[llvm-commits] [llvm] r43221 - in /llvm/trunk/docs/tutorial: LangImpl3.html index.html
Chris Lattner
sabre at nondot.org
Mon Oct 22 00:01:42 PDT 2007
Author: lattner
Date: Mon Oct 22 02:01:42 2007
New Revision: 43221
URL: http://llvm.org/viewvc/llvm-project?rev=43221&view=rev
Log:
start of chapter 3
Added:
llvm/trunk/docs/tutorial/LangImpl3.html
Modified:
llvm/trunk/docs/tutorial/index.html
Added: llvm/trunk/docs/tutorial/LangImpl3.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/tutorial/LangImpl3.html?rev=43221&view=auto
==============================================================================
--- llvm/trunk/docs/tutorial/LangImpl3.html (added)
+++ llvm/trunk/docs/tutorial/LangImpl3.html Mon Oct 22 02:01:42 2007
@@ -0,0 +1,787 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+ "http://www.w3.org/TR/html4/strict.dtd">
+
+<html>
+<head>
+ <title>Kaleidoscope: Implementing code generation to LLVM IR</title>
+ <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+ <meta name="author" content="Chris Lattner">
+ <link rel="stylesheet" href="../llvm.css" type="text/css">
+</head>
+
+<body>
+
+<div class="doc_title">Kaleidoscope: Code generation to LLVM IR</div>
+
+<div class="doc_author">
+ <p>Written by <a href="mailto:sabre at nondot.org">Chris Lattner</a></p>
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section"><a name="intro">Part 3 Introduction</a></div>
+<!-- *********************************************************************** -->
+
+<div class="doc_text">
+
+<p>Welcome to part 3 of the "<a href="index.html">Implementing a language with
+LLVM</a>" tutorial. This chapter shows you how to transform the <a
+href="LangImpl2.html">Abstract Syntax Tree built in Chapter 2</a> into LLVM IR.
+This will teach you a little bit about how LLVM does things, as well as
+demonstrate how easy it is to use. It's much more work to build a lexer and
+parser than it is to generate LLVM IR code.
+</p>
+
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section"><a name="basics">Code Generation setup</a></div>
+<!-- *********************************************************************** -->
+
+<div class="doc_text">
+
+<p>
+In order to generate LLVM IR, we want some simple setup to get started. First,
+we define virtual codegen methods in each AST class:</p>
+
+<div class="doc_code">
+<pre>
+/// ExprAST - Base class for all expression nodes.
+class ExprAST {
+public:
+ virtual ~ExprAST() {}
+ 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) {}
+ virtual Value *Codegen();
+};
+...
+</pre>
+</div>
+
+<p>"Value" is the class used to represent a "register" in LLVM. The Codegen()
+method says to emit IR for that AST node and all things it depends on. The
+second thing we want is an "Error" method like we used for parser, which will
+be used to report errors found during code generation (for example, use of an
+undeclared parameter):</p>
+
+<div class="doc_code">
+<pre>
+Value *ErrorV(const char *Str) { Error(Str); return 0; }
+
+static Module *TheModule;
+static LLVMBuilder Builder;
+static std::map<std::string, Value*> NamedValues;
+</pre>
+</div>
+
+<p>The static variables will be used during code generation. <tt>TheModule</tt>
+is the LLVM construct that contains all of the functions and global variables in
+a chunk of code. In many ways, it is the top-level structure that the LLVM IR
+uses to contain code.</p>
+
+<p>The <tt>Builder</tt> object is a helper object that makes it easy to generate
+LLVM instructions. The <tt>Builder</tt> keeps track of the current place to
+insert instructions and has methods to create new instructions.</p>
+
+<p>The <tt>NamedValues</tt> map keeps track of which values are defined in the
+current scope and what their LLVM representation is. In this form of
+Kaleidoscope, the only things that can be referenced are function parameters.
+As such, function parameters will be in this map when generating code for their
+function body.</p>
+
+<p>
+With these basics in place, we can start talking about how to generate code for
+each expression. Note that this assumes that the <tt>Builder</tt> has been set
+up to generate code <em>into</em> something. For now, we'll assume that this
+has already been done, and we'll just use it to emit code.
+</p>
+
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section"><a name="exprs">Expression Code Generation</a></div>
+<!-- *********************************************************************** -->
+
+<div class="doc_text">
+
+<p>Generating LLVM code for expression nodes is very straight-forward: less
+than 45 lines of commented code for all four of our expression nodes. First,
+we'll do numeric literals:</p>
+
+<div class="doc_code">
+<pre>
+Value *NumberExprAST::Codegen() {
+ return ConstantFP::get(Type::DoubleTy, APFloat(Val));
+}
+</pre>
+</div>
+
+<p>In the LLVM IR, numeric constants are represented with the ConstantFP class,
+which holds the numeric value in an APFloat internally (APFloat has the
+capability of holding floating point constants of arbitrary precision). This
+code basically just creates and returns a ConstantFP. Note that in the LLVM IR
+that constants are all uniqued together and shared. For this reason, the API
+uses "the foo::get(...)" idiom instead of a "create" method or "new foo".</p>
+
+<div class="doc_code">
+<pre>
+Value *VariableExprAST::Codegen() {
+ // Look this variable up in the function.
+ Value *V = NamedValues[Name];
+ return V ? V : ErrorV("Unknown variable name");
+}
+</pre>
+</div>
+
+<p>References to variables is also quite simple here. In our system, we assume
+that the variable has already been emited somewhere and its value is available.
+In practice, the only values in the NamedValues map will be arguments. This
+code simply checks to see that the specified name is in the map (if not, an
+unknown variable is being referenced) and returns the value for it.</p>
+
+<div class="doc_code">
+<pre>
+Value *BinaryExprAST::Codegen() {
+ Value *L = LHS->Codegen();
+ Value *R = RHS->Codegen();
+ if (L == 0 || R == 0) return 0;
+
+ switch (Op) {
+ case '+': return Builder.CreateAdd(L, R, "addtmp");
+ case '-': return Builder.CreateSub(L, R, "subtmp");
+ case '*': return Builder.CreateMul(L, R, "multmp");
+ case '<':
+ L = Builder.CreateFCmpULT(L, R, "multmp");
+ // Convert bool 0/1 to double 0.0 or 1.0
+ return Builder.CreateUIToFP(L, Type::DoubleTy, "booltmp");
+ default: return ErrorV("invalid binary operator");
+ }
+}
+</pre>
+</div>
+
+
+
+<div class="doc_code">
+<pre>
+Value *CallExprAST::Codegen() {
+ // Look up the name in the global module table.
+ Function *CalleeF = TheModule->getFunction(Callee);
+ if (CalleeF == 0)
+ return ErrorV("Unknown function referenced");
+
+ // If argument mismatch error.
+ if (CalleeF->arg_size() != Args.size())
+ return ErrorV("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() == 0) return 0;
+ }
+
+ return Builder.CreateCall(CalleeF, ArgsV.begin(), ArgsV.end(), "calltmp");
+}
+</pre>
+</div>
+
+<h1> more todo</h1>
+
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section"><a name="code">Conclusions and the Full Code</a></div>
+<!-- *********************************************************************** -->
+
+<div class="doc_text">
+
+<div class="doc_code">
+<pre>
+// To build this:
+// g++ -g toy.cpp `llvm-config --cppflags` `llvm-config --ldflags` \
+// `llvm-config --libs core` -I ~/llvm/include/
+// ./a.out
+// See example below.
+
+#include "llvm/DerivedTypes.h"
+#include "llvm/Module.h"
+#include "llvm/Support/LLVMBuilder.h"
+#include <cstdio>
+#include <string>
+#include <map>
+#include <vector>
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+// 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,
+};
+
+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;
+ 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(), 0);
+ 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)
+//===----------------------------------------------------------------------===//
+
+/// ExprAST - Base class for all expression nodes.
+class ExprAST {
+public:
+ virtual ~ExprAST() {}
+ 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) {}
+ virtual Value *Codegen();
+};
+
+/// VariableExprAST - Expression class for referencing a variable, like "a".
+class VariableExprAST : public ExprAST {
+ std::string Name;
+public:
+ VariableExprAST(const std::string &name) : Name(name) {}
+ virtual Value *Codegen();
+};
+
+/// BinaryExprAST - Expression class for a binary operator.
+class BinaryExprAST : public ExprAST {
+ char Op;
+ ExprAST *LHS, *RHS;
+public:
+ BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
+ : Op(op), LHS(lhs), RHS(rhs) {}
+ virtual Value *Codegen();
+};
+
+/// CallExprAST - Expression class for function calls.
+class CallExprAST : public ExprAST {
+ std::string Callee;
+ std::vector<ExprAST*> Args;
+public:
+ CallExprAST(const std::string &callee, std::vector<ExprAST*> &args)
+ : Callee(callee), Args(args) {}
+ virtual Value *Codegen();
+};
+
+/// 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;
+public:
+ PrototypeAST(const std::string &name, const std::vector<std::string> &args)
+ : Name(name), Args(args) {}
+
+ Function *Codegen();
+};
+
+/// FunctionAST - This class represents a function definition itself.
+class FunctionAST {
+ PrototypeAST *Proto;
+ ExprAST *Body;
+public:
+ FunctionAST(PrototypeAST *proto, ExprAST *body)
+ : Proto(proto), Body(body) {}
+
+ Function *Codegen();
+};
+
+//===----------------------------------------------------------------------===//
+// Parser
+//===----------------------------------------------------------------------===//
+
+/// CurTok/getNextToken - Provide a simple token buffer. CurTok is the current
+/// token the parser it 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.
+ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
+PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
+FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
+
+static ExprAST *ParseExpression();
+
+/// identifierexpr
+/// ::= identifer
+/// ::= identifer '(' expression* ')'
+static ExprAST *ParseIdentifierExpr() {
+ std::string IdName = IdentifierStr;
+
+ getNextToken(); // eat identifer.
+
+ if (CurTok != '(') // Simple variable ref.
+ return new VariableExprAST(IdName);
+
+ // Call.
+ getNextToken(); // eat (
+ std::vector<ExprAST*> Args;
+ while (1) {
+ ExprAST *Arg = ParseExpression();
+ if (!Arg) return 0;
+ Args.push_back(Arg);
+
+ if (CurTok == ')') break;
+
+ if (CurTok != ',')
+ return Error("Expected ')'");
+ getNextToken();
+ }
+
+ // Eat the ')'.
+ getNextToken();
+
+ return new CallExprAST(IdName, Args);
+}
+
+/// numberexpr ::= number
+static ExprAST *ParseNumberExpr() {
+ ExprAST *Result = new NumberExprAST(NumVal);
+ getNextToken(); // consume the number
+ return Result;
+}
+
+/// parenexpr ::= '(' expression ')'
+static ExprAST *ParseParenExpr() {
+ getNextToken(); // eat (.
+ ExprAST *V = ParseExpression();
+ if (!V) return 0;
+
+ if (CurTok != ')')
+ return Error("expected ')'");
+ getNextToken(); // eat ).
+ return V;
+}
+
+/// primary
+/// ::= identifierexpr
+/// ::= numberexpr
+/// ::= parenexpr
+static ExprAST *ParsePrimary() {
+ switch (CurTok) {
+ default: return Error("unknown token when expecting an expression");
+ case tok_identifier: return ParseIdentifierExpr();
+ case tok_number: return ParseNumberExpr();
+ case '(': return ParseParenExpr();
+ }
+}
+
+/// binoprhs
+/// ::= ('+' primary)*
+static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
+ // If this is a binop, find its precedence.
+ while (1) {
+ 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 primary expression after the binary operator.
+ ExprAST *RHS = ParsePrimary();
+ if (!RHS) return 0;
+
+ // 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, RHS);
+ if (RHS == 0) return 0;
+ }
+
+ // Merge LHS/RHS.
+ LHS = new BinaryExprAST(BinOp, LHS, RHS);
+ }
+}
+
+/// expression
+/// ::= primary binoprhs
+///
+static ExprAST *ParseExpression() {
+ ExprAST *LHS = ParsePrimary();
+ if (!LHS) return 0;
+
+ return ParseBinOpRHS(0, LHS);
+}
+
+/// prototype
+/// ::= id '(' id* ')'
+static PrototypeAST *ParsePrototype() {
+ if (CurTok != tok_identifier)
+ return ErrorP("Expected function name in prototype");
+
+ std::string FnName = IdentifierStr;
+ getNextToken();
+
+ if (CurTok != '(')
+ return ErrorP("Expected '(' in prototype");
+
+ std::vector<std::string> ArgNames;
+ while (getNextToken() == tok_identifier)
+ ArgNames.push_back(IdentifierStr);
+ if (CurTok != ')')
+ return ErrorP("Expected ')' in prototype");
+
+ // success.
+ getNextToken(); // eat ')'.
+
+ return new PrototypeAST(FnName, ArgNames);
+}
+
+/// definition ::= 'def' prototype expression
+static FunctionAST *ParseDefinition() {
+ getNextToken(); // eat def.
+ PrototypeAST *Proto = ParsePrototype();
+ if (Proto == 0) return 0;
+
+ if (ExprAST *E = ParseExpression())
+ return new FunctionAST(Proto, E);
+ return 0;
+}
+
+/// toplevelexpr ::= expression
+static FunctionAST *ParseTopLevelExpr() {
+ if (ExprAST *E = ParseExpression()) {
+ // Make an anonymous proto.
+ PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
+ return new FunctionAST(Proto, E);
+ }
+ return 0;
+}
+
+/// external ::= 'extern' prototype
+static PrototypeAST *ParseExtern() {
+ getNextToken(); // eat extern.
+ return ParsePrototype();
+}
+
+//===----------------------------------------------------------------------===//
+// Code Generation
+//===----------------------------------------------------------------------===//
+
+static Module *TheModule;
+static LLVMBuilder Builder;
+static std::map<std::string, Value*> NamedValues;
+
+Value *ErrorV(const char *Str) { Error(Str); return 0; }
+
+Value *NumberExprAST::Codegen() {
+ return ConstantFP::get(Type::DoubleTy, APFloat(Val));
+}
+
+Value *VariableExprAST::Codegen() {
+ // Look this variable up in the function.
+ Value *V = NamedValues[Name];
+ return V ? V : ErrorV("Unknown variable name");
+}
+
+Value *BinaryExprAST::Codegen() {
+ Value *L = LHS->Codegen();
+ Value *R = RHS->Codegen();
+ if (L == 0 || R == 0) return 0;
+
+ switch (Op) {
+ case '+': return Builder.CreateAdd(L, R, "addtmp");
+ case '-': return Builder.CreateSub(L, R, "subtmp");
+ case '*': return Builder.CreateMul(L, R, "multmp");
+ case '<':
+ L = Builder.CreateFCmpULT(L, R, "multmp");
+ // Convert bool 0/1 to double 0.0 or 1.0
+ return Builder.CreateUIToFP(L, Type::DoubleTy, "booltmp");
+ default: return ErrorV("invalid binary operator");
+ }
+}
+
+Value *CallExprAST::Codegen() {
+ // Look up the name in the global module table.
+ Function *CalleeF = TheModule->getFunction(Callee);
+ if (CalleeF == 0)
+ return ErrorV("Unknown function referenced");
+
+ // If argument mismatch error.
+ if (CalleeF->arg_size() != Args.size())
+ return ErrorV("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() == 0) return 0;
+ }
+
+ return Builder.CreateCall(CalleeF, ArgsV.begin(), ArgsV.end(), "calltmp");
+}
+
+Function *PrototypeAST::Codegen() {
+ // Make the function type: double(double,double) etc.
+ FunctionType *FT =
+ FunctionType::get(Type::DoubleTy, std::vector<const Type*>(Args.size(),
+ Type::DoubleTy),
+ false);
+
+ Function *F = new Function(FT, Function::ExternalLinkage, Name, TheModule);
+
+ // If F conflicted, there was already something named 'Name'. If it has a
+ // body, don't allow redefinition or reextern.
+ if (F->getName() != Name) {
+ // Delete the one we just made and get the existing one.
+ F->eraseFromParent();
+ F = TheModule->getFunction(Name);
+
+ // If F already has a body, reject this.
+ if (!F->empty()) {
+ ErrorF("redefinition of function");
+ return 0;
+ }
+
+ // If F took a different number of args, reject.
+ if (F->arg_size() != Args.size()) {
+ ErrorF("redefinition of function with different # args");
+ return 0;
+ }
+ }
+
+ // Set names for all arguments.
+ unsigned Idx = 0;
+ for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
+ ++AI, ++Idx) {
+ AI->setName(Args[Idx]);
+
+ // Add arguments to variable symbol table.
+ NamedValues[Args[Idx]] = AI;
+ }
+
+ return F;
+}
+
+Function *FunctionAST::Codegen() {
+ NamedValues.clear();
+
+ Function *TheFunction = Proto->Codegen();
+ if (TheFunction == 0)
+ return 0;
+
+ // Create a new basic block to start insertion into.
+ Builder.SetInsertPoint(new BasicBlock("entry", TheFunction));
+
+ if (Value *RetVal = Body->Codegen()) {
+ // Finish off the function.
+ Builder.CreateRet(RetVal);
+ return TheFunction;
+ }
+
+ // Error reading body, remove function.
+ TheFunction->eraseFromParent();
+ return 0;
+}
+
+//===----------------------------------------------------------------------===//
+// Top-Level parsing and JIT Driver
+//===----------------------------------------------------------------------===//
+
+static void HandleDefinition() {
+ if (FunctionAST *F = ParseDefinition()) {
+ if (Function *LF = F->Codegen()) {
+ fprintf(stderr, "Read function definition:");
+ LF->dump();
+ }
+ } else {
+ // Skip token for error recovery.
+ getNextToken();
+ }
+}
+
+static void HandleExtern() {
+ if (PrototypeAST *P = ParseExtern()) {
+ if (Function *F = P->Codegen()) {
+ fprintf(stderr, "Read extern: ");
+ F->dump();
+ }
+ } else {
+ // Skip token for error recovery.
+ getNextToken();
+ }
+}
+
+static void HandleTopLevelExpression() {
+ // Evaluate a top level expression into an anonymous function.
+ if (FunctionAST *F = ParseTopLevelExpr()) {
+ if (Function *LF = F->Codegen()) {
+ fprintf(stderr, "Read top-level expression:");
+ LF->dump();
+ }
+ } else {
+ // Skip token for error recovery.
+ getNextToken();
+ }
+}
+
+/// top ::= definition | external | expression | ';'
+static void MainLoop() {
+ while (1) {
+ fprintf(stderr, "ready> ");
+ switch (CurTok) {
+ case tok_eof: return;
+ case ';': getNextToken(); break; // ignore top level semicolons.
+ case tok_def: HandleDefinition(); break;
+ case tok_extern: HandleExtern(); break;
+ default: HandleTopLevelExpression(); break;
+ }
+ }
+}
+
+
+
+//===----------------------------------------------------------------------===//
+// "Library" functions that can be "extern'd" from user code.
+//===----------------------------------------------------------------------===//
+
+/// putchard - putchar that takes a double and returns 0.
+extern "C"
+double putchard(double X) {
+ putchar((char)X);
+ return 0;
+}
+
+//===----------------------------------------------------------------------===//
+// Main driver code.
+//===----------------------------------------------------------------------===//
+
+int main() {
+ TheModule = new Module("my cool jit");
+
+ // 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();
+
+ MainLoop();
+ TheModule->dump();
+ return 0;
+}
+
+/* Examples:
+
+def fib(x)
+ if (x < 3) then
+ 1
+ else
+ fib(x-1)+fib(x-2);
+
+fib(10);
+
+*/
+</pre>
+</div>
+</div>
+
+<!-- *********************************************************************** -->
+<hr>
+<address>
+ <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
+ src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
+ <a href="http://validator.w3.org/check/referer"><img
+ src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
+
+ <a href="mailto:sabre at nondot.org">Chris Lattner</a><br>
+ <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
+ Last modified: $Date: 2007-10-17 11:05:13 -0700 (Wed, 17 Oct 2007) $
+</address>
+</body>
+</html>
Modified: llvm/trunk/docs/tutorial/index.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/tutorial/index.html?rev=43221&r1=43220&r2=43221&view=diff
==============================================================================
--- llvm/trunk/docs/tutorial/index.html (original)
+++ llvm/trunk/docs/tutorial/index.html Mon Oct 22 02:01:42 2007
@@ -29,7 +29,7 @@
<ol>
<li><a href="LangImpl1.html">The basic language, with its lexer</a></li>
<li><a href="LangImpl2.html">Implementing a Parser and AST</a></li>
- <li>Implementing code generation to LLVM IR</li>
+ <li><a href="LangImpl3.html">Implementing code generation to LLVM IR</a></li>
<li>Adding JIT codegen support</li>
<li>Extending the language: if/then/else</li>
<li>Extending the language: operator overloading</li>
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