threads compile again; attempt to fix serious code gen issue (except + return)

compiler/ccgstmts.nim

@@ -117,7 +117,7 @@ proc genIfStmt(p: BProc, n: PNode) =
     else: internalError(n.info, "genIfStmt()")
   if sonsLen(n) > 1: fixLabel(p, Lend)
   
-proc popSafePoints(p: BProc, howMany: int) = 
+proc blockLeaveActions(p: BProc, howMany: int) = 
   var L = p.nestedTryStmts.len
   # danger of endless recursion! we workaround this here by a temp stack
   var stack: seq[PNode]
@@ -134,10 +134,12 @@ proc popSafePoints(p: BProc, howMany: int) =
   # push old elements again:
   for i in countdown(howMany-1, 0): 
     p.nestedTryStmts.add(stack[i])
+  for i in countdown(p.popCurrExc-1, 0):
+    appcg(p, cpsStmts, "#popCurrentException();$n", [])
 
 proc genReturnStmt(p: BProc, t: PNode) = 
   p.beforeRetNeeded = true
-  popSafePoints(p, min(1, p.nestedTryStmts.len))
+  blockLeaveActions(p, min(1, p.nestedTryStmts.len))
   genLineDir(p, t)
   if (t.sons[0].kind != nkEmpty): genStmts(p, t.sons[0])
   appff(p.s[cpsStmts], "goto BeforeRet;$n", "br label %BeforeRet$n", [])
@@ -196,7 +198,7 @@ proc genBreakStmt(p: BProc, t: PNode) =
     assert(sym.loc.k == locOther)
     idx = sym.loc.a
   p.blocks[idx].id = abs(p.blocks[idx].id) # label is used
-  popSafePoints(p, p.nestedTryStmts.len - p.blocks[idx].nestedTryStmts)
+  blockLeaveActions(p, p.nestedTryStmts.len - p.blocks[idx].nestedTryStmts)
   genLineDir(p, t)
   appf(p.s[cpsStmts], "goto LA$1;$n", [toRope(p.blocks[idx].id)])
 
@@ -510,16 +512,20 @@ proc genTryStmt(p: BProc, t: PNode) =
   add(p.nestedTryStmts, t)
   genStmts(p, t.sons[0])
   appcg(p, cpsStmts, "#popSafePoint();$n} else {$n#popSafePoint();$n")
+  discard pop(p.nestedTryStmts)
   var i = 1
   while (i < length) and (t.sons[i].kind == nkExceptBranch): 
     var blen = sonsLen(t.sons[i])
     if blen == 1: 
       # general except section:
       if i > 1: appf(p.s[cpsStmts], "else {$n")
+      inc p.popCurrExc
       genStmts(p, t.sons[i].sons[0])
+      dec p.popCurrExc
       appcg(p, cpsStmts, "$1.status = 0;#popCurrentException();$n", [safePoint])
       if i > 1: appf(p.s[cpsStmts], "}$n")
     else:
+      inc p.popCurrExc
       var orExpr: PRope = nil
       for j in countup(0, blen - 2): 
         assert(t.sons[i].sons[j].kind == nkType)
@@ -530,12 +536,12 @@ proc genTryStmt(p: BProc, t: PNode) =
       if i > 1: app(p.s[cpsStmts], "else ")
       appf(p.s[cpsStmts], "if ($1) {$n", [orExpr])
       genStmts(p, t.sons[i].sons[blen-1])
+      dec p.popCurrExc
       # code to clear the exception:
       appcg(p, cpsStmts, "$1.status = 0;#popCurrentException();}$n",
            [safePoint])
     inc(i)
   appf(p.s[cpsStmts], "}$n") # end of if statement
-  discard pop(p.nestedTryStmts)
   if i < length and t.sons[i].kind == nkFinally: 
     genStmts(p, t.sons[i].sons[0])
   appcg(p, cpsStmts, "if ($1.status != 0) #reraiseException();$n", [safePoint])

compiler/cgendata.nim

@@ -60,6 +60,8 @@ type
     ThreadVarAccessed*: bool  # true if the proc already accessed some threadvar
     nestedTryStmts*: seq[PNode] # in how many nested try statements we are
                                 # (the vars must be volatile then)
+    popCurrExc*: Natural      # how often to emit 'popCurrentException()'
+                              # before 'break'|'return'
     labels*: Natural          # for generating unique labels in the C proc
     blocks*: seq[TBlock]      # nested blocks
     options*: TOptions        # options that should be used for code

lib/system/channels.nim

@@ -62,14 +62,14 @@ proc storeAux(dest, src: Pointer, n: ptr TNimNode, t: PRawChannel,
             n.typ.size)
     var m = selectBranch(src, n)
     if m != nil: storeAux(dest, src, m, t, mode)
-  of nkNone: sysAssert(false)
+  of nkNone: sysAssert(false, "storeAux")
 
 proc storeAux(dest, src: Pointer, mt: PNimType, t: PRawChannel, 
               mode: TLoadStoreMode) =
   var
     d = cast[TAddress](dest)
     s = cast[TAddress](src)
-  sysAssert(mt != nil)
+  sysAssert(mt != nil, "mt == nil")
   case mt.Kind
   of tyString:
     if mode == mStore:
@@ -100,7 +100,7 @@ proc storeAux(dest, src: Pointer, mt: PNimType, t: PRawChannel,
       else:
         unsureAsgnRef(x, nil)
     else:
-      sysAssert(dest != nil)
+      sysAssert(dest != nil, "dest == nil")
       if mode == mStore:
         x[] = Alloc(t.region, seq.len *% mt.base.size +% GenericSeqSize)
       else:

lib/system/threads.nim

@@ -221,7 +221,7 @@ when not defined(useNimRtl):
       t.prev = nil
       t.next = threadList
       if threadList != nil: 
-        sysAssert(threadList.prev == nil)
+        sysAssert(threadList.prev == nil, "threadList.prev == nil")
         threadList.prev = t
       threadList = t
       ReleaseSys(HeapLock)
@@ -315,7 +315,7 @@ proc joinThreads*[TArg](t: openArray[TThread[TArg]]) =
   ## waits for every thread in `t` to finish.
   when hostOS == "windows":
     var a: array[0..255, TSysThread]
-    sysAssert a.len >= t.len
+    sysAssert a.len >= t.len, "a.len >= t.len"
     for i in 0..t.high: a[i] = t[i].sys
     discard WaitForMultipleObjects(t.len, cast[ptr TSysThread](addr(a)), 1, -1)
   else: