fix VM intsize for 32bits and smaller targetOS. (#6211)

This commit change the default behaviour of VM int/uint always being
64bits and make int/uint on VM behave identically to compiled code.

This insert 'opcNarrowU' or 'opcNarrow' opcode on Int/Uint operations
when needed to simulate smaller Int/Uint on VM.

1 files changed, 4 insertions, 3 deletions

diff --git a/compiler/vmgen.nim b/compiler/vmgen.nim
index ab969a42f..dbb8c9dcd 100644
--- a/compiler/vmgen.nim
+++ b/compiler/vmgen.nim
@@ -656,16 +656,17 @@ proc genNarrow(c: PCtx; n: PNode; dest: TDest) =
   let t = skipTypes(n.typ, abstractVar-{tyTypeDesc})
   # uint is uint64 in the VM, we we only need to mask the result for
   # other unsigned types:
-  if t.kind in {tyUInt8..tyUInt32}:
+  if t.kind in {tyUInt8..tyUInt32} or (t.kind == tyUInt and t.size < 8):
     c.gABC(n, opcNarrowU, dest, TRegister(t.size*8))
-  elif t.kind in {tyInt8..tyInt32}:
+  elif t.kind in {tyInt8..tyInt32} or (t.kind == tyInt and t.size < 8):
     c.gABC(n, opcNarrowS, dest, TRegister(t.size*8))
 
 proc genNarrowU(c: PCtx; n: PNode; dest: TDest) =
   let t = skipTypes(n.typ, abstractVar-{tyTypeDesc})
   # uint is uint64 in the VM, we we only need to mask the result for
   # other unsigned types:
-  if t.kind in {tyUInt8..tyUInt32, tyInt8..tyInt32}:
+  if t.kind in {tyUInt8..tyUInt32, tyInt8..tyInt32} or
+    (t.kind in {tyUInt, tyInt} and t.size < 8):
     c.gABC(n, opcNarrowU, dest, TRegister(t.size*8))
 
 proc genBinaryABCnarrow(c: PCtx; n: PNode; dest: var TDest; opc: TOpcode) =