP;
395 }
396 loop = 0;
397 break;
398
399 case ']':
400 if (cursym == SYM_NONE) {
401 cursym = SYM_ENDLOOP;
402 } else {
403 nextsym = SYM_ENDLOOP;
404 }
405 loop = 0;
406 break;
407
408 // Ignore other characters
409 default:
410 break;
411 }
412 }
413 }
414 }
415
416 if (cursym == SYM_ENDLOOP) {
417 if (!phi) {
418 std::cerr << "Error: Extra ']'\n";
419 abort();
420 }
421
422 // Write loop test
423 {
424 //br label %main.%d
425 builder->CreateBr(testbb);
426
427 //main.%d:
428
429 //%head.%d = phi i8 *[%head.%d, %main.%d], [%head.%d, %main.%d]
430 //Finish phi made at beginning of loop
431 phi->addIncoming(curhead, builder->GetInsertBlock());
432 Value *head_0 = phi;
433
434 //%tape.%d = load i8 *%head.%d
435 LoadInst *tape_0 = new LoadInst(head_0, tapereg, testbb);
436
437 //%test.%d = icmp eq i8 %tape.%d, 0
438 ICmpInst *test_0 = new ICmpInst(*testbb, ICmpInst::ICMP_EQ, tape_0,
439 ConstantInt::get(C, APInt(8, 0)), testreg);
440
441 //br i1 %test.%d, label %main.%d, label %main.%d
442 BasicBlock *bb_0 = BasicBlock::Create(C, label, brainf_func);
443 BranchInst::Create(bb_0, oldbb, test_0, testbb);
444
445 //main.%d:
446 builder->SetInsertPoint(bb_0);
447
448 //%head.%d = phi i8 *[%head.%d, %main.%d]
449 PHINode *phi_1 = builder->
450 CreatePHI(PointerType::getUnqual(IntegerType::getInt8Ty(C)), 1,
451 headreg);
452 phi_1->addIncoming(head_0, testbb);
453 curhead = phi_1;
454 }
455
456 return;
457 }
458
459 //End of the program, so go to return block
460 builder->CreateBr(endbb);
461
462 if (phi) {
463 std::cerr << "Error: Missing ']'\n";
464 abort();
465 }
466 }
467