Avoid unneeded tree duplicate/reset in default getter, case class synth

retronym · retronym · commit d89ab8398d1a · 2018-04-26T08:06:56.000+08:00
More of the same as scala#5875 The change to default getters reduced tree churn by 6x in a real world project.
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -1437,7 +1437,7 @@ trait Namers extends MethodSynthesis {
      * flag.
      */
     private def addDefaultGetters(meth: Symbol, ddef: DefDef, vparamss: List[List[ValDef]], tparams: List[TypeDef], overridden: Symbol) {
-      val DefDef(_, _, rtparams0, rvparamss0, _, _) = resetAttrs(ddef.duplicate)
+      val DefDef(_, _, rtparams0, rvparamss0, _, _) = resetAttrs(deriveDefDef(ddef)(_ => EmptyTree).duplicate)
       // having defs here is important to make sure that there's no sneaky tree sharing
       // in methods with multiple default parameters
       def rtparams = rtparams0.map(_.duplicate)
@@ -1523,7 +1523,7 @@ trait Namers extends MethodSynthesis {
                     return // fix #3649 (prevent crash in erroneous source code)
                 }
               }
-              val ClassDef(_, _, rtparams, _) = resetAttrs(cdef.duplicate)
+              val ClassDef(_, _, rtparams, _) = resetAttrs(deriveClassDef(cdef)(_ => Template(Nil, noSelfType, Nil)).duplicate)
               defTparams = rtparams.map(rt => copyTypeDef(rt)(mods = rt.mods &~ (COVARIANT | CONTRAVARIANT)))
               nmr
             }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Unapplies.scala b/src/compiler/scala/tools/nsc/typechecker/Unapplies.scala
@@ -60,7 +60,8 @@ trait Unapplies extends ast.TreeDSL {
   }
 
   private def constrTparamsInvariant(cdef: ClassDef): List[TypeDef] = {
-    val ClassDef(_, _, tparams, _) = resetAttrs(cdef.duplicate)
+    val prunedClassDef = deriveClassDef(cdef)(tmpl => deriveTemplate(tmpl)(_ => Nil))
+    val ClassDef(_, _, tparams, _) = resetAttrs(prunedClassDef.duplicate)
     val tparamsInvariant = tparams.map(tparam => copyTypeDef(tparam)(mods = tparam.mods &~ (COVARIANT | CONTRAVARIANT)))
     tparamsInvariant
   }

Original file line number	Diff line number	Diff line change
`@@ -1437,7 +1437,7 @@ trait Namers extends MethodSynthesis {`
`1437`	`1437`	`* flag.`
`1438`	`1438`	`*/`
`1439`	`1439`	`private def addDefaultGetters(meth: Symbol, ddef: DefDef, vparamss: List[List[ValDef]], tparams: List[TypeDef], overridden: Symbol) {`
`1440`		`- val DefDef(_, _, rtparams0, rvparamss0, _, _) = resetAttrs(ddef.duplicate)`
	`1440`	`+ val DefDef(_, _, rtparams0, rvparamss0, _, _) = resetAttrs(deriveDefDef(ddef)(_ => EmptyTree).duplicate)`
`1441`	`1441`	`// having defs here is important to make sure that there's no sneaky tree sharing`
`1442`	`1442`	`// in methods with multiple default parameters`
`1443`	`1443`	`def rtparams = rtparams0.map(_.duplicate)`
`@@ -1523,7 +1523,7 @@ trait Namers extends MethodSynthesis {`
`1523`	`1523`	`return // fix #3649 (prevent crash in erroneous source code)`
`1524`	`1524`	`}`
`1525`	`1525`	`}`
`1526`		`- val ClassDef(_, _, rtparams, _) = resetAttrs(cdef.duplicate)`
	`1526`	`+ val ClassDef(_, _, rtparams, _) = resetAttrs(deriveClassDef(cdef)(_ => Template(Nil, noSelfType, Nil)).duplicate)`
`1527`	`1527`	`defTparams = rtparams.map(rt => copyTypeDef(rt)(mods = rt.mods &~ (COVARIANT \| CONTRAVARIANT)))`
`1528`	`1528`	`nmr`
`1529`	`1529`	`}`
Original file line number	Diff line number	Diff line change
`@@ -60,7 +60,8 @@ trait Unapplies extends ast.TreeDSL {`
`60`	`60`	`}`
`61`	`61`
`62`	`62`	`private def constrTparamsInvariant(cdef: ClassDef): List[TypeDef] = {`
`63`		`- val ClassDef(_, _, tparams, _) = resetAttrs(cdef.duplicate)`
	`63`	`+ val prunedClassDef = deriveClassDef(cdef)(tmpl => deriveTemplate(tmpl)(_ => Nil))`
	`64`	`+ val ClassDef(_, _, tparams, _) = resetAttrs(prunedClassDef.duplicate)`
`64`	`65`	`val tparamsInvariant = tparams.map(tparam => copyTypeDef(tparam)(mods = tparam.mods &~ (COVARIANT \| CONTRAVARIANT)))`
`65`	`66`	`tparamsInvariant`
`66`	`67`	`}`