AriasCreations/LSL-PyOptimizer
3
0
Fork 0
mirror of https://github.com/Sei-Lisa/LSL-PyOptimizer synced 2025-07-01 15:48:21 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Get rid of DoesSomething() in favour of SEF

Browse source 
The missing bit was to mark labels are SEF when they are not referenced. Label references are now counted at parse time, enabling us to do this.

Also, make FoldStmt clearer when the node is an expression.
This commit is contained in:
Sei Lisa 2018-05-17 08:12:33 +02:00
parent a93ea0ca19
commit 285c7172fd
3 changed files with 71 additions and 55 deletions
Download patch file Download diff file Expand all files Collapse all files

43
lslopt/lslfoldconst.py
View file

@ -107,25 +107,6 @@ class foldconst(object):
else:
idx += 1
def DoesSomething(self, node, labels = False):
"""Tell if a subtree does something or is just empty statements
(a pure combination of ';' and '{}'). Labels are the top level are
considered to do something if labels is True, and vice versa.
Not to be confused with lslparse.does_something which always includes
labels, and applies to a block's statement list, not to a node.
"""
maybe_label = ';' if labels else '@'
if maybe_label != node.nt != ';' and not node.SEF:
if node.nt == '{}':
for subnode in node.ch:
# Labels embedded in {} are not reachable. They do nothing.
if self.DoesSomething(subnode):
return True
else:
return True
return False
def CompareTrees(self, node1, node2):
"""Try to compare two subtrees to see if they are equivalent."""
# They MUST be SEF and stable.
@ -186,8 +167,6 @@ class foldconst(object):
def FoldStmt(self, parent, index):
"""Simplify a statement."""
node = parent[index]
if node.nt == 'EXPR':
node = node.ch[0]
# If the statement is side-effect-free, remove it as it does nothing.
if node.SEF:
# When a statement is side-effect free, it does nothing except
@ -205,6 +184,8 @@ class foldconst(object):
# Other unary and binary operators are side effect-free.
parent[index] = nr(nt=';', t=None, SEF=True)
return
if node.nt == 'EXPR':
node = node.ch[0]
# Post-increments take more space than pre-increments.
if node.nt in ('V++', 'V--'):
node.nt = '++V' if node.nt == 'V++' else '--V';
@ -1525,14 +1506,15 @@ class foldconst(object):
self.CurEvent = node.name
self.FoldTree(child, 0)
# Test if the event is empty and SEF, and remove it if so.
if (not hasattr(node, 'scope') and not self.DoesSomething(child[0])
# Test if the event is SEF and does nothing, and remove it if so.
if (not hasattr(node, 'scope') and child[0].SEF
and 'SEF' in self.events[node.name]
):
# Delete ourselves.
del parent[index]
return
# Delete trailing bare RETURNs.
# TODO: This works, but analysis of code paths is DCR's thing
# and this is incomplete, e.g. x(){{return;}} is not detected.
while child[0].ch:
@ -1621,7 +1603,7 @@ class foldconst(object):
self.FoldTree(child, 2)
self.FoldStmt(child, 2)
# Check if it makes sense to swap if and else branches
if (self.DoesSomething(child[2])):
if not child[2].SEF:
# Check if we can gain something by negating the
# expression.
# Swap 'if' and 'else' branch when the condition has
@ -1637,10 +1619,10 @@ class foldconst(object):
child[0].nt = '^'
child[1], child[2] = child[2], child[1]
# Re-test just in case we swapped in the previous check.
if not self.DoesSomething(child[2]):
if child[2].SEF:
# no point in "... else ;" - remove else branch
del child[2]
if not self.DoesSomething(child[1]):
if child[1].SEF:
# if (X) ; -> X;
if len(child) == 2:
parent[index] = nr(nt='EXPR', t=child[0].t,
@ -1676,7 +1658,7 @@ class foldconst(object):
# out anyway. Otherwise we just don't know if it may be infinite,
# even if every component is SEF.
if self.DoesSomething(child[1]):
if not child[1].SEF:
self.ExpandCondition(child, 0)
self.FoldTree(child, 0)
@ -1822,7 +1804,12 @@ class foldconst(object):
node.SEF = True
return
if nt in ('JUMP', '@', 'V++', 'V--', '--V', '++V', 'LAMBDA'):
if nt == '@':
# SEF if there are no JUMPs jumping to it
node.SEF = not self.symtab[node.scope][node.name]['ref']
return
if nt in ('JUMP', 'V++', 'V--', '--V', '++V', 'LAMBDA'):
# Except LAMBDA, these all have side effects, as in, can't be
# eliminated as statements.
# LAMBDA can't be eliminated without scrolling Loc's.