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Remove redundant assignments with nested ifs (closes #842)

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Ryan Gonzalez 2015-08-25 11:45:20 -05:00
parent 456f33eb7c
commit 21bbab4e09
1 changed files with 21 additions and 6 deletions
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27
hy/compiler.py
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@ -375,6 +375,7 @@ class HyASTCompiler(object):
self.anon_var_count = 0 self.anon_var_count = 0
self.imports = defaultdict(set) self.imports = defaultdict(set)
self.module_name = module_name self.module_name = module_name
self.temp_if = None
if not module_name.startswith("hy.core"): if not module_name.startswith("hy.core"):
# everything in core needs to be explicit. # everything in core needs to be explicit.
load_stdlib() load_stdlib()
@ -1004,8 +1005,16 @@ class HyASTCompiler(object):
body = self.compile(expression.pop(0)) body = self.compile(expression.pop(0))
orel = Result() orel = Result()
nested = root = False
if expression: if expression:
orel = self.compile(expression.pop(0)) orel_expr = expression.pop(0)
if isinstance(orel_expr, HyExpression) and isinstance(orel_expr[0],
HySymbol) and orel_expr[0] == 'if':
# Nested ifs: don't waste temporaries
root = self.temp_if is None
nested = True
self.temp_if = self.temp_if or self.get_anon_var()
orel = self.compile(orel_expr)
# We want to hoist the statements from the condition # We want to hoist the statements from the condition
ret = cond ret = cond
@ -1013,7 +1022,7 @@ class HyASTCompiler(object):
if body.stmts or orel.stmts: if body.stmts or orel.stmts:
# We have statements in our bodies # We have statements in our bodies
# Get a temporary variable for the result storage # Get a temporary variable for the result storage
var = self.get_anon_var() var = self.temp_if or self.get_anon_var()
name = ast.Name(id=ast_str(var), arg=ast_str(var), name = ast.Name(id=ast_str(var), arg=ast_str(var),
ctx=ast.Store(), ctx=ast.Store(),
lineno=expression.start_line, lineno=expression.start_line,
@ -1026,10 +1035,12 @@ class HyASTCompiler(object):
col_offset=expression.start_column) col_offset=expression.start_column)
# and of the else clause # and of the else clause
orel += ast.Assign(targets=[name], if not nested or not orel.stmts or (not root and
value=orel.force_expr, var != self.temp_if):
lineno=expression.start_line, orel += ast.Assign(targets=[name],
col_offset=expression.start_column) value=orel.force_expr,
lineno=expression.start_line,
col_offset=expression.start_column)
# Then build the if # Then build the if
ret += ast.If(test=ret.force_expr, ret += ast.If(test=ret.force_expr,
@ -1052,6 +1063,10 @@ class HyASTCompiler(object):
orelse=orel.force_expr, orelse=orel.force_expr,
lineno=expression.start_line, lineno=expression.start_line,
col_offset=expression.start_column) col_offset=expression.start_column)
if root:
self.temp_if = None
return ret return ret
@builds("break") @builds("break")