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#
#
# The Nim Compiler
# (c) Copyright 2013 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
# This include implements the high level optimization pass.
proc hlo(c: PContext, n: PNode): PNode
proc evalPattern(c: PContext, n, orig: PNode): PNode =
internalAssert n.kind == nkCall and n.sons[0].kind == nkSym
# we need to ensure that the resulting AST is semchecked. However, it's
# aweful to semcheck before macro invocation, so we don't and treat
# templates and macros as immediate in this context.
var rule: string
if optHints in gOptions and hintPattern in gNotes:
rule = renderTree(n, {renderNoComments})
let s = n.sons[0].sym
case s.kind
of skMacro:
result = semMacroExpr(c, n, orig, s)
of skTemplate:
result = semTemplateExpr(c, n, s, {efFromHlo})
else:
result = semDirectOp(c, n, {})
if optHints in gOptions and hintPattern in gNotes:
message(orig.info, hintPattern, rule & " --> '" &
renderTree(result, {renderNoComments}) & "'")
proc applyPatterns(c: PContext, n: PNode): PNode =
result = n
# we apply the last pattern first, so that pattern overriding is possible;
# however the resulting AST would better not trigger the old rule then
# anymore ;-)
for i in countdown(<c.patterns.len, 0):
let pattern = c.patterns[i]
if not isNil(pattern):
let x = applyRule(c, pattern, result)
if not isNil(x):
assert x.kind in {nkStmtList, nkCall}
# better be safe than sorry, so check evalTemplateCounter too:
inc(evalTemplateCounter)
if evalTemplateCounter > 100:
globalError(n.info, errTemplateInstantiationTooNested)
# deactivate this pattern:
c.patterns[i] = nil
if x.kind == nkStmtList:
assert x.len == 3
x.sons[1] = evalPattern(c, x.sons[1], result)
result = flattenStmts(x)
else:
result = evalPattern(c, x, result)
dec(evalTemplateCounter)
# activate this pattern again:
c.patterns[i] = pattern
proc hlo(c: PContext, n: PNode): PNode =
inc(c.hloLoopDetector)
# simply stop and do not perform any further transformations:
if c.hloLoopDetector > 300: return n
case n.kind
of nkMacroDef, nkTemplateDef, procDefs:
# already processed (special cases in semstmts.nim)
result = n
else:
if n.kind in {nkFastAsgn, nkAsgn, nkIdentDefs, nkVarTuple} and
n.sons[0].kind == nkSym and
{sfGlobal, sfPure} * n.sons[0].sym.flags == {sfGlobal, sfPure}:
# do not optimize 'var g {.global} = re(...)' again!
return n
result = applyPatterns(c, n)
if result == n:
# no optimization applied, try subtrees:
for i in 0 .. < safeLen(result):
let a = result.sons[i]
let h = hlo(c, a)
if h != a: result.sons[i] = h
else:
# perform type checking, so that the replacement still fits:
if isEmptyType(n.typ) and isEmptyType(result.typ):
discard
else:
result = fitNode(c, n.typ, result)
# optimization has been applied so check again:
result = commonOptimizations(c.module, result)
result = hlo(c, result)
result = commonOptimizations(c.module, result)
proc hloBody(c: PContext, n: PNode): PNode =
# fast exit:
if c.patterns.len == 0 or optPatterns notin gOptions: return n
c.hloLoopDetector = 0
result = hlo(c, n)
proc hloStmt(c: PContext, n: PNode): PNode =
# fast exit:
if c.patterns.len == 0 or optPatterns notin gOptions: return n
c.hloLoopDetector = 0
result = hlo(c, n)
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