Skip to content

Latest commit

 

History

History
71 lines (57 loc) · 2.46 KB

README.md

File metadata and controls

71 lines (57 loc) · 2.46 KB
Raw

Expressions - due in only one week on 2020-7-14

Implement an expression interpreter and an expression compiler for your database. Your implementation should support the following type of expressions:

  • Constants
    Constants are either 8 byte float values or 8 byte signed integers.
  • Arguments
    Refers to a fixed index of an argument array storing 8 byte values (either floats or signed integers).
  • Cast
    Cast an expression from one type to another.
  • Addition
    Add two expressions.
  • Subtraction
    Subtract two expressions.
  • Multiplication
    Multiply two expressions.
  • Division
    Divide two expressions.

Add your implementation to the files
include/moderndbs/codegen/expression.h and
src/moderndbs/codegen/expression.cc.

Interpreter

For the expression interpreter, each expression type should implement the method

virtual data64_t evaluate(const data64_t* args)

which evaluates the expression tree given an argument array.

Compiler

For the expression compiler, each expression type should implement the method

virtual llvm::Value* build(llvm::IRBuilder& builder, llvm::Value* args)

which generates code for the expression using the LLVM framework. The expression compiler should then implement the method void compile(Expression& expression) that compiles a function data64_t (*fnPtr)(data64_t* args) for the expression tree. Use the class include/moderndbs/codegen/jit.h to simplify the LLVM module compilation significantly. Refer to the simple printf example for information on how to generate a LLVM module.

You don't need to implement implicit type casts.
Subtrees of a binary expression (Add, Sub, Mul, Div) are guaranteed to have the same type: either a float or an integer.

Testing

Your implementation should pass all tests in test/expression_test.cc.

Run the benchmark bench/bm_expression.cc to compare the efficiency of both approaches.

Setup

This task requires LLVM 10 which must be installed separately.

MacOS:

# Install LLVM 10 via homebrew
brew install llvm@10

# Configure the project
cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS=1 $PROJECT_DIRECTORY

Ubuntu:

# Install LLVM 10 via apt
sudo apt install llvm-10 llvm-10-dev llvm-10-tools

# Configure the project
cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS=1 $PROJECT_DIRECTORY

If you encounter problems, please ask on Mattermost.