Make first parameter of substitute by-name; fixes bug with SC-backend

Issue was that what was passed to `substitute` escaped to the outer
scope when using PardisIR; we need to enclose it into a block so that
does not happen…

This change is not necessarily something useful in general; it may be 
better to revert it once PardisIR is phased out (by-name params are more
expensive)

core/src/main/scala/squid/ir/BaseInterpreter.scala

@@ -201,7 +201,7 @@ class BaseInterpreter extends Base with RuntimeSymbols with TraceDebug {
   }
   def hole(name: String, typ: TypeRep): Rep = ???
   def splicedHole(name: String, typ: TypeRep): Rep = ???
-  def substitute(r: Rep,defs: scala.collection.immutable.Map[String,Rep]): Rep = ???
+  def substitute(r: => Rep,defs: scala.collection.immutable.Map[String,Rep]): Rep = ???
   def typeHole(name: String): TypeRep = ???
 
 

core/src/main/scala/squid/quasi/MetaBases.scala

@@ -168,7 +168,7 @@ trait MetaBases {
     def hole(name: String, typ: TypeRep): Rep = q"$Base.hole($name, $typ)"
     def splicedHole(name: String, typ: TypeRep): Rep = q"$Base.splicedHole($name, $typ)"
 
-    def substitute(r: Rep, defs: Map[String, Rep]): Rep =
+    def substitute(r: => Rep, defs: Map[String, Rep]): Rep =
     //if (defs isEmpty) r else  // <- This "optimization" is not welcome, as some IRs (ANF) may relie on `substitute` being called for all insertions
       q"$Base.substitute($r, ..${defs map {case (name, rep) => q"$name -> $rep"}})"
     /* 
@@ -312,7 +312,7 @@ trait MetaBases {
     def hole(name: String, typ: TypeRep): Rep = q"${TermName(name)}" // TODO ensure hygiene... (this should not clash!)
     def splicedHole(name: String, typ: TypeRep): Rep = q"${TermName(name)}: _*"
 
-    def substitute(r: Rep, defs: Map[String, Rep]): Rep = r transform {
+    def substitute(r: => Rep, defs: Map[String, Rep]): Rep = r transform {
       //case h @ q"${TermName(name)}" =>  // Weird! this does not seem to match...
       case h @ Ident(TermName(name)) =>
         defs.getOrElse(name, h)

core/src/main/scala/squid/quasi/QuasiBase.scala

@@ -26,8 +26,8 @@ self: Base =>
   // TODO impl correctly
   //def substitute(r: Rep, defs: Map[String, Rep]): Rep = substituteLazy(r, defs map (kv => kv._1 -> (() => kv._2)))
   //def substituteLazy(r: Rep, defs: Map[String, () => Rep]): Rep
-  def substitute(r: Rep, defs: Map[String, Rep]): Rep
-  def substituteLazy(r: Rep, defs: Map[String, () => Rep]): Rep = substitute(r, defs map (kv => kv._1 -> kv._2()))
+  def substitute(r: => Rep, defs: Map[String, Rep]): Rep
+  def substituteLazy(r: => Rep, defs: Map[String, () => Rep]): Rep = substitute(r, defs map (kv => kv._1 -> kv._2()))
 
   def hole(name: String, typ: TypeRep): Rep
   def splicedHole(name: String, typ: TypeRep): Rep
@@ -42,7 +42,7 @@ self: Base =>
   /* --- --- --- Provided defs --- --- --- */
 
 
-  final def substitute(r: Rep, defs: (String, Rep)*): Rep =
+  final def substitute(r: => Rep, defs: (String, Rep)*): Rep =
   /* if (defs isEmpty) r else */  // <- This "optimization" is not welcome, as some IRs (ANF) may relie on `substitute` being called for all insertions
     substitute(r, defs.toMap)
 

sc-backend/src/main/scala/squid/scback/PardisIR.scala

@@ -279,13 +279,14 @@ abstract class PardisIR(val sc: pardis.ir.Base) extends Base with squid.ir.Runti
   protected def inlineUnlessEnclosedOr(dontInline: Bool)(r: Rep) = r |>=? {
     case b: Block if !dontInline => inlineBlockIfEnclosed(b)
   }
-  override def substitute(r: Rep, defs: Map[String, Rep]): Rep = substituteLazy(r, defs.mapValues(() => _))
-  override def substituteLazy(r: Rep, defs: Map[String, () => Rep]): Rep = {
+  override def substitute(r: => Rep, defs: Map[String, Rep]): Rep = substituteLazy(r, defs.mapValues(() => _))
+  override def substituteLazy(mkR: => Rep, defs: Map[String, () => Rep]): Rep = {
+    val r = if (defs isEmpty) mkR else typedBlock(mkR |> toExpr)
     //debug(s"SUBST $r with "+(defs mapValues (f=>util.Try(typedBlock(f())))))
 
     val nameMap = curSubs collect { case k -> Hole(n,_,_) => k -> n }
 
-    if (defs isEmpty) r else bottomUp(r) {
+    val res = if (defs isEmpty) r else bottomUp(r) {
       case h @ Hole(n,_,_) => defs get n map (_()) getOrElse h
       case h @ SplicedHole(n,_) => defs get n map (_()) getOrElse h
       case s: Sym =>
@@ -294,7 +295,8 @@ abstract class PardisIR(val sc: pardis.ir.Base) extends Base with squid.ir.Runti
       case r => r
     }
 
-  } |> inlineUnlessEnclosedOr(r.isInstanceOf[PardisBlock[_]])  alsoApply (r => debug(s"SUBS RESULT = $r"))
+    res |> inlineUnlessEnclosedOr(r.isInstanceOf[PardisBlock[_]])  alsoApply (r => debug(s"SUBS RESULT = $r"))
+  }
 
   def hole(name: String, typ: TypeRep): Rep = Hole(name, typ, None)
   def splicedHole(name: String, typ: TypeRep): Rep = SplicedHole(name, typ)

src/main/scala/squid/ir/AST.scala

@@ -69,12 +69,12 @@ trait AST extends InspectableBase with ScalaTyping with ASTReinterpreter with Ru
     case r => r
   }
 
-  override def substituteLazy(r: Rep, defs: Map[String, () => Rep]): Rep = if (defs isEmpty) r else bottomUp(r) { r => dfn(r) match {
+  override def substituteLazy(r: => Rep, defs: Map[String, () => Rep]): Rep = if (defs isEmpty) r else bottomUp(r) { r => dfn(r) match {
     case h @ Hole(n) => defs get n map (_()) getOrElse r
     case h @ SplicedHole(n) => defs get n map (_()) getOrElse r
     case _ => r
   }}
-  override def substitute(r: Rep, defs: Map[String, Rep]): Rep = if (defs isEmpty) r else bottomUp(r) { r => dfn(r) match {
+  override def substitute(r: => Rep, defs: Map[String, Rep]): Rep = if (defs isEmpty) r else bottomUp(r) { r => dfn(r) match {
     case h @ Hole(n) => defs getOrElse (n, r)
     case h @ SplicedHole(n) => defs getOrElse (n, r)
     case _ => r