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Copy pathopt.rb
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135 lines (117 loc) · 3.9 KB
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# Copyright (C) 2011 Apple Inc. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
# THE POSSIBILITY OF SUCH DAMAGE.
require "config"
require "ast"
#
# "Optimization" passes. These are used to lower the representation for
# backends that cannot handle some of our higher-level instructions.
#
#
# A temporary - a variable that will be allocated to a register after we're
# done.
#
class Node
def replaceTemporariesWithRegisters(kind)
mapChildren {
| node |
node.replaceTemporariesWithRegisters(kind)
}
end
end
class Tmp < NoChildren
attr_reader :firstMention, :lastMention
attr_reader :kind
attr_accessor :register
def initialize(codeOrigin, kind)
super(codeOrigin)
@kind = kind
end
def dump
"$tmp#{object_id}"
end
def mention!(position)
if not @firstMention or position < @firstMention
@firstMention = position
end
if not @lastMention or position > @lastMention
@lastMention = position
end
end
def replaceTemporariesWithRegisters(kind)
if @kind == kind
raise "Did not allocate register to temporary at #{codeOriginString}" unless @register
@register
else
self
end
end
def address?
false
end
def label?
false
end
def immediate?
false
end
def register?
true
end
end
# Assign registers to temporaries, by finding which temporaries interfere
# with each other. Note that this relies on temporary live ranges not crossing
# basic block boundaries.
def assignRegistersToTemporaries(list, kind, registers)
list.each_with_index {
| node, index |
node.filter(Tmp).uniq.each {
| tmp |
if tmp.kind == kind
tmp.mention! index
end
}
}
freeRegisters = registers.dup
list.each_with_index {
| node, index |
tmpList = node.filter(Tmp).uniq
tmpList.each {
| tmp |
if tmp.kind == kind and tmp.firstMention == index
raise "Could not allocate register to temporary at #{node.codeOriginString}" if freeRegisters.empty?
tmp.register = freeRegisters.pop
end
}
tmpList.each {
| tmp |
if tmp.kind == kind and tmp.lastMention == index
freeRegisters.push tmp.register
raise "Register allocation inconsistency at #{node.codeOriginString}" if freeRegisters.size > registers.size
end
}
}
list.map {
| node |
node.replaceTemporariesWithRegisters(kind)
}
end