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llvm-mirror/examples/BrainF/BrainF.cpp
Serge Guelton 6ca59da244 Module::getOrInsertFunction is using C-style vararg instead of variadic templates. 
From a user prospective, it forces the use of an annoying nullptr to mark the end of the vararg, and there's not type checking on the arguments.
The variadic template is an obvious solution to both issues.

Differential Revision: https://reviews.llvm.org/D31070

llvm-svn: 299949
2017-04-11 15:01:18 +00:00

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//===-- BrainF.cpp - BrainF compiler example ------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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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