basic-block - Factor Documentation

basic-block

Vocabulary
compiler.cfg

Class description
Factors representation of a basic block in the Call Flow Graph (CFG). A basic block is a sequence of instructions that always are executed sequentially and doesn't contain any internal branching. It has the following slots:

number	The blocks sequence number. Generated by calling number-blocks.
successors	A vector of basic blocks that may be executed directly after this block. Most blocks only have one successor but a block that checks where an if-condition should branch to would have two for example.
predecessors	The opposite of successors -- a vector of basic blocks from which the execution may have arrived into this block.
instructions	A vector of insn tuples which form the instructions of the basic block.
kill-block?	The first and the last block in a cfg and all blocks containing ##call instructions are kill blocks. Kill blocks can't be optimized so they are omitted from certain optimization steps.
height	Block's height as a height-state. What the heights of the block was at entry and how much they were increased in the block.
replaces	Used by compiler.cfg.stacks.local for local stack analysis.
peeks	Used by compiler.cfg.stacks.local for local stack analysis.
kills	Used by compiler.cfg.stacks.local for local stack analysis.

Notes
A basic-block is an identity-tuple because it is used as a hash table key by the compiler.

Definition

USING: kernel vectors ;

IN: compiler.cfg

TUPLE: basic-block < identity-tuple
number
{ instructions vector initial: V{ } }
{ successors vector initial: V{ } }
{ predecessors vector initial: V{ } }
{ kill-block? boolean initial: f } height replaces peeks
kills ;