Initial commit

devtools/tasmrecover/tasm/proc.py

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+# ScummVM - Graphic Adventure Engine
+#
+# ScummVM is the legal property of its developers, whose names
+# are too numerous to list here. Please refer to the COPYRIGHT
+# file distributed with this source distribution.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import re
+import op
+
+class proc:
+	last_addr = 0xc000
+
+	def __init__(self, name):
+		self.name = name
+		self.calls = []
+		self.stmts = []
+		self.labels = set()
+		self.retlabels = set()
+		self.__label_re = re.compile(r'^(\S+):(.*)$')
+		self.offset = proc.last_addr
+		proc.last_addr += 4
+
+	def add_label(self, label):
+		self.stmts.append(op.label(label))
+		self.labels.add(label)
+
+	def remove_label(self, label):
+		try:
+			self.labels.remove(label)
+		except:
+			pass
+		for i in xrange(len(self.stmts)):
+			if isinstance(self.stmts[i], op.label) and self.stmts[i].name == label:
+				self.stmts[i] = op._nop(None)
+				return
+
+	def optimize_sequence(self, cls):
+		i = 0
+		stmts = self.stmts
+		while i < len(stmts):
+			if not isinstance(stmts[i], cls):
+				i += 1
+				continue
+			if i > 0 and isinstance(stmts[i - 1], op._rep): #skip rep prefixed instructions for now
+				i += 1
+				continue
+			j = i + 1
+
+			while j < len(stmts):
+				if not isinstance(stmts[j], cls):
+					break
+				j = j + 1
+
+			n = j - i
+			if n > 1:
+				print "Eliminate consequtive storage instructions at %u-%u" %(i, j)
+				for k in range(i+1,j):
+					stmts[k] = op._nop(None)
+				stmts[i].repeat = n
+			else:
+				i = j
+
+		i = 0
+		while i < len(stmts):
+			if not isinstance(stmts[i], op._rep):
+				i += 1
+				continue
+			if i + 1 >= len(stmts):
+				break
+			if isinstance(stmts[i + 1], cls):
+				stmts[i + 1].repeat = 'cx'
+				stmts[i + 1].clear_cx = True
+				stmts[i] = op._nop(None)
+			i += 1
+		return
+
+	def optimize(self, keep_labels=[]):
+		print "optimizing..."
+		#trivial simplifications
+		while len(self.stmts) and isinstance(self.stmts[-1], op.label):
+			print "stripping last label"
+			self.stmts.pop()
+		#mark labels that directly precede a ret
+		for i in range(len(self.stmts)):
+			if not isinstance(self.stmts[i], op.label):
+				continue
+			j = i
+			while j < len(self.stmts) and isinstance(self.stmts[j], (op.label, op._nop)):
+				j += 1
+			if j == len(self.stmts) or isinstance(self.stmts[j], op._ret):
+				print "Return label: %s" % (self.stmts[i].name,)
+				self.retlabels.add(self.stmts[i].name)
+		#merging push ax pop bx constructs
+		i = 0
+		while i + 1 < len(self.stmts):
+			a, b = self.stmts[i], self.stmts[i + 1]
+			if isinstance(a, op._push) and isinstance(b, op._pop):
+				ar, br = a.regs, b.regs
+				movs = []
+				while len(ar) and len(br):
+					src = ar.pop()
+					dst = br.pop(0)
+					movs.append(op._mov2(dst, src))
+				if len(br) == 0:
+					self.stmts.pop(i + 1)
+				print "merging %d push-pops into movs" %(len(movs))
+				for m in movs:
+					print "\t%s <- %s" %(m.dst, m.src)
+				self.stmts[i + 1:i + 1] = movs
+				if len(ar) == 0:
+					self.stmts.pop(i)
+			else:
+				i += 1
+
+		#eliminating unused labels
+		for s in list(self.stmts):
+			if not isinstance(s, op.label):
+				continue
+			print "checking label %s..." %s.name
+			used = s.name in keep_labels
+			if s.name not in self.retlabels:
+				for j in self.stmts:
+					if isinstance(j, op.basejmp) and j.label == s.name:
+						print "used"
+						used = True
+						break
+			if not used:
+				print self.labels
+				self.remove_label(s.name)
+
+		#removing duplicate rets and rets at end
+		for i in xrange(len(self.stmts)):
+			if isinstance(self.stmts[i], op._ret):
+				j = i+1
+				while j < len(self.stmts) and isinstance(self.stmts[j], op._nop):
+					j += 1
+				if j == len(self.stmts) or isinstance(self.stmts[j], op._ret):
+					self.stmts[i] = op._nop(None)
+
+		self.optimize_sequence(op._stosb);
+		self.optimize_sequence(op._stosw);
+		self.optimize_sequence(op._movsb);
+		self.optimize_sequence(op._movsw);
+
+	def add(self, stmt):
+		#print stmt
+		comment = stmt.rfind(';')
+		if comment >= 0:
+			stmt = stmt[:comment]
+		stmt = stmt.strip()
+
+		r = self.__label_re.search(stmt)
+		if r is not None:
+			#label
+			self.add_label(r.group(1).lower())
+			#print "remains: %s" %r.group(2)
+			stmt = r.group(2).strip()
+
+		if len(stmt) == 0:
+			return
+
+		s = stmt.split(None)
+		cmd = s[0]
+		cl = getattr(op, '_' + cmd)
+		arg = " ".join(s[1:]) if len(s) > 1 else str()
+		o = cl(arg)
+		self.stmts.append(o)
+
+	def __str__(self):
+		r = []
+		for i in self.stmts:
+			r.append(i.__str__())
+		return "\n".join(r)
+
+	def visit(self, visitor, skip = 0):
+		for i in xrange(skip, len(self.stmts)):
+			self.stmts[i].visit(visitor)