optimize /MODF U/MOD; test division optimization

fold.fs

@@ -202,3 +202,20 @@ optimizes fpick
 ' opt-modf optimizes umod
 \ does not optimize MIN-N UMOD; add another optimizer if you want that.
 
+: opt-/modf ( xt -- )
+    lits# 1 = if
+	lits> dup 0> over pow2? and if
+	    dup 1- ]] dup literal and [[ ctz ]] swap literal arshift [[
+	    drop exit then
+	>lits then
+    fold2-2 ;
+' opt-/modf optimizes /modf
+
+: opt-u/mod ( xt -- )
+    lits# 1 = if
+	lits> dup pow2? if
+	    dup 1- ]] dup literal and [[ ctz ]] swap literal rshift [[
+	    drop exit then
+	>lits then
+    fold2-2 ;
+' opt-u/mod optimizes u/mod

peeprules.vmg

@@ -60,6 +60,9 @@ super33 = noop flit
 super34 = lit+ @
 super35 = f@ f*
 super36 = f@ f+
+super37 = lit and
+super38 = lit arshift
+super39 = dup lit and swap
 
 \ compare-and-branch; comment them out if we take up work on gforth-native again
 cb1 = 0< ?branch

test/gforth.fs

@@ -409,3 +409,12 @@ t{  2 5 -7 */mod  -> -4 -2 }t
 t{ -2 5 -7 */mod  -> -3  1 }t
 
 t{ -2 15 -1 u*/mod -> -16 14 }t
+
+\ optimization of division words
+
+t{ :noname -21 4 /f    ; execute -> -6 }t
+t{ :noname -21 4 modf  ; execute ->  3 }t
+t{ :noname -21 4 /modf ; execute ->  3 -6 }t
+t{ :noname  25 4 u/    ; execute ->  6 }t
+t{ :noname  25 4 umod  ; execute ->  1 }t
+t{ :noname  25 4 u/mod ; execute ->  1 6 }t