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Contents
# frozen_string_literal: true
module SyntaxTree
module YARV
# This object represents a single basic block, wherein all contained
# instructions do not branch except for the last one.
class BasicBlock
# This is the unique identifier for this basic block.
attr_reader :id
# This is the index into the list of instructions where this block starts.
attr_reader :block_start
# This is the set of instructions that this block contains.
attr_reader :insns
# This is an array of basic blocks that lead into this block.
attr_reader :incoming_blocks
# This is an array of basic blocks that this block leads into.
attr_reader :outgoing_blocks
def initialize(block_start, insns)
@id = "block_#{block_start}"
@block_start = block_start
@insns = insns
@incoming_blocks = []
@outgoing_blocks = []
end
# Yield each instruction in this basic block along with its index from the
# original instruction sequence.
def each_with_length
return enum_for(:each_with_length) unless block_given?
length = block_start
insns.each do |insn|
yield insn, length
length += insn.length
end
end
# This method is used to verify that the basic block is well formed. It
# checks that the only instruction in this basic block that branches is
# the last instruction.
def verify
insns[0...-1].each { |insn| raise unless insn.branch_targets.empty? }
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems