fix setglobal popping

config.nim

@@ -9,8 +9,8 @@ const debugCompiler* = false
 const debugDumpChunk* = defined(debug)
 const assertionsCompiler* = true # sanity checks in the compiler
 # vm debug options (setting any to true will slow runtime down!)
-const debugVM* = false
-const assertionsVM* = false # sanity checks in the VM, such as the stack being empty at the end
+const debugVM* = defined(debug)
+const assertionsVM* = defined(debug) # sanity checks in the VM, such as the stack being empty at the end
 const profileInstructions* = false # if true, the time spent on every opcode is measured
 
 const compileTests* = defined(debug)

tests/while.nds

@@ -0,0 +1,8 @@
+
+var i = 1;
+
+while (i < 300) {
+  i = i + 1;
+};
+
+print i;

tests/while2.nds

@@ -0,0 +1,4 @@
+var i = 5; 
+while (i > 0) 
+  print i = i - 1
+;

types/stack.nim

@@ -1,7 +1,7 @@
 import ../pointerutils
 
 # configure stacks here
-const boundsChecks = false
+const boundsChecks = defined(debug)
   # boundsChecks default: false, true has a large performance impact, and emitting correct code is on the compiler's job
   # boundsChecking is only meant for debugging
 const growthFactor = 2
@@ -74,7 +74,7 @@ proc deleteTopN*[T](stack: var Stack[T], n: Natural) =
 proc getIndex*[T](stack: Stack[T], index: int): T =
   when boundsChecks:
     if index < 0 or index >= stack.len():
-      raise newException(Defect, "Attempt to getIndex with an index out of bounds.")
+      raise newException(Defect, &"Attempt to getIndex with an index {index} which is out of bounds (len: {stack.len()}).")
   stack.start.padd(index * sizeof(T))[]
 
 proc getIndexNeg*[T](stack: Stack[T], index: int): T =

vm.nim

@@ -71,9 +71,9 @@ proc run*(chunk: Chunk): InterpretResult =
     ip = ip.padd(1)
 
     when debugVM:
-      let ii = ip.pdiff(chunk.code[0].unsafeAddr)
+      let ii = ip.pdiff(chunk.code[0].unsafeAddr) - 1
       let opname = ($ins)
-      var msg = &"[{ii:4}] {opname}"
+      var msg = &"[{ii:04}] {opname}"
       msg &= " Stack: [ "
       for i in 0 .. stack.high():
         let e = stack[i]
@@ -175,7 +175,7 @@ proc run*(chunk: Chunk): InterpretResult =
           break
       of opSetGlobal:
         let name = readConstant().asString()
-        let existed = globals.tableSet(name.fromNdString(), stack.pop())
+        let existed = globals.tableSet(name.fromNdString(), stack.peek())
         if not existed:
           runtimeError("Attempt to redefine an existing global variable.")
           break
@@ -187,11 +187,11 @@ proc run*(chunk: Chunk): InterpretResult =
         stack[slot + frameBottom] = stack.peek()
       of opJumpIfFalse:
         let offset = readDU8()
-        if stack.peek().isFalsey:
+        if stack.peek().isFalsey():
           ip = ip.padd(offset)
       of opJumpIfFalsePop:
         let offset = readDU8()
-        if stack.pop().isFalsey:
+        if stack.pop().isFalsey():
           ip = ip.padd(offset)
       of opJump:
         let offset = readDU8()