added #903 to the test suite

compiler/vm.nim

@@ -448,7 +448,7 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
         let n = src.sons[rc]
         regs[ra].node = n
       else:
-        stackTrace(c, tos, pc, errIndexOutOfBounds)
+        stackTrace(c, tos, pc, errNilAccess)
     of opcWrObj:
       # a.b = c
       decodeBC(rkNode)
@@ -902,6 +902,10 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       let rb = instr.regBx - wordExcess - 1
       ensureKind(rkNode)
       regs[ra].node = c.globals.sons[rb]
+    of opcLdGlobalAddr:
+      let rb = instr.regBx - wordExcess - 1
+      ensureKind(rkNodeAddr)
+      regs[ra].nodeAddr = addr(c.globals.sons[rb])
     of opcRepr:
       decodeB(rkNode)
       createStr regs[ra]

compiler/vmdef.nim

@@ -126,6 +126,7 @@ type
     opcLdConst,   # dest = constants[Bx]
     opcAsgnConst, # dest = copy(constants[Bx])
     opcLdGlobal,  # dest = globals[Bx]
+    opcLdGlobalAddr, # dest = addr(globals[Bx])
 
     opcLdImmInt,  # dest = immediate value
     opcNBindSym,

compiler/vmgen.nim

@@ -1614,7 +1614,7 @@ proc genProc(c: PCtx; s: PSym): int =
     c.gABC(body, opcEof, eofInstr.regA)
     c.optimizeJumps(result)
     s.offset = c.prc.maxSlots
-    #if s.name.s == "tupleUnpack":
+    #if s.name.s == "addStuff":
     #  echo renderTree(body)
     #  c.echoCode(result)
     c.prc = oldPrc

tests/vm/tcompiletimetable.nim

@@ -12,13 +12,13 @@ import macros, tables
 var ZOOT{.compileTime.} = initTable[int, int](2)
 var iii {.compiletime.} = 1
 
-macro x:stmt=
+macro zoo:stmt=
   zoot[iii] = iii*2
   inc iii
   echo iii
 
-x
-x
+zoo
+zoo
 
 
 macro tupleUnpack: stmt =
@@ -27,3 +27,24 @@ macro tupleUnpack: stmt =
 
 tupleUnpack
 
+# bug #903
+
+import strtabs
+
+var x {.compileTime.}: PStringTable
+
+macro addStuff(stuff, body: expr): stmt {.immediate.} =
+  result = newNimNode(nnkStmtList)
+
+  if x.isNil:
+    x = newStringTable(modeStyleInsensitive)
+  x[$stuff] = ""
+
+macro dump(): stmt =
+  result = newNimNode(nnkStmtList)
+  for y in x.keys: echo "Got ", y
+
+addStuff("Hey"): echo "Hey"
+addStuff("Hi"): echo "Hi"
+dump()
+

todo.txt

@@ -154,7 +154,7 @@ Optimizations
 =============
 
 - optimize 'if' with a constant condition --> necessary in frontend for better
-  dead code elimination
+  dead code elimination; also necessary to prevent  ``if c > 0: 1 div c``
 - escape analysis for string/seq seems to be easy to do too;
   even further write barrier specialization
 - inlining of first class functions