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https://github.com/Sei-Lisa/LSL-PyOptimizer
synced 2025-07-23 04:59:34 -07:00
Implement optimization of a>=const -> a>const-1 and similar, and fix cases where | -> & or a<0 -> a&0x80000000 is counter-productive.
The logic becomes quite convoluted.
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Sei Lisa
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274b563390
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a19d49d193
1 changed files with 106 additions and 22 deletions
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@ -95,7 +95,7 @@ class foldconst(object):
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return False
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def FoldCond(self, parent, index):
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def FoldCond(self, parent, index, ParentIsNegation = False):
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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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@ -156,28 +156,84 @@ class foldconst(object):
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child[b]['value'] = -1
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return
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if child[0]['nt'] == child[1]['nt'] == '!':
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# Both operands are negated.
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# Check if the operands are a negation ('!') or can be inverted
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# without adding more than 1 byte and are boolean.
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# We only support '<' and some cases of '&' (are there more?)
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Invertible0 = child[0]['nt'] == '!'
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Invertible1 = child[1]['nt'] == '!'
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if child[0]['nt'] == '<' \
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and child[0]['ch'][0]['t'] == child[0]['ch'][1]['t'] == 'integer':
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if child[0]['ch'][0]['nt'] == 'CONST' \
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and child[0]['ch'][0]['value'] != 2147483647 \
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or child[0]['ch'][1]['nt'] == 'CONST' \
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and child[0]['ch'][1]['value'] != int(-2147483648):
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Invertible0 = True
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if child[1]['nt'] == '<' \
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and child[1]['ch'][0]['t'] == child[1]['ch'][1]['t'] == 'integer':
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if child[1]['ch'][0]['nt'] == 'CONST' \
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and child[1]['ch'][0]['value'] != 2147483647 \
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or child[1]['ch'][1]['nt'] == 'CONST' \
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and child[1]['ch'][1]['value'] != int(-2147483648):
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Invertible1 = True
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# Deal with our optimization of a<0 -> a&0x80000000 (see below)
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if child[0]['nt'] == '&' and (
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child[0]['ch'][0]['nt'] == 'CONST' and child[0]['ch'][0]['value'] == int(-2147483648)
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or child[0]['ch'][1]['nt'] == 'CONST' and child[0]['ch'][1]['value'] == int(-2147483648)
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):
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Invertible0 |= ParentIsNegation
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if child[1]['nt'] == '&' and (
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child[1]['ch'][0]['nt'] == 'CONST' and child[1]['ch'][0]['value'] == int(-2147483648)
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or child[1]['ch'][1]['nt'] == 'CONST' and child[1]['ch'][1]['value'] == int(-2147483648)
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):
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Invertible1 |= ParentIsNegation
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if (Invertible0 or Invertible1) and ParentIsNegation:
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# !(!a|b) -> a&-!b or better
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if not Invertible0:
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child[0] = {'nt':'!', 't':'integer',
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'ch':[{'nt':'!', 't':'integer', 'ch':[child[0]]}]
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}
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Invertible0 = True
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if not Invertible1:
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child[1] = {'nt':'!', 't':'integer',
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'ch':[{'nt':'!', 't':'integer', 'ch':[child[1]]}]
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}
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Invertible1 = True
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if Invertible0 and Invertible1:
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# Both operands are negated, or negable.
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# Make them a negation if they aren't already.
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for a in (0, 1):
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if child[a]['nt'] == '<':
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if child[a]['ch'][0]['nt'] == 'CONST':
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child[a]['ch'][0]['value'] += 1
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else:
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child[a]['ch'][1]['value'] -= 1
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child[a]['ch'][0], child[a]['ch'][1] = \
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child[a]['ch'][1], child[a]['ch'][0]
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child[a] = {'nt':'!','t':'integer','ch':[child[a]]}
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elif child[a]['nt'] == '&':
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child[a] = {'nt':'!', 't':'integer',
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'ch':[{'nt':'!', 't':'integer', 'ch':[child[a]]}]
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}
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self.FoldTree(child[a]['ch'], 0)
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# If they are boolean, the expression can be turned into
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# !(a&b) which hopefully will have a ! uptree if it came
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# from a '&&' and cancel out (if not, we still remove one
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# ! so it's good). If one is bool, another transformation
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# can be performed: !nonbool|!bool -> !(nonbool&-bool)
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# which is still a gain.
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# Deal with operands in any order
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a, b = 0, 1
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# Put the bool in child[b]['ch'][0].
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if not self.IsBool(child[b]['ch'][0]):
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a, b = 1, 0
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if self.IsBool(child[b]['ch'][0]):
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if not self.IsBool(child[a]['ch'][0]):
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# HACK: Wrap in a a dummy node so that the code
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# below can extract it properly, without swapping
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# left and right hand sides (purely for aesthetic
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# reasons).
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child[b] = {'ch':[
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{'nt':'NEG', 't':'integer',
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child[b]['ch'][0] = {'nt':'NEG','t':'integer',
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'ch':[child[b]['ch'][0]]}
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]}
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node = parent[index] = {'nt':'!', 't':'integer',
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'ch':[{'nt':'&','t':'integer',
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@ -191,10 +247,14 @@ class foldconst(object):
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return
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# This optimization turns out to be counter-productive for some
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# common cases, e.g. it turns i >= 0 into !(i & 0x80000000)
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# instead of the more optimal (integer)-1 < i. So we revert it
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# where appropriate (in FoldTree, case '!', and above, case '|').
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if nt == '<':
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if child[1]['nt'] == 'CONST' and child[1]['value'] == 0:
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nt = node['nt'] = '&'
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child[1]['value'] = -2147483648
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child[1]['value'] = int(-2147483648)
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# Fall through to check & 0x80000000
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if nt == '&':
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@ -204,14 +264,13 @@ class foldconst(object):
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# Put constant in child[b], if present
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if child[b]['nt'] != 'CONST':
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a, b = 1, 0
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if child[b]['nt'] == 'CONST' and child[b]['value'] == -2147483648 \
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if child[b]['nt'] == 'CONST' and child[b]['value'] == int(-2147483648) \
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and child[a]['nt'] == 'FNCALL':
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sym = self.symtab[0][child[a]['name']]
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if 'min' in sym and sym['min'] == -1:
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node = parent[index] = {'nt':'~', 't':'integer',
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'ch':[child[a]]}
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if 'SEF' in child[a]:
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node['SEF'] = True
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self.FoldTree(parent, index)
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return
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def CopyNode(self, node):
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@ -287,16 +346,43 @@ class foldconst(object):
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if nt == '!':
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self.FoldTree(child, 0)
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self.FoldCond(child, 0)
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self.FoldCond(child, 0, True)
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# !! does *not* cancel out (unless in cond), but !!! can be simplified to !
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subexpr = child[0]
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snt = subexpr['nt']
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if 'SEF' in subexpr:
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node['SEF'] = True
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if subexpr['nt'] == 'CONST':
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node = parent[index] = subexpr
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node['value'] = int(not node['value'])
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# TODO: !(const < i) -> i < const+1, !(i < const) -> const-1 < i
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# (if no overflow)
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return
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if snt == '<':
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lop = subexpr['ch'][0]
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rop = subexpr['ch'][1]
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if lop['nt'] == 'CONST' and lop['t'] == rop['t'] == 'integer' \
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and lop['value'] < 2147483647:
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lop['value'] += 1
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subexpr['ch'][0], subexpr['ch'][1] = subexpr['ch'][1], subexpr['ch'][0]
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parent[index] = subexpr # remove !
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return
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if rop['nt'] == 'CONST' and lop['t'] == rop['t'] == 'integer' \
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and rop['value'] > int(-2147483648):
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rop['value'] -= 1
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subexpr['ch'][0], subexpr['ch'][1] = subexpr['ch'][1], subexpr['ch'][0]
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parent[index] = subexpr # remove !
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return
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if snt == '&':
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a, b = 0, 1
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if subexpr['ch'][b]['nt'] != 'CONST':
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a, b = 1, 0
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if subexpr['ch'][b]['nt'] == 'CONST' and subexpr['ch'][b]['value'] == int(-2147483648):
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# !(i & 0x80000000) -> -1 < i (because one of our
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# optimizations can be counter-productive, see FoldCond)
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subexpr['nt'] = '<'
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subexpr['ch'][b]['value'] = -1
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subexpr['ch'] = [subexpr['ch'][b], subexpr['ch'][a]]
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parent[index] = subexpr
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return
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return
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if nt == '~':
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@ -635,7 +721,7 @@ class foldconst(object):
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or child[b]['t'] != 'float'
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):
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# Expression is of the form (-float)*const or (-float)/const or const/(-float)
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if val != -2147483648 or child[a]['t'] == 'integer': # can't be optimized otherwise
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if val != int(-2147483648) or child[a]['t'] == 'integer': # can't be optimized otherwise
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child[a] = child[a]['ch'][0] # remove NEG
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child[b]['value'] = val = -val
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@ -680,11 +766,9 @@ class foldconst(object):
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# as !(a>b) etc. so we transform them here in order to reduce
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# the number of cases to check.
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# a<=b --> !(a>b); a>=b --> !(a<b); a!=b --> !(a==b)
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SEF = 'SEF' in node
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node['nt'] = {'<=':'>', '>=':'<', '!=':'=='}[nt]
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node = parent[index] = {'nt':'!', 't':node['t'], 'ch':[node]}
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if SEF:
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node['SEF'] = True
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self.FoldTree(parent, index)
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# Fall through to optimize as '<' or '>' or '=='
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if nt == '>':
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@ -698,7 +782,7 @@ class foldconst(object):
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# Convert 2147483647<i and i<-2147483648 to i&0
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if child[0]['t'] == child[1]['t'] == 'integer' \
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and (child[0]['nt'] == 'CONST' and child[0]['value'] == 2147483647
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or child[1]['nt'] == 'CONST' and child[1]['value'] == -2147483648):
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or child[1]['nt'] == 'CONST' and child[1]['value'] == int(-2147483648)):
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a, b = 0, 1
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# Put the constant in child[b]
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if child[a]['nt'] == 'CONST':
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