Basic Blocks

A basic block is a straight-line sequence of instructions with no internal control flow. Blocks are named bb0, bb1, etc. in text format.

Block Arguments

Tuffy IR uses block arguments instead of PHI nodes to represent values that merge at control flow join points. Block arguments are declared in the block header and receive values from predecessor branches:

bb0:
  v0 = iconst 1
  br bb1(v0)

bb1(v1: int):       // v1 is a block argument
  ret v1

Each branch instruction (br, brif, continue) passes values to the target block’s arguments. The number and types of passed values must match the target block’s argument list.

Instruction Ordering

Instructions within a block execute sequentially. The last instruction in a block must be a terminator (ret, br, brif, continue, region_yield).