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1 =======================================================================
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2 Building a JIT: Extreme Laziness - Using LazyReexports to JIT from ASTs
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3 =======================================================================
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4
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5 .. contents::
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6 :local:
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7
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8 **This tutorial is under active development. It is incomplete and details may
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9 change frequently.** Nonetheless we invite you to try it out as it stands, and
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10 we welcome any feedback.
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11
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12 Chapter 4 Introduction
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13 ======================
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14
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15 Welcome to Chapter 4 of the "Building an ORC-based JIT in LLVM" tutorial. This
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16 chapter introduces custom MaterializationUnits and Layers, and the lazy
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17 reexports API. Together these will be used to replace the CompileOnDemandLayer
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18 from `Chapter 3 <BuildingAJIT3.html>`_ with a custom lazy-JITing scheme that JITs
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19 directly from Kaleidoscope ASTs.
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20
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21 **To be done:**
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22
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23 **(1) Describe the drawbacks of JITing from IR (have to compile to IR first,
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24 which reduces the benefits of laziness).**
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25
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26 **(2) Describe CompileCallbackManagers and IndirectStubManagers in detail.**
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27
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28 **(3) Run through the implementation of addFunctionAST.**
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29
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30 Full Code Listing
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31 =================
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32
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33 Here is the complete code listing for our running example that JITs lazily from
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34 Kaleidoscope ASTS. To build this example, use:
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35
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36 .. code-block:: bash
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37
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38 # Compile
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39 clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native` -O3 -o toy
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40 # Run
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41 ./toy
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42
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43 Here is the code:
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44
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45 .. literalinclude:: ../../examples/Kaleidoscope/BuildingAJIT/Chapter4/KaleidoscopeJIT.h
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46 :language: c++
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47
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48 `Next: Remote-JITing -- Process-isolation and laziness-at-a-distance <BuildingAJIT5.html>`_
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