new VM: some progress for the FFI support

compiler/evalffi.nim

@@ -9,7 +9,7 @@
 
 ## This file implements the FFI part of the evaluator for Nimrod code.
 
-import ast, astalgo, ropes, types, options, tables, dynlib, libffi, msgs
+import ast, astalgo, ropes, types, options, tables, dynlib, libffi, msgs, os
 
 when defined(windows):
   const libcDll = "msvcrt.dll"
@@ -20,7 +20,11 @@ type
   TDllCache = tables.TTable[string, TLibHandle]
 var
   gDllCache = initTable[string, TLibHandle]()
-  gExeHandle = LoadLib()
+
+when defined(windows):
+  var gExeHandle = loadLib(os.getAppFilename())
+else:
+  var gExeHandle = loadLib()
 
 proc getDll(cache: var TDllCache; dll: string; info: TLineInfo): pointer =
   result = cache[dll]
@@ -28,10 +32,10 @@ proc getDll(cache: var TDllCache; dll: string; info: TLineInfo): pointer =
     var libs: seq[string] = @[]
     libCandidates(dll, libs)
     for c in libs:
-      result = LoadLib(c)
+      result = loadLib(c)
       if not result.isNil: break
     if result.isNil:
-      GlobalError(info, "cannot load: " & dll)
+      globalError(info, "cannot load: " & dll)
     cache[dll] = result
 
 const
@@ -50,7 +54,7 @@ proc importcSymbol*(sym: PSym): PNode =
   else:
     let lib = sym.annex
     if lib != nil and lib.path.kind notin {nkStrLit..nkTripleStrLit}:
-      GlobalError(sym.info, "dynlib needs to be a string lit for the REPL")
+      globalError(sym.info, "dynlib needs to be a string lit for the REPL")
     var theAddr: pointer
     if lib.isNil and not gExehandle.isNil:
       # first try this exe itself:
@@ -58,10 +62,12 @@ proc importcSymbol*(sym: PSym): PNode =
       # then try libc:
       if theAddr.isNil:
         let dllhandle = gDllCache.getDll(libcDll, sym.info)
-        theAddr = dllhandle.checkedSymAddr(name)
-    else:
-      let dllhandle = gDllCache.getDll(lib.path.strVal, sym.info)
-      theAddr = dllhandle.checkedSymAddr(name)
+        theAddr = dllhandle.symAddr(name)
+    elif not lib.isNil:
+      let dllhandle = gDllCache.getDll(if lib.kind == libHeader: libcDll 
+                                       else: lib.path.strVal, sym.info)
+      theAddr = dllhandle.symAddr(name)
+    if theAddr.isNil: globalError(sym.info, "cannot import: " & sym.name.s)
     result.intVal = cast[TAddress](theAddr)
 
 proc mapType(t: ast.PType): ptr libffi.TType =
@@ -139,7 +145,7 @@ proc getField(n: PNode; position: int): PSym =
       else: internalError(n.info, "getField(record case branch)")
   of nkSym:
     if n.sym.position == position: result = n.sym
-  else: nil
+  else: discard
 
 proc packObject(x: PNode, typ: PType, res: pointer) =
   InternalAssert x.kind in {nkObjConstr, nkPar}
@@ -192,7 +198,7 @@ proc pack(v: PNode, typ: PType, res: pointer) =
   of tyPointer, tyProc,  tyCString, tyString:
     if v.kind == nkNilLit:
       # nothing to do since the memory is 0 initialized anyway
-      nil
+      discard
     elif v.kind == nkPtrLit:
       awr(pointer, cast[pointer](v.intVal))
     elif v.kind in {nkStrLit..nkTripleStrLit}:
@@ -202,7 +208,7 @@ proc pack(v: PNode, typ: PType, res: pointer) =
   of tyPtr, tyRef, tyVar:
     if v.kind == nkNilLit:
       # nothing to do since the memory is 0 initialized anyway
-      nil
+      discard
     elif v.kind == nkPtrLit:
       awr(pointer, cast[pointer](v.intVal))
     else:
@@ -220,7 +226,7 @@ proc pack(v: PNode, typ: PType, res: pointer) =
   of tyObject, tyTuple:
     packObject(v, typ, res)
   of tyNil:
-    nil
+    discard
   of tyDistinct, tyGenericInst:
     pack(v, typ.sons[0], res)
   else:
@@ -241,7 +247,7 @@ proc unpackObjectAdd(x: pointer, n, result: PNode) =
     pair.sons[1] = unpack(x +! n.sym.offset, n.sym.typ, nil)
     #echo "offset: ", n.sym.name.s, " ", n.sym.offset
     result.add pair
-  else: nil
+  else: discard
 
 proc unpackObject(x: pointer, typ: PType, n: PNode): PNode =
   # compute the field's offsets:

compiler/vm.nim

@@ -632,12 +632,14 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): PNode =
         # we pass 'tos.slots' instead of 'regs' so that the compiler can keep
         # 'regs' in a register:
         when hasFFI:
+          if c.globals.sons[prc.position-1].kind == nkEmpty:
+            globalError(c.debug[pc], errGenerated, "canot run " & prc.name.s)
           let newValue = callForeignFunction(c.globals.sons[prc.position-1],
                                              prc.typ, tos.slots,
                                              rb+1, rc-1, c.debug[pc])
           if newValue.kind != nkEmpty:
             assert instr.opcode == opcIndCallAsgn
-            regs[ra] = newValue
+            asgnRef(regs[ra], newValue)
         else:
           globalError(c.debug[pc], errGenerated, "VM not built with FFI support")
       elif prc.kind != skTemplate:
@@ -796,7 +798,7 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): PNode =
       decodeB(nkBracket)
       let newLen = regs[rb].getOrdValue.int
       setLen(regs[ra].sons, newLen)
-    of opcSwap, opcCast, opcReset:
+    of opcSwap, opcReset:
       internalError(c.debug[pc], "too implement")
     of opcIsNil:
       decodeB(nkIntLit)
@@ -938,6 +940,15 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): PNode =
         stackTrace(c, tos, pc, errGenerated,
           msgKindToString(errIllegalConvFromXtoY) % [
           "unknown type" , "unknown type"])
+    of opcCast:
+      let rb = instr.regB
+      inc pc
+      let typ = c.types[c.code[pc].regBx - wordExcess]
+      when hasFFI:
+        let dest = fficast(regs[rb], typ)
+        asgnRef(regs[ra], dest)
+      else:
+        globalError(c.debug[pc], "cannot evaluate cast")
     of opcNSetIntVal:
       decodeB(nkMetaNode)
       var dest = regs[ra].uast
@@ -1074,6 +1085,8 @@ proc myOpen(module: PSym): PPassContext =
   # XXX produce a new 'globals' environment here:
   setupGlobalCtx(module)
   result = globalCtx
+  when hasFFI:
+    globalCtx.features = {allowFFI, allowCast}
 
 var oldErrorCount: int
 

compiler/vmgen.nim

@@ -945,7 +945,10 @@ proc genTypeLit(c: PCtx; t: PType; dest: var TDest) =
 proc importcSym(c: PCtx; info: TLineInfo; s: PSym) =
   when hasFFI:
     if allowFFI in c.features:
-      c.globals.add(importcSymbol(s))
+      if s.kind == skVar and lfNoDecl in s.loc.flags:
+        c.globals.add(copyNode(emptyNode))
+      else:
+        c.globals.add(importcSymbol(s))
       s.position = c.globals.len
     else:
       localError(info, errGenerated, "VM is not allowed to 'importc'")
@@ -1303,6 +1306,11 @@ proc gen(c: PCtx; n: PNode; dest: var TDest) =
   of nkCurly: genSetConstr(c, n, dest)
   of nkObjConstr: genObjConstr(c, n, dest)
   of nkPar, nkClosure: genTupleConstr(c, n, dest)
+  of nkCast:
+    if allowCast in c.features:
+      genConv(c, n, n.sons[1], dest, opcCast)
+    else:
+      localError(n.info, errGenerated, "VM is not allowed to 'cast'")
   else:
     InternalError n.info, "too implement " & $n.kind