more work on large moves, including the notion of linking again

This commit is contained in:
Torsten Ruger 2014-09-17 17:00:19 +03:00
parent 4af93493fb
commit 49b6b99ab9
5 changed files with 45 additions and 47 deletions

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@ -13,37 +13,18 @@ module Arm
@immediate = 0
@rn = :r0 # register zero = zero bit pattern
@from = Virtual::IntegerConstant.new( @from ) if( @from.is_a? Fixnum )
@extra = nil
end
# arm intrucions are pretty sensible, and always 4 bytes (thumb not supported)
# but not all constants fit into the part of the instruction that is left after the instruction code,
# so large moves have to be split into two instrucitons. we handle this here, just this instruciton looks
# longer
# so large moves have to be split into two instructions.
# we handle this "transparently", just this instruction looks longer
# alas, full transparency is not achieved as we only know when to use 2 instruction once we know where def the
# other object is, and that position is only set after code positions have been determined (in link) and so
# see below in assemble
def mem_length
return 4
is_simple ? 4 : 8
end
# a constant (the one we want to move) can either be < 256 or be rotated in a funny arm way
# if neither works (not simple !) we need two instructions to make the move
def is_simple
right = @from
if right.is_a?(Virtual::ObjectConstant)
r_pos = right.position
# do pc relative addressing with the difference to the instuction
# 8 is for the funny pipeline adjustment (ie pc pointing to fetch and not execute)
right = Virtual::IntegerConstant.new( r_pos - self.position - 8 )
end
if (right.is_a?(Virtual::IntegerConstant))
if (right.fits_u8?)
return true
elsif (calculate_u8_with_rr(right))
return true
else
return false
end
end
return true
@extra ? 8 : 4
end
def assemble(io)
@ -72,10 +53,15 @@ module Arm
immediate = 1
raise "hmm"
else
operand = right.integer / 256
immediate = 1
raise "cannot fit numeric literal argument in operand #{right.inspect}"
# and so it continues: when we notice that the const doesn't fit, first time we raise an
# error,but set the extra flag, to say the instruction is now 8 bytes
# then on subsequent assemlies we can assemble
unless @extra
@extra = 1
raise ::Register::LinkException.new("cannot fit numeric literal argument in operand #{right.inspect}")
end
# now we can do the actual breaking of instruction
raise "at leat we got here"
end
elsif (right.is_a?(Symbol) or right.is_a?(Virtual::Integer))
operand = reg_code(right) #integer means the register the integer is in (otherwise constant)

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@ -1,5 +1,6 @@
module Register
class LinkException < Exception
end
# Assmble the object space into a binary.
# Link first to get positions, then assemble
# link and assemble functions for each class are close to each other, so to get them the same.
@ -36,6 +37,7 @@ module Register
end
def assemble
begin
link
@stream = StringIO.new
mid , main = @objects.find{|k,objekt| objekt.is_a?(Virtual::CompiledMethod) and (objekt.name == :__init__ )}
@ -51,6 +53,10 @@ module Register
next if objekt.is_a? Virtual::CompiledMethod
assemble_object( objekt )
end
rescue LinkException => e
puts "coought #{e}"
retry
end
puts "Assembled #{@stream.length.to_s(16)}"
return @stream.string
end

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@ -1,4 +1,3 @@
require_relative "code"
module Register
# The register machine model is close to current hardware and has following instruction classes

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@ -56,6 +56,10 @@ module Virtual
def mem_length
padded(1 + string.length)
end
def set_position pos
puts "STRING #{pos} #{string}"
super
end
def position
return @position if @position
return @string.position if @string.position

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@ -26,7 +26,10 @@ module Virtual
@position
end
def set_position pos
raise "position set again #{pos}!=#{@position} for #{self}" if @position != nil and (@position != pos)
# resetting of position used to be error, but since relink and dynamic instruction size it is ok. in measures
if @position != nil and ((@position - pos).abs > 15)
raise "position set again #{pos}!=#{@position} for #{self}"
end
@position = pos
end
def inspect