lower x^literal as x^Val{literal} for small integer literals (closes #…

…20527)

base/intfuncs.jl

@@ -195,6 +195,11 @@ end
 ^(x::Number, p::Integer)  = power_by_squaring(x,p)
 ^(x, p::Integer)          = power_by_squaring(x,p)
 
+# x^p for small literal p is lowered to x^Val{p},
+# to enable compile-time optimizations specialized to p.
+# However, we still need a fallback that calls the general ^:
+^{p}(x, ::Type{Val{p}}) = x^p
+
 # b^p mod m
 
 """

src/ast.c

@@ -245,12 +245,26 @@ value_t fl_julia_scalar(fl_context_t *fl_ctx, value_t *args, uint32_t nargs)
     return fl_ctx->F;
 }
 
+value_t fl_julia_smallnum(fl_context_t *fl_ctx, value_t *args, uint32_t nargs)
+{
+    argcount(fl_ctx, "julia-smallnum?", nargs, 1);
+    if (isfixnum(args[0]) && numval(args[0]) < 32 && numval(args[0]) > -32)
+        return fl_ctx->T;
+    else if (iscvalue(args[0]) && fl_ctx->jl_sym == cv_type((cvalue_t*)ptr(args[0]))) {
+        jl_value_t *v = *(jl_value_t**)cptr(args[0]);
+        if (jl_is_long(v) && jl_unbox_long(v) < 32 && jl_unbox_long(v) > -32)
+            return fl_ctx->T;
+    }
+    return fl_ctx->F;
+}
+
 static const builtinspec_t julia_flisp_ast_ext[] = {
     { "defined-julia-global", fl_defined_julia_global },
     { "invoke-julia-macro", fl_invoke_julia_macro },
     { "current-julia-module", fl_current_julia_module },
     { "current-julia-module-counter", fl_current_module_counter },
     { "julia-scalar?", fl_julia_scalar },
+    { "julia-smallnum?", fl_julia_smallnum },
     { NULL, NULL }
 };
 

src/julia-syntax.scm

@@ -2050,6 +2050,10 @@
                     (expand-forms
                      `(call (core _apply) ,f ,@(tuple-wrap argl '())))))
 
+                 ((and (eq? f '^) (length= e 4) (julia-smallnum? (cadddr e)))
+                  (expand-forms
+                   `(call ^ ,(caddr e) (call (core apply_type) (top Val) ,(cadddr e)))))
+
                  ((and (eq? f '*) (length= e 4))
                   (expand-transposed-op
                    e