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llvm-mirror/examples/BrainF/BrainF.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo 
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

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//===-- BrainF.cpp - BrainF compiler example ------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This class compiles the BrainF language into LLVM assembly.
//
// The BrainF language has 8 commands:
// Command Equivalent C Action
// ------- ------------ ------
// , *h=getchar(); Read a character from stdin, 255 on EOF
// . putchar(*h); Write a character to stdout
// - --*h; Decrement tape
// + ++*h; Increment tape
// < --h; Move head left
// > ++h; Move head right
// [ while(*h) { Start loop
// ] } End loop
//
//===----------------------------------------------------------------------===//
#include "BrainF.h"
#include "llvm/ADT/APInt.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/Casting.h"
#include <cstdlib>
#include <iostream>
using namespace llvm;
//Set the constants for naming
const char *BrainF::tapereg = "tape";
const char *BrainF::headreg = "head";
const char *BrainF::label = "brainf";
const char *BrainF::testreg = "test";
Module *BrainF::parse(std::istream *in1, int mem, CompileFlags cf,
LLVMContext& Context) {
in = in1;
memtotal = mem;
comflag = cf;
header(Context);
readloop(nullptr, nullptr, nullptr, Context);
delete builder;
return module;
}
void BrainF::header(LLVMContext& C) {
module = new Module("BrainF", C);
//Function prototypes
//declare void @llvm.memset.p0i8.i32(i8 *, i8, i32, i32, i1)
Type *Tys[] = { Type::getInt8PtrTy(C), Type::getInt32Ty(C) };
Function *memset_func = Intrinsic::getDeclaration(module, Intrinsic::memset,
Tys);
//declare i32 @getchar()
getchar_func = cast<Function>(module->
getOrInsertFunction("getchar", IntegerType::getInt32Ty(C)));
//declare i32 @putchar(i32)
putchar_func = cast<Function>(module->
getOrInsertFunction("putchar", IntegerType::getInt32Ty(C),
IntegerType::getInt32Ty(C)));
//Function header
//define void @brainf()
brainf_func = cast<Function>(module->
getOrInsertFunction("brainf", Type::getVoidTy(C)));
builder = new IRBuilder<>(BasicBlock::Create(C, label, brainf_func));
//%arr = malloc i8, i32 %d
ConstantInt *val_mem = ConstantInt::get(C, APInt(32, memtotal));
BasicBlock* BB = builder->GetInsertBlock();
Type* IntPtrTy = IntegerType::getInt32Ty(C);
Type* Int8Ty = IntegerType::getInt8Ty(C);
Constant* allocsize = ConstantExpr::getSizeOf(Int8Ty);
allocsize = ConstantExpr::getTruncOrBitCast(allocsize, IntPtrTy);
ptr_arr = CallInst::CreateMalloc(BB, IntPtrTy, Int8Ty, allocsize, val_mem,
nullptr, "arr");
BB->getInstList().push_back(cast<Instruction>(ptr_arr));
//call void @llvm.memset.p0i8.i32(i8 *%arr, i8 0, i32 %d, i32 1, i1 0)
{
Value *memset_params[] = {
ptr_arr,
ConstantInt::get(C, APInt(8, 0)),
val_mem,
ConstantInt::get(C, APInt(32, 1)),
ConstantInt::get(C, APInt(1, 0))
};
CallInst *memset_call = builder->
CreateCall(memset_func, memset_params);
memset_call->setTailCall(false);
}
//%arrmax = getelementptr i8 *%arr, i32 %d
if (comflag & flag_arraybounds) {
ptr_arrmax = builder->
CreateGEP(ptr_arr, ConstantInt::get(C, APInt(32, memtotal)), "arrmax");
}
//%head.%d = getelementptr i8 *%arr, i32 %d
curhead = builder->CreateGEP(ptr_arr,
ConstantInt::get(C, APInt(32, memtotal/2)),
headreg);
//Function footer
//brainf.end:
endbb = BasicBlock::Create(C, label, brainf_func);
//call free(i8 *%arr)
endbb->getInstList().push_back(CallInst::CreateFree(ptr_arr, endbb));
//ret void
ReturnInst::Create(C, endbb);
//Error block for array out of bounds
if (comflag & flag_arraybounds)
{
//@aberrormsg = internal constant [%d x i8] c"\00"
Constant *msg_0 =
ConstantDataArray::getString(C, "Error: The head has left the tape.",
true);
GlobalVariable *aberrormsg = new GlobalVariable(
*module,
msg_0->getType(),
true,
GlobalValue::InternalLinkage,
msg_0,
"aberrormsg");
//declare i32 @puts(i8 *)
Function *puts_func = cast<Function>(module->
getOrInsertFunction("puts", IntegerType::getInt32Ty(C),
PointerType::getUnqual(IntegerType::getInt8Ty(C))));
//brainf.aberror:
aberrorbb = BasicBlock::Create(C, label, brainf_func);
//call i32 @puts(i8 *getelementptr([%d x i8] *@aberrormsg, i32 0, i32 0))
{
Constant *zero_32 = Constant::getNullValue(IntegerType::getInt32Ty(C));
Constant *gep_params[] = {
zero_32,
zero_32
};
Constant *msgptr = ConstantExpr::
getGetElementPtr(aberrormsg->getValueType(), aberrormsg, gep_params);
Value *puts_params[] = {
msgptr
};
CallInst *puts_call =
CallInst::Create(puts_func,
puts_params,
"", aberrorbb);
puts_call->setTailCall(false);
}
//br label %brainf.end
BranchInst::Create(endbb, aberrorbb);
}
}
void BrainF::readloop(PHINode *phi, BasicBlock *oldbb, BasicBlock *testbb,
LLVMContext &C) {
Symbol cursym = SYM_NONE;
int curvalue = 0;
Symbol nextsym = SYM_NONE;
int nextvalue = 0;
char c;
int loop;
int direction;
while(cursym != SYM_EOF && cursym != SYM_ENDLOOP) {
// Write out commands
switch(cursym) {
case SYM_NONE:
// Do nothing
break;
case SYM_READ:
{
//%tape.%d = call i32 @getchar()
CallInst *getchar_call =
builder->CreateCall(getchar_func, {}, tapereg);
getchar_call->setTailCall(false);
Value *tape_0 = getchar_call;
//%tape.%d = trunc i32 %tape.%d to i8
Value *tape_1 = builder->
CreateTrunc(tape_0, IntegerType::getInt8Ty(C), tapereg);
//store i8 %tape.%d, i8 *%head.%d
builder->CreateStore(tape_1, curhead);
}
break;
case SYM_WRITE:
{
//%tape.%d = load i8 *%head.%d
LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
//%tape.%d = sext i8 %tape.%d to i32
Value *tape_1 = builder->
CreateSExt(tape_0, IntegerType::getInt32Ty(C), tapereg);
//call i32 @putchar(i32 %tape.%d)
Value *putchar_params[] = {
tape_1
};
CallInst *putchar_call = builder->
CreateCall(putchar_func,
putchar_params);
putchar_call->setTailCall(false);
}
break;
case SYM_MOVE:
{
//%head.%d = getelementptr i8 *%head.%d, i32 %d
curhead = builder->
CreateGEP(curhead, ConstantInt::get(C, APInt(32, curvalue)),
headreg);
//Error block for array out of bounds
if (comflag & flag_arraybounds)
{
//%test.%d = icmp uge i8 *%head.%d, %arrmax
Value *test_0 = builder->
CreateICmpUGE(curhead, ptr_arrmax, testreg);
//%test.%d = icmp ult i8 *%head.%d, %arr
Value *test_1 = builder->
CreateICmpULT(curhead, ptr_arr, testreg);
//%test.%d = or i1 %test.%d, %test.%d
Value *test_2 = builder->
CreateOr(test_0, test_1, testreg);
//br i1 %test.%d, label %main.%d, label %main.%d
BasicBlock *nextbb = BasicBlock::Create(C, label, brainf_func);
builder->CreateCondBr(test_2, aberrorbb, nextbb);
//main.%d:
builder->SetInsertPoint(nextbb);
}
}
break;
case SYM_CHANGE:
{
//%tape.%d = load i8 *%head.%d
LoadInst *tape_0 = builder->CreateLoad(curhead, tapereg);
//%tape.%d = add i8 %tape.%d, %d
Value *tape_1 = builder->
CreateAdd(tape_0, ConstantInt::get(C, APInt(8, curvalue)), tapereg);
//store i8 %tape.%d, i8 *%head.%d\n"
builder->CreateStore(tape_1, curhead);
}
break;
case SYM_LOOP:
{
//br label %main.%d
BasicBlock *testbb = BasicBlock::Create(C, label, brainf_func);
builder->CreateBr(testbb);
//main.%d:
BasicBlock *bb_0 = builder->GetInsertBlock();
BasicBlock *bb_1 = BasicBlock::Create(C, label, brainf_func);
builder->SetInsertPoint(bb_1);
// Make part of PHI instruction now, wait until end of loop to finish
PHINode *phi_0 =
PHINode::Create(PointerType::getUnqual(IntegerType::getInt8Ty(C)),
2, headreg, testbb);
phi_0->addIncoming(curhead, bb_0);
curhead = phi_0;
readloop(phi_0, bb_1, testbb, C);
}
break;
default:
std::cerr << "Error: Unknown symbol.\n";
abort();
break;
}
cursym = nextsym;
curvalue = nextvalue;
nextsym = SYM_NONE;
// Reading stdin loop
loop = (cursym == SYM_NONE)
|| (cursym == SYM_MOVE)
|| (cursym == SYM_CHANGE);
while(loop) {
*in>>c;
if (in->eof()) {
if (cursym == SYM_NONE) {
cursym = SYM_EOF;
} else {
nextsym = SYM_EOF;
}
loop = 0;
} else {
direction = 1;
switch(c) {
case '-':
direction = -1;
LLVM_FALLTHROUGH;
case '+':
if (cursym == SYM_CHANGE) {
curvalue += direction;
// loop = 1
} else {
if (cursym == SYM_NONE) {
cursym = SYM_CHANGE;
curvalue = direction;
// loop = 1
} else {
nextsym = SYM_CHANGE;
nextvalue = direction;
loop = 0;
}
}
break;
case '<':
direction = -1;
LLVM_FALLTHROUGH;
case '>':
if (cursym == SYM_MOVE) {
curvalue += direction;
// loop = 1
} else {
if (cursym == SYM_NONE) {
cursym = SYM_MOVE;
curvalue = direction;
// loop = 1
} else {
nextsym = SYM_MOVE;
nextvalue = direction;
loop = 0;
}
}
break;
case ',':
if (cursym == SYM_NONE) {
cursym = SYM_READ;
} else {
nextsym = SYM_READ;
}
loop = 0;
break;
case '.':
if (cursym == SYM_NONE) {
cursym = SYM_WRITE;
} else {
nextsym = SYM_WRITE;
}
loop = 0;
break;
case '[':
if (cursym == SYM_NONE) {
cursym = SYM_LOOP;
} else {
nextsym = SYM_LOOP;
}
loop = 0;
break;
case ']':
if (cursym == SYM_NONE) {
cursym = SYM_ENDLOOP;
} else {
nextsym = SYM_ENDLOOP;
}
loop = 0;
break;
// Ignore other characters
default:
break;
}
}
}
}
if (cursym == SYM_ENDLOOP) {
if (!phi) {
std::cerr << "Error: Extra ']'\n";
abort();
}
// Write loop test
{
//br label %main.%d
builder->CreateBr(testbb);
//main.%d:
//%head.%d = phi i8 *[%head.%d, %main.%d], [%head.%d, %main.%d]
//Finish phi made at beginning of loop
phi->addIncoming(curhead, builder->GetInsertBlock());
Value *head_0 = phi;
//%tape.%d = load i8 *%head.%d
LoadInst *tape_0 = new LoadInst(head_0, tapereg, testbb);
//%test.%d = icmp eq i8 %tape.%d, 0
ICmpInst *test_0 = new ICmpInst(*testbb, ICmpInst::ICMP_EQ, tape_0,
ConstantInt::get(C, APInt(8, 0)), testreg);
//br i1 %test.%d, label %main.%d, label %main.%d
BasicBlock *bb_0 = BasicBlock::Create(C, label, brainf_func);
BranchInst::Create(bb_0, oldbb, test_0, testbb);
//main.%d:
builder->SetInsertPoint(bb_0);
//%head.%d = phi i8 *[%head.%d, %main.%d]
PHINode *phi_1 = builder->
CreatePHI(PointerType::getUnqual(IntegerType::getInt8Ty(C)), 1,
headreg);
phi_1->addIncoming(head_0, testbb);
curhead = phi_1;
}
return;
}
//End of the program, so go to return block
builder->CreateBr(endbb);
if (phi) {
std::cerr << "Error: Missing ']'\n";
abort();
}
}
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