mirror of
https://github.com/Sei-Lisa/LSL-PyOptimizer
synced 2025-07-01 23:58:20 +00:00
Implement side-effect-free (SEF) analysis. Also optimize x++ to ++x.
As an additional bonus, the condition folding function is now the one that converts a condition to -1, relieving that burden from the rest of the code and simplifying tests.
This commit is contained in:
Sei Lisa
parent
0a7d409a4e
commit
9c4d81db08
2 changed files with 172 additions and 43 deletions
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@ -20,8 +20,6 @@ class optimizer(renamer, deadcode):
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LSL2PythonType = {'integer':int, 'float':float, 'string':unicode, 'key':lslfuncs.Key,
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'vector':lslfuncs.Vector, 'rotation':lslfuncs.Quaternion, 'list':list}
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ignored_stmts = frozenset(('V++','V--','--V','++V',';','STSW','JUMP','@'))
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def FoldAndRemoveEmptyStmts(self, lst):
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"""Utility function for elimination of useless expressions in FOR"""
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idx = 0
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@ -35,22 +33,41 @@ class optimizer(renamer, deadcode):
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idx += 1
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def FoldStmt(self, parent, index):
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"""If the statement is a constant or an identifier, remove it as it does
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nothing.
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"""
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# Ideally this should consider side effect analysis of the whole thing.
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"""Simplify a statement."""
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node = parent[index]
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if node['nt'] == 'EXPR':
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node = node['ch'][0]
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if node['nt'] in ('CONST', 'IDENT', 'FLD'):
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parent[index] = {'nt':';','t':None}
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# If the statement is side-effect-free, remove it as it does nothing.
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if 'SEF' in node:
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# Side-effect free means that a statement does nothing except
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# wasting CPU, and can thus be removed without affecting the
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# program. But side effect freedom is propagated from the
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# constituents of the statement, e.g. function calls in expressions
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# or substatements in FOR, or even individual variables.
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#
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# Many library functions like llSameGroup or llGetVel() are
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# side-effect free. Many other functions like llSleep() or
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# llSetScale() are not. User functions may or may not be.
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#
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# Assignments do have side effects, except those of the form x = x.
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# Pre- and post-increment and decrement also have side effects.
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# Type casts do not add side effects. Neither do binary operators.
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parent[index] = {'nt':';', 't':None, 'SEF': True}
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return
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# Post-increments take more space than pre-increments.
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if node['nt'] in ('V++', 'V--'):
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node['nt'] = '++V' if node['nt'] == 'V++' else '--V';
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def FoldCond(self, parent, index):
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"""When we know that the parent is interested only in the truth value
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of the node, we can perform further optimizations. This function deals
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with them.
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"""
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if parent[index]['nt'] in ('CONST', 'IDENT', 'FIELD'):
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node = parent[index]
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if node['nt'] in ('CONST', 'IDENT', 'FLD'):
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if node['nt'] == 'CONST':
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node['t'] = 'integer'
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node['value'] = -1 if lslfuncs.cond(node['value']) else 0
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return # Nothing to do if it's already simplified.
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# TODO: Implement FoldCond
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@ -83,11 +100,14 @@ class optimizer(renamer, deadcode):
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child = node['ch'] if 'ch' in node else None
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if nt == 'CONST':
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# Job already done
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# Job already done. But mark as side-effect free.
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node['SEF'] = True
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return
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if nt == 'CAST':
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self.FoldTree(child, 0)
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if 'SEF' in child[0]:
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node['SEF'] = True
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if child[0]['nt'] == 'CONST':
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# Enable key constants. We'll typecast them back on output, but
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# this enables some optimizations.
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@ -101,13 +121,18 @@ class optimizer(renamer, deadcode):
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if nt == 'NEG':
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self.FoldTree(child, 0)
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while child[0]['nt'] == '()' and child[0]['ch'][0]['nt'] == 'NEG':
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child[0] = child[0]['ch'][0] # Remove parentheses
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# Remove parentheses: - ( - expr ) --> - - expr
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child[0] = child[0]['ch'][0]
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if child[0]['nt'] == 'NEG':
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# Double negation: - - expr
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# Double negation: - - expr --> expr
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# NOTE: Not 100% sure this doesn't need parentheses around expr.
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parent[index] = child[0]['ch'][0]
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elif child[0]['nt'] == 'CONST':
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node = parent[index] = child[0]
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node['value'] = lslfuncs.neg(node['value'])
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elif 'SEF' in child[0]:
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# propagate Side Effect Free flag
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node['SEF'] = True
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return
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if nt == '!':
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@ -115,6 +140,8 @@ class optimizer(renamer, deadcode):
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self.FoldCond(child, 0)
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# !! does *not* cancel out, but !!! can be simplified to !
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subexpr = child[0]
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if 'SEF' in subexpr:
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node['SEF'] = True
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while subexpr['nt'] == '()' and subexpr['ch'][0]['nt'] in ('()', '~', '!', '++V', '--V'):
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subexpr = child[0] = subexpr['ch'][0] # Remove parentheses
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if subexpr['nt'] == '!' and subexpr['ch'][0]['nt'] == '!':
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@ -128,7 +155,10 @@ class optimizer(renamer, deadcode):
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if nt == '~':
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self.FoldTree(child, 0)
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subexpr = child[0]
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while subexpr['nt'] == '()' and subexpr['ch'][0]['nt'] in ('()', '~', '!', '++V', '--V'):
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if 'SEF' in subexpr:
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node['SEF'] = True
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while subexpr['nt'] == '()' and subexpr['ch'][0]['nt'] in ('()',
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'~', '!', '++V', '--V'):
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subexpr = child[0] = subexpr['ch'][0] # Remove parentheses
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if subexpr['nt'] == '~':
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# Double negation: ~~expr
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@ -140,6 +170,8 @@ class optimizer(renamer, deadcode):
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if nt == '()':
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self.FoldTree(child, 0)
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if 'SEF' in child[0]:
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node['SEF'] = True
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if child[0]['nt'] in ('()', 'CONST', 'VECTOR', 'ROTATION', 'LIST',
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'IDENT', 'FIELD', 'V++', 'V--', 'FUNCTION', 'PRINT'):
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# Child is an unary postfix expression (highest priority);
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@ -155,6 +187,9 @@ class optimizer(renamer, deadcode):
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# RTL evaluation
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self.FoldTree(child, 1)
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self.FoldTree(child, 0)
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if 'SEF' in child[0] and 'SEF' in child[1]:
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# Propagate SEF flag if both sides are side-effect free.
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node['SEF'] = True
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if child[0]['nt'] == child[1]['nt'] == 'CONST':
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op1 = child[0]['value']
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op2 = child[1]['value']
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@ -377,6 +412,8 @@ class optimizer(renamer, deadcode):
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# Transform the whole thing into a regular assignment, as there are
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# no gains and it simplifies the optimization.
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# An assignment has no side effects only if it's of the form x = x.
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if nt != '=':
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# Replace the node with the expression alone
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child[1] = {'nt':'()', 't':child[1]['t'], 'ch':[child[1]]}
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@ -391,13 +428,19 @@ class optimizer(renamer, deadcode):
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node = self.Cast(node, 'integer')
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# And wrap it in an assignment.
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node = parent[index] = {'nt':'=', 't':child[0]['t'], 'ch':[child[0].copy(), node]}
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child = [child[0].copy(), node]
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node = parent[index] = {'nt':'=', 't':child[0]['t'], 'ch':child}
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# We have a regular assignment either way now. Simplify the RHS.
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self.FoldTree(node['ch'], 1)
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if child[1]['nt'] == 'IDENT' and child[1]['name'] == child[0]['name'] \
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and child[1]['scope'] == child[0]['scope']:
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node['SEF'] = True
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self.FoldStmt(parent, index)
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return
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if nt == 'IDENT' or nt == 'FLD':
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node['SEF'] = True
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if self.globalmode:
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ident = child[0] if nt == 'FLD' else node
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# Resolve constant values so they can be optimized
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@ -422,10 +465,22 @@ class optimizer(renamer, deadcode):
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return
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if nt == 'FNCALL':
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SEFargs = True
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CONSTargs = True
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for idx in xrange(len(child)-1, -1, -1):
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self.FoldTree(child, idx)
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# Function is not SEF if any argument is not SEF
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if 'SEF' not in child[idx]:
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SEFargs = False
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# Function is not a constant if any argument is not a constant
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if child[idx]['nt'] != 'CONST':
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CONSTargs = False
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if 'Fn' in self.symtab[0][node['name']]:
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if all(arg['nt'] == 'CONST' for arg in child):
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# Guaranteed to be side-effect free if the children are.
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if SEFargs:
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node['SEF'] = True
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if CONSTargs:
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# Call it
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fn = self.symtab[0][node['name']]['Fn']
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value = fn(*tuple(arg['value'] for arg in child))
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@ -438,18 +493,42 @@ class optimizer(renamer, deadcode):
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node = {'nt':'CONST', 't':'list', 'value':[]}
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node = {'nt':'!=', 't':'list', 'ch':[child[0], node]}
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parent[index] = {'nt':'()', 't':'list', 'ch':[node]}
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elif SEFargs and 'SEF' in self.symtab[0][node['name']]:
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# The function is marked as SEF in the symbol table, and the
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# arguments are all side-effect-free. The result is SEF.
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node['SEF'] = True
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return
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if nt in ('PRINT', 'EXPR'):
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if nt == 'PRINT':
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self.FoldTree(child, 0)
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# PRINT is considered to have side effects. If it's there, assume
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# there's a reason.
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return
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if nt == 'EXPR':
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self.FoldTree(child, 0)
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if 'SEF' in child[0]:
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node['SEF'] = True
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return
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if nt == 'FNDEF':
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self.FoldTree(child, 0)
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if 'SEF' in child[0]:
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node['SEF'] = True
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if node['name'] in self.symtab[0]:
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# Mark the symbol table entry if it's not an event.
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self.symtab[0][node['name']]['SEF'] = True
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return
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if nt in ('VECTOR', 'ROTATION', 'LIST'):
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isconst = True
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issef = True
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for idx in xrange(len(child)-1, -1, -1):
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self.FoldTree(child, idx)
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if child[idx]['nt'] != 'CONST':
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isconst = False
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if 'SEF' not in child[idx]:
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issef = False
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if isconst:
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value = [elem['value'] for elem in child]
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if nt == 'VECTOR':
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@ -457,6 +536,8 @@ class optimizer(renamer, deadcode):
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elif nt == 'ROTATION':
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value = lslfuncs.Quaternion([lslfuncs.ff(x) for x in value])
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parent[index] = {'nt':'CONST', 't':node['t'], 'value':value}
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if issef:
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node['SEF'] = True
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return
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if nt == 'STDEF':
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@ -464,11 +545,14 @@ class optimizer(renamer, deadcode):
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self.FoldTree(child, idx)
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return
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if nt in ('{}', 'FNDEF'):
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if nt == '{}':
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idx = 0
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issef = True
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while idx < len(child):
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self.FoldTree(child, idx)
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self.FoldStmt(child, idx)
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if 'SEF' not in child[idx]:
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issef = False
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if child[idx]['nt'] == ';' \
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or nt == '{}' and child[idx]['nt'] == '{}' and not child[idx]['ch']:
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del child[idx]
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@ -476,6 +560,8 @@ class optimizer(renamer, deadcode):
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if 'StSw' in child[idx]:
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node['StSw'] = True
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idx += 1
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if issef:
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node['SEF'] = True
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return
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if nt == 'IF':
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@ -483,7 +569,7 @@ class optimizer(renamer, deadcode):
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self.FoldCond(child, 0)
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if child[0]['nt'] == 'CONST':
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# We might be able to remove one of the branches.
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if lslfuncs.cond(child[0]['value']):
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if child[0]['value']:
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self.FoldTree(child, 1)
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# If it has a state switch, the if() must be preserved
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# (but the else branch may be removed).
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@ -494,19 +580,22 @@ class optimizer(renamer, deadcode):
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# result of optimization so they must be wrapped in an
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# IF statement). The current approach leaves unnecessary
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# IFs behind.
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if len(child) > 2:
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if len(child) == 3:
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del child[2] # Delete ELSE if present
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child[0].update({'t':'integer', 'value':-1})
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return
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else:
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self.FoldStmt(child, 1)
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parent[index] = child[1]
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elif len(child) > 2:
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return
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elif len(child) == 3:
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self.FoldTree(child, 2)
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self.FoldStmt(child, 2)
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parent[index] = child[2]
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return
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else:
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# No ELSE branch, replace the statement with an empty one.
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parent[index] = {'nt':';', 't':None}
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parent[index] = {'nt':';', 't':None, 'SEF':True}
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return
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else:
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self.FoldTree(child, 1)
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self.FoldStmt(child, 1)
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@ -517,26 +606,32 @@ class optimizer(renamer, deadcode):
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or child[2]['nt'] == '{}' and not child[2]['ch']:
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# no point in "... else ;" - remove else branch
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del child[2]
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if all('SEF' in subnode for subnode in child):
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node['SEF'] = True
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return
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if nt == 'WHILE':
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self.FoldTree(child, 0)
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self.FoldCond(child, 0)
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allSEF = 'SEF' in child[0]
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if child[0]['nt'] == 'CONST':
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# See if the whole WHILE can be eliminated.
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if lslfuncs.cond(child[0]['value']):
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if child[0]['value']:
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# Endless loop which must be kept.
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# First, replace the constant.
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child[0].update({'t':'integer', 'value':-1})
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# Recurse on the statement.
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self.FoldTree(child, 1)
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self.FoldStmt(child, 1)
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allSEF &= 'SEF' in child[1]
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else:
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# Can be removed.
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parent[index] = {'nt':';', 't':None}
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parent[index] = {'nt':';', 't':None, 'SEF':True}
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return
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else:
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self.FoldTree(child, 1)
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self.FoldStmt(child, 1)
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allSEF &= 'SEF' in child[1]
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if allSEF:
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node['SEF'] = True
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return
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if nt == 'DO':
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@ -544,12 +639,11 @@ class optimizer(renamer, deadcode):
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self.FoldStmt(child, 0)
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self.FoldTree(child, 1)
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self.FoldCond(child, 1)
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if 'SEF' in child[0] and 'SEF' in child[1]:
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node['SEF'] = True
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# See if the latest part is a constant.
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if child[1]['nt'] == 'CONST':
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if lslfuncs.cond(child[1]['value']):
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# Endless loop. Replace the constant.
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child[1].update({'t':'integer', 'value':-1})
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else:
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if not child[1]['value']:
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# Only one go. Replace with the statement(s).
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parent[index] = child[0]
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return
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@ -559,45 +653,59 @@ class optimizer(renamer, deadcode):
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assert child[2]['nt'] == 'EXPRLIST'
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self.FoldAndRemoveEmptyStmts(child[0]['ch'])
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# If there were side-effect-free elements, they're already removed.
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# So if there are remaining element, they're not SEF.
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allSEF = bool(child[0]['ch'])
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self.FoldTree(child, 1) # Condition.
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self.FoldCond(child, 1)
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if child[1]['nt'] == 'CONST':
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# FOR is delicate. It can have multiple expressions at start.
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# And if there is more than one, these expressions will need a
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# new block, which means new scope, which is dangerous.
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# They are expressions, no declarations or labels allowed, but
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# it feels creepy.
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if lslfuncs.cond(child[1]['value']):
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# Endless loop. Just replace the constant and traverse the rest.
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child[1].update({'t':'integer', 'value':-1})
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# They are expressions, no declarations or labels allowed, thus
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# no new identifiers, but it still feels uneasy.
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if child[1]['value']:
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# Endless loop. Traverse the loop and the iterator.
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self.FoldTree(child, 3)
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self.FoldStmt(child, 3)
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self.FoldAndRemoveEmptyStmts(child[2]['ch'])
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elif child[0]['ch']:
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allSEF &= bool(child[2]['ch']) and 'SEF' in child[3]
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else:
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# Convert expression list to code block.
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exprlist = []
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for expr in child[0]['ch']:
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# Fold into expression statements.
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exprlist.append({'nt':'EXPR', 't':expr['t'], 'ch':[expr]})
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# returns type None, as FOR does
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# We're in the case where there are expressions. If any
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# remain, they are not SEF (or they would have been
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# removed earlier) so don't mark this node as SEF.
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if exprlist:
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parent[index] = {'nt':'{}', 't':None, 'ch':exprlist}
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else:
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parent[index] = {'nt':';', 't':None}
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parent[index] = {'nt':';', 't':None, 'SEF': True}
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return
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else:
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self.FoldTree(child, 3)
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self.FoldStmt(child, 3)
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self.FoldAndRemoveEmptyStmts(child[2]['ch'])
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allSEF &= bool(child[2]['ch']) and 'SEF' in child[3]
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if allSEF:
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node['SEF'] = True
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return
|
||||
|
||||
if nt == 'RETURN':
|
||||
if child:
|
||||
self.FoldTree(child, 0)
|
||||
if 'SEF' in child[0]:
|
||||
node['SEF'] = True
|
||||
return
|
||||
|
||||
if nt == 'DECL':
|
||||
if child:
|
||||
# Check if child is a simple_expr. If it is, then we keep the
|
||||
# original attached to the folded node and use it in the output.
|
||||
# original attached to the folded node to use it in the output.
|
||||
if child[0].pop('Simple', False):
|
||||
orig = self.CopyNode(child[0])
|
||||
self.FoldTree(child, 0)
|
||||
|
|
@ -609,21 +717,30 @@ class optimizer(renamer, deadcode):
|
|||
and not child[0]['value']:
|
||||
del node['ch']
|
||||
child = None
|
||||
return
|
||||
else:
|
||||
# Add assignment if vector, rotation or float.
|
||||
if node['t'] in ('float', 'vector', 'rotation'):
|
||||
typ = node['t']
|
||||
node['ch'] = [{'nt':'CONST', 't':typ, 'value':
|
||||
node['ch'] = [{'nt':'CONST', 't':typ, 'SEF': True, 'value':
|
||||
0.0 if typ == 'float' else
|
||||
lslfuncs.ZERO_VECTOR if typ == 'vector' else
|
||||
lslfuncs.ZERO_ROTATION}]
|
||||
# Declarations always have side effects.
|
||||
return
|
||||
|
||||
if nt == 'STSW':
|
||||
# State switch always has side effects.
|
||||
node['StSw'] = True
|
||||
return
|
||||
|
||||
if nt in self.ignored_stmts:
|
||||
if nt == ';':
|
||||
node['SEF'] = True
|
||||
return
|
||||
|
||||
if nt in ('JUMP', '@', 'V++', 'V--', '--V', '++V'):
|
||||
# These all have side effects, as in, can't be eliminated as
|
||||
# statements.
|
||||
return
|
||||
|
||||
assert False, 'Internal error: This should not happen,' \
|
||||
|
|
@ -643,7 +760,6 @@ class optimizer(renamer, deadcode):
|
|||
"""Optimize the symbolic table symtab in place. Requires a table of
|
||||
predefined functions for folding constants.
|
||||
"""
|
||||
|
||||
if 'optimize' not in options:
|
||||
return treesymtab
|
||||
|
||||
|
|
|
|||
|
|
@ -2050,3 +2050,16 @@ class parser(object):
|
|||
|
||||
finally:
|
||||
f.close()
|
||||
|
||||
# Load the side-effect-free table as well.
|
||||
f = open('seftable.txt', 'rb')
|
||||
try:
|
||||
while True:
|
||||
line = f.readline()
|
||||
if line == '':
|
||||
break
|
||||
line = line.strip()
|
||||
if line and line[0] != '#' and line in self.functions:
|
||||
self.functions[line]['SEF'] = True
|
||||
finally:
|
||||
f.close()
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue