2008-03-31 08:44:50 +00:00
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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"http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<title>Kaleidoscope: Extending the Language: Mutable Variables / SSA
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construction</title>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="author" content="Chris Lattner">
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<meta name="author" content="Erick Tryzelaar">
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<link rel="stylesheet" href="../llvm.css" type="text/css">
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</head>
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<body>
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<div class="doc_title">Kaleidoscope: Extending the Language: Mutable Variables</div>
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<ul>
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<li><a href="index.html">Up to Tutorial Index</a></li>
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<li>Chapter 7
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<ol>
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<li><a href="#intro">Chapter 7 Introduction</a></li>
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<li><a href="#why">Why is this a hard problem?</a></li>
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<li><a href="#memory">Memory in LLVM</a></li>
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<li><a href="#kalvars">Mutable Variables in Kaleidoscope</a></li>
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<li><a href="#adjustments">Adjusting Existing Variables for
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Mutation</a></li>
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<li><a href="#assignment">New Assignment Operator</a></li>
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<li><a href="#localvars">User-defined Local Variables</a></li>
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<li><a href="#code">Full Code Listing</a></li>
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</ol>
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</li>
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2011-01-01 03:27:43 +00:00
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<li><a href="OCamlLangImpl8.html">Chapter 8</a>: Conclusion and other useful LLVM
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2008-03-31 08:44:50 +00:00
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tidbits</li>
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</ul>
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<div class="doc_author">
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<p>
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Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
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and <a href="mailto:idadesub@users.sourceforge.net">Erick Tryzelaar</a>
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</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"><a name="intro">Chapter 7 Introduction</a></div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>Welcome to Chapter 7 of the "<a href="index.html">Implementing a language
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with LLVM</a>" tutorial. In chapters 1 through 6, we've built a very
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respectable, albeit simple, <a
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href="http://en.wikipedia.org/wiki/Functional_programming">functional
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programming language</a>. In our journey, we learned some parsing techniques,
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how to build and represent an AST, how to build LLVM IR, and how to optimize
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the resultant code as well as JIT compile it.</p>
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<p>While Kaleidoscope is interesting as a functional language, the fact that it
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is functional makes it "too easy" to generate LLVM IR for it. In particular, a
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functional language makes it very easy to build LLVM IR directly in <a
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href="http://en.wikipedia.org/wiki/Static_single_assignment_form">SSA form</a>.
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Since LLVM requires that the input code be in SSA form, this is a very nice
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property and it is often unclear to newcomers how to generate code for an
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imperative language with mutable variables.</p>
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<p>The short (and happy) summary of this chapter is that there is no need for
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your front-end to build SSA form: LLVM provides highly tuned and well tested
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support for this, though the way it works is a bit unexpected for some.</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"><a name="why">Why is this a hard problem?</a></div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>
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To understand why mutable variables cause complexities in SSA construction,
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consider this extremely simple C example:
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</p>
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<div class="doc_code">
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<pre>
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int G, H;
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int test(_Bool Condition) {
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int X;
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if (Condition)
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X = G;
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else
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X = H;
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return X;
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}
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</pre>
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</div>
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<p>In this case, we have the variable "X", whose value depends on the path
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executed in the program. Because there are two different possible values for X
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before the return instruction, a PHI node is inserted to merge the two values.
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The LLVM IR that we want for this example looks like this:</p>
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<div class="doc_code">
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<pre>
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@G = weak global i32 0 ; type of @G is i32*
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@H = weak global i32 0 ; type of @H is i32*
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define i32 @test(i1 %Condition) {
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entry:
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br i1 %Condition, label %cond_true, label %cond_false
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cond_true:
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%X.0 = load i32* @G
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br label %cond_next
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cond_false:
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%X.1 = load i32* @H
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br label %cond_next
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cond_next:
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%X.2 = phi i32 [ %X.1, %cond_false ], [ %X.0, %cond_true ]
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ret i32 %X.2
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}
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</pre>
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</div>
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<p>In this example, the loads from the G and H global variables are explicit in
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the LLVM IR, and they live in the then/else branches of the if statement
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(cond_true/cond_false). In order to merge the incoming values, the X.2 phi node
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in the cond_next block selects the right value to use based on where control
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flow is coming from: if control flow comes from the cond_false block, X.2 gets
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the value of X.1. Alternatively, if control flow comes from cond_true, it gets
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the value of X.0. The intent of this chapter is not to explain the details of
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SSA form. For more information, see one of the many <a
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href="http://en.wikipedia.org/wiki/Static_single_assignment_form">online
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references</a>.</p>
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<p>The question for this article is "who places the phi nodes when lowering
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assignments to mutable variables?". The issue here is that LLVM
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<em>requires</em> that its IR be in SSA form: there is no "non-ssa" mode for it.
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However, SSA construction requires non-trivial algorithms and data structures,
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so it is inconvenient and wasteful for every front-end to have to reproduce this
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logic.</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"><a name="memory">Memory in LLVM</a></div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>The 'trick' here is that while LLVM does require all register values to be
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in SSA form, it does not require (or permit) memory objects to be in SSA form.
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In the example above, note that the loads from G and H are direct accesses to
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G and H: they are not renamed or versioned. This differs from some other
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compiler systems, which do try to version memory objects. In LLVM, instead of
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encoding dataflow analysis of memory into the LLVM IR, it is handled with <a
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href="../WritingAnLLVMPass.html">Analysis Passes</a> which are computed on
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demand.</p>
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<p>
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With this in mind, the high-level idea is that we want to make a stack variable
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(which lives in memory, because it is on the stack) for each mutable object in
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a function. To take advantage of this trick, we need to talk about how LLVM
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represents stack variables.
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</p>
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<p>In LLVM, all memory accesses are explicit with load/store instructions, and
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it is carefully designed not to have (or need) an "address-of" operator. Notice
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how the type of the @G/@H global variables is actually "i32*" even though the
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variable is defined as "i32". What this means is that @G defines <em>space</em>
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for an i32 in the global data area, but its <em>name</em> actually refers to the
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address for that space. Stack variables work the same way, except that instead of
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being declared with global variable definitions, they are declared with the
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<a href="../LangRef.html#i_alloca">LLVM alloca instruction</a>:</p>
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<div class="doc_code">
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<pre>
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define i32 @example() {
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entry:
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%X = alloca i32 ; type of %X is i32*.
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...
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%tmp = load i32* %X ; load the stack value %X from the stack.
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%tmp2 = add i32 %tmp, 1 ; increment it
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store i32 %tmp2, i32* %X ; store it back
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...
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</pre>
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</div>
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<p>This code shows an example of how you can declare and manipulate a stack
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variable in the LLVM IR. Stack memory allocated with the alloca instruction is
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fully general: you can pass the address of the stack slot to functions, you can
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store it in other variables, etc. In our example above, we could rewrite the
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example to use the alloca technique to avoid using a PHI node:</p>
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<div class="doc_code">
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<pre>
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@G = weak global i32 0 ; type of @G is i32*
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@H = weak global i32 0 ; type of @H is i32*
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define i32 @test(i1 %Condition) {
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entry:
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%X = alloca i32 ; type of %X is i32*.
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br i1 %Condition, label %cond_true, label %cond_false
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cond_true:
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%X.0 = load i32* @G
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store i32 %X.0, i32* %X ; Update X
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br label %cond_next
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cond_false:
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%X.1 = load i32* @H
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store i32 %X.1, i32* %X ; Update X
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br label %cond_next
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cond_next:
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%X.2 = load i32* %X ; Read X
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ret i32 %X.2
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}
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</pre>
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</div>
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<p>With this, we have discovered a way to handle arbitrary mutable variables
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without the need to create Phi nodes at all:</p>
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<ol>
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<li>Each mutable variable becomes a stack allocation.</li>
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<li>Each read of the variable becomes a load from the stack.</li>
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<li>Each update of the variable becomes a store to the stack.</li>
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<li>Taking the address of a variable just uses the stack address directly.</li>
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</ol>
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<p>While this solution has solved our immediate problem, it introduced another
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one: we have now apparently introduced a lot of stack traffic for very simple
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and common operations, a major performance problem. Fortunately for us, the
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LLVM optimizer has a highly-tuned optimization pass named "mem2reg" that handles
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this case, promoting allocas like this into SSA registers, inserting Phi nodes
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as appropriate. If you run this example through the pass, for example, you'll
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get:</p>
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<div class="doc_code">
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<pre>
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$ <b>llvm-as < example.ll | opt -mem2reg | llvm-dis</b>
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@G = weak global i32 0
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@H = weak global i32 0
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define i32 @test(i1 %Condition) {
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entry:
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br i1 %Condition, label %cond_true, label %cond_false
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cond_true:
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%X.0 = load i32* @G
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br label %cond_next
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cond_false:
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%X.1 = load i32* @H
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br label %cond_next
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cond_next:
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%X.01 = phi i32 [ %X.1, %cond_false ], [ %X.0, %cond_true ]
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ret i32 %X.01
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}
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</pre>
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</div>
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<p>The mem2reg pass implements the standard "iterated dominance frontier"
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algorithm for constructing SSA form and has a number of optimizations that speed
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up (very common) degenerate cases. The mem2reg optimization pass is the answer
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to dealing with mutable variables, and we highly recommend that you depend on
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it. Note that mem2reg only works on variables in certain circumstances:</p>
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<ol>
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<li>mem2reg is alloca-driven: it looks for allocas and if it can handle them, it
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promotes them. It does not apply to global variables or heap allocations.</li>
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<li>mem2reg only looks for alloca instructions in the entry block of the
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function. Being in the entry block guarantees that the alloca is only executed
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once, which makes analysis simpler.</li>
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<li>mem2reg only promotes allocas whose uses are direct loads and stores. If
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the address of the stack object is passed to a function, or if any funny pointer
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arithmetic is involved, the alloca will not be promoted.</li>
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<li>mem2reg only works on allocas of <a
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href="../LangRef.html#t_classifications">first class</a>
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values (such as pointers, scalars and vectors), and only if the array size
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of the allocation is 1 (or missing in the .ll file). mem2reg is not capable of
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promoting structs or arrays to registers. Note that the "scalarrepl" pass is
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more powerful and can promote structs, "unions", and arrays in many cases.</li>
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</ol>
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<p>
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All of these properties are easy to satisfy for most imperative languages, and
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we'll illustrate it below with Kaleidoscope. The final question you may be
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asking is: should I bother with this nonsense for my front-end? Wouldn't it be
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better if I just did SSA construction directly, avoiding use of the mem2reg
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optimization pass? In short, we strongly recommend that you use this technique
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for building SSA form, unless there is an extremely good reason not to. Using
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this technique is:</p>
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<ul>
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<li>Proven and well tested: llvm-gcc and clang both use this technique for local
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mutable variables. As such, the most common clients of LLVM are using this to
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handle a bulk of their variables. You can be sure that bugs are found fast and
|
|
|
|
|
fixed early.</li>
|
|
|
|
|
|
|
|
|
|
<li>Extremely Fast: mem2reg has a number of special cases that make it fast in
|
|
|
|
|
common cases as well as fully general. For example, it has fast-paths for
|
|
|
|
|
variables that are only used in a single block, variables that only have one
|
|
|
|
|
assignment point, good heuristics to avoid insertion of unneeded phi nodes, etc.
|
|
|
|
|
</li>
|
|
|
|
|
|
|
|
|
|
<li>Needed for debug info generation: <a href="../SourceLevelDebugging.html">
|
|
|
|
|
Debug information in LLVM</a> relies on having the address of the variable
|
|
|
|
|
exposed so that debug info can be attached to it. This technique dovetails
|
|
|
|
|
very naturally with this style of debug info.</li>
|
|
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
<p>If nothing else, this makes it much easier to get your front-end up and
|
|
|
|
|
running, and is very simple to implement. Lets extend Kaleidoscope with mutable
|
|
|
|
|
variables now!
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
<div class="doc_section"><a name="kalvars">Mutable Variables in
|
|
|
|
|
Kaleidoscope</a></div>
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<p>Now that we know the sort of problem we want to tackle, lets see what this
|
|
|
|
|
looks like in the context of our little Kaleidoscope language. We're going to
|
|
|
|
|
add two features:</p>
|
|
|
|
|
|
|
|
|
|
<ol>
|
|
|
|
|
<li>The ability to mutate variables with the '=' operator.</li>
|
|
|
|
|
<li>The ability to define new variables.</li>
|
|
|
|
|
</ol>
|
|
|
|
|
|
|
|
|
|
<p>While the first item is really what this is about, we only have variables
|
|
|
|
|
for incoming arguments as well as for induction variables, and redefining those only
|
|
|
|
|
goes so far :). Also, the ability to define new variables is a
|
|
|
|
|
useful thing regardless of whether you will be mutating them. Here's a
|
|
|
|
|
motivating example that shows how we could use these:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
# Define ':' for sequencing: as a low-precedence operator that ignores operands
|
|
|
|
|
# and just returns the RHS.
|
|
|
|
|
def binary : 1 (x y) y;
|
|
|
|
|
|
|
|
|
|
# Recursive fib, we could do this before.
|
|
|
|
|
def fib(x)
|
|
|
|
|
if (x < 3) then
|
|
|
|
|
1
|
|
|
|
|
else
|
|
|
|
|
fib(x-1)+fib(x-2);
|
|
|
|
|
|
|
|
|
|
# Iterative fib.
|
|
|
|
|
def fibi(x)
|
|
|
|
|
<b>var a = 1, b = 1, c in</b>
|
|
|
|
|
(for i = 3, i < x in
|
|
|
|
|
<b>c = a + b</b> :
|
|
|
|
|
<b>a = b</b> :
|
|
|
|
|
<b>b = c</b>) :
|
|
|
|
|
b;
|
|
|
|
|
|
|
|
|
|
# Call it.
|
|
|
|
|
fibi(10);
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
In order to mutate variables, we have to change our existing variables to use
|
|
|
|
|
the "alloca trick". Once we have that, we'll add our new operator, then extend
|
|
|
|
|
Kaleidoscope to support new variable definitions.
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
<div class="doc_section"><a name="adjustments">Adjusting Existing Variables for
|
|
|
|
|
Mutation</a></div>
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
The symbol table in Kaleidoscope is managed at code generation time by the
|
|
|
|
|
'<tt>named_values</tt>' map. This map currently keeps track of the LLVM
|
|
|
|
|
"Value*" that holds the double value for the named variable. In order to
|
|
|
|
|
support mutation, we need to change this slightly, so that it
|
|
|
|
|
<tt>named_values</tt> holds the <em>memory location</em> of the variable in
|
|
|
|
|
question. Note that this change is a refactoring: it changes the structure of
|
|
|
|
|
the code, but does not (by itself) change the behavior of the compiler. All of
|
|
|
|
|
these changes are isolated in the Kaleidoscope code generator.</p>
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
At this point in Kaleidoscope's development, it only supports variables for two
|
|
|
|
|
things: incoming arguments to functions and the induction variable of 'for'
|
|
|
|
|
loops. For consistency, we'll allow mutation of these variables in addition to
|
|
|
|
|
other user-defined variables. This means that these will both need memory
|
|
|
|
|
locations.
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
<p>To start our transformation of Kaleidoscope, we'll change the
|
|
|
|
|
<tt>named_values</tt> map so that it maps to AllocaInst* instead of Value*.
|
|
|
|
|
Once we do this, the C++ compiler will tell us what parts of the code we need to
|
|
|
|
|
update:</p>
|
|
|
|
|
|
|
|
|
|
<p><b>Note:</b> the ocaml bindings currently model both <tt>Value*</tt>s and
|
|
|
|
|
<tt>AllocInst*</tt>s as <tt>Llvm.llvalue</tt>s, but this may change in the
|
|
|
|
|
future to be more type safe.</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
let named_values:(string, llvalue) Hashtbl.t = Hashtbl.create 10
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Also, since we will need to create these alloca's, we'll use a helper
|
|
|
|
|
function that ensures that the allocas are created in the entry block of the
|
|
|
|
|
function:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(* Create an alloca instruction in the entry block of the function. This
|
|
|
|
|
* is used for mutable variables etc. *)
|
|
|
|
|
let create_entry_block_alloca the_function var_name =
|
|
|
|
|
let builder = builder_at (instr_begin (entry_block the_function)) in
|
|
|
|
|
build_alloca double_type var_name builder
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>This funny looking code creates an <tt>Llvm.llbuilder</tt> object that is
|
|
|
|
|
pointing at the first instruction of the entry block. It then creates an alloca
|
|
|
|
|
with the expected name and returns it. Because all values in Kaleidoscope are
|
|
|
|
|
doubles, there is no need to pass in a type to use.</p>
|
|
|
|
|
|
|
|
|
|
<p>With this in place, the first functionality change we want to make is to
|
|
|
|
|
variable references. In our new scheme, variables live on the stack, so code
|
|
|
|
|
generating a reference to them actually needs to produce a load from the stack
|
|
|
|
|
slot:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
let rec codegen_expr = function
|
|
|
|
|
...
|
|
|
|
|
| Ast.Variable name ->
|
|
|
|
|
let v = try Hashtbl.find named_values name with
|
|
|
|
|
| Not_found -> raise (Error "unknown variable name")
|
|
|
|
|
in
|
|
|
|
|
<b>(* Load the value. *)
|
|
|
|
|
build_load v name builder</b>
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>As you can see, this is pretty straightforward. Now we need to update the
|
|
|
|
|
things that define the variables to set up the alloca. We'll start with
|
|
|
|
|
<tt>codegen_expr Ast.For ...</tt> (see the <a href="#code">full code listing</a>
|
|
|
|
|
for the unabridged code):</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
| Ast.For (var_name, start, end_, step, body) ->
|
|
|
|
|
let the_function = block_parent (insertion_block builder) in
|
|
|
|
|
|
|
|
|
|
(* Create an alloca for the variable in the entry block. *)
|
|
|
|
|
<b>let alloca = create_entry_block_alloca the_function var_name in</b>
|
|
|
|
|
|
|
|
|
|
(* Emit the start code first, without 'variable' in scope. *)
|
|
|
|
|
let start_val = codegen_expr start in
|
|
|
|
|
|
|
|
|
|
<b>(* Store the value into the alloca. *)
|
|
|
|
|
ignore(build_store start_val alloca builder);</b>
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
|
|
|
|
|
(* 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. *)
|
|
|
|
|
let old_val =
|
|
|
|
|
try Some (Hashtbl.find named_values var_name) with Not_found -> None
|
|
|
|
|
in
|
|
|
|
|
<b>Hashtbl.add named_values var_name alloca;</b>
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
|
|
|
|
|
(* Compute the end condition. *)
|
|
|
|
|
let end_cond = codegen_expr end_ in
|
|
|
|
|
|
|
|
|
|
<b>(* Reload, increment, and restore the alloca. This handles the case where
|
|
|
|
|
* the body of the loop mutates the variable. *)
|
|
|
|
|
let cur_var = build_load alloca var_name builder in
|
|
|
|
|
let next_var = build_add cur_var step_val "nextvar" builder in
|
|
|
|
|
ignore(build_store next_var alloca builder);</b>
|
|
|
|
|
...
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>This code is virtually identical to the code <a
|
|
|
|
|
href="OCamlLangImpl5.html#forcodegen">before we allowed mutable variables</a>.
|
|
|
|
|
The big difference is that we no longer have to construct a PHI node, and we use
|
|
|
|
|
load/store to access the variable as needed.</p>
|
|
|
|
|
|
|
|
|
|
<p>To support mutable argument variables, we need to also make allocas for them.
|
|
|
|
|
The code for this is also pretty simple:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(* Create an alloca for each argument and register the argument in the symbol
|
|
|
|
|
* table so that references to it will succeed. *)
|
|
|
|
|
let create_argument_allocas the_function proto =
|
|
|
|
|
let args = match proto with
|
|
|
|
|
| Ast.Prototype (_, args) | Ast.BinOpPrototype (_, args, _) -> args
|
|
|
|
|
in
|
|
|
|
|
Array.iteri (fun i ai ->
|
|
|
|
|
let var_name = args.(i) in
|
|
|
|
|
(* Create an alloca for this variable. *)
|
|
|
|
|
let alloca = create_entry_block_alloca the_function var_name in
|
|
|
|
|
|
|
|
|
|
(* Store the initial value into the alloca. *)
|
|
|
|
|
ignore(build_store ai alloca builder);
|
|
|
|
|
|
|
|
|
|
(* Add arguments to variable symbol table. *)
|
|
|
|
|
Hashtbl.add named_values var_name alloca;
|
|
|
|
|
) (params the_function)
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>For each argument, we make an alloca, store the input value to the function
|
|
|
|
|
into the alloca, and register the alloca as the memory location for the
|
|
|
|
|
argument. This method gets invoked by <tt>Codegen.codegen_func</tt> right after
|
|
|
|
|
it sets up the entry block for the function.</p>
|
|
|
|
|
|
|
|
|
|
<p>The final missing piece is adding the mem2reg pass, which allows us to get
|
|
|
|
|
good codegen once again:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
let main () =
|
|
|
|
|
...
|
2010-03-08 19:32:18 +00:00
|
|
|
let the_fpm = PassManager.create_function Codegen.the_module in
|
2008-03-31 08:44:50 +00:00
|
|
|
|
|
|
|
|
(* Set up the optimizer pipeline. Start with registering info about how the
|
|
|
|
|
* target lays out data structures. *)
|
|
|
|
|
TargetData.add (ExecutionEngine.target_data the_execution_engine) the_fpm;
|
|
|
|
|
|
|
|
|
|
<b>(* Promote allocas to registers. *)
|
|
|
|
|
add_memory_to_register_promotion the_fpm;</b>
|
|
|
|
|
|
|
|
|
|
(* Do simple "peephole" optimizations and bit-twiddling optzn. *)
|
|
|
|
|
add_instruction_combining the_fpm;
|
|
|
|
|
|
|
|
|
|
(* reassociate expressions. *)
|
|
|
|
|
add_reassociation the_fpm;
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>It is interesting to see what the code looks like before and after the
|
|
|
|
|
mem2reg optimization runs. For example, this is the before/after code for our
|
|
|
|
|
recursive fib function. Before the optimization:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
define double @fib(double %x) {
|
|
|
|
|
entry:
|
|
|
|
|
<b>%x1 = alloca double
|
|
|
|
|
store double %x, double* %x1
|
|
|
|
|
%x2 = load double* %x1</b>
|
|
|
|
|
%cmptmp = fcmp ult double %x2, 3.000000e+00
|
|
|
|
|
%booltmp = uitofp i1 %cmptmp to double
|
|
|
|
|
%ifcond = fcmp one double %booltmp, 0.000000e+00
|
|
|
|
|
br i1 %ifcond, label %then, label %else
|
|
|
|
|
|
|
|
|
|
then: ; preds = %entry
|
|
|
|
|
br label %ifcont
|
|
|
|
|
|
|
|
|
|
else: ; preds = %entry
|
|
|
|
|
<b>%x3 = load double* %x1</b>
|
2010-03-02 01:11:08 +00:00
|
|
|
%subtmp = fsub double %x3, 1.000000e+00
|
2010-05-28 17:07:41 +00:00
|
|
|
%calltmp = call double @fib(double %subtmp)
|
2008-03-31 08:44:50 +00:00
|
|
|
<b>%x4 = load double* %x1</b>
|
2010-03-02 01:11:08 +00:00
|
|
|
%subtmp5 = fsub double %x4, 2.000000e+00
|
2010-05-28 17:07:41 +00:00
|
|
|
%calltmp6 = call double @fib(double %subtmp5)
|
2010-03-02 01:11:08 +00:00
|
|
|
%addtmp = fadd double %calltmp, %calltmp6
|
2008-03-31 08:44:50 +00:00
|
|
|
br label %ifcont
|
|
|
|
|
|
|
|
|
|
ifcont: ; preds = %else, %then
|
|
|
|
|
%iftmp = phi double [ 1.000000e+00, %then ], [ %addtmp, %else ]
|
|
|
|
|
ret double %iftmp
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Here there is only one variable (x, the input argument) but you can still
|
|
|
|
|
see the extremely simple-minded code generation strategy we are using. In the
|
|
|
|
|
entry block, an alloca is created, and the initial input value is stored into
|
|
|
|
|
it. Each reference to the variable does a reload from the stack. Also, note
|
|
|
|
|
that we didn't modify the if/then/else expression, so it still inserts a PHI
|
|
|
|
|
node. While we could make an alloca for it, it is actually easier to create a
|
|
|
|
|
PHI node for it, so we still just make the PHI.</p>
|
|
|
|
|
|
|
|
|
|
<p>Here is the code after the mem2reg pass runs:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
define double @fib(double %x) {
|
|
|
|
|
entry:
|
|
|
|
|
%cmptmp = fcmp ult double <b>%x</b>, 3.000000e+00
|
|
|
|
|
%booltmp = uitofp i1 %cmptmp to double
|
|
|
|
|
%ifcond = fcmp one double %booltmp, 0.000000e+00
|
|
|
|
|
br i1 %ifcond, label %then, label %else
|
|
|
|
|
|
|
|
|
|
then:
|
|
|
|
|
br label %ifcont
|
|
|
|
|
|
|
|
|
|
else:
|
2010-03-02 01:11:08 +00:00
|
|
|
%subtmp = fsub double <b>%x</b>, 1.000000e+00
|
2010-05-28 17:07:41 +00:00
|
|
|
%calltmp = call double @fib(double %subtmp)
|
2010-03-02 01:11:08 +00:00
|
|
|
%subtmp5 = fsub double <b>%x</b>, 2.000000e+00
|
2010-05-28 17:07:41 +00:00
|
|
|
%calltmp6 = call double @fib(double %subtmp5)
|
2010-03-02 01:11:08 +00:00
|
|
|
%addtmp = fadd double %calltmp, %calltmp6
|
2008-03-31 08:44:50 +00:00
|
|
|
br label %ifcont
|
|
|
|
|
|
|
|
|
|
ifcont: ; preds = %else, %then
|
|
|
|
|
%iftmp = phi double [ 1.000000e+00, %then ], [ %addtmp, %else ]
|
|
|
|
|
ret double %iftmp
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>This is a trivial case for mem2reg, since there are no redefinitions of the
|
|
|
|
|
variable. The point of showing this is to calm your tension about inserting
|
|
|
|
|
such blatent inefficiencies :).</p>
|
|
|
|
|
|
|
|
|
|
<p>After the rest of the optimizers run, we get:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
define double @fib(double %x) {
|
|
|
|
|
entry:
|
|
|
|
|
%cmptmp = fcmp ult double %x, 3.000000e+00
|
|
|
|
|
%booltmp = uitofp i1 %cmptmp to double
|
|
|
|
|
%ifcond = fcmp ueq double %booltmp, 0.000000e+00
|
|
|
|
|
br i1 %ifcond, label %else, label %ifcont
|
|
|
|
|
|
|
|
|
|
else:
|
2010-03-02 01:11:08 +00:00
|
|
|
%subtmp = fsub double %x, 1.000000e+00
|
2010-05-28 17:07:41 +00:00
|
|
|
%calltmp = call double @fib(double %subtmp)
|
2010-03-02 01:11:08 +00:00
|
|
|
%subtmp5 = fsub double %x, 2.000000e+00
|
2010-05-28 17:07:41 +00:00
|
|
|
%calltmp6 = call double @fib(double %subtmp5)
|
2010-03-02 01:11:08 +00:00
|
|
|
%addtmp = fadd double %calltmp, %calltmp6
|
2008-03-31 08:44:50 +00:00
|
|
|
ret double %addtmp
|
|
|
|
|
|
|
|
|
|
ifcont:
|
|
|
|
|
ret double 1.000000e+00
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Here we see that the simplifycfg pass decided to clone the return instruction
|
|
|
|
|
into the end of the 'else' block. This allowed it to eliminate some branches
|
|
|
|
|
and the PHI node.</p>
|
|
|
|
|
|
|
|
|
|
<p>Now that all symbol table references are updated to use stack variables,
|
|
|
|
|
we'll add the assignment operator.</p>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
<div class="doc_section"><a name="assignment">New Assignment Operator</a></div>
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<p>With our current framework, adding a new assignment operator is really
|
|
|
|
|
simple. We will parse it just like any other binary operator, but handle it
|
|
|
|
|
internally (instead of allowing the user to define it). The first step is to
|
|
|
|
|
set a precedence:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
let main () =
|
|
|
|
|
(* Install standard binary operators.
|
|
|
|
|
* 1 is the lowest precedence. *)
|
|
|
|
|
<b>Hashtbl.add Parser.binop_precedence '=' 2;</b>
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '<' 10;
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '+' 20;
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '-' 20;
|
|
|
|
|
...
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Now that the parser knows the precedence of the binary operator, it takes
|
|
|
|
|
care of all the parsing and AST generation. We just need to implement codegen
|
|
|
|
|
for the assignment operator. This looks like:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
let rec codegen_expr = function
|
|
|
|
|
begin match op with
|
|
|
|
|
| '=' ->
|
|
|
|
|
(* Special case '=' because we don't want to emit the LHS as an
|
|
|
|
|
* expression. *)
|
|
|
|
|
let name =
|
|
|
|
|
match lhs with
|
|
|
|
|
| Ast.Variable name -> name
|
|
|
|
|
| _ -> raise (Error "destination of '=' must be a variable")
|
|
|
|
|
in
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Unlike the rest of the binary operators, our assignment operator doesn't
|
|
|
|
|
follow the "emit LHS, emit RHS, do computation" model. As such, it is handled
|
|
|
|
|
as a special case before the other binary operators are handled. The other
|
|
|
|
|
strange thing is that it requires the LHS to be a variable. It is invalid to
|
|
|
|
|
have "(x+1) = expr" - only things like "x = expr" are allowed.
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(* Codegen the rhs. *)
|
|
|
|
|
let val_ = codegen_expr rhs in
|
|
|
|
|
|
|
|
|
|
(* Lookup the name. *)
|
|
|
|
|
let variable = try Hashtbl.find named_values name with
|
|
|
|
|
| Not_found -> raise (Error "unknown variable name")
|
|
|
|
|
in
|
|
|
|
|
ignore(build_store val_ variable builder);
|
|
|
|
|
val_
|
|
|
|
|
| _ ->
|
|
|
|
|
...
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Once we have the variable, codegen'ing the assignment is straightforward:
|
|
|
|
|
we emit the RHS of the assignment, create a store, and return the computed
|
|
|
|
|
value. Returning a value allows for chained assignments like "X = (Y = Z)".</p>
|
|
|
|
|
|
|
|
|
|
<p>Now that we have an assignment operator, we can mutate loop variables and
|
|
|
|
|
arguments. For example, we can now run code like this:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
# Function to print a double.
|
|
|
|
|
extern printd(x);
|
|
|
|
|
|
|
|
|
|
# Define ':' for sequencing: as a low-precedence operator that ignores operands
|
|
|
|
|
# and just returns the RHS.
|
|
|
|
|
def binary : 1 (x y) y;
|
|
|
|
|
|
|
|
|
|
def test(x)
|
|
|
|
|
printd(x) :
|
|
|
|
|
x = 4 :
|
|
|
|
|
printd(x);
|
|
|
|
|
|
|
|
|
|
test(123);
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>When run, this example prints "123" and then "4", showing that we did
|
|
|
|
|
actually mutate the value! Okay, we have now officially implemented our goal:
|
|
|
|
|
getting this to work requires SSA construction in the general case. However,
|
|
|
|
|
to be really useful, we want the ability to define our own local variables, lets
|
|
|
|
|
add this next!
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
<div class="doc_section"><a name="localvars">User-defined Local
|
|
|
|
|
Variables</a></div>
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<p>Adding var/in is just like any other other extensions we made to
|
|
|
|
|
Kaleidoscope: we extend the lexer, the parser, the AST and the code generator.
|
|
|
|
|
The first step for adding our new 'var/in' construct is to extend the lexer.
|
|
|
|
|
As before, this is pretty trivial, the code looks like this:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
type token =
|
|
|
|
|
...
|
|
|
|
|
<b>(* var definition *)
|
|
|
|
|
| Var</b>
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
|
|
|
|
|
and lex_ident buffer = parser
|
|
|
|
|
...
|
|
|
|
|
| "in" -> [< 'Token.In; stream >]
|
|
|
|
|
| "binary" -> [< 'Token.Binary; stream >]
|
|
|
|
|
| "unary" -> [< 'Token.Unary; stream >]
|
|
|
|
|
<b>| "var" -> [< 'Token.Var; stream >]</b>
|
|
|
|
|
...
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>The next step is to define the AST node that we will construct. For var/in,
|
|
|
|
|
it looks like this:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
type expr =
|
|
|
|
|
...
|
|
|
|
|
(* variant for var/in. *)
|
|
|
|
|
| Var of (string * expr option) array * expr
|
|
|
|
|
...
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>var/in allows a list of names to be defined all at once, and each name can
|
|
|
|
|
optionally have an initializer value. As such, we capture this information in
|
|
|
|
|
the VarNames vector. Also, var/in has a body, this body is allowed to access
|
|
|
|
|
the variables defined by the var/in.</p>
|
|
|
|
|
|
|
|
|
|
<p>With this in place, we can define the parser pieces. The first thing we do
|
|
|
|
|
is add it as a primary expression:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(* primary
|
|
|
|
|
* ::= identifier
|
|
|
|
|
* ::= numberexpr
|
|
|
|
|
* ::= parenexpr
|
|
|
|
|
* ::= ifexpr
|
|
|
|
|
* ::= forexpr
|
|
|
|
|
<b>* ::= varexpr</b> *)
|
|
|
|
|
let rec parse_primary = parser
|
|
|
|
|
...
|
|
|
|
|
<b>(* varexpr
|
|
|
|
|
* ::= 'var' identifier ('=' expression?
|
|
|
|
|
* (',' identifier ('=' expression)?)* 'in' expression *)
|
|
|
|
|
| [< 'Token.Var;
|
|
|
|
|
(* At least one variable name is required. *)
|
|
|
|
|
'Token.Ident id ?? "expected identifier after var";
|
|
|
|
|
init=parse_var_init;
|
|
|
|
|
var_names=parse_var_names [(id, init)];
|
|
|
|
|
(* At this point, we have to have 'in'. *)
|
|
|
|
|
'Token.In ?? "expected 'in' keyword after 'var'";
|
|
|
|
|
body=parse_expr >] ->
|
|
|
|
|
Ast.Var (Array.of_list (List.rev var_names), body)</b>
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
|
|
|
|
|
and parse_var_init = parser
|
|
|
|
|
(* read in the optional initializer. *)
|
|
|
|
|
| [< 'Token.Kwd '='; e=parse_expr >] -> Some e
|
|
|
|
|
| [< >] -> None
|
|
|
|
|
|
|
|
|
|
and parse_var_names accumulator = parser
|
|
|
|
|
| [< 'Token.Kwd ',';
|
|
|
|
|
'Token.Ident id ?? "expected identifier list after var";
|
|
|
|
|
init=parse_var_init;
|
|
|
|
|
e=parse_var_names ((id, init) :: accumulator) >] -> e
|
|
|
|
|
| [< >] -> accumulator
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Now that we can parse and represent the code, we need to support emission of
|
|
|
|
|
LLVM IR for it. This code starts out with:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
let rec codegen_expr = function
|
|
|
|
|
...
|
|
|
|
|
| Ast.Var (var_names, body)
|
|
|
|
|
let old_bindings = ref [] in
|
|
|
|
|
|
|
|
|
|
let the_function = block_parent (insertion_block builder) in
|
|
|
|
|
|
|
|
|
|
(* Register all variables and emit their initializer. *)
|
|
|
|
|
Array.iter (fun (var_name, init) ->
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Basically it loops over all the variables, installing them one at a time.
|
|
|
|
|
For each variable we put into the symbol table, we remember the previous value
|
|
|
|
|
that we replace in OldBindings.</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(* Emit the initializer before adding the variable to scope, this
|
|
|
|
|
* prevents the initializer from referencing the variable itself, and
|
|
|
|
|
* permits stuff like this:
|
|
|
|
|
* var a = 1 in
|
|
|
|
|
* var a = a in ... # refers to outer 'a'. *)
|
|
|
|
|
let init_val =
|
|
|
|
|
match init with
|
|
|
|
|
| Some init -> codegen_expr init
|
|
|
|
|
(* If not specified, use 0.0. *)
|
|
|
|
|
| None -> const_float double_type 0.0
|
|
|
|
|
in
|
|
|
|
|
|
|
|
|
|
let alloca = create_entry_block_alloca the_function var_name in
|
|
|
|
|
ignore(build_store init_val alloca builder);
|
|
|
|
|
|
|
|
|
|
(* Remember the old variable binding so that we can restore the binding
|
|
|
|
|
* when we unrecurse. *)
|
|
|
|
|
|
|
|
|
|
begin
|
|
|
|
|
try
|
|
|
|
|
let old_value = Hashtbl.find named_values var_name in
|
|
|
|
|
old_bindings := (var_name, old_value) :: !old_bindings;
|
|
|
|
|
with Not_found > ()
|
|
|
|
|
end;
|
|
|
|
|
|
|
|
|
|
(* Remember this binding. *)
|
|
|
|
|
Hashtbl.add named_values var_name alloca;
|
|
|
|
|
) var_names;
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>There are more comments here than code. The basic idea is that we emit the
|
|
|
|
|
initializer, create the alloca, then update the symbol table to point to it.
|
|
|
|
|
Once all the variables are installed in the symbol table, we evaluate the body
|
|
|
|
|
of the var/in expression:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(* Codegen the body, now that all vars are in scope. *)
|
|
|
|
|
let body_val = codegen_expr body in
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Finally, before returning, we restore the previous variable bindings:</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(* Pop all our variables from scope. *)
|
|
|
|
|
List.iter (fun (var_name, old_value) ->
|
|
|
|
|
Hashtbl.add named_values var_name old_value
|
|
|
|
|
) !old_bindings;
|
|
|
|
|
|
|
|
|
|
(* Return the body computation. *)
|
|
|
|
|
body_val
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>The end result of all of this is that we get properly scoped variable
|
|
|
|
|
definitions, and we even (trivially) allow mutation of them :).</p>
|
|
|
|
|
|
|
|
|
|
<p>With this, we completed what we set out to do. Our nice iterative fib
|
|
|
|
|
example from the intro compiles and runs just fine. The mem2reg pass optimizes
|
|
|
|
|
all of our stack variables into SSA registers, inserting PHI nodes where needed,
|
|
|
|
|
and our front-end remains simple: no "iterated dominance frontier" computation
|
|
|
|
|
anywhere in sight.</p>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
<div class="doc_section"><a name="code">Full Code Listing</a></div>
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
Here is the complete code listing for our running example, enhanced with mutable
|
|
|
|
|
variables and var/in support. To build this example, use:
|
|
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
<div class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
# Compile
|
|
|
|
|
ocamlbuild toy.byte
|
|
|
|
|
# Run
|
|
|
|
|
./toy.byte
|
|
|
|
|
</pre>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>Here is the code:</p>
|
|
|
|
|
|
|
|
|
|
<dl>
|
|
|
|
|
<dt>_tags:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
<{lexer,parser}.ml>: use_camlp4, pp(camlp4of)
|
|
|
|
|
<*.{byte,native}>: g++, use_llvm, use_llvm_analysis
|
|
|
|
|
<*.{byte,native}>: use_llvm_executionengine, use_llvm_target
|
|
|
|
|
<*.{byte,native}>: use_llvm_scalar_opts, use_bindings
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>myocamlbuild.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
open Ocamlbuild_plugin;;
|
|
|
|
|
|
|
|
|
|
ocaml_lib ~extern:true "llvm";;
|
|
|
|
|
ocaml_lib ~extern:true "llvm_analysis";;
|
|
|
|
|
ocaml_lib ~extern:true "llvm_executionengine";;
|
|
|
|
|
ocaml_lib ~extern:true "llvm_target";;
|
|
|
|
|
ocaml_lib ~extern:true "llvm_scalar_opts";;
|
|
|
|
|
|
2010-03-21 23:15:13 +00:00
|
|
|
flag ["link"; "ocaml"; "g++"] (S[A"-cc"; A"g++"; A"-cclib"; A"-rdynamic"]);;
|
2008-03-31 08:44:50 +00:00
|
|
|
dep ["link"; "ocaml"; "use_bindings"] ["bindings.o"];;
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>token.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(*===----------------------------------------------------------------------===
|
|
|
|
|
* Lexer Tokens
|
|
|
|
|
*===----------------------------------------------------------------------===*)
|
|
|
|
|
|
|
|
|
|
(* The lexer returns these 'Kwd' if it is an unknown character, otherwise one of
|
|
|
|
|
* these others for known things. *)
|
|
|
|
|
type token =
|
|
|
|
|
(* commands *)
|
|
|
|
|
| Def | Extern
|
|
|
|
|
|
|
|
|
|
(* primary *)
|
|
|
|
|
| Ident of string | Number of float
|
|
|
|
|
|
|
|
|
|
(* unknown *)
|
|
|
|
|
| Kwd of char
|
|
|
|
|
|
|
|
|
|
(* control *)
|
|
|
|
|
| If | Then | Else
|
|
|
|
|
| For | In
|
|
|
|
|
|
|
|
|
|
(* operators *)
|
|
|
|
|
| Binary | Unary
|
|
|
|
|
|
|
|
|
|
(* var definition *)
|
|
|
|
|
| Var
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>lexer.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(*===----------------------------------------------------------------------===
|
|
|
|
|
* Lexer
|
|
|
|
|
*===----------------------------------------------------------------------===*)
|
|
|
|
|
|
|
|
|
|
let rec lex = parser
|
|
|
|
|
(* Skip any whitespace. *)
|
|
|
|
|
| [< ' (' ' | '\n' | '\r' | '\t'); stream >] -> lex stream
|
|
|
|
|
|
|
|
|
|
(* identifier: [a-zA-Z][a-zA-Z0-9] *)
|
|
|
|
|
| [< ' ('A' .. 'Z' | 'a' .. 'z' as c); stream >] ->
|
|
|
|
|
let buffer = Buffer.create 1 in
|
|
|
|
|
Buffer.add_char buffer c;
|
|
|
|
|
lex_ident buffer stream
|
|
|
|
|
|
|
|
|
|
(* number: [0-9.]+ *)
|
|
|
|
|
| [< ' ('0' .. '9' as c); stream >] ->
|
|
|
|
|
let buffer = Buffer.create 1 in
|
|
|
|
|
Buffer.add_char buffer c;
|
|
|
|
|
lex_number buffer stream
|
|
|
|
|
|
|
|
|
|
(* Comment until end of line. *)
|
|
|
|
|
| [< ' ('#'); stream >] ->
|
|
|
|
|
lex_comment stream
|
|
|
|
|
|
|
|
|
|
(* Otherwise, just return the character as its ascii value. *)
|
|
|
|
|
| [< 'c; stream >] ->
|
|
|
|
|
[< 'Token.Kwd c; lex stream >]
|
|
|
|
|
|
|
|
|
|
(* end of stream. *)
|
|
|
|
|
| [< >] -> [< >]
|
|
|
|
|
|
|
|
|
|
and lex_number buffer = parser
|
|
|
|
|
| [< ' ('0' .. '9' | '.' as c); stream >] ->
|
|
|
|
|
Buffer.add_char buffer c;
|
|
|
|
|
lex_number buffer stream
|
|
|
|
|
| [< stream=lex >] ->
|
|
|
|
|
[< 'Token.Number (float_of_string (Buffer.contents buffer)); stream >]
|
|
|
|
|
|
|
|
|
|
and lex_ident buffer = parser
|
|
|
|
|
| [< ' ('A' .. 'Z' | 'a' .. 'z' | '0' .. '9' as c); stream >] ->
|
|
|
|
|
Buffer.add_char buffer c;
|
|
|
|
|
lex_ident buffer stream
|
|
|
|
|
| [< stream=lex >] ->
|
|
|
|
|
match Buffer.contents buffer with
|
|
|
|
|
| "def" -> [< 'Token.Def; stream >]
|
|
|
|
|
| "extern" -> [< 'Token.Extern; stream >]
|
|
|
|
|
| "if" -> [< 'Token.If; stream >]
|
|
|
|
|
| "then" -> [< 'Token.Then; stream >]
|
|
|
|
|
| "else" -> [< 'Token.Else; stream >]
|
|
|
|
|
| "for" -> [< 'Token.For; stream >]
|
|
|
|
|
| "in" -> [< 'Token.In; stream >]
|
|
|
|
|
| "binary" -> [< 'Token.Binary; stream >]
|
|
|
|
|
| "unary" -> [< 'Token.Unary; stream >]
|
|
|
|
|
| "var" -> [< 'Token.Var; stream >]
|
|
|
|
|
| id -> [< 'Token.Ident id; stream >]
|
|
|
|
|
|
|
|
|
|
and lex_comment = parser
|
|
|
|
|
| [< ' ('\n'); stream=lex >] -> stream
|
|
|
|
|
| [< 'c; e=lex_comment >] -> e
|
|
|
|
|
| [< >] -> [< >]
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>ast.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(*===----------------------------------------------------------------------===
|
|
|
|
|
* Abstract Syntax Tree (aka Parse Tree)
|
|
|
|
|
*===----------------------------------------------------------------------===*)
|
|
|
|
|
|
|
|
|
|
(* expr - Base type for all expression nodes. *)
|
|
|
|
|
type expr =
|
|
|
|
|
(* variant for numeric literals like "1.0". *)
|
|
|
|
|
| Number of float
|
|
|
|
|
|
|
|
|
|
(* variant for referencing a variable, like "a". *)
|
|
|
|
|
| Variable of string
|
|
|
|
|
|
|
|
|
|
(* variant for a unary operator. *)
|
|
|
|
|
| Unary of char * expr
|
|
|
|
|
|
|
|
|
|
(* variant for a binary operator. *)
|
|
|
|
|
| Binary of char * expr * expr
|
|
|
|
|
|
|
|
|
|
(* variant for function calls. *)
|
|
|
|
|
| Call of string * expr array
|
|
|
|
|
|
|
|
|
|
(* variant for if/then/else. *)
|
|
|
|
|
| If of expr * expr * expr
|
|
|
|
|
|
|
|
|
|
(* variant for for/in. *)
|
|
|
|
|
| For of string * expr * expr * expr option * expr
|
|
|
|
|
|
|
|
|
|
(* variant for var/in. *)
|
|
|
|
|
| Var of (string * expr option) array * expr
|
|
|
|
|
|
|
|
|
|
(* proto - This type represents the "prototype" for a function, which captures
|
|
|
|
|
* its name, and its argument names (thus implicitly the number of arguments the
|
|
|
|
|
* function takes). *)
|
|
|
|
|
type proto =
|
|
|
|
|
| Prototype of string * string array
|
|
|
|
|
| BinOpPrototype of string * string array * int
|
|
|
|
|
|
|
|
|
|
(* func - This type represents a function definition itself. *)
|
|
|
|
|
type func = Function of proto * expr
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>parser.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(*===---------------------------------------------------------------------===
|
|
|
|
|
* Parser
|
|
|
|
|
*===---------------------------------------------------------------------===*)
|
|
|
|
|
|
|
|
|
|
(* binop_precedence - This holds the precedence for each binary operator that is
|
|
|
|
|
* defined *)
|
|
|
|
|
let binop_precedence:(char, int) Hashtbl.t = Hashtbl.create 10
|
|
|
|
|
|
|
|
|
|
(* precedence - Get the precedence of the pending binary operator token. *)
|
|
|
|
|
let precedence c = try Hashtbl.find binop_precedence c with Not_found -> -1
|
|
|
|
|
|
|
|
|
|
(* primary
|
|
|
|
|
* ::= identifier
|
|
|
|
|
* ::= numberexpr
|
|
|
|
|
* ::= parenexpr
|
|
|
|
|
* ::= ifexpr
|
|
|
|
|
* ::= forexpr
|
|
|
|
|
* ::= varexpr *)
|
|
|
|
|
let rec parse_primary = parser
|
|
|
|
|
(* numberexpr ::= number *)
|
|
|
|
|
| [< 'Token.Number n >] -> Ast.Number n
|
|
|
|
|
|
|
|
|
|
(* parenexpr ::= '(' expression ')' *)
|
|
|
|
|
| [< 'Token.Kwd '('; e=parse_expr; 'Token.Kwd ')' ?? "expected ')'" >] -> e
|
|
|
|
|
|
|
|
|
|
(* identifierexpr
|
|
|
|
|
* ::= identifier
|
|
|
|
|
* ::= identifier '(' argumentexpr ')' *)
|
|
|
|
|
| [< 'Token.Ident id; stream >] ->
|
|
|
|
|
let rec parse_args accumulator = parser
|
|
|
|
|
| [< e=parse_expr; stream >] ->
|
|
|
|
|
begin parser
|
|
|
|
|
| [< 'Token.Kwd ','; e=parse_args (e :: accumulator) >] -> e
|
|
|
|
|
| [< >] -> e :: accumulator
|
|
|
|
|
end stream
|
|
|
|
|
| [< >] -> accumulator
|
|
|
|
|
in
|
|
|
|
|
let rec parse_ident id = parser
|
|
|
|
|
(* Call. *)
|
|
|
|
|
| [< 'Token.Kwd '(';
|
|
|
|
|
args=parse_args [];
|
|
|
|
|
'Token.Kwd ')' ?? "expected ')'">] ->
|
|
|
|
|
Ast.Call (id, Array.of_list (List.rev args))
|
|
|
|
|
|
|
|
|
|
(* Simple variable ref. *)
|
|
|
|
|
| [< >] -> Ast.Variable id
|
|
|
|
|
in
|
|
|
|
|
parse_ident id stream
|
|
|
|
|
|
|
|
|
|
(* ifexpr ::= 'if' expr 'then' expr 'else' expr *)
|
|
|
|
|
| [< 'Token.If; c=parse_expr;
|
|
|
|
|
'Token.Then ?? "expected 'then'"; t=parse_expr;
|
|
|
|
|
'Token.Else ?? "expected 'else'"; e=parse_expr >] ->
|
|
|
|
|
Ast.If (c, t, e)
|
|
|
|
|
|
|
|
|
|
(* forexpr
|
|
|
|
|
::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression *)
|
|
|
|
|
| [< 'Token.For;
|
|
|
|
|
'Token.Ident id ?? "expected identifier after for";
|
|
|
|
|
'Token.Kwd '=' ?? "expected '=' after for";
|
|
|
|
|
stream >] ->
|
|
|
|
|
begin parser
|
|
|
|
|
| [<
|
|
|
|
|
start=parse_expr;
|
|
|
|
|
'Token.Kwd ',' ?? "expected ',' after for";
|
|
|
|
|
end_=parse_expr;
|
|
|
|
|
stream >] ->
|
|
|
|
|
let step =
|
|
|
|
|
begin parser
|
|
|
|
|
| [< 'Token.Kwd ','; step=parse_expr >] -> Some step
|
|
|
|
|
| [< >] -> None
|
|
|
|
|
end stream
|
|
|
|
|
in
|
|
|
|
|
begin parser
|
|
|
|
|
| [< 'Token.In; body=parse_expr >] ->
|
|
|
|
|
Ast.For (id, start, end_, step, body)
|
|
|
|
|
| [< >] ->
|
|
|
|
|
raise (Stream.Error "expected 'in' after for")
|
|
|
|
|
end stream
|
|
|
|
|
| [< >] ->
|
|
|
|
|
raise (Stream.Error "expected '=' after for")
|
|
|
|
|
end stream
|
|
|
|
|
|
|
|
|
|
(* varexpr
|
|
|
|
|
* ::= 'var' identifier ('=' expression?
|
|
|
|
|
* (',' identifier ('=' expression)?)* 'in' expression *)
|
|
|
|
|
| [< 'Token.Var;
|
|
|
|
|
(* At least one variable name is required. *)
|
|
|
|
|
'Token.Ident id ?? "expected identifier after var";
|
|
|
|
|
init=parse_var_init;
|
|
|
|
|
var_names=parse_var_names [(id, init)];
|
|
|
|
|
(* At this point, we have to have 'in'. *)
|
|
|
|
|
'Token.In ?? "expected 'in' keyword after 'var'";
|
|
|
|
|
body=parse_expr >] ->
|
|
|
|
|
Ast.Var (Array.of_list (List.rev var_names), body)
|
|
|
|
|
|
|
|
|
|
| [< >] -> raise (Stream.Error "unknown token when expecting an expression.")
|
|
|
|
|
|
|
|
|
|
(* unary
|
|
|
|
|
* ::= primary
|
|
|
|
|
* ::= '!' unary *)
|
|
|
|
|
and parse_unary = parser
|
|
|
|
|
(* If this is a unary operator, read it. *)
|
|
|
|
|
| [< 'Token.Kwd op when op != '(' && op != ')'; operand=parse_expr >] ->
|
|
|
|
|
Ast.Unary (op, operand)
|
|
|
|
|
|
|
|
|
|
(* If the current token is not an operator, it must be a primary expr. *)
|
|
|
|
|
| [< stream >] -> parse_primary stream
|
|
|
|
|
|
|
|
|
|
(* binoprhs
|
|
|
|
|
* ::= ('+' primary)* *)
|
|
|
|
|
and parse_bin_rhs expr_prec lhs stream =
|
|
|
|
|
match Stream.peek stream with
|
|
|
|
|
(* If this is a binop, find its precedence. *)
|
|
|
|
|
| Some (Token.Kwd c) when Hashtbl.mem binop_precedence c ->
|
|
|
|
|
let token_prec = precedence c in
|
|
|
|
|
|
|
|
|
|
(* If this is a binop that binds at least as tightly as the current binop,
|
|
|
|
|
* consume it, otherwise we are done. *)
|
|
|
|
|
if token_prec < expr_prec then lhs else begin
|
|
|
|
|
(* Eat the binop. *)
|
|
|
|
|
Stream.junk stream;
|
|
|
|
|
|
|
|
|
|
(* Parse the primary expression after the binary operator. *)
|
|
|
|
|
let rhs = parse_unary stream in
|
|
|
|
|
|
|
|
|
|
(* Okay, we know this is a binop. *)
|
|
|
|
|
let rhs =
|
|
|
|
|
match Stream.peek stream with
|
|
|
|
|
| Some (Token.Kwd c2) ->
|
|
|
|
|
(* If BinOp binds less tightly with rhs than the operator after
|
|
|
|
|
* rhs, let the pending operator take rhs as its lhs. *)
|
|
|
|
|
let next_prec = precedence c2 in
|
|
|
|
|
if token_prec < next_prec
|
|
|
|
|
then parse_bin_rhs (token_prec + 1) rhs stream
|
|
|
|
|
else rhs
|
|
|
|
|
| _ -> rhs
|
|
|
|
|
in
|
|
|
|
|
|
|
|
|
|
(* Merge lhs/rhs. *)
|
|
|
|
|
let lhs = Ast.Binary (c, lhs, rhs) in
|
|
|
|
|
parse_bin_rhs expr_prec lhs stream
|
|
|
|
|
end
|
|
|
|
|
| _ -> lhs
|
|
|
|
|
|
|
|
|
|
and parse_var_init = parser
|
|
|
|
|
(* read in the optional initializer. *)
|
|
|
|
|
| [< 'Token.Kwd '='; e=parse_expr >] -> Some e
|
|
|
|
|
| [< >] -> None
|
|
|
|
|
|
|
|
|
|
and parse_var_names accumulator = parser
|
|
|
|
|
| [< 'Token.Kwd ',';
|
|
|
|
|
'Token.Ident id ?? "expected identifier list after var";
|
|
|
|
|
init=parse_var_init;
|
|
|
|
|
e=parse_var_names ((id, init) :: accumulator) >] -> e
|
|
|
|
|
| [< >] -> accumulator
|
|
|
|
|
|
|
|
|
|
(* expression
|
|
|
|
|
* ::= primary binoprhs *)
|
|
|
|
|
and parse_expr = parser
|
|
|
|
|
| [< lhs=parse_unary; stream >] -> parse_bin_rhs 0 lhs stream
|
|
|
|
|
|
|
|
|
|
(* prototype
|
|
|
|
|
* ::= id '(' id* ')'
|
|
|
|
|
* ::= binary LETTER number? (id, id)
|
|
|
|
|
* ::= unary LETTER number? (id) *)
|
|
|
|
|
let parse_prototype =
|
|
|
|
|
let rec parse_args accumulator = parser
|
|
|
|
|
| [< 'Token.Ident id; e=parse_args (id::accumulator) >] -> e
|
|
|
|
|
| [< >] -> accumulator
|
|
|
|
|
in
|
|
|
|
|
let parse_operator = parser
|
|
|
|
|
| [< 'Token.Unary >] -> "unary", 1
|
|
|
|
|
| [< 'Token.Binary >] -> "binary", 2
|
|
|
|
|
in
|
|
|
|
|
let parse_binary_precedence = parser
|
|
|
|
|
| [< 'Token.Number n >] -> int_of_float n
|
|
|
|
|
| [< >] -> 30
|
|
|
|
|
in
|
|
|
|
|
parser
|
|
|
|
|
| [< 'Token.Ident id;
|
|
|
|
|
'Token.Kwd '(' ?? "expected '(' in prototype";
|
|
|
|
|
args=parse_args [];
|
|
|
|
|
'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
|
|
|
|
|
(* success. *)
|
|
|
|
|
Ast.Prototype (id, Array.of_list (List.rev args))
|
|
|
|
|
| [< (prefix, kind)=parse_operator;
|
|
|
|
|
'Token.Kwd op ?? "expected an operator";
|
|
|
|
|
(* Read the precedence if present. *)
|
|
|
|
|
binary_precedence=parse_binary_precedence;
|
|
|
|
|
'Token.Kwd '(' ?? "expected '(' in prototype";
|
|
|
|
|
args=parse_args [];
|
|
|
|
|
'Token.Kwd ')' ?? "expected ')' in prototype" >] ->
|
|
|
|
|
let name = prefix ^ (String.make 1 op) in
|
|
|
|
|
let args = Array.of_list (List.rev args) in
|
|
|
|
|
|
|
|
|
|
(* Verify right number of arguments for operator. *)
|
|
|
|
|
if Array.length args != kind
|
|
|
|
|
then raise (Stream.Error "invalid number of operands for operator")
|
|
|
|
|
else
|
|
|
|
|
if kind == 1 then
|
|
|
|
|
Ast.Prototype (name, args)
|
|
|
|
|
else
|
|
|
|
|
Ast.BinOpPrototype (name, args, binary_precedence)
|
|
|
|
|
| [< >] ->
|
|
|
|
|
raise (Stream.Error "expected function name in prototype")
|
|
|
|
|
|
|
|
|
|
(* definition ::= 'def' prototype expression *)
|
|
|
|
|
let parse_definition = parser
|
|
|
|
|
| [< 'Token.Def; p=parse_prototype; e=parse_expr >] ->
|
|
|
|
|
Ast.Function (p, e)
|
|
|
|
|
|
|
|
|
|
(* toplevelexpr ::= expression *)
|
|
|
|
|
let parse_toplevel = parser
|
|
|
|
|
| [< e=parse_expr >] ->
|
|
|
|
|
(* Make an anonymous proto. *)
|
|
|
|
|
Ast.Function (Ast.Prototype ("", [||]), e)
|
|
|
|
|
|
|
|
|
|
(* external ::= 'extern' prototype *)
|
|
|
|
|
let parse_extern = parser
|
|
|
|
|
| [< 'Token.Extern; e=parse_prototype >] -> e
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>codegen.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(*===----------------------------------------------------------------------===
|
|
|
|
|
* Code Generation
|
|
|
|
|
*===----------------------------------------------------------------------===*)
|
|
|
|
|
|
|
|
|
|
open Llvm
|
|
|
|
|
|
|
|
|
|
exception Error of string
|
|
|
|
|
|
2009-08-19 17:32:38 +00:00
|
|
|
let context = global_context ()
|
|
|
|
|
let the_module = create_module context "my cool jit"
|
|
|
|
|
let builder = builder context
|
2008-03-31 08:44:50 +00:00
|
|
|
let named_values:(string, llvalue) Hashtbl.t = Hashtbl.create 10
|
2010-03-08 19:32:18 +00:00
|
|
|
let double_type = double_type context
|
2008-03-31 08:44:50 +00:00
|
|
|
|
|
|
|
|
(* Create an alloca instruction in the entry block of the function. This
|
|
|
|
|
* is used for mutable variables etc. *)
|
|
|
|
|
let create_entry_block_alloca the_function var_name =
|
2009-08-19 17:32:38 +00:00
|
|
|
let builder = builder_at context (instr_begin (entry_block the_function)) in
|
2008-03-31 08:44:50 +00:00
|
|
|
build_alloca double_type var_name builder
|
|
|
|
|
|
|
|
|
|
let rec codegen_expr = function
|
|
|
|
|
| Ast.Number n -> const_float double_type n
|
|
|
|
|
| Ast.Variable name ->
|
|
|
|
|
let v = try Hashtbl.find named_values name with
|
|
|
|
|
| Not_found -> raise (Error "unknown variable name")
|
|
|
|
|
in
|
|
|
|
|
(* Load the value. *)
|
|
|
|
|
build_load v name builder
|
|
|
|
|
| Ast.Unary (op, operand) ->
|
|
|
|
|
let operand = codegen_expr operand in
|
|
|
|
|
let callee = "unary" ^ (String.make 1 op) in
|
|
|
|
|
let callee =
|
|
|
|
|
match lookup_function callee the_module with
|
|
|
|
|
| Some callee -> callee
|
|
|
|
|
| None -> raise (Error "unknown unary operator")
|
|
|
|
|
in
|
|
|
|
|
build_call callee [|operand|] "unop" builder
|
|
|
|
|
| Ast.Binary (op, lhs, rhs) ->
|
|
|
|
|
begin match op with
|
|
|
|
|
| '=' ->
|
|
|
|
|
(* Special case '=' because we don't want to emit the LHS as an
|
|
|
|
|
* expression. *)
|
|
|
|
|
let name =
|
|
|
|
|
match lhs with
|
|
|
|
|
| Ast.Variable name -> name
|
|
|
|
|
| _ -> raise (Error "destination of '=' must be a variable")
|
|
|
|
|
in
|
|
|
|
|
|
|
|
|
|
(* Codegen the rhs. *)
|
|
|
|
|
let val_ = codegen_expr rhs in
|
|
|
|
|
|
|
|
|
|
(* Lookup the name. *)
|
|
|
|
|
let variable = try Hashtbl.find named_values name with
|
|
|
|
|
| Not_found -> raise (Error "unknown variable name")
|
|
|
|
|
in
|
|
|
|
|
ignore(build_store val_ variable builder);
|
|
|
|
|
val_
|
|
|
|
|
| _ ->
|
|
|
|
|
let lhs_val = codegen_expr lhs in
|
|
|
|
|
let rhs_val = codegen_expr rhs in
|
|
|
|
|
begin
|
|
|
|
|
match op with
|
|
|
|
|
| '+' -> build_add lhs_val rhs_val "addtmp" builder
|
|
|
|
|
| '-' -> build_sub lhs_val rhs_val "subtmp" builder
|
|
|
|
|
| '*' -> build_mul lhs_val rhs_val "multmp" builder
|
|
|
|
|
| '<' ->
|
|
|
|
|
(* Convert bool 0/1 to double 0.0 or 1.0 *)
|
|
|
|
|
let i = build_fcmp Fcmp.Ult lhs_val rhs_val "cmptmp" builder in
|
|
|
|
|
build_uitofp i double_type "booltmp" builder
|
|
|
|
|
| _ ->
|
|
|
|
|
(* If it wasn't a builtin binary operator, it must be a user defined
|
|
|
|
|
* one. Emit a call to it. *)
|
|
|
|
|
let callee = "binary" ^ (String.make 1 op) in
|
|
|
|
|
let callee =
|
|
|
|
|
match lookup_function callee the_module with
|
|
|
|
|
| Some callee -> callee
|
|
|
|
|
| None -> raise (Error "binary operator not found!")
|
|
|
|
|
in
|
|
|
|
|
build_call callee [|lhs_val; rhs_val|] "binop" builder
|
|
|
|
|
end
|
|
|
|
|
end
|
|
|
|
|
| Ast.Call (callee, args) ->
|
|
|
|
|
(* Look up the name in the module table. *)
|
|
|
|
|
let callee =
|
|
|
|
|
match lookup_function callee the_module with
|
|
|
|
|
| Some callee -> callee
|
|
|
|
|
| None -> raise (Error "unknown function referenced")
|
|
|
|
|
in
|
|
|
|
|
let params = params callee in
|
|
|
|
|
|
|
|
|
|
(* If argument mismatch error. *)
|
|
|
|
|
if Array.length params == Array.length args then () else
|
|
|
|
|
raise (Error "incorrect # arguments passed");
|
|
|
|
|
let args = Array.map codegen_expr args in
|
|
|
|
|
build_call callee args "calltmp" builder
|
|
|
|
|
| Ast.If (cond, then_, else_) ->
|
|
|
|
|
let cond = codegen_expr cond in
|
|
|
|
|
|
|
|
|
|
(* Convert condition to a bool by comparing equal to 0.0 *)
|
|
|
|
|
let zero = const_float double_type 0.0 in
|
|
|
|
|
let cond_val = build_fcmp Fcmp.One cond zero "ifcond" builder in
|
|
|
|
|
|
|
|
|
|
(* Grab the first block so that we might later add the conditional branch
|
|
|
|
|
* to it at the end of the function. *)
|
|
|
|
|
let start_bb = insertion_block builder in
|
|
|
|
|
let the_function = block_parent start_bb in
|
|
|
|
|
|
2010-03-08 19:32:18 +00:00
|
|
|
let then_bb = append_block context "then" the_function in
|
2008-03-31 08:44:50 +00:00
|
|
|
|
|
|
|
|
(* Emit 'then' value. *)
|
|
|
|
|
position_at_end then_bb builder;
|
|
|
|
|
let then_val = codegen_expr then_ in
|
|
|
|
|
|
|
|
|
|
(* Codegen of 'then' can change the current block, update then_bb for the
|
|
|
|
|
* phi. We create a new name because one is used for the phi node, and the
|
|
|
|
|
* other is used for the conditional branch. *)
|
|
|
|
|
let new_then_bb = insertion_block builder in
|
|
|
|
|
|
|
|
|
|
(* Emit 'else' value. *)
|
2010-03-08 19:32:18 +00:00
|
|
|
let else_bb = append_block context "else" the_function in
|
2008-03-31 08:44:50 +00:00
|
|
|
position_at_end else_bb builder;
|
|
|
|
|
let else_val = codegen_expr else_ in
|
|
|
|
|
|
|
|
|
|
(* Codegen of 'else' can change the current block, update else_bb for the
|
|
|
|
|
* phi. *)
|
|
|
|
|
let new_else_bb = insertion_block builder in
|
|
|
|
|
|
|
|
|
|
(* Emit merge block. *)
|
2010-03-08 19:32:18 +00:00
|
|
|
let merge_bb = append_block context "ifcont" the_function in
|
2008-03-31 08:44:50 +00:00
|
|
|
position_at_end merge_bb builder;
|
|
|
|
|
let incoming = [(then_val, new_then_bb); (else_val, new_else_bb)] in
|
|
|
|
|
let phi = build_phi incoming "iftmp" builder in
|
|
|
|
|
|
|
|
|
|
(* Return to the start block to add the conditional branch. *)
|
|
|
|
|
position_at_end start_bb builder;
|
|
|
|
|
ignore (build_cond_br cond_val then_bb else_bb builder);
|
|
|
|
|
|
|
|
|
|
(* Set a unconditional branch at the end of the 'then' block and the
|
|
|
|
|
* 'else' block to the 'merge' block. *)
|
|
|
|
|
position_at_end new_then_bb builder; ignore (build_br merge_bb builder);
|
|
|
|
|
position_at_end new_else_bb builder; ignore (build_br merge_bb builder);
|
|
|
|
|
|
|
|
|
|
(* Finally, set the builder to the end of the merge block. *)
|
|
|
|
|
position_at_end merge_bb builder;
|
|
|
|
|
|
|
|
|
|
phi
|
|
|
|
|
| Ast.For (var_name, start, end_, step, body) ->
|
|
|
|
|
(* Output this as:
|
|
|
|
|
* var = alloca double
|
|
|
|
|
* ...
|
|
|
|
|
* start = startexpr
|
|
|
|
|
* store start -> var
|
|
|
|
|
* goto loop
|
|
|
|
|
* loop:
|
|
|
|
|
* ...
|
|
|
|
|
* bodyexpr
|
|
|
|
|
* ...
|
|
|
|
|
* loopend:
|
|
|
|
|
* step = stepexpr
|
|
|
|
|
* endcond = endexpr
|
|
|
|
|
*
|
|
|
|
|
* curvar = load var
|
|
|
|
|
* nextvar = curvar + step
|
|
|
|
|
* store nextvar -> var
|
|
|
|
|
* br endcond, loop, endloop
|
|
|
|
|
* outloop: *)
|
|
|
|
|
|
|
|
|
|
let the_function = block_parent (insertion_block builder) in
|
|
|
|
|
|
|
|
|
|
(* Create an alloca for the variable in the entry block. *)
|
|
|
|
|
let alloca = create_entry_block_alloca the_function var_name in
|
|
|
|
|
|
|
|
|
|
(* Emit the start code first, without 'variable' in scope. *)
|
|
|
|
|
let start_val = codegen_expr start in
|
|
|
|
|
|
|
|
|
|
(* Store the value into the alloca. *)
|
|
|
|
|
ignore(build_store start_val alloca builder);
|
|
|
|
|
|
|
|
|
|
(* Make the new basic block for the loop header, inserting after current
|
|
|
|
|
* block. *)
|
2010-03-08 19:32:18 +00:00
|
|
|
let loop_bb = append_block context "loop" the_function in
|
2008-03-31 08:44:50 +00:00
|
|
|
|
|
|
|
|
(* Insert an explicit fall through from the current block to the
|
|
|
|
|
* loop_bb. *)
|
|
|
|
|
ignore (build_br loop_bb builder);
|
|
|
|
|
|
|
|
|
|
(* Start insertion in loop_bb. *)
|
|
|
|
|
position_at_end loop_bb builder;
|
|
|
|
|
|
|
|
|
|
(* 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. *)
|
|
|
|
|
let old_val =
|
|
|
|
|
try Some (Hashtbl.find named_values var_name) with Not_found -> None
|
|
|
|
|
in
|
|
|
|
|
Hashtbl.add named_values var_name alloca;
|
|
|
|
|
|
|
|
|
|
(* 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 *)
|
|
|
|
|
ignore (codegen_expr body);
|
|
|
|
|
|
|
|
|
|
(* Emit the step value. *)
|
|
|
|
|
let step_val =
|
|
|
|
|
match step with
|
|
|
|
|
| Some step -> codegen_expr step
|
|
|
|
|
(* If not specified, use 1.0. *)
|
|
|
|
|
| None -> const_float double_type 1.0
|
|
|
|
|
in
|
|
|
|
|
|
|
|
|
|
(* Compute the end condition. *)
|
|
|
|
|
let end_cond = codegen_expr end_ in
|
|
|
|
|
|
|
|
|
|
(* Reload, increment, and restore the alloca. This handles the case where
|
|
|
|
|
* the body of the loop mutates the variable. *)
|
|
|
|
|
let cur_var = build_load alloca var_name builder in
|
|
|
|
|
let next_var = build_add cur_var step_val "nextvar" builder in
|
|
|
|
|
ignore(build_store next_var alloca builder);
|
|
|
|
|
|
|
|
|
|
(* Convert condition to a bool by comparing equal to 0.0. *)
|
|
|
|
|
let zero = const_float double_type 0.0 in
|
|
|
|
|
let end_cond = build_fcmp Fcmp.One end_cond zero "loopcond" builder in
|
|
|
|
|
|
|
|
|
|
(* Create the "after loop" block and insert it. *)
|
2010-03-08 19:32:18 +00:00
|
|
|
let after_bb = append_block context "afterloop" the_function in
|
2008-03-31 08:44:50 +00:00
|
|
|
|
|
|
|
|
(* Insert the conditional branch into the end of loop_end_bb. *)
|
|
|
|
|
ignore (build_cond_br end_cond loop_bb after_bb builder);
|
|
|
|
|
|
|
|
|
|
(* Any new code will be inserted in after_bb. *)
|
|
|
|
|
position_at_end after_bb builder;
|
|
|
|
|
|
|
|
|
|
(* Restore the unshadowed variable. *)
|
|
|
|
|
begin match old_val with
|
|
|
|
|
| Some old_val -> Hashtbl.add named_values var_name old_val
|
|
|
|
|
| None -> ()
|
|
|
|
|
end;
|
|
|
|
|
|
|
|
|
|
(* for expr always returns 0.0. *)
|
|
|
|
|
const_null double_type
|
|
|
|
|
| Ast.Var (var_names, body) ->
|
|
|
|
|
let old_bindings = ref [] in
|
|
|
|
|
|
|
|
|
|
let the_function = block_parent (insertion_block builder) in
|
|
|
|
|
|
|
|
|
|
(* Register all variables and emit their initializer. *)
|
|
|
|
|
Array.iter (fun (var_name, init) ->
|
|
|
|
|
(* Emit the initializer before adding the variable to scope, this
|
|
|
|
|
* prevents the initializer from referencing the variable itself, and
|
|
|
|
|
* permits stuff like this:
|
|
|
|
|
* var a = 1 in
|
|
|
|
|
* var a = a in ... # refers to outer 'a'. *)
|
|
|
|
|
let init_val =
|
|
|
|
|
match init with
|
|
|
|
|
| Some init -> codegen_expr init
|
|
|
|
|
(* If not specified, use 0.0. *)
|
|
|
|
|
| None -> const_float double_type 0.0
|
|
|
|
|
in
|
|
|
|
|
|
|
|
|
|
let alloca = create_entry_block_alloca the_function var_name in
|
|
|
|
|
ignore(build_store init_val alloca builder);
|
|
|
|
|
|
|
|
|
|
(* Remember the old variable binding so that we can restore the binding
|
|
|
|
|
* when we unrecurse. *)
|
|
|
|
|
begin
|
|
|
|
|
try
|
|
|
|
|
let old_value = Hashtbl.find named_values var_name in
|
|
|
|
|
old_bindings := (var_name, old_value) :: !old_bindings;
|
|
|
|
|
with Not_found -> ()
|
|
|
|
|
end;
|
|
|
|
|
|
|
|
|
|
(* Remember this binding. *)
|
|
|
|
|
Hashtbl.add named_values var_name alloca;
|
|
|
|
|
) var_names;
|
|
|
|
|
|
|
|
|
|
(* Codegen the body, now that all vars are in scope. *)
|
|
|
|
|
let body_val = codegen_expr body in
|
|
|
|
|
|
|
|
|
|
(* Pop all our variables from scope. *)
|
|
|
|
|
List.iter (fun (var_name, old_value) ->
|
|
|
|
|
Hashtbl.add named_values var_name old_value
|
|
|
|
|
) !old_bindings;
|
|
|
|
|
|
|
|
|
|
(* Return the body computation. *)
|
|
|
|
|
body_val
|
|
|
|
|
|
|
|
|
|
let codegen_proto = function
|
|
|
|
|
| Ast.Prototype (name, args) | Ast.BinOpPrototype (name, args, _) ->
|
|
|
|
|
(* Make the function type: double(double,double) etc. *)
|
|
|
|
|
let doubles = Array.make (Array.length args) double_type in
|
|
|
|
|
let ft = function_type double_type doubles in
|
|
|
|
|
let f =
|
|
|
|
|
match lookup_function name the_module with
|
|
|
|
|
| None -> declare_function name ft the_module
|
|
|
|
|
|
|
|
|
|
(* If 'f' conflicted, there was already something named 'name'. If it
|
|
|
|
|
* has a body, don't allow redefinition or reextern. *)
|
|
|
|
|
| Some f ->
|
|
|
|
|
(* If 'f' already has a body, reject this. *)
|
|
|
|
|
if block_begin f <> At_end f then
|
|
|
|
|
raise (Error "redefinition of function");
|
|
|
|
|
|
|
|
|
|
(* If 'f' took a different number of arguments, reject. *)
|
|
|
|
|
if element_type (type_of f) <> ft then
|
|
|
|
|
raise (Error "redefinition of function with different # args");
|
|
|
|
|
f
|
|
|
|
|
in
|
|
|
|
|
|
|
|
|
|
(* Set names for all arguments. *)
|
|
|
|
|
Array.iteri (fun i a ->
|
|
|
|
|
let n = args.(i) in
|
|
|
|
|
set_value_name n a;
|
|
|
|
|
Hashtbl.add named_values n a;
|
|
|
|
|
) (params f);
|
|
|
|
|
f
|
|
|
|
|
|
|
|
|
|
(* Create an alloca for each argument and register the argument in the symbol
|
|
|
|
|
* table so that references to it will succeed. *)
|
|
|
|
|
let create_argument_allocas the_function proto =
|
|
|
|
|
let args = match proto with
|
|
|
|
|
| Ast.Prototype (_, args) | Ast.BinOpPrototype (_, args, _) -> args
|
|
|
|
|
in
|
|
|
|
|
Array.iteri (fun i ai ->
|
|
|
|
|
let var_name = args.(i) in
|
|
|
|
|
(* Create an alloca for this variable. *)
|
|
|
|
|
let alloca = create_entry_block_alloca the_function var_name in
|
|
|
|
|
|
|
|
|
|
(* Store the initial value into the alloca. *)
|
|
|
|
|
ignore(build_store ai alloca builder);
|
|
|
|
|
|
|
|
|
|
(* Add arguments to variable symbol table. *)
|
|
|
|
|
Hashtbl.add named_values var_name alloca;
|
|
|
|
|
) (params the_function)
|
|
|
|
|
|
|
|
|
|
let codegen_func the_fpm = function
|
|
|
|
|
| Ast.Function (proto, body) ->
|
|
|
|
|
Hashtbl.clear named_values;
|
|
|
|
|
let the_function = codegen_proto proto in
|
|
|
|
|
|
|
|
|
|
(* If this is an operator, install it. *)
|
|
|
|
|
begin match proto with
|
|
|
|
|
| Ast.BinOpPrototype (name, args, prec) ->
|
|
|
|
|
let op = name.[String.length name - 1] in
|
|
|
|
|
Hashtbl.add Parser.binop_precedence op prec;
|
|
|
|
|
| _ -> ()
|
|
|
|
|
end;
|
|
|
|
|
|
|
|
|
|
(* Create a new basic block to start insertion into. *)
|
2010-03-08 19:32:18 +00:00
|
|
|
let bb = append_block context "entry" the_function in
|
2008-03-31 08:44:50 +00:00
|
|
|
position_at_end bb builder;
|
|
|
|
|
|
|
|
|
|
try
|
|
|
|
|
(* Add all arguments to the symbol table and create their allocas. *)
|
|
|
|
|
create_argument_allocas the_function proto;
|
|
|
|
|
|
|
|
|
|
let ret_val = codegen_expr body in
|
|
|
|
|
|
|
|
|
|
(* Finish off the function. *)
|
|
|
|
|
let _ = build_ret ret_val builder in
|
|
|
|
|
|
|
|
|
|
(* Validate the generated code, checking for consistency. *)
|
|
|
|
|
Llvm_analysis.assert_valid_function the_function;
|
|
|
|
|
|
|
|
|
|
(* Optimize the function. *)
|
|
|
|
|
let _ = PassManager.run_function the_function the_fpm in
|
|
|
|
|
|
|
|
|
|
the_function
|
|
|
|
|
with e ->
|
|
|
|
|
delete_function the_function;
|
|
|
|
|
raise e
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>toplevel.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(*===----------------------------------------------------------------------===
|
|
|
|
|
* Top-Level parsing and JIT Driver
|
|
|
|
|
*===----------------------------------------------------------------------===*)
|
|
|
|
|
|
|
|
|
|
open Llvm
|
|
|
|
|
open Llvm_executionengine
|
|
|
|
|
|
|
|
|
|
(* top ::= definition | external | expression | ';' *)
|
|
|
|
|
let rec main_loop the_fpm the_execution_engine stream =
|
|
|
|
|
match Stream.peek stream with
|
|
|
|
|
| None -> ()
|
|
|
|
|
|
|
|
|
|
(* ignore top-level semicolons. *)
|
|
|
|
|
| Some (Token.Kwd ';') ->
|
|
|
|
|
Stream.junk stream;
|
|
|
|
|
main_loop the_fpm the_execution_engine stream
|
|
|
|
|
|
|
|
|
|
| Some token ->
|
|
|
|
|
begin
|
|
|
|
|
try match token with
|
|
|
|
|
| Token.Def ->
|
|
|
|
|
let e = Parser.parse_definition stream in
|
|
|
|
|
print_endline "parsed a function definition.";
|
|
|
|
|
dump_value (Codegen.codegen_func the_fpm e);
|
|
|
|
|
| Token.Extern ->
|
|
|
|
|
let e = Parser.parse_extern stream in
|
|
|
|
|
print_endline "parsed an extern.";
|
|
|
|
|
dump_value (Codegen.codegen_proto e);
|
|
|
|
|
| _ ->
|
|
|
|
|
(* Evaluate a top-level expression into an anonymous function. *)
|
|
|
|
|
let e = Parser.parse_toplevel stream in
|
|
|
|
|
print_endline "parsed a top-level expr";
|
|
|
|
|
let the_function = Codegen.codegen_func the_fpm e in
|
|
|
|
|
dump_value the_function;
|
|
|
|
|
|
|
|
|
|
(* JIT the function, returning a function pointer. *)
|
|
|
|
|
let result = ExecutionEngine.run_function the_function [||]
|
|
|
|
|
the_execution_engine in
|
|
|
|
|
|
|
|
|
|
print_string "Evaluated to ";
|
2010-03-08 19:32:18 +00:00
|
|
|
print_float (GenericValue.as_float Codegen.double_type result);
|
2008-03-31 08:44:50 +00:00
|
|
|
print_newline ();
|
|
|
|
|
with Stream.Error s | Codegen.Error s ->
|
|
|
|
|
(* Skip token for error recovery. *)
|
|
|
|
|
Stream.junk stream;
|
|
|
|
|
print_endline s;
|
|
|
|
|
end;
|
|
|
|
|
print_string "ready> "; flush stdout;
|
|
|
|
|
main_loop the_fpm the_execution_engine stream
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>toy.ml:</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
(*===----------------------------------------------------------------------===
|
|
|
|
|
* Main driver code.
|
|
|
|
|
*===----------------------------------------------------------------------===*)
|
|
|
|
|
|
|
|
|
|
open Llvm
|
|
|
|
|
open Llvm_executionengine
|
|
|
|
|
open Llvm_target
|
|
|
|
|
open Llvm_scalar_opts
|
|
|
|
|
|
|
|
|
|
let main () =
|
2009-09-14 21:54:32 +00:00
|
|
|
ignore (initialize_native_target ());
|
|
|
|
|
|
2008-03-31 08:44:50 +00:00
|
|
|
(* Install standard binary operators.
|
|
|
|
|
* 1 is the lowest precedence. *)
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '=' 2;
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '<' 10;
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '+' 20;
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '-' 20;
|
|
|
|
|
Hashtbl.add Parser.binop_precedence '*' 40; (* highest. *)
|
|
|
|
|
|
|
|
|
|
(* Prime the first token. *)
|
|
|
|
|
print_string "ready> "; flush stdout;
|
|
|
|
|
let stream = Lexer.lex (Stream.of_channel stdin) in
|
|
|
|
|
|
|
|
|
|
(* Create the JIT. *)
|
2010-03-08 19:32:18 +00:00
|
|
|
let the_execution_engine = ExecutionEngine.create Codegen.the_module in
|
|
|
|
|
let the_fpm = PassManager.create_function Codegen.the_module in
|
2008-03-31 08:44:50 +00:00
|
|
|
|
|
|
|
|
(* Set up the optimizer pipeline. Start with registering info about how the
|
|
|
|
|
* target lays out data structures. *)
|
|
|
|
|
TargetData.add (ExecutionEngine.target_data the_execution_engine) the_fpm;
|
|
|
|
|
|
|
|
|
|
(* Promote allocas to registers. *)
|
|
|
|
|
add_memory_to_register_promotion the_fpm;
|
|
|
|
|
|
|
|
|
|
(* Do simple "peephole" optimizations and bit-twiddling optzn. *)
|
2010-03-08 19:32:18 +00:00
|
|
|
add_instruction_combination the_fpm;
|
2008-03-31 08:44:50 +00:00
|
|
|
|
|
|
|
|
(* reassociate expressions. *)
|
|
|
|
|
add_reassociation the_fpm;
|
|
|
|
|
|
|
|
|
|
(* Eliminate Common SubExpressions. *)
|
|
|
|
|
add_gvn the_fpm;
|
|
|
|
|
|
|
|
|
|
(* Simplify the control flow graph (deleting unreachable blocks, etc). *)
|
|
|
|
|
add_cfg_simplification the_fpm;
|
|
|
|
|
|
2009-09-14 21:54:15 +00:00
|
|
|
ignore (PassManager.initialize the_fpm);
|
|
|
|
|
|
2008-03-31 08:44:50 +00:00
|
|
|
(* Run the main "interpreter loop" now. *)
|
|
|
|
|
Toplevel.main_loop the_fpm the_execution_engine stream;
|
|
|
|
|
|
|
|
|
|
(* Print out all the generated code. *)
|
|
|
|
|
dump_module Codegen.the_module
|
|
|
|
|
;;
|
|
|
|
|
|
|
|
|
|
main ()
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
|
|
|
|
|
<dt>bindings.c</dt>
|
|
|
|
|
<dd class="doc_code">
|
|
|
|
|
<pre>
|
|
|
|
|
#include <stdio.h>
|
|
|
|
|
|
|
|
|
|
/* putchard - putchar that takes a double and returns 0. */
|
|
|
|
|
extern double putchard(double X) {
|
|
|
|
|
putchar((char)X);
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* printd - printf that takes a double prints it as "%f\n", returning 0. */
|
|
|
|
|
extern double printd(double X) {
|
|
|
|
|
printf("%f\n", X);
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
</dd>
|
|
|
|
|
</dl>
|
|
|
|
|
|
|
|
|
|
<a href="LangImpl8.html">Next: Conclusion and other useful LLVM tidbits</a>
|
|
|
|
|
</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@nondot.org">Chris Lattner</a><br>
|
2011-04-09 02:13:37 +00:00
|
|
|
<a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
|
2008-03-31 08:44:50 +00:00
|
|
|
<a href="mailto:idadesub@users.sourceforge.net">Erick Tryzelaar</a><br>
|
2010-02-03 17:27:31 +00:00
|
|
|
Last modified: $Date$
|
2008-03-31 08:44:50 +00:00
|
|
|
</address>
|
|
|
|
|
</body>
|
|
|
|
|
</html>
|
