From 13b57dbc2f686ba9beb410ad9fef848926de38c5 Mon Sep 17 00:00:00 2001 From: Adam Strzelecki Date: Tue, 2 Jun 2015 21:29:28 +0200 Subject: [PATCH] Introduce {.noRewrite.} expr pragma disabling TR Term rewriting macros/templates are currently greedy and they will rewrite as long as there is a match. So there was no way to ensure some rewrite happens only once, eg. when rewriting term to same term plus extra content. With new macro we can actually prevent further rewriting on marked expr or stmts, eg. with given example echo(...) will be rewritten just once: template pwnEcho{echo(x)}(x: expr) = {.noRewrite.}: echo("pwned!") echo "ab" --- compiler/ast.nim | 1 + compiler/patterns.nim | 4 +++- compiler/pragmas.nim | 4 +++- compiler/semstmts.nim | 2 ++ compiler/wordrecg.nim | 4 ++-- 5 files changed, 11 insertions(+), 4 deletions(-) diff --git a/compiler/ast.nim b/compiler/ast.nim index 64cb1b1bc4..52ba935650 100644 --- a/compiler/ast.nim +++ b/compiler/ast.nim @@ -423,6 +423,7 @@ type # but unfortunately it has measurable impact for compilation # efficiency nfTransf, # node has been transformed + nfNoRewrite # node should not be transformed anymore nfSem # node has been checked for semantics nfLL # node has gone through lambda lifting nfDotField # the call can use a dot operator diff --git a/compiler/patterns.nim b/compiler/patterns.nim index 368b0b37be..3f8b05940c 100644 --- a/compiler/patterns.nim +++ b/compiler/patterns.nim @@ -130,7 +130,9 @@ proc matchNested(c: PPatternContext, p, n: PNode, rpn: bool): bool = proc matches(c: PPatternContext, p, n: PNode): bool = # hidden conversions (?) - if isPatternParam(c, p): + if nfNoRewrite in n.flags: + result = false + elif isPatternParam(c, p): result = bindOrCheck(c, p.sym, n) elif n.kind == nkSym and p.kind == nkIdent: result = p.ident.id == n.sym.name.id diff --git a/compiler/pragmas.nim b/compiler/pragmas.nim index c048d78e9e..6f37fe756b 100644 --- a/compiler/pragmas.nim +++ b/compiler/pragmas.nim @@ -37,7 +37,7 @@ const wImportc, wExportc, wNodecl, wMagic, wDeprecated, wBorrow, wExtern, wImportCpp, wImportObjC, wError, wDiscardable, wGensym, wInject, wRaises, wTags, wLocks, wGcSafe} - exprPragmas* = {wLine, wLocks} + exprPragmas* = {wLine, wLocks, wNoRewrite} stmtPragmas* = {wChecks, wObjChecks, wFieldChecks, wRangechecks, wBoundchecks, wOverflowchecks, wNilchecks, wAssertions, wWarnings, wHints, wLinedir, wStacktrace, wLinetrace, wOptimization, wHint, wWarning, wError, @@ -859,6 +859,8 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: int, c.module.flags.incl sfExperimental else: localError(it.info, "'experimental' pragma only valid as toplevel statement") + of wNoRewrite: + noVal(it) else: invalidPragma(it) else: invalidPragma(it) else: processNote(c, it) diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim index c355a5bf11..43cdca8669 100644 --- a/compiler/semstmts.nim +++ b/compiler/semstmts.nim @@ -1268,6 +1268,8 @@ proc semPragmaBlock(c: PContext, n: PNode): PNode = of wLocks: result = n result.typ = n.sons[1].typ + of wNoRewrite: + incl(result.flags, nfNoRewrite) else: discard proc semStaticStmt(c: PContext, n: PNode): PNode = diff --git a/compiler/wordrecg.nim b/compiler/wordrecg.nim index 63fd995c46..deb12536f8 100644 --- a/compiler/wordrecg.nim +++ b/compiler/wordrecg.nim @@ -55,7 +55,7 @@ type wFloatchecks, wNanChecks, wInfChecks, wAssertions, wPatterns, wWarnings, wHints, wOptimization, wRaises, wWrites, wReads, wSize, wEffects, wTags, - wDeadCodeElim, wSafecode, wNoForward, + wDeadCodeElim, wSafecode, wNoForward, wNoRewrite, wPragma, wCompileTime, wNoInit, wPassc, wPassl, wBorrow, wDiscardable, @@ -139,7 +139,7 @@ const "assertions", "patterns", "warnings", "hints", "optimization", "raises", "writes", "reads", "size", "effects", "tags", - "deadcodeelim", "safecode", "noforward", + "deadcodeelim", "safecode", "noforward", "norewrite", "pragma", "compiletime", "noinit", "passc", "passl", "borrow", "discardable", "fieldchecks",