support methods with the VM backend

compiler/vm/vmbackend.nim

@@ -22,7 +22,8 @@ import
     lineinfos
   ],
   compiler/backend/[
-    backends
+    backends,
+    cgmeth
   ],
   compiler/front/[
     msgs,
@@ -357,14 +358,12 @@ proc generateCode*(g: ModuleGraph, mlist: sink ModuleList) =
     for s in m.structs.threadvars.items:
       declareGlobal(s)
 
+  generateMethodDispatchers(g)
+
   # generate code for all alive routines
   generateAliveProcs(c, mlist)
   reset(c.linkState.newProcs) # free the occupied memory already
 
-  # XXX: generation of method dispatchers would go here. Note that `method`
-  #      support will require adjustments to DCE handling
-  #generateMethods(c)
-
   # create procs from the global initializer code fragments
   for m in mlist.modules.mitems:
     template frag: untyped = m.initGlobalsCode

compiler/vm/vmgen.nim

@@ -186,6 +186,11 @@ proc genRegLoad(c: var TCtx, n: PNode, dest, src: TRegister)
 template isUnset(x: TDest): bool = x < 0
 
 
+proc realType(s: PSym): PType {.inline.} =
+  ## Returns the signature type of the routine `s`
+  if s.kind == skMacro: s.internal
+  else:                 s.typ
+
 func underlyingLoc(n: PNode): PSym =
   ## Computes and returns the symbol of the complete location (i.e., a location
   ## not part of a compound location) that l-value expression `n` names. If no
@@ -942,7 +947,7 @@ proc writeBackResult(c: var TCtx, info: PNode) =
   ## If the result value fits into a register but is not stored in one
   ## (because it has its address taken, etc.), emits the code for storing it
   ## back into a register. `info` is only used to provide line information.
-  if resultPos < c.prc.sym.ast.len:
+  if not isEmptyType(c.prc.sym.realType[0]):
     let
       res = c.prc.sym.ast[resultPos]
       typ = res.typ
@@ -3011,7 +3016,9 @@ proc gen(c: var TCtx; n: PNode; dest: var TDest) =
       let s = n[0].sym
       if s.magic != mNone:
         genMagic(c, n, dest, s.magic)
-      elif s.kind == skMethod:
+      elif s.kind == skMethod and c.mode != emStandalone:
+        # XXX: detect and reject this earlier -- it's not a code
+        #      generation error
         fail(n.info, vmGenDiagCannotCallMethod, sym = s)
       else:
         genCall(c, n, dest)
@@ -3180,20 +3187,15 @@ proc genExpr*(c: var TCtx; n: PNode): Result[TRegister, VmGenDiag] =
 
   result = typeof(result).ok(TRegister(d))
 
-proc realType(s: PSym): PType {.inline.} =
-  ## Returns the signature type of the routine `s`
-  if s.kind == skMacro: s.internal
-  else:                 s.typ
 
 proc genParams(prc: PProc; s: PSym) =
   let
     params = s.realType.n
-    res = if resultPos < s.ast.len: s.ast[resultPos] else: nil
 
   setLen(prc.regInfo, max(params.len, 1))
 
-  if res != nil:
-    prc.locals[res.sym.id] = 0
+  if not isEmptyType(s.realType[0]):
+    prc.locals[s.ast[resultPos].sym.id] = 0
     prc.regInfo[0] = RegInfo(refCount: 1, kind: slotFixedVar)
 
   for i in 1..<params.len:

lib/system.nim

@@ -2242,6 +2242,9 @@ when not defined(js):
   # Error: system module needs: nimGCvisit
   {.pop.} # stackTrace: off, profiler: off
 
+proc chckNilDisp(p: pointer) {.compilerproc.} =
+  if p.isNil:
+    sysFatal(NilAccessDefect, "cannot dispatch; dispatcher is nil")
 
 
 when notJSnotNims:

lib/system/chcks.nim

@@ -115,10 +115,6 @@ proc chckNil(p: pointer) =
   if p == nil:
     sysFatal(NilAccessDefect, "attempt to write to a nil address")
 
-proc chckNilDisp(p: pointer) {.compilerproc.} =
-  if p == nil:
-    sysFatal(NilAccessDefect, "cannot dispatch; dispatcher is nil")
-
 when defined(nimV2):
   proc raiseObjectCaseTransition() {.compilerproc.} =
     sysFatal(FieldDefect, "assignment to discriminant changes object branch")

lib/system/jssys.nim

@@ -528,10 +528,6 @@ when not defined(nimNoZeroExtendMagic):
 proc nimMin(a, b: int): int {.compilerproc.} = return if a <= b: a else: b
 proc nimMax(a, b: int): int {.compilerproc.} = return if a >= b: a else: b
 
-proc chckNilDisp(p: pointer) {.compilerproc.} =
-  if p == nil:
-    sysFatal(NilAccessDefect, "cannot dispatch; dispatcher is nil")
-
 include "system/hti"
 
 proc isFatPointer(ti: PNimType): bool =

tests/lang_callable/generics/tobjecttyperel.nim

@@ -9,7 +9,9 @@ cool
 test'''
 """
 
-# disabled on VM until it supports methods (knownIssue)
+# knownIssue: fails for the VM target because ``astgen`` emits the
+#             incorrect conversion operator for ``ref`` types involving
+#             generics
 
 # bug #5241
 type

tests/lang_callable/method/tgeneric_methods.nim

@@ -1,12 +1,9 @@
 discard """
-  target: !vm
   output: '''wow2
 X 1
 X 3'''
 """
 
-# disabled on VM until we support methods (knownIssue)
-
 type
   First[T] = ref object of RootObj
     value: T

tests/lang_callable/method/tmethod_issues.nim

@@ -1,12 +1,10 @@
 discard """
-  target: "!vm"
   output: '''
 wof!
 wof!
 '''
 """
 
-# disabled on VM until we support methods (knownIssue)
 
 
 # bug #1659

tests/lang_callable/method/tmethod_various.nim

@@ -1,13 +1,10 @@
 discard """
-  target: "!vm"
   output: '''
 do nothing
 HELLO WORLD!
 '''
 """
 
-# disabled on VM until we support methods (knownIssue)
-
 
 # tmethods1
 method somethin(obj: RootObj) {.base.} =

tests/lang_callable/method/tmultim.nim

@@ -13,8 +13,8 @@ do nothing
 '''
 """
 
-# disabled on VM until we support methods (knownIssue)
-
+# knownIssue: the ``of`` operator only considers the static type when using
+#             the VM backend
 
 # tmultim2
 type

tests/lang_callable/method/tnildispatcher.nim

@@ -1,11 +1,9 @@
 discard """
-  target: "!vm !js"
+  target: "!js"
   outputsub: '''Error: unhandled exception: cannot dispatch; dispatcher is nil [NilAccessDefect]'''
   exitcode: 1
 """
 
-# disabled on VM until we support methods (knownIssue)
-
 # disabled on JS because sem/codegen lets it through and we get a runtime NPE
 
 # bug #5599

tests/lang_callable/method/treturn_var_t.nim

@@ -1,11 +1,8 @@
 discard """
-  target: "!vm"
   output: '''Inh
 45'''
 """
 
-# disabled on VM until we support methods (knownIssue)
-
 type
   Base = ref object of RootObj
     field: int

tests/lang_callable/method/tsingle_methods.nim

@@ -1,6 +1,5 @@
 discard """
   matrix: "--multimethods:off"
-  target: "!vm"
   output: '''base
 base
 base
@@ -10,8 +9,6 @@ base
 '''
 """
 
-# disabled on VM until we support methods (knownIssue)
-
 # bug #10912
 
 type