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1
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2 import ir
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3 import irmach
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4
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5 def genTemps():
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6 n = 900
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7 while True:
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8 yield 't{}'.format(n)
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9 n = n + 1
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10
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11 class InstructionSelector:
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12 """
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13 Base instruction selector. This class must be overridden by
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14 backends.
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15 """
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16 def newTmp(self):
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17 return self.temps.__next__()
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18
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19 def getTempReg(self, tmp):
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20 if tmp not in self.tempMap:
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21 self.tempMap[tmp] = self.newTmp()
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22 return self.tempMap[tmp]
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23
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24 def munchProgram(self, p):
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25 # Entry point for instruction selection
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26 self.temps = genTemps()
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27 assert isinstance(p, ir.Module)
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28 self.result = []
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29 self.targets = {}
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30 self.tempMap = {} # Mapping from temporaries to infinite register
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31 for f in p.Functions:
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32 # First define labels:
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33 for bb in f.BasicBlocks:
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34 itgt = self.makeIns('{}:'.format(bb.name))
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35 self.targets[bb] = itgt
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36 for bb in f.BasicBlocks:
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37 self.emit2(self.targets[bb])
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38 for i in bb.Instructions:
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39 self.munchStm(i)
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40 bb.machIns = self.result
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41 return self.result
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42
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43 def makeIns(self, *args, **kwargs):
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44 return irmach.AbstractInstruction(*args, **kwargs)
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45
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46 def emit(self, *args, **kwargs):
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47 """ Abstract instruction emitter """
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48 i = self.makeIns(*args, **kwargs)
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49 return self.emit2(i)
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50
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51 def emit2(self, i):
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52 self.result.append(i)
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53 return i
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54
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55 def munchStm(self, s):
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56 raise NotImplementedError()
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57
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58 def munchExpr(self, e):
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59 raise NotImplementedError()
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60
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