While this code is open source, you may not use it or even look at it if you are taking CS 160 or a similar compilers course. You have been warned.

Andres Riofrio ariofrio@cs.ucsb.edu

Add test harness: Feb 2-3

• ./simple --only-scanner outputs a space-separated list of tokens
• make test compares generated tokens with expected tokens
• make test ensures parser accepts valid programs (there's no output)
• make test ensures parser rejects invalid programs (there is output)
• Added tests for each new feature introduced

Implement scanner: Feb 3

• The rule for octal numbers is above the rule for decimal numbers
• Tokens that are not single-character operators get a %token declaration in parser.ypp
• Used a start condition to implement multi-line, non-greedy comments

Implement parser: Feb 3

• Used left-recursion for efficiency
• Use %left, %right, and %nonassoc to disambiguate the grammar according to this C/C++ precedence table

Implement AST generator: Feb 17

• Add harness files from class website
• Add actions to parser rules to construct the AST
• Separate Assignment parser rule into Assignment and ArrayAssignment; likewise with FunctionCall
• Add Identifier and Number parser rules that have an action that creates a Primitive() instead of adding the code to create a Primitive() every time IDENTIFIER and NUMBER are used.
• Set yylval in lexer rules to propagate integer values and symbol names
• Check that each test passes (done manually: test harness not updated)

Implement type checking and semantic analysis: Mar 5-12

• Replace my code with harness files from class website
• Remove --only-scanner option and associated tests
• Add semantic tests from class website
• Implement type checker, including checking that operators like magnitude get integers as their inner expression
• Implement constant folding
  • BOTTOM propagates in order to catch errors more easily
  • Division by zero gives zero

Implement code generation: Mar 17-20

• Test that correct programs compile and produce expected output
• Literals and identifiers push a value to the stack
• Operators pop one or two values from the stack and push the result
• Comparison operators implemented with SETcc %eal followed by ANDL $255 %eax
• Function arguments are copied to occupy the same space as local variables, for ease of access
• Constants are folded (behave as literal integers/booleans)
• if statements with constant values only output the selected branch
• while statements with constant values either eliminate the statement or simplify the infinite loop