parser than it is to generate LLVM IR code. :)
</p>
+<p><b>Please note</b>: the code in this chapter and later require LLVM 2.2 or
+later. LLVM 2.1 and before will not work with it. Also note that you need
+to use a version of this tutorial that matches your LLVM release: If you are
+using an official LLVM release, use the version of the documentation included
+with your release or on the <a href="http://llvm.org/releases/">llvm.org
+releases page</a>.</p>
+
</div>
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<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>
+In order to generate LLVM IR, we want some simple setup to get started. First
+we define virtual code generation (codegen) methods in each AST class:</p>
<div class="doc_code">
<pre>
Assignment</a> - the concepts are really quite natural once you grok them.</p>
<p>Note that instead of adding virtual methods to the ExprAST class hierarchy,
-it could also make sense to use a visitor pattern or some other way to model
-this. Again, this tutorial won't dwell on good software engineering practices:
-for our purposes, adding a virtual method is simplest.</p>
+it could also make sense to use a <a
+href="http://en.wikipedia.org/wiki/Visitor_pattern">visitor pattern</a> or some
+other way to model this. Again, this tutorial won't dwell on good software
+engineering practices: for our purposes, adding a virtual method is
+simplest.</p>
<p>The
second thing we want is an "Error" method like we used for the parser, which will
Value *ErrorV(const char *Str) { Error(Str); return 0; }
static Module *TheModule;
-static LLVMBuilder Builder;
+static IRBuilder Builder;
static std::map<std::string, Value*> NamedValues;
</pre>
</div>
<p>The <tt>Builder</tt> object is a helper object that makes it easy to generate
LLVM instructions. Instances of the <a
-href="http://llvm.org/doxygen/LLVMBuilder_8h-source.html"><tt>LLVMBuilder</tt>
-class</a> keep track of the current place to
-insert instructions and has methods to create new instructions.</p>
+href="http://llvm.org/doxygen/IRBuilder_8h-source.html"><tt>IRBuilder</tt></a>
+class keep 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 other words, it is a
-symbol table for the code). 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>
+current scope and what their LLVM representation is. (In other words, it is a
+symbol table for the code). 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
<div class="doc_text">
<p>Generating LLVM code for expression nodes is very straightforward: less
-than 45 lines of commented code for all four of our expression nodes. First,
+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));
+ return ConstantFP::get(APFloat(Val));
}
</pre>
</div>
constants of <em>A</em>rbitrary <em>P</em>recision). This code basically just
creates and returns a <tt>ConstantFP</tt>. 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 "new foo(..)" or "foo::create(..)".</p>
+uses "the foo::get(..)" idiom instead of "new foo(..)" or "foo::Create(..)".</p>
<div class="doc_code">
<pre>
</p>
<p>In the example above, the LLVM builder class is starting to show its value.
-LLVMBuilder knows where to insert the newly created instruction, all you have to
+IRBuilder knows where to insert the newly created instruction, all you have to
do is specify what instruction to create (e.g. with <tt>CreateAdd</tt>), which
operands to use (<tt>L</tt> and <tt>R</tt> here) and optionally provide a name
-for the generated instruction. One nice thing about LLVM is that the name is
-just a hint: if there are multiple additions in a single function, the first
-will be named "addtmp" and the second will be "autorenamed" by adding a suffix,
-giving it a name like "addtmp42". Local value names for instructions are purely
-optional, but it makes it much easier to read the IR dumps.</p>
+for the generated instruction.</p>
+
+<p>One nice thing about LLVM is that the name is just a hint. For instance, if
+the code above emits multiple "addtmp" variables, LLVM will automatically
+provide each one with an increasing, unique numeric suffix. Local value names
+for instructions are purely optional, but it makes it much easier to read the
+IR dumps.</p>
<p><a href="../LangRef.html#instref">LLVM instructions</a> are constrained by
strict rules: for example, the Left and Right operators of
std::vector<const Type*> Doubles(Args.size(), Type::DoubleTy);
FunctionType *FT = FunctionType::get(Type::DoubleTy, Doubles, false);
- Function *F = new Function(FT, Function::ExternalLinkage, Name, TheModule);
+ Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
</pre>
</div>
<p>The final line above actually creates the function that the prototype will
correspond to. This indicates the type, linkage and name to use, as well as which
-module to insert into. "<a href="LangRef.html#linkage">external linkage</a>"
+module to insert into. "<a href="../LangRef.html#linkage">external linkage</a>"
means that the function may be defined outside the current module and/or that it
is callable by functions outside the module. The Name passed in is the name the
user specified: since "<tt>TheModule</tt>" is specified, this name is registered
<div class="doc_code">
<pre>
// Create a new basic block to start insertion into.
- BasicBlock *BB = new BasicBlock("entry", TheFunction);
+ BasicBlock *BB = BasicBlock::Create("entry", TheFunction);
Builder.SetInsertPoint(BB);
if (Value *RetVal = Body->Codegen()) {
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Analysis/Verifier.h"
-#include "llvm/Support/LLVMBuilder.h"
+#include "llvm/Support/IRBuilder.h"
#include <cstdio>
#include <string>
#include <map>
if (LastChar == '#') {
// Comment until end of line.
do LastChar = getchar();
- while (LastChar != EOF && LastChar != '\n' & LastChar != '\r');
+ while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
if (LastChar != EOF)
return gettok();
if (CurTok == ')') break;
if (CurTok != ',')
- return Error("Expected ')'");
+ return Error("Expected ')' or ',' in argument list");
getNextToken();
}
}
//===----------------------------------------------------------------------===//
static Module *TheModule;
-static LLVMBuilder Builder;
+static IRBuilder 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));
+ return ConstantFP::get(APFloat(Val));
}
Value *VariableExprAST::Codegen() {
std::vector<const Type*> Doubles(Args.size(), Type::DoubleTy);
FunctionType *FT = FunctionType::get(Type::DoubleTy, Doubles, false);
- Function *F = new Function(FT, Function::ExternalLinkage, Name, TheModule);
+ Function *F = Function::Create(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.
return 0;
// Create a new basic block to start insertion into.
- BasicBlock *BB = new BasicBlock("entry", TheFunction);
+ BasicBlock *BB = BasicBlock::Create("entry", TheFunction);
Builder.SetInsertPoint(BB);
if (Value *RetVal = Body->Codegen()) {
}
</pre>
</div>
+<a href="LangImpl4.html">Next: Adding JIT and Optimizer Support</a>
</div>
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projects / oota-llvm.git / blobdiff