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173
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1 from ir import *
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2 # Standard passes:
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3
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4 class FunctionPass:
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5 def run(self, ir):
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6 """ Main entry point for the pass """
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176
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7 self.prepare()
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8 for f in ir.Functions:
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9 self.onFunction(f)
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10 def onFunction(self, f):
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11 """ Override this virtual method """
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12 raise NotImplementedError()
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176
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13 def prepare(self):
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14 pass
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15
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16 class BasicBlockPass(FunctionPass):
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17 def onFunction(self, f):
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18 for bb in f.BasicBlocks:
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19 self.onBasicBlock(bb)
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20 def onBasicBlock(self, bb):
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21 """ Override this virtual method """
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22 raise NotImplementedError()
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23
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24 class InstructionPass(BasicBlockPass):
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25 def onBasicBlock(self, bb):
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174
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26 for ins in iter(bb.Instructions):
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173
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27 self.onInstruction(ins)
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28 def onInstruction(self, ins):
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29 """ Override this virtual method """
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30 raise NotImplementedError()
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31
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32 # Usefull transforms:
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33 class ConstantFolder(InstructionPass):
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176
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34 def prepare(self):
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35 self.constMap = {}
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173
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36 def onInstruction(self, i):
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37 if type(i) is ImmLoad:
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38 self.constMap[i.target] = i.value
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39 elif type(i) is BinaryOperator:
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40 if i.value1 in self.constMap and i.value2 in self.constMap:
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41 op = i.operation
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42 va = self.constMap[i.value1]
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43 vb = self.constMap[i.value2]
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44 if op == '+':
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45 vr = va + vb
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46 elif op == '*':
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47 vr = va * vb
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48 elif op == '-':
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49 vr = va - vb
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50 else:
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51 vr = None
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52 return
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53 self.constMap[i.result] = vr
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54 i2 = ImmLoad(i.result, vr)
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55 i.Parent.replaceInstruction(i, i2)
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173
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56
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237
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57
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58 class ConstantMerge(InstructionPass):
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59 def prepare(self):
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60 self.constMap = {}
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61 def onInstruction(self, i):
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62 if type(i) is ImmLoad:
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63 v = i.value
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64 if v in self.constMap:
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65 # v is already defined, re-use the imm-load from elsewhere
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66 pass
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67 else:
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68 self.constMap[v] = i
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69 elif type(i) is BinaryOperator:
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70 if i.value1 in self.constMap and i.value2 in self.constMap:
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71 op = i.operation
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72 va = self.constMap[i.value1]
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73 vb = self.constMap[i.value2]
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74 if op == '+':
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75 vr = va + vb
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76 elif op == '*':
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77 vr = va * vb
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78 elif op == '-':
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79 vr = va - vb
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80 else:
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81 vr = None
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82 return
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83 self.constMap[i.result] = vr
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84 i2 = ImmLoad(i.result, vr)
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85 i.Parent.replaceInstruction(i, i2)
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86
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87
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174
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88 class DeadCodeDeleter(BasicBlockPass):
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89 def onBasicBlock(self, bb):
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90 def instructionUsed(ins):
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91 if len(ins.defs) == 0:
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92 # In case this instruction does not define any variables, assume it is usefull.
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93 return True
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94 for d in ins.defs:
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95 if d.IsUsed:
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96 return True
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97 return False
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98 bb.Instructions = list(filter(instructionUsed, bb.Instructions))
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173
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99
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175
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100 def isAllocPromotable(allocinst):
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101 # Check if alloc value is only used by load and store operations.
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102 assert type(allocinst) is Alloc
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103 for use in ai.value.used_by:
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104 if not type(use.user) in [Load, Store]:
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105 # TODO: check volatile
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106 return False
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107 otherUse = True
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108 return True
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109
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177
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110 class CleanPass(FunctionPass):
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219
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111 def onFunction(self, f):
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177
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112 bbs = list(f.BasicBlocks)
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113 for bb in bbs:
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114 # TODO: determine check for 'empty'
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219
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115
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116 # If a block only contains a branch, it can be removed:
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117 if len(bb.Instructions) == 1:
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118 # This block is empty.
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119 # find predecessors of this block and replace this block reference with the jumped reference.
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120 ins = bb.LastInstruction
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121 if type(ins) is Branch:
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219
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122 preds = bb.Predecessors
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123 if bb in preds:
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124 # Do not remove if preceeded by itself
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125 pass
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126 else:
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127 for pred in bb.Predecessors:
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128 pred.LastInstruction.changeTarget(bb, ins.target)
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129 f.removeBasicBlock(bb)
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177
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130
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175
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131 class Mem2RegPromotor(FunctionPass):
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132 def onFunction(self, f):
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176
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133 # TODO
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235
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134 pass
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175
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135
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