spirv: Implement IsInf using an integer comparison

Since we already do fabs on the one source, we're guaranteed to get
positive infinity if we get any infinity at all.  Since +inf only has
one IEEE 754 representation, we can use an integer comparison and avoid
all of the ordered/unordered issues.

Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: Elie Tournier <elie.tournier@collabora.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>

src/compiler/spirv/vtn_alu.c

@@ -447,7 +447,7 @@ vtn_handle_alu(struct vtn_builder *b, SpvOp opcode,
       break;
 
    case SpvOpIsInf:
-      val->ssa->def = nir_feq(&b->nb, nir_fabs(&b->nb, src[0]),
+      val->ssa->def = nir_ieq(&b->nb, nir_fabs(&b->nb, src[0]),
                                       nir_imm_float(&b->nb, INFINITY));
       break;