correct code generation for tforstmt

1 files changed, 34 insertions, 20 deletions

diff --git a/compiler/lowerings.nim b/compiler/lowerings.nim
index 13d4bf60e..5636d423f 100644
--- a/compiler/lowerings.nim
+++ b/compiler/lowerings.nim
@@ -160,8 +160,8 @@ We generate roughly this:
 
 proc f_wrapper(args) =
   barrierEnter(args.barrier)  # for parallel statement
-  var a = args.a # copy strings/seqs; thread transfer; not generated for
-                 # the 'parallel' statement
+  var a = args.a # thread transfer; deepCopy or shallowCopy or no copy
+                 # depending on whether we're in a 'parallel' statement
   var b = args.b
 
   args.prom = nimCreatePromise(thread, sizeof(T)) # optional
@@ -199,9 +199,9 @@ proc createNimCreatePromiseCall(prom, threadParam: PNode): PNode =
 proc createWrapperProc(f: PNode; threadParam, argsParam: PSym;
                        varSection, call, barrier, prom: PNode): PSym =
   var body = newNodeI(nkStmtList, f.info)
-  body.add varSection
   if barrier != nil:
     body.add callCodeGenProc("barrierEnter", barrier)
+  body.add varSection
   if prom != nil:
     body.add createNimCreatePromiseCall(prom, threadParam.newSymNode)
     if barrier == nil:
@@ -248,6 +248,17 @@ proc createCastExpr(argsParam: PSym; objType: PType): PNode =
   result.typ = newType(tyPtr, objType.owner)
   result.typ.rawAddSon(objType)
 
+proc addLocalVar(varSection: PNode; owner: PSym; typ: PType; v: PNode): PSym =
+  result = newSym(skTemp, getIdent(genPrefix), owner, varSection.info)
+  result.typ = typ
+  incl(result.flags, sfFromGeneric)
+
+  var vpart = newNodeI(nkIdentDefs, varSection.info, 3)
+  vpart.sons[0] = newSymNode(result)
+  vpart.sons[1] = ast.emptyNode
+  vpart.sons[2] = v
+  varSection.add vpart
+
 proc setupArgsForConcurrency(n: PNode; objType: PType; scratchObj: PSym, 
                              castExpr, call, varSection, result: PNode) =
   let formals = n[0].typ.n
@@ -267,16 +278,8 @@ proc setupArgsForConcurrency(n: PNode; objType: PType; scratchObj: PSym,
     objType.addField(field)
     result.add newFastAsgnStmt(newDotExpr(scratchObj, field), n[i])
 
-    var temp = newSym(skTemp, tmpName, objType.owner, n.info)
-    temp.typ = argType
-    incl(temp.flags, sfFromGeneric)
-
-    var vpart = newNodeI(nkIdentDefs, n.info, 3)
-    vpart.sons[0] = newSymNode(temp)
-    vpart.sons[1] = ast.emptyNode
-    vpart.sons[2] = indirectAccess(castExpr, field, n.info)
-    varSection.add vpart
-    
+    let temp = addLocalVar(varSection, objType.owner, argType,
+                           indirectAccess(castExpr, field, n.info))    
     call.add(newSymNode(temp))
 
 proc getRoot*(n: PNode): PSym =
@@ -310,9 +313,11 @@ proc genHigh(n: PNode): PNode =
     result.sons[1] = n
 
 proc setupArgsForParallelism(n: PNode; objType: PType; scratchObj: PSym;
-                             castExpr, call, result: PNode) =
+                             castExpr, call, varSection, result: PNode) =
   let formals = n[0].typ.n
   let tmpName = getIdent(genPrefix)
+  # we need to copy the foreign scratch object fields into local variables
+  # for correctness: These are called 'threadLocal' here.
   for i in 1 .. <n.len:
     let n = n[i]
     let argType = skipTypes(if i < formals.len: formals[i].typ else: n.typ,
@@ -344,7 +349,9 @@ proc setupArgsForParallelism(n: PNode; objType: PType; scratchObj: PSym;
         result.add newFastAsgnStmt(newDotExpr(scratchObj, fieldA), n[2])
         result.add newFastAsgnStmt(newDotExpr(scratchObj, fieldB), n[3])
 
-        slice.sons[2] = indirectAccess(castExpr, fieldA, n.info)
+        let threadLocal = addLocalVar(varSection, objType.owner, fieldA.typ,
+                                      indirectAccess(castExpr, fieldA, n.info))
+        slice.sons[2] = threadLocal.newSymNode
       else:
         let a = genAddrOf(n)
         field.typ = a.typ
@@ -353,9 +360,12 @@ proc setupArgsForParallelism(n: PNode; objType: PType; scratchObj: PSym;
         result.add newFastAsgnStmt(newDotExpr(scratchObj, fieldB), genHigh(n))
 
         slice.sons[2] = newIntLit(0)
-        
+      # the array itself does not need to go through a thread local variable:
       slice.sons[1] = genDeref(indirectAccess(castExpr, field, n.info))
-      slice.sons[3] = indirectAccess(castExpr, fieldB, n.info)
+
+      let threadLocal = addLocalVar(varSection, objType.owner, fieldB.typ,
+                                    indirectAccess(castExpr, fieldB, n.info))
+      slice.sons[3] = threadLocal.newSymNode
       call.add slice
     elif (let size = computeSize(argType); size < 0 or size > 16) and
         n.getRoot != nil:
@@ -364,13 +374,17 @@ proc setupArgsForParallelism(n: PNode; objType: PType; scratchObj: PSym;
       field.typ = a.typ
       objType.addField(field)
       result.add newFastAsgnStmt(newDotExpr(scratchObj, field), a)
-      call.add(genDeref(indirectAccess(castExpr, field, n.info)))
+      let threadLocal = addLocalVar(varSection, objType.owner, field.typ,
+                                    indirectAccess(castExpr, field, n.info))
+      call.add(genDeref(threadLocal.newSymNode))
     else:
       # boring case
       field.typ = argType
       objType.addField(field)
       result.add newFastAsgnStmt(newDotExpr(scratchObj, field), n)
-      call.add(indirectAccess(castExpr, field, n.info))
+      let threadLocal = addLocalVar(varSection, objType.owner, field.typ,
+                                    indirectAccess(castExpr, field, n.info))
+      call.add(threadLocal.newSymNode)
 
 proc wrapProcForSpawn*(owner: PSym; n: PNode; retType: PType; 
                        barrier, dest: PNode = nil): PNode =
@@ -438,7 +452,7 @@ proc wrapProcForSpawn*(owner: PSym; n: PNode; retType: PType;
   if barrier.isNil:
     setupArgsForConcurrency(n, objType, scratchObj, castExpr, call, varSection, result)
   else: 
-    setupArgsForParallelism(n, objType, scratchObj, castExpr, call, result)
+    setupArgsForParallelism(n, objType, scratchObj, castExpr, call, varSection, result)
 
   var barrierAsExpr: PNode = nil
   if barrier != nil: