Three-Address Code IR

Generating TAC from the AST

This task bridges tree-shaped ASTs to flat instruction lists. GCC's GIMPLE lowering and LLVM's IRBuilder::CreateAdd both flatten expressions into temporaries. Stack machines like JVM bytecode are three-address code with implicit operand stacks.

Recursive Code Generation

generate_expression returns the operand holding the result. For binary nodes, recurse on children, emit t = left op right, return t. Statements emit sequences: labels for control flow, param/call for functions.

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• new_temp() allocates fresh temporaries
• emit() appends to the instruction list
• If/else needs labels, conditional jumps, and merge
• Do not return placeholder constants; wire each node kind

Connecting to real compilers

Production compilers embed this step inside a longer pipeline. GCC flows through cpp, cc1, assembly, and ld; Clang uses the driver, Sema, LLVM IR passes, and a target backend. LLVM bitcode, JVM bytecode, and WASM are other familiar IRs at the same layer. The exercise isolates one pass so you can test it alone before chaining it to the next stage.

Why for this exercise

You will implement a three-address code generator that walks the AST and emits instructions. This exercise requires generate_expression, generate_statement, and temporary allocation without stub placeholders that fake results.