6. Kaleidoscope：擴展語言：使用者自定義運算符¶
6.1. 第 6 章 簡介¶
歡迎來到「使用 LLVM 實作語言」教學的第 6 章。在教學的這個階段，我們現在擁有一個功能齊全的語言，它雖然極簡，但也非常實用。然而，它仍然存在一個很大的問題。我們的語言沒有很多實用的運算符（例如除法、邏輯否定，甚至除了小於之外的任何比較）。
本教學章節將深入探討如何在簡單而美觀的 Kaleidoscope 語言中新增使用者自定義運算符。這種探討現在在某些方面為我們提供了一種簡單而醜陋的語言，但同時也是一種強大的語言。建立自己的語言的一大優點是您可以決定什麼是好是壞。在本教學中，我們將假設可以使用它來展示一些有趣的解析技術。
在本教學結束時，我們將運行一個 Kaleidoscope 應用程式範例，它呈現曼德博集合。這提供了一個可以使用 Kaleidoscope 及其功能集建構的範例。
6.2. 使用者自定義運算符：概念¶
我們將新增到 Kaleidoscope 的「運算符重載」比 C++ 等語言中的更為通用。在 C++ 中，您只能重新定義現有的運算符：您無法以程式設計方式更改文法、引入新的運算符、更改優先順序級別等。在本章中，我們將把此功能新增到 Kaleidoscope，這將允許使用者完善支援的運算符集。
在像這樣的教學中探討使用者自定義運算符的目的是展示使用手寫解析器的強大功能和靈活性。到目前為止，我們一直在實作的解析器在文法的多數部分使用遞迴下降，並在表達式中使用運算符優先順序解析。詳情請參閱第 2 章。通過使用運算符優先順序解析，允許程式設計師在文法中引入新的運算符非常容易：文法在 JIT 運行時是動態可擴展的。
我們將新增的兩個具體功能是可程式化一元運算符（目前，Kaleidoscope 根本沒有任何一元運算符）以及二元運算符。以下是一個範例：
# Logical unary not.
def unary!(v)
if v then
0
else
1;
# Define > with the same precedence as <.
def binary> 10 (LHS RHS)
RHS < LHS;
# Binary "logical or", (note that it does not "short circuit")
def binary| 5 (LHS RHS)
if LHS then
1
else if RHS then
1
else
0;
# Define = with slightly lower precedence than relationals.
def binary= 9 (LHS RHS)
!(LHS < RHS | LHS > RHS);
許多語言都渴望能夠以語言本身實作其標準運行時程式庫。在 Kaleidoscope 中，我們可以在程式庫中實作語言的重要部分！
我們會將這些功能的實作分為兩部分：實作對使用者自定義二元運算符的支援以及新增一元運算符。
6.3. 使用者自訂二元運算子¶
在我們目前的框架下，新增對使用者自訂二元運算子的支援相當簡單。我們首先新增對 unary/binary 關鍵字的支援
enum Token {
...
// operators
tok_binary = -11,
tok_unary = -12
};
...
static int gettok() {
...
if (IdentifierStr == "for")
return tok_for;
if (IdentifierStr == "in")
return tok_in;
if (IdentifierStr == "binary")
return tok_binary;
if (IdentifierStr == "unary")
return tok_unary;
return tok_identifier;
這就像我們在前面的章節中所做的那樣，僅僅是為 unary 和 binary 關鍵字新增詞法分析器的支援。我們目前的 AST 的一個優點是，我們使用 ASCII 碼作為操作碼，以完全通用的方式來表示二元運算子。對於我們擴展的運算子，我們將使用相同的表示方式，因此我們不需要任何新的 AST 或解析器支援。
另一方面，我們必須能夠表示這些新運算子的定義，在函式定義的「def binary| 5」部分。到目前為止，在我們的語法中，函式定義的「名稱」被解析為「原型」產生式，並放入 PrototypeAST AST 節點中。為了將我們新的使用者自訂運算子表示為原型，我們必須像這樣擴展 PrototypeAST AST 節點
/// PrototypeAST - This class represents the "prototype" for a function,
/// which captures its argument names as well as if it is an operator.
class PrototypeAST {
std::string Name;
std::vector<std::string> Args;
bool IsOperator;
unsigned Precedence; // Precedence if a binary op.
public:
PrototypeAST(const std::string &Name, std::vector<std::string> Args,
bool IsOperator = false, unsigned Prec = 0)
: Name(Name), Args(std::move(Args)), IsOperator(IsOperator),
Precedence(Prec) {}
Function *codegen();
const std::string &getName() const { return Name; }
bool isUnaryOp() const { return IsOperator && Args.size() == 1; }
bool isBinaryOp() const { return IsOperator && Args.size() == 2; }
char getOperatorName() const {
assert(isUnaryOp() || isBinaryOp());
return Name[Name.size() - 1];
}
unsigned getBinaryPrecedence() const { return Precedence; }
};
基本上，除了知道原型的名稱之外，我們現在還追蹤它是否是運算子，如果是，則運算子的優先順序級別是多少。優先順序僅用於二元運算子（如下所示，它不適用於單元運算子）。現在我們有了一種表示使用者自訂運算子原型的的方法，我們需要解析它
/// prototype
/// ::= id '(' id* ')'
/// ::= binary LETTER number? (id, id)
static std::unique_ptr<PrototypeAST> ParsePrototype() {
std::string FnName;
unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
unsigned BinaryPrecedence = 30;
switch (CurTok) {
default:
return LogErrorP("Expected function name in prototype");
case tok_identifier:
FnName = IdentifierStr;
Kind = 0;
getNextToken();
break;
case tok_binary:
getNextToken();
if (!isascii(CurTok))
return LogErrorP("Expected binary operator");
FnName = "binary";
FnName += (char)CurTok;
Kind = 2;
getNextToken();
// Read the precedence if present.
if (CurTok == tok_number) {
if (NumVal < 1 || NumVal > 100)
return LogErrorP("Invalid precedence: must be 1..100");
BinaryPrecedence = (unsigned)NumVal;
getNextToken();
}
break;
}
if (CurTok != '(')
return LogErrorP("Expected '(' in prototype");
std::vector<std::string> ArgNames;
while (getNextToken() == tok_identifier)
ArgNames.push_back(IdentifierStr);
if (CurTok != ')')
return LogErrorP("Expected ')' in prototype");
// success.
getNextToken(); // eat ')'.
// Verify right number of names for operator.
if (Kind && ArgNames.size() != Kind)
return LogErrorP("Invalid number of operands for operator");
return std::make_unique<PrototypeAST>(FnName, std::move(ArgNames), Kind != 0,
BinaryPrecedence);
}
這都是相當簡單的解析程式碼，而且我們過去已經見過很多類似的程式碼。上面程式碼中一個有趣的部分是設定 FnName 的幾行程式碼。這會為新定義的「@」運算子建構「binary@」之類的名稱。然後，它利用了 LLVM 符號表中的符號名稱允許包含任何字元的事實，包括嵌入的 nul 字元。
下一個要新增的有趣內容是這些二元運算子的程式碼生成支援。考慮到我們目前的結構，這是對我們現有二元運算子節點的預設情況的簡單新增
Value *BinaryExprAST::codegen() {
Value *L = LHS->codegen();
Value *R = RHS->codegen();
if (!L || !R)
return nullptr;
switch (Op) {
case '+':
return Builder->CreateFAdd(L, R, "addtmp");
case '-':
return Builder->CreateFSub(L, R, "subtmp");
case '*':
return Builder->CreateFMul(L, R, "multmp");
case '<':
L = Builder->CreateFCmpULT(L, R, "cmptmp");
// Convert bool 0/1 to double 0.0 or 1.0
return Builder->CreateUIToFP(L, Type::getDoubleTy(*TheContext),
"booltmp");
default:
break;
}
// If it wasn't a builtin binary operator, it must be a user defined one. Emit
// a call to it.
Function *F = getFunction(std::string("binary") + Op);
assert(F && "binary operator not found!");
Value *Ops[2] = { L, R };
return Builder->CreateCall(F, Ops, "binop");
}
如您在上方所見，新程式碼實際上非常簡單。它只是在符號表中查詢相應的運算子，並產生對它的函式呼叫。由於使用者自訂運算子只是作為普通函式建構的（因為「原型」歸結為具有正確名稱的函式），因此一切都已準備就緒。
我們缺少的最後一部分程式碼是一些頂級的魔法
Function *FunctionAST::codegen() {
// Transfer ownership of the prototype to the FunctionProtos map, but keep a
// reference to it for use below.
auto &P = *Proto;
FunctionProtos[Proto->getName()] = std::move(Proto);
Function *TheFunction = getFunction(P.getName());
if (!TheFunction)
return nullptr;
// If this is an operator, install it.
if (P.isBinaryOp())
BinopPrecedence[P.getOperatorName()] = P.getBinaryPrecedence();
// Create a new basic block to start insertion into.
BasicBlock *BB = BasicBlock::Create(*TheContext, "entry", TheFunction);
...
基本上，在產生函式的程式碼之前，如果它是使用者自訂的運算子，我們會將其註冊到優先順序表中。這允許我們已經存在的二元運算子解析邏輯來處理它。由於我們正在處理一個完全通用的運算子優先順序解析器，因此這就是「擴展語法」所需的全部操作。
現在我們有了有用的使用者自訂二元運算子。這在很大程度上建立在我們為其他運算子建構的先前框架之上。新增單元運算子更具挑戰性，因為我們目前還沒有任何框架——讓我們看看需要什麼。
6.4. 使用者自訂單元運算子¶
由於我們目前在 Kaleidoscope 語言中不支援單元運算子，因此我們需要新增所有內容來支援它們。在上方，我們為詞法分析器添加了對「unary」關鍵字的簡單支援。除此之外，我們還需要一個 AST 節點
/// UnaryExprAST - Expression class for a unary operator.
class UnaryExprAST : public ExprAST {
char Opcode;
std::unique_ptr<ExprAST> Operand;
public:
UnaryExprAST(char Opcode, std::unique_ptr<ExprAST> Operand)
: Opcode(Opcode), Operand(std::move(Operand)) {}
Value *codegen() override;
};
這個 AST 節點現在非常簡單和明顯。它直接反映了二元運算子 AST 節點，只是它只有一個子節點。有了這個，我們需要新增解析邏輯。解析單元運算子非常簡單：我們將新增一個函式來完成它
/// unary
/// ::= primary
/// ::= '!' unary
static std::unique_ptr<ExprAST> ParseUnary() {
// If the current token is not an operator, it must be a primary expr.
if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
return ParsePrimary();
// If this is a unary operator, read it.
int Opc = CurTok;
getNextToken();
if (auto Operand = ParseUnary())
return std::make_unique<UnaryExprAST>(Opc, std::move(Operand));
return nullptr;
}
我們加入的語法相當簡單明瞭。當我們在解析主運算式時看到一個單元運算子，我們會將運算子作為前綴並將剩餘的部分解析為另一個單元運算子。這使我們能夠處理多個單元運算子（例如「!!x」）。請注意，單元運算子不像二元運算子那樣可以有模糊的解析，因此不需要優先順序資訊。
這個函式的問題是，我們需要從某個地方呼叫 ParseUnary。為此，我們將先前 ParsePrimary 的呼叫者改為呼叫 ParseUnary。
/// binoprhs
/// ::= ('+' unary)*
static std::unique_ptr<ExprAST> ParseBinOpRHS(int ExprPrec,
std::unique_ptr<ExprAST> LHS) {
...
// Parse the unary expression after the binary operator.
auto RHS = ParseUnary();
if (!RHS)
return nullptr;
...
}
/// expression
/// ::= unary binoprhs
///
static std::unique_ptr<ExprAST> ParseExpression() {
auto LHS = ParseUnary();
if (!LHS)
return nullptr;
return ParseBinOpRHS(0, std::move(LHS));
}
透過這兩個簡單的更改，我們現在可以解析單元運算子並為它們建構 AST。接下來，我們需要為原型添加解析器支援，以解析單元運算子原型。我們使用以下程式碼擴充上面的二元運算子程式碼。
/// prototype
/// ::= id '(' id* ')'
/// ::= binary LETTER number? (id, id)
/// ::= unary LETTER (id)
static std::unique_ptr<PrototypeAST> ParsePrototype() {
std::string FnName;
unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
unsigned BinaryPrecedence = 30;
switch (CurTok) {
default:
return LogErrorP("Expected function name in prototype");
case tok_identifier:
FnName = IdentifierStr;
Kind = 0;
getNextToken();
break;
case tok_unary:
getNextToken();
if (!isascii(CurTok))
return LogErrorP("Expected unary operator");
FnName = "unary";
FnName += (char)CurTok;
Kind = 1;
getNextToken();
break;
case tok_binary:
...
與二元運算子一樣，我們使用包含運算子字元的的名稱來命名單元運算子。這在程式碼生成時對我們有所幫助。說到這裡，我們需要添加的最後一部分是對單元運算子的程式碼生成支援。它看起來像這樣。
Value *UnaryExprAST::codegen() {
Value *OperandV = Operand->codegen();
if (!OperandV)
return nullptr;
Function *F = getFunction(std::string("unary") + Opcode);
if (!F)
return LogErrorV("Unknown unary operator");
return Builder->CreateCall(F, OperandV, "unop");
}
這段程式碼與二元運算子的程式碼類似，但更簡單。它更簡單主要是因為它不需要處理任何預先定義的運算子。
6.5. 試用看看¶
這可能有點難以置信，但透過過去幾章中介紹的一些簡單擴充，我們已經發展出了一種真實且強大的語言。有了它，我們可以做很多有趣的事情，包括輸入/輸出、數學運算以及其他一些事情。例如，我們現在可以添加一個很好的排序運算子（printd 定義為列印指定的值和換行符）。
ready> extern printd(x);
Read extern:
declare double @printd(double)
ready> def binary : 1 (x y) 0; # Low-precedence operator that ignores operands.
...
ready> printd(123) : printd(456) : printd(789);
123.000000
456.000000
789.000000
Evaluated to 0.000000
我們還可以定義許多其他「基本」運算，例如：
# Logical unary not.
def unary!(v)
if v then
0
else
1;
# Unary negate.
def unary-(v)
0-v;
# Define > with the same precedence as <.
def binary> 10 (LHS RHS)
RHS < LHS;
# Binary logical or, which does not short circuit.
def binary| 5 (LHS RHS)
if LHS then
1
else if RHS then
1
else
0;
# Binary logical and, which does not short circuit.
def binary& 6 (LHS RHS)
if !LHS then
0
else
!!RHS;
# Define = with slightly lower precedence than relationals.
def binary = 9 (LHS RHS)
!(LHS < RHS | LHS > RHS);
# Define ':' for sequencing: as a low-precedence operator that ignores operands
# and just returns the RHS.
def binary : 1 (x y) y;
考慮到先前的 if/then/else 支援，我們還可以定義用於輸入/輸出的有趣函式。例如，以下程式碼列印一個字元，其「密度」反映了傳入的值：值越低，字元越密集。
ready> extern putchard(char);
...
ready> def printdensity(d)
if d > 8 then
putchard(32) # ' '
else if d > 4 then
putchard(46) # '.'
else if d > 2 then
putchard(43) # '+'
else
putchard(42); # '*'
...
ready> printdensity(1): printdensity(2): printdensity(3):
printdensity(4): printdensity(5): printdensity(9):
putchard(10);
**++.
Evaluated to 0.000000
基於這些簡單的基本運算，我們可以開始定義更有趣的事情。例如，以下是一個小函式，它確定複平面上某個函式發散所需的迭代次數。
# Determine whether the specific location diverges.
# Solve for z = z^2 + c in the complex plane.
def mandelconverger(real imag iters creal cimag)
if iters > 255 | (real*real + imag*imag > 4) then
iters
else
mandelconverger(real*real - imag*imag + creal,
2*real*imag + cimag,
iters+1, creal, cimag);
# Return the number of iterations required for the iteration to escape
def mandelconverge(real imag)
mandelconverger(real, imag, 0, real, imag);
這個「z = z2 + c」函式是一個精美的小東西，它是計算曼德博集合的基礎。我們的 mandelconverge 函式返回複數軌道逃逸所需的迭代次數，飽和為 255。這本身並不是一個非常有用的函式，但如果您將其值繪製在二維平面上，您就可以看到曼德博集合。鑑於我們在這裡只能使用 putchard，因此我們驚人的圖形輸出有限，但我們可以使用上面的密度繪圖器拼湊出一些東西。
# Compute and plot the mandelbrot set with the specified 2 dimensional range
# info.
def mandelhelp(xmin xmax xstep ymin ymax ystep)
for y = ymin, y < ymax, ystep in (
(for x = xmin, x < xmax, xstep in
printdensity(mandelconverge(x,y)))
: putchard(10)
)
# mandel - This is a convenient helper function for plotting the mandelbrot set
# from the specified position with the specified Magnification.
def mandel(realstart imagstart realmag imagmag)
mandelhelp(realstart, realstart+realmag*78, realmag,
imagstart, imagstart+imagmag*40, imagmag);
有了這個，我們可以嘗試繪製曼德博集合了！讓我們來試試看。
ready> mandel(-2.3, -1.3, 0.05, 0.07);
*******************************+++++++++++*************************************
*************************+++++++++++++++++++++++*******************************
**********************+++++++++++++++++++++++++++++****************************
*******************+++++++++++++++++++++.. ...++++++++*************************
*****************++++++++++++++++++++++.... ...+++++++++***********************
***************+++++++++++++++++++++++..... ...+++++++++*********************
**************+++++++++++++++++++++++.... ....+++++++++********************
*************++++++++++++++++++++++...... .....++++++++*******************
************+++++++++++++++++++++....... .......+++++++******************
***********+++++++++++++++++++.... ... .+++++++*****************
**********+++++++++++++++++....... .+++++++****************
*********++++++++++++++........... ...+++++++***************
********++++++++++++............ ...++++++++**************
********++++++++++... .......... .++++++++**************
*******+++++++++..... .+++++++++*************
*******++++++++...... ..+++++++++*************
*******++++++....... ..+++++++++*************
*******+++++...... ..+++++++++*************
*******.... .... ...+++++++++*************
*******.... . ...+++++++++*************
*******+++++...... ...+++++++++*************
*******++++++....... ..+++++++++*************
*******++++++++...... .+++++++++*************
*******+++++++++..... ..+++++++++*************
********++++++++++... .......... .++++++++**************
********++++++++++++............ ...++++++++**************
*********++++++++++++++.......... ...+++++++***************
**********++++++++++++++++........ .+++++++****************
**********++++++++++++++++++++.... ... ..+++++++****************
***********++++++++++++++++++++++....... .......++++++++*****************
************+++++++++++++++++++++++...... ......++++++++******************
**************+++++++++++++++++++++++.... ....++++++++********************
***************+++++++++++++++++++++++..... ...+++++++++*********************
*****************++++++++++++++++++++++.... ...++++++++***********************
*******************+++++++++++++++++++++......++++++++*************************
*********************++++++++++++++++++++++.++++++++***************************
*************************+++++++++++++++++++++++*******************************
******************************+++++++++++++************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
Evaluated to 0.000000
ready> mandel(-2, -1, 0.02, 0.04);
**************************+++++++++++++++++++++++++++++++++++++++++++++++++++++
***********************++++++++++++++++++++++++++++++++++++++++++++++++++++++++
*********************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.
*******************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++...
*****************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++.....
***************++++++++++++++++++++++++++++++++++++++++++++++++++++++++........
**************++++++++++++++++++++++++++++++++++++++++++++++++++++++...........
************+++++++++++++++++++++++++++++++++++++++++++++++++++++..............
***********++++++++++++++++++++++++++++++++++++++++++++++++++........ .
**********++++++++++++++++++++++++++++++++++++++++++++++.............
********+++++++++++++++++++++++++++++++++++++++++++..................
*******+++++++++++++++++++++++++++++++++++++++.......................
******+++++++++++++++++++++++++++++++++++...........................
*****++++++++++++++++++++++++++++++++............................
*****++++++++++++++++++++++++++++...............................
****++++++++++++++++++++++++++...... .........................
***++++++++++++++++++++++++......... ...... ...........
***++++++++++++++++++++++............
**+++++++++++++++++++++..............
**+++++++++++++++++++................
*++++++++++++++++++.................
*++++++++++++++++............ ...
*++++++++++++++..............
*+++....++++................
*.......... ...........
*
*.......... ...........
*+++....++++................
*++++++++++++++..............
*++++++++++++++++............ ...
*++++++++++++++++++.................
**+++++++++++++++++++................
**+++++++++++++++++++++..............
***++++++++++++++++++++++............
***++++++++++++++++++++++++......... ...... ...........
****++++++++++++++++++++++++++...... .........................
*****++++++++++++++++++++++++++++...............................
*****++++++++++++++++++++++++++++++++............................
******+++++++++++++++++++++++++++++++++++...........................
*******+++++++++++++++++++++++++++++++++++++++.......................
********+++++++++++++++++++++++++++++++++++++++++++..................
Evaluated to 0.000000
ready> mandel(-0.9, -1.4, 0.02, 0.03);
*******************************************************************************
*******************************************************************************
*******************************************************************************
**********+++++++++++++++++++++************************************************
*+++++++++++++++++++++++++++++++++++++++***************************************
+++++++++++++++++++++++++++++++++++++++++++++**********************************
++++++++++++++++++++++++++++++++++++++++++++++++++*****************************
++++++++++++++++++++++++++++++++++++++++++++++++++++++*************************
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++**********************
+++++++++++++++++++++++++++++++++.........++++++++++++++++++*******************
+++++++++++++++++++++++++++++++.... ......+++++++++++++++++++****************
+++++++++++++++++++++++++++++....... ........+++++++++++++++++++**************
++++++++++++++++++++++++++++........ ........++++++++++++++++++++************
+++++++++++++++++++++++++++......... .. ...+++++++++++++++++++++**********
++++++++++++++++++++++++++........... ....++++++++++++++++++++++********
++++++++++++++++++++++++............. .......++++++++++++++++++++++******
+++++++++++++++++++++++............. ........+++++++++++++++++++++++****
++++++++++++++++++++++........... ..........++++++++++++++++++++++***
++++++++++++++++++++........... .........++++++++++++++++++++++*
++++++++++++++++++............ ...........++++++++++++++++++++
++++++++++++++++............... .............++++++++++++++++++
++++++++++++++................. ...............++++++++++++++++
++++++++++++.................. .................++++++++++++++
+++++++++.................. .................+++++++++++++
++++++........ . ......... ..++++++++++++
++............ ...... ....++++++++++
.............. ...++++++++++
.............. ....+++++++++
.............. .....++++++++
............. ......++++++++
........... .......++++++++
......... ........+++++++
......... ........+++++++
......... ....+++++++
........ ...+++++++
....... ...+++++++
....+++++++
.....+++++++
....+++++++
....+++++++
....+++++++
Evaluated to 0.000000
ready> ^D
此時，您可能開始意識到 Kaleidoscope 是一種真實且強大的語言。它本身可能不是自相似的 :)，但它可以用來繪製自相似的東西！
至此，我們結束了本教程「添加使用者定義的運算子」這一章。我們已經成功地增強了我們的語言，添加了在程式庫中擴充語言的能力，並且我們已經展示了如何使用它在 Kaleidoscope 中建構一個簡單但有趣的終端使用者應用程式。此時，Kaleidoscope 可以建構各種功能齊全且可以呼叫具有副作用的函式的應用程式，但它本身實際上不能定義和修改變數。
值得注意的是，變數變異是某些語言的一項重要特性，而且如何在不需在前端添加「SSA 建構」階段的情況下添加對可變變數的支援並非顯而易見。在下一章中，我們將描述如何在無需在前端建構 SSA 的情況下添加變數變異。
6.6. 完整程式碼清單¶
以下是我們執行範例的完整程式碼清單，其中強化了對使用者定義運算子的支援。若要建構此範例，請使用
# Compile
clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native` -O3 -o toy
# Run
./toy
在某些平台上，您需要在連結時指定 -rdynamic 或 -Wl,–export-dynamic。這可確保在主執行檔中定義的符號會匯出至動態連結器，以便在執行階段進行符號解析。如果您將支援程式碼編譯成共用程式庫，則不需要這樣做，不過這樣做會在 Windows 上造成問題。
程式碼如下
#include "../include/KaleidoscopeJIT.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/StandardInstrumentations.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/InstCombine/InstCombine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/GVN.h"
#include "llvm/Transforms/Scalar/Reassociate.h"
#include "llvm/Transforms/Scalar/SimplifyCFG.h"
#include <algorithm>
#include <cassert>
#include <cctype>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <map>
#include <memory>
#include <string>
#include <vector>
using namespace llvm;
using namespace llvm::orc;
//===----------------------------------------------------------------------===//
// Lexer
//===----------------------------------------------------------------------===//
// The lexer returns tokens [0-255] if it is an unknown character, otherwise one
// of these for known things.
enum Token {
tok_eof = -1,
// commands
tok_def = -2,
tok_extern = -3,
// primary
tok_identifier = -4,
tok_number = -5,
// control
tok_if = -6,
tok_then = -7,
tok_else = -8,
tok_for = -9,
tok_in = -10,
// operators
tok_binary = -11,
tok_unary = -12
};
static std::string IdentifierStr; // Filled in if tok_identifier
static double NumVal; // Filled in if tok_number
/// gettok - Return the next token from standard input.
static int gettok() {
static int LastChar = ' ';
// Skip any whitespace.
while (isspace(LastChar))
LastChar = getchar();
if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
IdentifierStr = LastChar;
while (isalnum((LastChar = getchar())))
IdentifierStr += LastChar;
if (IdentifierStr == "def")
return tok_def;
if (IdentifierStr == "extern")
return tok_extern;
if (IdentifierStr == "if")
return tok_if;
if (IdentifierStr == "then")
return tok_then;
if (IdentifierStr == "else")
return tok_else;
if (IdentifierStr == "for")
return tok_for;
if (IdentifierStr == "in")
return tok_in;
if (IdentifierStr == "binary")
return tok_binary;
if (IdentifierStr == "unary")
return tok_unary;
return tok_identifier;
}
if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+
std::string NumStr;
do {
NumStr += LastChar;
LastChar = getchar();
} while (isdigit(LastChar) || LastChar == '.');
NumVal = strtod(NumStr.c_str(), nullptr);
return tok_number;
}
if (LastChar == '#') {
// Comment until end of line.
do
LastChar = getchar();
while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
if (LastChar != EOF)
return gettok();
}
// Check for end of file. Don't eat the EOF.
if (LastChar == EOF)
return tok_eof;
// Otherwise, just return the character as its ascii value.
int ThisChar = LastChar;
LastChar = getchar();
return ThisChar;
}
//===----------------------------------------------------------------------===//
// Abstract Syntax Tree (aka Parse Tree)
//===----------------------------------------------------------------------===//
namespace {
/// ExprAST - Base class for all expression nodes.
class ExprAST {
public:
virtual ~ExprAST() = default;
virtual Value *codegen() = 0;
};
/// NumberExprAST - Expression class for numeric literals like "1.0".
class NumberExprAST : public ExprAST {
double Val;
public:
NumberExprAST(double Val) : Val(Val) {}
Value *codegen() override;
};
/// VariableExprAST - Expression class for referencing a variable, like "a".
class VariableExprAST : public ExprAST {
std::string Name;
public:
VariableExprAST(const std::string &Name) : Name(Name) {}
Value *codegen() override;
};
/// UnaryExprAST - Expression class for a unary operator.
class UnaryExprAST : public ExprAST {
char Opcode;
std::unique_ptr<ExprAST> Operand;
public:
UnaryExprAST(char Opcode, std::unique_ptr<ExprAST> Operand)
: Opcode(Opcode), Operand(std::move(Operand)) {}
Value *codegen() override;
};
/// BinaryExprAST - Expression class for a binary operator.
class BinaryExprAST : public ExprAST {
char Op;
std::unique_ptr<ExprAST> LHS, RHS;
public:
BinaryExprAST(char Op, std::unique_ptr<ExprAST> LHS,
std::unique_ptr<ExprAST> RHS)
: Op(Op), LHS(std::move(LHS)), RHS(std::move(RHS)) {}
Value *codegen() override;
};
/// CallExprAST - Expression class for function calls.
class CallExprAST : public ExprAST {
std::string Callee;
std::vector<std::unique_ptr<ExprAST>> Args;
public:
CallExprAST(const std::string &Callee,
std::vector<std::unique_ptr<ExprAST>> Args)
: Callee(Callee), Args(std::move(Args)) {}
Value *codegen() override;
};
/// IfExprAST - Expression class for if/then/else.
class IfExprAST : public ExprAST {
std::unique_ptr<ExprAST> Cond, Then, Else;
public:
IfExprAST(std::unique_ptr<ExprAST> Cond, std::unique_ptr<ExprAST> Then,
std::unique_ptr<ExprAST> Else)
: Cond(std::move(Cond)), Then(std::move(Then)), Else(std::move(Else)) {}
Value *codegen() override;
};
/// ForExprAST - Expression class for for/in.
class ForExprAST : public ExprAST {
std::string VarName;
std::unique_ptr<ExprAST> Start, End, Step, Body;
public:
ForExprAST(const std::string &VarName, std::unique_ptr<ExprAST> Start,
std::unique_ptr<ExprAST> End, std::unique_ptr<ExprAST> Step,
std::unique_ptr<ExprAST> Body)
: VarName(VarName), Start(std::move(Start)), End(std::move(End)),
Step(std::move(Step)), Body(std::move(Body)) {}
Value *codegen() override;
};
/// PrototypeAST - This class represents the "prototype" for a function,
/// which captures its name, and its argument names (thus implicitly the number
/// of arguments the function takes), as well as if it is an operator.
class PrototypeAST {
std::string Name;
std::vector<std::string> Args;
bool IsOperator;
unsigned Precedence; // Precedence if a binary op.
public:
PrototypeAST(const std::string &Name, std::vector<std::string> Args,
bool IsOperator = false, unsigned Prec = 0)
: Name(Name), Args(std::move(Args)), IsOperator(IsOperator),
Precedence(Prec) {}
Function *codegen();
const std::string &getName() const { return Name; }
bool isUnaryOp() const { return IsOperator && Args.size() == 1; }
bool isBinaryOp() const { return IsOperator && Args.size() == 2; }
char getOperatorName() const {
assert(isUnaryOp() || isBinaryOp());
return Name[Name.size() - 1];
}
unsigned getBinaryPrecedence() const { return Precedence; }
};
/// FunctionAST - This class represents a function definition itself.
class FunctionAST {
std::unique_ptr<PrototypeAST> Proto;
std::unique_ptr<ExprAST> Body;
public:
FunctionAST(std::unique_ptr<PrototypeAST> Proto,
std::unique_ptr<ExprAST> Body)
: Proto(std::move(Proto)), Body(std::move(Body)) {}
Function *codegen();
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// Parser
//===----------------------------------------------------------------------===//
/// CurTok/getNextToken - Provide a simple token buffer. CurTok is the current
/// token the parser is looking at. getNextToken reads another token from the
/// lexer and updates CurTok with its results.
static int CurTok;
static int getNextToken() { return CurTok = gettok(); }
/// BinopPrecedence - This holds the precedence for each binary operator that is
/// defined.
static std::map<char, int> BinopPrecedence;
/// GetTokPrecedence - Get the precedence of the pending binary operator token.
static int GetTokPrecedence() {
if (!isascii(CurTok))
return -1;
// Make sure it's a declared binop.
int TokPrec = BinopPrecedence[CurTok];
if (TokPrec <= 0)
return -1;
return TokPrec;
}
/// Error* - These are little helper functions for error handling.
std::unique_ptr<ExprAST> LogError(const char *Str) {
fprintf(stderr, "Error: %s\n", Str);
return nullptr;
}
std::unique_ptr<PrototypeAST> LogErrorP(const char *Str) {
LogError(Str);
return nullptr;
}
static std::unique_ptr<ExprAST> ParseExpression();
/// numberexpr ::= number
static std::unique_ptr<ExprAST> ParseNumberExpr() {
auto Result = std::make_unique<NumberExprAST>(NumVal);
getNextToken(); // consume the number
return std::move(Result);
}
/// parenexpr ::= '(' expression ')'
static std::unique_ptr<ExprAST> ParseParenExpr() {
getNextToken(); // eat (.
auto V = ParseExpression();
if (!V)
return nullptr;
if (CurTok != ')')
return LogError("expected ')'");
getNextToken(); // eat ).
return V;
}
/// identifierexpr
/// ::= identifier
/// ::= identifier '(' expression* ')'
static std::unique_ptr<ExprAST> ParseIdentifierExpr() {
std::string IdName = IdentifierStr;
getNextToken(); // eat identifier.
if (CurTok != '(') // Simple variable ref.
return std::make_unique<VariableExprAST>(IdName);
// Call.
getNextToken(); // eat (
std::vector<std::unique_ptr<ExprAST>> Args;
if (CurTok != ')') {
while (true) {
if (auto Arg = ParseExpression())
Args.push_back(std::move(Arg));
else
return nullptr;
if (CurTok == ')')
break;
if (CurTok != ',')
return LogError("Expected ')' or ',' in argument list");
getNextToken();
}
}
// Eat the ')'.
getNextToken();
return std::make_unique<CallExprAST>(IdName, std::move(Args));
}
/// ifexpr ::= 'if' expression 'then' expression 'else' expression
static std::unique_ptr<ExprAST> ParseIfExpr() {
getNextToken(); // eat the if.
// condition.
auto Cond = ParseExpression();
if (!Cond)
return nullptr;
if (CurTok != tok_then)
return LogError("expected then");
getNextToken(); // eat the then
auto Then = ParseExpression();
if (!Then)
return nullptr;
if (CurTok != tok_else)
return LogError("expected else");
getNextToken();
auto Else = ParseExpression();
if (!Else)
return nullptr;
return std::make_unique<IfExprAST>(std::move(Cond), std::move(Then),
std::move(Else));
}
/// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
static std::unique_ptr<ExprAST> ParseForExpr() {
getNextToken(); // eat the for.
if (CurTok != tok_identifier)
return LogError("expected identifier after for");
std::string IdName = IdentifierStr;
getNextToken(); // eat identifier.
if (CurTok != '=')
return LogError("expected '=' after for");
getNextToken(); // eat '='.
auto Start = ParseExpression();
if (!Start)
return nullptr;
if (CurTok != ',')
return LogError("expected ',' after for start value");
getNextToken();
auto End = ParseExpression();
if (!End)
return nullptr;
// The step value is optional.
std::unique_ptr<ExprAST> Step;
if (CurTok == ',') {
getNextToken();
Step = ParseExpression();
if (!Step)
return nullptr;
}
if (CurTok != tok_in)
return LogError("expected 'in' after for");
getNextToken(); // eat 'in'.
auto Body = ParseExpression();
if (!Body)
return nullptr;
return std::make_unique<ForExprAST>(IdName, std::move(Start), std::move(End),
std::move(Step), std::move(Body));
}
/// primary
/// ::= identifierexpr
/// ::= numberexpr
/// ::= parenexpr
/// ::= ifexpr
/// ::= forexpr
static std::unique_ptr<ExprAST> ParsePrimary() {
switch (CurTok) {
default:
return LogError("unknown token when expecting an expression");
case tok_identifier:
return ParseIdentifierExpr();
case tok_number:
return ParseNumberExpr();
case '(':
return ParseParenExpr();
case tok_if:
return ParseIfExpr();
case tok_for:
return ParseForExpr();
}
}
/// unary
/// ::= primary
/// ::= '!' unary
static std::unique_ptr<ExprAST> ParseUnary() {
// If the current token is not an operator, it must be a primary expr.
if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
return ParsePrimary();
// If this is a unary operator, read it.
int Opc = CurTok;
getNextToken();
if (auto Operand = ParseUnary())
return std::make_unique<UnaryExprAST>(Opc, std::move(Operand));
return nullptr;
}
/// binoprhs
/// ::= ('+' unary)*
static std::unique_ptr<ExprAST> ParseBinOpRHS(int ExprPrec,
std::unique_ptr<ExprAST> LHS) {
// If this is a binop, find its precedence.
while (true) {
int TokPrec = GetTokPrecedence();
// If this is a binop that binds at least as tightly as the current binop,
// consume it, otherwise we are done.
if (TokPrec < ExprPrec)
return LHS;
// Okay, we know this is a binop.
int BinOp = CurTok;
getNextToken(); // eat binop
// Parse the unary expression after the binary operator.
auto RHS = ParseUnary();
if (!RHS)
return nullptr;
// If BinOp binds less tightly with RHS than the operator after RHS, let
// the pending operator take RHS as its LHS.
int NextPrec = GetTokPrecedence();
if (TokPrec < NextPrec) {
RHS = ParseBinOpRHS(TokPrec + 1, std::move(RHS));
if (!RHS)
return nullptr;
}
// Merge LHS/RHS.
LHS =
std::make_unique<BinaryExprAST>(BinOp, std::move(LHS), std::move(RHS));
}
}
/// expression
/// ::= unary binoprhs
///
static std::unique_ptr<ExprAST> ParseExpression() {
auto LHS = ParseUnary();
if (!LHS)
return nullptr;
return ParseBinOpRHS(0, std::move(LHS));
}
/// prototype
/// ::= id '(' id* ')'
/// ::= binary LETTER number? (id, id)
/// ::= unary LETTER (id)
static std::unique_ptr<PrototypeAST> ParsePrototype() {
std::string FnName;
unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
unsigned BinaryPrecedence = 30;
switch (CurTok) {
default:
return LogErrorP("Expected function name in prototype");
case tok_identifier:
FnName = IdentifierStr;
Kind = 0;
getNextToken();
break;
case tok_unary:
getNextToken();
if (!isascii(CurTok))
return LogErrorP("Expected unary operator");
FnName = "unary";
FnName += (char)CurTok;
Kind = 1;
getNextToken();
break;
case tok_binary:
getNextToken();
if (!isascii(CurTok))
return LogErrorP("Expected binary operator");
FnName = "binary";
FnName += (char)CurTok;
Kind = 2;
getNextToken();
// Read the precedence if present.
if (CurTok == tok_number) {
if (NumVal < 1 || NumVal > 100)
return LogErrorP("Invalid precedence: must be 1..100");
BinaryPrecedence = (unsigned)NumVal;
getNextToken();
}
break;
}
if (CurTok != '(')
return LogErrorP("Expected '(' in prototype");
std::vector<std::string> ArgNames;
while (getNextToken() == tok_identifier)
ArgNames.push_back(IdentifierStr);
if (CurTok != ')')
return LogErrorP("Expected ')' in prototype");
// success.
getNextToken(); // eat ')'.
// Verify right number of names for operator.
if (Kind && ArgNames.size() != Kind)
return LogErrorP("Invalid number of operands for operator");
return std::make_unique<PrototypeAST>(FnName, ArgNames, Kind != 0,
BinaryPrecedence);
}
/// definition ::= 'def' prototype expression
static std::unique_ptr<FunctionAST> ParseDefinition() {
getNextToken(); // eat def.
auto Proto = ParsePrototype();
if (!Proto)
return nullptr;
if (auto E = ParseExpression())
return std::make_unique<FunctionAST>(std::move(Proto), std::move(E));
return nullptr;
}
/// toplevelexpr ::= expression
static std::unique_ptr<FunctionAST> ParseTopLevelExpr() {
if (auto E = ParseExpression()) {
// Make an anonymous proto.
auto Proto = std::make_unique<PrototypeAST>("__anon_expr",
std::vector<std::string>());
return std::make_unique<FunctionAST>(std::move(Proto), std::move(E));
}
return nullptr;
}
/// external ::= 'extern' prototype
static std::unique_ptr<PrototypeAST> ParseExtern() {
getNextToken(); // eat extern.
return ParsePrototype();
}
//===----------------------------------------------------------------------===//
// Code Generation
//===----------------------------------------------------------------------===//
static std::unique_ptr<LLVMContext> TheContext;
static std::unique_ptr<Module> TheModule;
static std::unique_ptr<IRBuilder<>> Builder;
static std::map<std::string, Value *> NamedValues;
static std::unique_ptr<KaleidoscopeJIT> TheJIT;
static std::unique_ptr<FunctionPassManager> TheFPM;
static std::unique_ptr<LoopAnalysisManager> TheLAM;
static std::unique_ptr<FunctionAnalysisManager> TheFAM;
static std::unique_ptr<CGSCCAnalysisManager> TheCGAM;
static std::unique_ptr<ModuleAnalysisManager> TheMAM;
static std::unique_ptr<PassInstrumentationCallbacks> ThePIC;
static std::unique_ptr<StandardInstrumentations> TheSI;
static std::map<std::string, std::unique_ptr<PrototypeAST>> FunctionProtos;
static ExitOnError ExitOnErr;
Value *LogErrorV(const char *Str) {
LogError(Str);
return nullptr;
}
Function *getFunction(std::string Name) {
// First, see if the function has already been added to the current module.
if (auto *F = TheModule->getFunction(Name))
return F;
// If not, check whether we can codegen the declaration from some existing
// prototype.
auto FI = FunctionProtos.find(Name);
if (FI != FunctionProtos.end())
return FI->second->codegen();
// If no existing prototype exists, return null.
return nullptr;
}
Value *NumberExprAST::codegen() {
return ConstantFP::get(*TheContext, APFloat(Val));
}
Value *VariableExprAST::codegen() {
// Look this variable up in the function.
Value *V = NamedValues[Name];
if (!V)
return LogErrorV("Unknown variable name");
return V;
}
Value *UnaryExprAST::codegen() {
Value *OperandV = Operand->codegen();
if (!OperandV)
return nullptr;
Function *F = getFunction(std::string("unary") + Opcode);
if (!F)
return LogErrorV("Unknown unary operator");
return Builder->CreateCall(F, OperandV, "unop");
}
Value *BinaryExprAST::codegen() {
Value *L = LHS->codegen();
Value *R = RHS->codegen();
if (!L || !R)
return nullptr;
switch (Op) {
case '+':
return Builder->CreateFAdd(L, R, "addtmp");
case '-':
return Builder->CreateFSub(L, R, "subtmp");
case '*':
return Builder->CreateFMul(L, R, "multmp");
case '<':
L = Builder->CreateFCmpULT(L, R, "cmptmp");
// Convert bool 0/1 to double 0.0 or 1.0
return Builder->CreateUIToFP(L, Type::getDoubleTy(*TheContext), "booltmp");
default:
break;
}
// If it wasn't a builtin binary operator, it must be a user defined one. Emit
// a call to it.
Function *F = getFunction(std::string("binary") + Op);
assert(F && "binary operator not found!");
Value *Ops[] = {L, R};
return Builder->CreateCall(F, Ops, "binop");
}
Value *CallExprAST::codegen() {
// Look up the name in the global module table.
Function *CalleeF = getFunction(Callee);
if (!CalleeF)
return LogErrorV("Unknown function referenced");
// If argument mismatch error.
if (CalleeF->arg_size() != Args.size())
return LogErrorV("Incorrect # arguments passed");
std::vector<Value *> ArgsV;
for (unsigned i = 0, e = Args.size(); i != e; ++i) {
ArgsV.push_back(Args[i]->codegen());
if (!ArgsV.back())
return nullptr;
}
return Builder->CreateCall(CalleeF, ArgsV, "calltmp");
}
Value *IfExprAST::codegen() {
Value *CondV = Cond->codegen();
if (!CondV)
return nullptr;
// Convert condition to a bool by comparing non-equal to 0.0.
CondV = Builder->CreateFCmpONE(
CondV, ConstantFP::get(*TheContext, APFloat(0.0)), "ifcond");
Function *TheFunction = Builder->GetInsertBlock()->getParent();
// Create blocks for the then and else cases. Insert the 'then' block at the
// end of the function.
BasicBlock *ThenBB = BasicBlock::Create(*TheContext, "then", TheFunction);
BasicBlock *ElseBB = BasicBlock::Create(*TheContext, "else");
BasicBlock *MergeBB = BasicBlock::Create(*TheContext, "ifcont");
Builder->CreateCondBr(CondV, ThenBB, ElseBB);
// Emit then value.
Builder->SetInsertPoint(ThenBB);
Value *ThenV = Then->codegen();
if (!ThenV)
return nullptr;
Builder->CreateBr(MergeBB);
// Codegen of 'Then' can change the current block, update ThenBB for the PHI.
ThenBB = Builder->GetInsertBlock();
// Emit else block.
TheFunction->insert(TheFunction->end(), ElseBB);
Builder->SetInsertPoint(ElseBB);
Value *ElseV = Else->codegen();
if (!ElseV)
return nullptr;
Builder->CreateBr(MergeBB);
// Codegen of 'Else' can change the current block, update ElseBB for the PHI.
ElseBB = Builder->GetInsertBlock();
// Emit merge block.
TheFunction->insert(TheFunction->end(), MergeBB);
Builder->SetInsertPoint(MergeBB);
PHINode *PN = Builder->CreatePHI(Type::getDoubleTy(*TheContext), 2, "iftmp");
PN->addIncoming(ThenV, ThenBB);
PN->addIncoming(ElseV, ElseBB);
return PN;
}
// Output for-loop as:
// ...
// start = startexpr
// goto loop
// loop:
// variable = phi [start, loopheader], [nextvariable, loopend]
// ...
// bodyexpr
// ...
// loopend:
// step = stepexpr
// nextvariable = variable + step
// endcond = endexpr
// br endcond, loop, endloop
// outloop:
Value *ForExprAST::codegen() {
// Emit the start code first, without 'variable' in scope.
Value *StartVal = Start->codegen();
if (!StartVal)
return nullptr;
// Make the new basic block for the loop header, inserting after current
// block.
Function *TheFunction = Builder->GetInsertBlock()->getParent();
BasicBlock *PreheaderBB = Builder->GetInsertBlock();
BasicBlock *LoopBB = BasicBlock::Create(*TheContext, "loop", TheFunction);
// Insert an explicit fall through from the current block to the LoopBB.
Builder->CreateBr(LoopBB);
// Start insertion in LoopBB.
Builder->SetInsertPoint(LoopBB);
// Start the PHI node with an entry for Start.
PHINode *Variable =
Builder->CreatePHI(Type::getDoubleTy(*TheContext), 2, VarName);
Variable->addIncoming(StartVal, PreheaderBB);
// Within the loop, the variable is defined equal to the PHI node. If it
// shadows an existing variable, we have to restore it, so save it now.
Value *OldVal = NamedValues[VarName];
NamedValues[VarName] = Variable;
// Emit the body of the loop. This, like any other expr, can change the
// current BB. Note that we ignore the value computed by the body, but don't
// allow an error.
if (!Body->codegen())
return nullptr;
// Emit the step value.
Value *StepVal = nullptr;
if (Step) {
StepVal = Step->codegen();
if (!StepVal)
return nullptr;
} else {
// If not specified, use 1.0.
StepVal = ConstantFP::get(*TheContext, APFloat(1.0));
}
Value *NextVar = Builder->CreateFAdd(Variable, StepVal, "nextvar");
// Compute the end condition.
Value *EndCond = End->codegen();
if (!EndCond)
return nullptr;
// Convert condition to a bool by comparing non-equal to 0.0.
EndCond = Builder->CreateFCmpONE(
EndCond, ConstantFP::get(*TheContext, APFloat(0.0)), "loopcond");
// Create the "after loop" block and insert it.
BasicBlock *LoopEndBB = Builder->GetInsertBlock();
BasicBlock *AfterBB =
BasicBlock::Create(*TheContext, "afterloop", TheFunction);
// Insert the conditional branch into the end of LoopEndBB.
Builder->CreateCondBr(EndCond, LoopBB, AfterBB);
// Any new code will be inserted in AfterBB.
Builder->SetInsertPoint(AfterBB);
// Add a new entry to the PHI node for the backedge.
Variable->addIncoming(NextVar, LoopEndBB);
// Restore the unshadowed variable.
if (OldVal)
NamedValues[VarName] = OldVal;
else
NamedValues.erase(VarName);
// for expr always returns 0.0.
return Constant::getNullValue(Type::getDoubleTy(*TheContext));
}
Function *PrototypeAST::codegen() {
// Make the function type: double(double,double) etc.
std::vector<Type *> Doubles(Args.size(), Type::getDoubleTy(*TheContext));
FunctionType *FT =
FunctionType::get(Type::getDoubleTy(*TheContext), Doubles, false);
Function *F =
Function::Create(FT, Function::ExternalLinkage, Name, TheModule.get());
// Set names for all arguments.
unsigned Idx = 0;
for (auto &Arg : F->args())
Arg.setName(Args[Idx++]);
return F;
}
Function *FunctionAST::codegen() {
// Transfer ownership of the prototype to the FunctionProtos map, but keep a
// reference to it for use below.
auto &P = *Proto;
FunctionProtos[Proto->getName()] = std::move(Proto);
Function *TheFunction = getFunction(P.getName());
if (!TheFunction)
return nullptr;
// If this is an operator, install it.
if (P.isBinaryOp())
BinopPrecedence[P.getOperatorName()] = P.getBinaryPrecedence();
// Create a new basic block to start insertion into.
BasicBlock *BB = BasicBlock::Create(*TheContext, "entry", TheFunction);
Builder->SetInsertPoint(BB);
// Record the function arguments in the NamedValues map.
NamedValues.clear();
for (auto &Arg : TheFunction->args())
NamedValues[std::string(Arg.getName())] = &Arg;
if (Value *RetVal = Body->codegen()) {
// Finish off the function.
Builder->CreateRet(RetVal);
// Validate the generated code, checking for consistency.
verifyFunction(*TheFunction);
// Run the optimizer on the function.
TheFPM->run(*TheFunction, *TheFAM);
return TheFunction;
}
// Error reading body, remove function.
TheFunction->eraseFromParent();
if (P.isBinaryOp())
BinopPrecedence.erase(P.getOperatorName());
return nullptr;
}
//===----------------------------------------------------------------------===//
// Top-Level parsing and JIT Driver
//===----------------------------------------------------------------------===//
static void InitializeModuleAndManagers() {
// Open a new context and module.
TheContext = std::make_unique<LLVMContext>();
TheModule = std::make_unique<Module>("KaleidoscopeJIT", *TheContext);
TheModule->setDataLayout(TheJIT->getDataLayout());
// Create a new builder for the module.
Builder = std::make_unique<IRBuilder<>>(*TheContext);
// Create new pass and analysis managers.
TheFPM = std::make_unique<FunctionPassManager>();
TheLAM = std::make_unique<LoopAnalysisManager>();
TheFAM = std::make_unique<FunctionAnalysisManager>();
TheCGAM = std::make_unique<CGSCCAnalysisManager>();
TheMAM = std::make_unique<ModuleAnalysisManager>();
ThePIC = std::make_unique<PassInstrumentationCallbacks>();
TheSI = std::make_unique<StandardInstrumentations>(*TheContext,
/*DebugLogging*/ true);
TheSI->registerCallbacks(*ThePIC, TheMAM.get());
// Add transform passes.
// Do simple "peephole" optimizations and bit-twiddling optzns.
TheFPM->addPass(InstCombinePass());
// Reassociate expressions.
TheFPM->addPass(ReassociatePass());
// Eliminate Common SubExpressions.
TheFPM->addPass(GVNPass());
// Simplify the control flow graph (deleting unreachable blocks, etc).
TheFPM->addPass(SimplifyCFGPass());
// Register analysis passes used in these transform passes.
PassBuilder PB;
PB.registerModuleAnalyses(*TheMAM);
PB.registerFunctionAnalyses(*TheFAM);
PB.crossRegisterProxies(*TheLAM, *TheFAM, *TheCGAM, *TheMAM);
}
static void HandleDefinition() {
if (auto FnAST = ParseDefinition()) {
if (auto *FnIR = FnAST->codegen()) {
fprintf(stderr, "Read function definition:");
FnIR->print(errs());
fprintf(stderr, "\n");
ExitOnErr(TheJIT->addModule(
ThreadSafeModule(std::move(TheModule), std::move(TheContext))));
InitializeModuleAndManagers();
}
} else {
// Skip token for error recovery.
getNextToken();
}
}
static void HandleExtern() {
if (auto ProtoAST = ParseExtern()) {
if (auto *FnIR = ProtoAST->codegen()) {
fprintf(stderr, "Read extern: ");
FnIR->print(errs());
fprintf(stderr, "\n");
FunctionProtos[ProtoAST->getName()] = std::move(ProtoAST);
}
} else {
// Skip token for error recovery.
getNextToken();
}
}
static void HandleTopLevelExpression() {
// Evaluate a top-level expression into an anonymous function.
if (auto FnAST = ParseTopLevelExpr()) {
if (FnAST->codegen()) {
// Create a ResourceTracker to track JIT'd memory allocated to our
// anonymous expression -- that way we can free it after executing.
auto RT = TheJIT->getMainJITDylib().createResourceTracker();
auto TSM = ThreadSafeModule(std::move(TheModule), std::move(TheContext));
ExitOnErr(TheJIT->addModule(std::move(TSM), RT));
InitializeModuleAndManagers();
// Search the JIT for the __anon_expr symbol.
auto ExprSymbol = ExitOnErr(TheJIT->lookup("__anon_expr"));
// Get the symbol's address and cast it to the right type (takes no
// arguments, returns a double) so we can call it as a native function.
double (*FP)() = ExprSymbol.getAddress().toPtr<double (*)()>();
fprintf(stderr, "Evaluated to %f\n", FP());
// Delete the anonymous expression module from the JIT.
ExitOnErr(RT->remove());
}
} else {
// Skip token for error recovery.
getNextToken();
}
}
/// top ::= definition | external | expression | ';'
static void MainLoop() {
while (true) {
fprintf(stderr, "ready> ");
switch (CurTok) {
case tok_eof:
return;
case ';': // ignore top-level semicolons.
getNextToken();
break;
case tok_def:
HandleDefinition();
break;
case tok_extern:
HandleExtern();
break;
default:
HandleTopLevelExpression();
break;
}
}
}
//===----------------------------------------------------------------------===//
// "Library" functions that can be "extern'd" from user code.
//===----------------------------------------------------------------------===//
#ifdef _WIN32
#define DLLEXPORT __declspec(dllexport)
#else
#define DLLEXPORT
#endif
/// putchard - putchar that takes a double and returns 0.
extern "C" DLLEXPORT double putchard(double X) {
fputc((char)X, stderr);
return 0;
}
/// printd - printf that takes a double prints it as "%f\n", returning 0.
extern "C" DLLEXPORT double printd(double X) {
fprintf(stderr, "%f\n", X);
return 0;
}
//===----------------------------------------------------------------------===//
// Main driver code.
//===----------------------------------------------------------------------===//
int main() {
InitializeNativeTarget();
InitializeNativeTargetAsmPrinter();
InitializeNativeTargetAsmParser();
// Install standard binary operators.
// 1 is lowest precedence.
BinopPrecedence['<'] = 10;
BinopPrecedence['+'] = 20;
BinopPrecedence['-'] = 20;
BinopPrecedence['*'] = 40; // highest.
// Prime the first token.
fprintf(stderr, "ready> ");
getNextToken();
TheJIT = ExitOnErr(KaleidoscopeJIT::Create());
InitializeModuleAndManagers();
// Run the main "interpreter loop" now.
MainLoop();
return 0;
}