Merge pull request #1972 from skyfex/vm_opcLdConst

Test and fix for VM issue

compiler/vm.nim

@@ -984,6 +984,7 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       let rb = instr.regBx - wordExcess
       let cnst = c.constants.sons[rb]
       if fitsRegister(cnst.typ):
+        myreset(regs[ra])
         putIntoReg(regs[ra], cnst)
       else:
         ensureKind(rkNode)

tests/vm/tldconst.nim

@@ -0,0 +1,14 @@
+# Passes if it compiles
+# From issue #1946
+
+type
+  Part = object
+    index: int ## array index of argument to be accessed
+
+proc foobar(): int =
+    var x: Part
+    if x.index < high(int):
+        discard
+    0
+
+const x = foobar()