fix #16469 vm float constants: do not conflate -0.0 and 0.0 (#16470)

* fix #16469 vm float constants: do not conflate -0.0 and 0.0

* fix test for 32bit

compiler/vmgen.nim

@@ -453,7 +453,12 @@ proc sameConstant*(a, b: PNode): bool =
     of nkSym: result = a.sym == b.sym
     of nkIdent: result = a.ident.id == b.ident.id
     of nkCharLit..nkUInt64Lit: result = a.intVal == b.intVal
-    of nkFloatLit..nkFloat64Lit: result = a.floatVal == b.floatVal
+    of nkFloatLit..nkFloat64Lit:
+      result = cast[uint64](a.floatVal) == cast[uint64](b.floatVal)
+      # refs bug #16469
+      # if we wanted to only distinguish 0.0 vs -0.0:
+      # if a.floatVal == 0.0: result = cast[uint64](a.floatVal) == cast[uint64](b.floatVal)
+      # else: result = a.floatVal == b.floatVal
     of nkStrLit..nkTripleStrLit: result = a.strVal == b.strVal
     of nkType, nkNilLit: result = a.typ == b.typ
     of nkEmpty: result = true

tests/float/tfloatnan.nim

@@ -15,7 +15,7 @@ echo "Nim: ", f32, " (float)"
 let f64: float64 = NaN
 echo "Nim: ", f64, " (double)"
 
-block: # issue #10305
+block: # bug #10305
   # with `-O3 -ffast-math`, generated C/C++ code is not nan compliant
   # user can pass `--passC:-ffast-math` if he doesn't care.
   proc fun() =
@@ -42,3 +42,16 @@ block: # issue #10305
   fun()
   fun2(0)
 
+template main() =
+  # xxx move all tests under here
+  block: # bug #16469
+    let a1 = 0.0
+    let a2 = -0.0
+    let a3 = 1.0 / a1
+    let a4 = 1.0 / a2
+    doAssert a3 == Inf
+    doAssert a4 == -Inf
+    doAssert $(a1, a2, a3, a4) == "(0.0, -0.0, inf, -inf)"
+
+static: main()
+main()