VM: allow all importc var, cast[int](ptr)

compiler/cgen.nim

@@ -694,6 +694,8 @@ proc loadDynamicLib(m: BModule, lib: PLib) =
   if lib.name == nil: internalError(m.config, "loadDynamicLib")
 
 proc mangleDynLibProc(sym: PSym): Rope =
+  if sym.loc.r != nil:
+    return sym.loc.r # should that be `rope($sym.loc.r)`? (see comment below)
   # we have to build this as a single rope in order not to trip the
   # optimization in genInfixCall
   if sfCompilerProc in sym.flags:

compiler/evalffi.nim

@@ -46,19 +46,12 @@ proc getDll(conf: ConfigRef, cache: var TDllCache; dll: string; info: TLineInfo)
 const
   nkPtrLit = nkIntLit # hopefully we can get rid of this hack soon
 
-var myerrno {.importc: "errno", header: "<errno.h>".}: cint ## error variable
-
 proc importcSymbol*(conf: ConfigRef, sym: PSym): PNode =
   let name = $sym.loc.r
   # the AST does not support untyped pointers directly, so we use an nkIntLit
   # that contains the address instead:
   result = newNodeIT(nkPtrLit, sym.info, sym.typ)
-  case name
-  of "stdin":  result.intVal = cast[ByteAddress](system.stdin)
-  of "stdout": result.intVal = cast[ByteAddress](system.stdout)
-  of "stderr": result.intVal = cast[ByteAddress](system.stderr)
-  of "vmErrnoWrapper": result.intVal = cast[ByteAddress](myerrno)
-  else:
+  when true:
     let lib = sym.annex
     if lib != nil and lib.path.kind notin {nkStrLit..nkTripleStrLit}:
       globalError(conf, sym.info, "dynlib needs to be a string lit")
@@ -74,7 +67,7 @@ proc importcSymbol*(conf: ConfigRef, sym: PSym): PNode =
       let dll = if lib.kind == libHeader: libcDll else: lib.path.strVal
       let dllhandle = getDll(conf, gDllCache, dll, sym.info)
       theAddr = dllhandle.symAddr(name)
-    if theAddr.isNil: globalError(conf, sym.info, "cannot import: " & sym.name.s)
+    if theAddr.isNil: globalError(conf, sym.info, "cannot import: " & name)
     result.intVal = cast[ByteAddress](theAddr)
 
 proc mapType(conf: ConfigRef, t: ast.PType): ptr libffi.TType =

compiler/vm.nim

@@ -140,6 +140,40 @@ template decodeBx(k: untyped) {.dirty.} =
 template move(a, b: untyped) {.dirty.} = system.shallowCopy(a, b)
 # XXX fix minor 'shallowCopy' overloading bug in compiler
 
+proc derefPtrToReg(address: BiggestInt, typ: PType, r: var TFullReg, isAssign: bool): bool =
+  # nim bug: `isAssign: static bool` doesn't work, giving odd compiler error
+  template fun(field, T, rkind) =
+    if isAssign:
+      cast[ptr T](address)[] = T(r.field)
+    else:
+      # ensureKind(rkind)
+      if r.kind != rkind:
+        myreset(r)
+        r.kind = rkind
+      let val = cast[ptr T](address)[]
+      when T is SomeInteger:
+        r.field = BiggestInt(val)
+      else:
+        r.field = val
+    return true
+
+  ## see also typeinfo.getBiggestInt
+  case typ.kind
+  of tyInt: fun(intVal, int, rkInt)
+  of tyInt8: fun(intVal, int8, rkInt)
+  of tyInt16: fun(intVal, int16, rkInt)
+  of tyInt32: fun(intVal, int32, rkInt)
+  of tyInt64: fun(intVal, int64, rkInt)
+  of tyUInt: fun(intVal, uint, rkInt)
+  of tyUInt8: fun(intVal, uint8, rkInt)
+  of tyUInt16: fun(intVal, uint16, rkInt)
+  of tyUInt32: fun(intVal, uint32, rkInt)
+  of tyUInt64: fun(intVal, uint64, rkInt) # checkme: differs from typeinfo.getBiggestInt
+  of tyFloat: fun(floatVal, float, rkFloat)
+  of tyFloat32: fun(floatVal, float32, rkFloat)
+  of tyFloat64: fun(floatVal, float64, rkFloat)
+  else: return false
+
 proc createStrKeepNode(x: var TFullReg; keepNode=true) =
   if x.node.isNil or not keepNode:
     x.node = newNode(nkStrLit)
@@ -242,6 +276,11 @@ proc writeField(n: var PNode, x: TFullReg) =
   of rkNodeAddr: n = x.nodeAddr[]
 
 proc putIntoReg(dest: var TFullReg; n: PNode) =
+  if dest.kind == rkNode and n.kind == nkIntLit:
+    # use `nkPtrLit` once this becomes a thing
+    dest.node = n
+    return
+
   case n.kind
   of nkStrLit..nkTripleStrLit:
     dest.kind = rkNode
@@ -567,6 +606,12 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       let rb = instr.regB
       ensureKind(rkFloat)
       regs[ra].floatVal = cast[float64](int64(regs[rb].intVal))
+    of opcCastPtrToInt:
+      let rb = instr.regB
+      ensureKind(rkInt)
+      if regs[rb].kind != rkNode:
+        stackTrace(c, tos, pc, "opcCastPtrToInt: regs[rb].kind: " & $regs[rb].kind)
+      regs[ra].intVal = cast[int](regs[rb].node.intVal)
     of opcAsgnComplex:
       asgnComplex(regs[ra], regs[instr.regB])
     of opcFastAsgnComplex:
@@ -651,7 +696,9 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       let src = regs[rb].node
       case src.kind
       of nkEmpty..nkNilLit:
-        stackTrace(c, tos, pc, errNilAccess)
+        # TODO: for nkPtrLit, use something like: derefPtrToReg(src.intVal + offsetof(src.typ, rc), typ_field, regs[ra], isAssign = false)
+        # where we compute the offset in bytes for field rc
+        stackTrace(c, tos, pc, errNilAccess & " " & $("kind", src.kind, "typ", typeToString(src.typ), "rc", rc))
       of nkObjConstr:
         let n = src[rc + 1].skipColon
         regs[ra].node = n
@@ -718,10 +765,21 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
         if regs[rb].node.kind == nkRefTy:
           regs[ra].node = regs[rb].node[0]
         else:
-          ensureKind(rkNode)
-          regs[ra].node = regs[rb].node
+          let node = regs[rb].node
+          let typ = node.typ
+          if node.kind == nkIntLit:
+            var typ2 = typ
+            if typ.kind == tyPtr:
+              typ2 = typ2[0]
+            if not derefPtrToReg(node.intVal, typ2, regs[ra], isAssign = false):
+              # tyObject not supported in this context
+              stackTrace(c, tos, pc, "opcLdDeref unsupported ptr type: " & $(typeToString(typ), typ.kind))
+          else:
+            ## eg: typ.kind = tyObject
+            ensureKind(rkNode)
+            regs[ra].node = regs[rb].node
       else:
-        stackTrace(c, tos, pc, errNilAccess)
+        stackTrace(c, tos, pc, errNilAccess & " kind: " & $regs[rb].kind)
     of opcWrDeref:
       # a[] = c; b unused
       let ra = instr.regA
@@ -742,8 +800,17 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       of rkNode:
         if regs[ra].node.kind == nkNilLit:
           stackTrace(c, tos, pc, errNilAccess)
-        regs[ra].node[] = regs[rc].regToNode[]
-        regs[ra].node.flags.incl nfIsRef
+        let node = regs[ra].node
+        let typ = node.typ
+        if node.kind == nkIntLit: # IMPROVE: use a flag?
+          var typ2 = typ
+          if typ.kind == tyPtr:
+            typ2 = typ2[0]
+          if not derefPtrToReg(node.intVal, typ2, regs[rc], isAssign = true):
+            stackTrace(c, tos, pc, "opcWrDeref unsupported ptr type: " & $(typeToString(typ), typ.kind))
+        else:
+          regs[ra].node[] = regs[rc].regToNode[]
+          regs[ra].node.flags.incl nfIsRef
       else: stackTrace(c, tos, pc, errNilAccess)
     of opcAddInt:
       decodeBC(rkInt)
@@ -1338,6 +1405,26 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       let rb = instr.regBx - wordExcess - 1
       ensureKind(rkNode)
       regs[ra].node = c.globals[rb]
+    of opcLdGlobalDeref:
+      let rb = instr.regBx - wordExcess - 1
+      let node = c.globals[rb]
+      let typ = node.typ
+      doAssert node.kind == nkIntLit, $(node.kind)
+      if typ.kind == tyPtr:
+        ensureKind(rkNode)
+        # checkme: nkPtrTy ? nkPtrLit?
+        regs[ra].node = newNodeIT(nkIntLit, node.info, typ)
+        regs[ra].node.intVal = cast[ptr int](node.intVal)[]
+      elif not derefPtrToReg(node.intVal, typ, regs[ra], isAssign = false):
+        stackTrace(c, tos, pc, "opcLdDeref unsupported ptr type: " & $(typeToString(typ), typ[0].kind))
+    of opcLdGlobalAddrDeref:
+      let rb = instr.regBx - wordExcess - 1
+      let node = c.globals[rb]
+      let typ = node.typ
+      var node2 = newNodeIT(nkIntLit, node.info, typ)
+      node2.intVal = node.intVal
+      ensureKind(rkNode)
+      regs[ra].node = node2
     of opcLdGlobalAddr:
       let rb = instr.regBx - wordExcess - 1
       ensureKind(rkNodeAddr)

compiler/vmdef.nim

@@ -63,6 +63,7 @@ type
     opcCastIntToFloat64,    # int and float must be of the same byte size
     opcCastFloatToInt32,    # int and float must be of the same byte size
     opcCastFloatToInt64,    # int and float must be of the same byte size
+    opcCastPtrToInt,
     opcFastAsgnComplex,
     opcNodeToReg,
 
@@ -169,6 +170,8 @@ type
     opcAsgnConst, # dest = copy(constants[Bx])
     opcLdGlobal,  # dest = globals[Bx]
     opcLdGlobalAddr, # dest = addr(globals[Bx])
+    opcLdGlobalDeref, # dest = globals[Bx][]
+    opcLdGlobalAddrDeref, # globals[Bx][] = ...
 
     opcLdImmInt,  # dest = immediate value
     opcNBindSym, opcNDynBindSym,

compiler/vmgen.nim

@@ -885,8 +885,13 @@ proc genCastIntFloat(c: PCtx; n: PNode; dest: var TDest) =
       c.gABC(n, opcCastFloatToInt64, dest, tmp)
       # narrowing for 64 bits not needed (no extended sign bits available).
     c.freeTemp(tmp)
+  elif src.kind == tyPtr and dst.kind == tyInt:
+    let tmp = c.genx(n[1])
+    if dest < 0: dest = c.getTemp(n[0].typ)
+    c.gABC(n, opcCastPtrToInt, dest, tmp)
+    c.freeTemp(tmp)
   else:
-    globalError(c.config, n.info, "VM is only allowed to 'cast' between integers and/or floats of same size")
+    globalError(c.config, n.info, "VM is only allowed to 'cast' between integers and/or floats of same size " & $(src.kind, dst.kind))
 
 proc genVoidABC(c: PCtx, n: PNode, dest: TDest, opcode: TOpcode) =
   unused(c, n, dest)
@@ -1624,17 +1629,24 @@ proc genRdVar(c: PCtx; n: PNode; dest: var TDest; flags: TGenFlags) =
   assert card(flags * {gfNodeAddr, gfNode}) < 2
   let s = n.sym
   if s.isGlobal:
-    if sfCompileTime in s.flags or c.mode == emRepl or importcCondVar(s):
+    let isImportcVar = importcCondVar(s)
+    if sfCompileTime in s.flags or c.mode == emRepl or isImportcVar:
       discard
     elif s.position == 0:
       cannotEval(c, n)
     if s.position == 0:
-      if importcCond(s) or importcCondVar(s): c.importcSym(n.info, s)
+      if importcCond(s) or isImportcVar: c.importcSym(n.info, s)
       else: genGlobalInit(c, n, s)
     if dest < 0: dest = c.getTemp(n.typ)
     assert s.typ != nil
+
     if gfNodeAddr in flags:
-      c.gABx(n, opcLdGlobalAddr, dest, s.position)
+      if isImportcVar:
+        c.gABx(n, opcLdGlobalAddrDeref, dest, s.position)
+      else:
+        c.gABx(n, opcLdGlobalAddr, dest, s.position)
+    elif isImportcVar:
+      c.gABx(n, opcLdGlobalDeref, dest, s.position)
     elif fitsRegister(s.typ) and gfNode notin flags:
       var cc = c.getTemp(n.typ)
       c.gABx(n, opcLdGlobal, cc, s.position)