Optimized blitting between strings and bigstrings

runtime/wasm/bigarray.wat

@@ -69,6 +69,14 @@
    (import "bindings" "ta_subarray"
       (func $ta_subarray
          (param (ref extern)) (param i32) (param i32) (result (ref extern))))
+   (import "bindings" "ta_blit_from_string"
+      (func $ta_blit_from_string
+         (param (ref $string)) (param i32) (param (ref extern)) (param i32)
+         (param i32)))
+   (import "bindings" "ta_blit_to_string"
+      (func $ta_blit_to_string
+         (param (ref extern)) (param i32) (param (ref $string)) (param i32)
+         (param i32)))
    (import "fail" "caml_bound_error" (func $caml_bound_error))
    (import "fail" "caml_raise_out_of_memory" (func $caml_raise_out_of_memory))
    (import "fail" "caml_invalid_argument"
@@ -2016,42 +2024,32 @@
    (func $caml_string_of_array (export "caml_string_of_array")
       (param (ref eq)) (result (ref eq))
       ;; used to convert a typed array to a string
-      (local $a (ref extern)) (local $len i32) (local $i i32)
+      (local $a (ref extern)) (local $len i32)
       (local $s (ref $string))
       (local.set $a
          (ref.as_non_null (extern.convert_any (call $unwrap (local.get 0)))))
       (local.set $len (call $ta_length (local.get $a)))
       (local.set $s (array.new $string (i32.const 0) (local.get $len)))
-      (loop $loop
-         (if (i32.lt_u (local.get $i) (local.get $len))
-            (then
-               (array.set $string (local.get $s) (local.get $i)
-                  (call $ta_get_ui8 (local.get $a) (local.get $i)))
-               (local.set $i (i32.add (local.get $i) (i32.const 1)))
-               (br $loop))))
+      (call $ta_blit_to_string
+         (local.get $a) (i32.const 0) (local.get $s) (i32.const 0)
+         (local.get $len))
       (local.get $s))
 
    (export "caml_uint8_array_of_bytes" (func $caml_uint8_array_of_string))
    (func $caml_uint8_array_of_string (export "caml_uint8_array_of_string")
       (param (ref eq)) (result (ref eq))
       ;; Convert a string to a typed array
-      (local $ta (ref extern)) (local $len i32) (local $i i32)
+      (local $ta (ref extern)) (local $len i32)
       (local $s (ref $string))
       (local.set $s (ref.cast (ref $string) (local.get 0)))
       (local.set $len (array.len (local.get $s)))
       (local.set $ta
          (call $ta_create
             (i32.const 3) ;; Uint8Array
             (local.get $len)))
-      (loop $loop
-         (if (i32.lt_u (local.get $i) (local.get $len))
-            (then
-               (call $ta_set_ui8
-                  (local.get $ta)
-                  (local.get $i)
-                  (ref.i31 (array.get $string (local.get $s) (local.get $i))))
-               (local.set $i (i32.add (local.get $i) (i32.const 1)))
-               (br $loop))))
+      (call $ta_blit_from_string
+         (local.get $s) (i32.const 0) (local.get $ta) (i32.const 0)
+         (local.get $len))
       (call $wrap (any.convert_extern (local.get $ta))))
 
    (func (export "caml_ba_get_kind") (param (ref eq)) (result i32)
@@ -2082,4 +2080,16 @@
          (local.get $num_dims)
          (local.get $kind)
          (local.get $layout)))
+
+   (func (export "string_set")
+      (param $s externref) (param $i i32) (param $v i32)
+      (array.set $string
+         (ref.cast (ref null $string) (any.convert_extern (local.get $s)))
+         (local.get $i) (local.get $v)))
+
+   (func (export "string_get")
+      (param $s externref) (param $i i32) (result i32)
+      (array.get $string
+         (ref.cast (ref null $string) (any.convert_extern (local.get $s)))
+         (local.get $i)))
 )

runtime/wasm/bigstring.wat

@@ -48,6 +48,14 @@
       (func $ta_length (param (ref extern)) (result i32)))
    (import "bindings" "ta_bytes"
       (func $ta_bytes (param anyref) (result anyref)))
+   (import "bindings" "ta_blit_from_string"
+      (func $ta_blit_from_string
+         (param (ref $string)) (param i32) (param (ref extern)) (param i32)
+         (param i32)))
+   (import "bindings" "ta_blit_to_string"
+      (func $ta_blit_to_string
+         (param (ref extern)) (param i32) (param (ref $string)) (param i32)
+         (param i32)))
    (import "hash" "caml_hash_mix_int"
       (func $caml_hash_mix_int (param i32) (param i32) (result i32)))
 
@@ -202,47 +210,36 @@
       (param $str1 (ref eq)) (param $vpos1 (ref eq))
       (param $ba2 (ref eq)) (param $vpos2 (ref eq))
       (param $vlen (ref eq)) (result (ref eq))
-      (local $i i32) (local $pos1 i32) (local $pos2 i32) (local $len i32)
+      (local $pos1 i32) (local $pos2 i32) (local $len i32)
       (local $s1 (ref $string))
       (local $d2 (ref extern))
       (local.set $s1 (ref.cast (ref $string) (local.get $str1)))
       (local.set $pos1 (i31.get_s (ref.cast (ref i31) (local.get $vpos1))))
       (local.set $d2 (call $caml_ba_get_data (local.get $ba2)))
       (local.set $pos2 (i31.get_s (ref.cast (ref i31) (local.get $vpos2))))
       (local.set $len (i31.get_s (ref.cast (ref i31) (local.get $vlen))))
-      (loop $loop
-         (if (i32.lt_u (local.get $i) (local.get $len))
-            (then
-               (call $ta_set_ui8 (local.get $d2)
-                  (i32.add (local.get $pos2) (local.get $i))
-                  (ref.i31
-                     (array.get_u $string (local.get $s1)
-                        (i32.add (local.get $pos1) (local.get $i)))))
-               (local.set $i (i32.add (local.get $i) (i32.const 1)))
-               (br $loop))))
+      (call $ta_blit_from_string
+         (local.get $s1) (local.get $pos1)
+         (local.get $d2) (local.get $pos2)
+         (local.get $len))
       (ref.i31 (i32.const 0)))
 
    (func (export "caml_bigstring_blit_ba_to_bytes")
       (param $ba1 (ref eq)) (param $vpos1 (ref eq))
       (param $str2 (ref eq)) (param $vpos2 (ref eq))
       (param $vlen (ref eq)) (result (ref eq))
-      (local $i i32) (local $pos1 i32) (local $pos2 i32) (local $len i32)
+      (local $pos1 i32) (local $pos2 i32) (local $len i32)
       (local $d1 (ref extern))
       (local $s2 (ref $string))
       (local.set $d1 (call $caml_ba_get_data (local.get $ba1)))
       (local.set $pos1 (i31.get_s (ref.cast (ref i31) (local.get $vpos1))))
       (local.set $s2 (ref.cast (ref $string) (local.get $str2)))
       (local.set $pos2 (i31.get_s (ref.cast (ref i31) (local.get $vpos2))))
       (local.set $len (i31.get_s (ref.cast (ref i31) (local.get $vlen))))
-      (loop $loop
-         (if (i32.lt_u (local.get $i) (local.get $len))
-            (then
-               (array.set $string (local.get $s2)
-                  (i32.add (local.get $pos2) (local.get $i))
-                  (call $ta_get_ui8 (local.get $d1)
-                     (i32.add (local.get $pos1) (local.get $i))))
-               (local.set $i (i32.add (local.get $i) (i32.const 1)))
-               (br $loop))))
+      (call $ta_blit_to_string
+         (local.get $d1) (local.get $pos1)
+         (local.get $s2) (local.get $pos2)
+         (local.get $len))
       (ref.i31 (i32.const 0)))
 
    (func (export "caml_bigstring_blit_ba_to_ba")

runtime/wasm/deps.json

@@ -1,7 +1,7 @@
 [
   {
     "name": "root",
-    "reaches": ["init", "exn", "mem", "strings"],
+    "reaches": ["init", "exn", "mem", "strings", "string_get", "string_set"],
     "root": true
   },
   {
@@ -20,6 +20,14 @@
     "name": "strings",
     "export": "caml_extract_string"
   },
+  {
+    "name": "string_get",
+    "export": "string_get"
+  },
+  {
+    "name": "string_set",
+    "export": "string_set"
+  },
   {
     "name": "callback",
     "export": "caml_callback"

runtime/wasm/io.wat

@@ -56,6 +56,14 @@
       (func $ta_set_ui8 (param (ref extern)) (param i32) (param i32))) ;; ZZZ ??
    (import "bindings" "ta_get_ui8"
       (func $ta_get_ui8 (param (ref extern)) (param i32) (result i32)))
+   (import "bindings" "ta_blit_from_string"
+      (func $ta_blit_from_string
+         (param (ref $string)) (param i32) (param (ref extern)) (param i32)
+         (param i32)))
+   (import "bindings" "ta_blit_to_string"
+      (func $ta_blit_to_string
+         (param (ref extern)) (param i32) (param (ref $string)) (param i32)
+         (param i32)))
    (import "custom" "custom_compare_id"
       (func $custom_compare_id
         (param (ref eq)) (param (ref eq)) (param i32) (result i32)))
@@ -330,20 +338,6 @@
          (i64.add (local.get $offset) (i64.extend_i32_u (local.get $n))))
       (local.get $n))
 
-   (func $copy_from_buffer
-      (param $buf (ref extern)) (param $curr i32)
-      (param $s (ref $string)) (param $pos i32) (param $len i32)
-      (local $i i32)
-      (loop $loop
-        (if (i32.lt_u (local.get $i) (local.get $len))
-           (then
-              (array.set $string (local.get $s)
-                 (i32.add (local.get $pos) (local.get $i))
-                 (call $ta_get_ui8 (local.get $buf)
-                    (i32.add (local.get $curr) (local.get $i))))
-              (local.set $i (i32.add (local.get $i) (i32.const 1)))
-              (br $loop)))))
-
    (func $caml_refill (param $ch (ref $channel)) (result i32)
       (local $n i32)
       (local $buf (ref extern))
@@ -374,7 +368,7 @@
          (then
             (if (i32.gt_u (local.get $len) (local.get $avail))
                (then (local.set $len (local.get $avail))))
-            (call $copy_from_buffer
+            (call $ta_blit_to_string
                (struct.get $channel $buffer (local.get $ch))
                (struct.get $channel $curr (local.get $ch))
                (local.get $s) (local.get $pos)
@@ -389,7 +383,7 @@
       (struct.set $channel $max (local.get $ch) (local.get $nread))
       (if (i32.gt_u (local.get $len) (local.get $nread))
          (then (local.set $len (local.get $nread))))
-      (call $copy_from_buffer
+      (call $ta_blit_to_string
          (struct.get $channel $buffer (local.get $ch))
          (i32.const 0)
          (local.get $s) (local.get $pos)
@@ -445,7 +439,7 @@
                   (local.set $curr (i32.const 0))
                   (if (i32.gt_u (local.get $len) (local.get $nread))
                      (then (local.set $len (local.get $nread))))))))
-      (call $copy_from_buffer
+      (call $ta_blit_to_string
          (local.get $buf) (local.get $curr)
          (local.get $s) (local.get $pos) (local.get $len))
       (struct.set $channel $curr (local.get $ch)
@@ -730,23 +724,17 @@
    (func $caml_putblock
       (param $ch (ref $channel)) (param $s (ref $string)) (param $pos i32)
       (param $len i32) (result i32)
-      (local $free i32) (local $curr i32) (local $i i32)
+      (local $free i32) (local $curr i32)
       (local $buf (ref extern))
       (local.set $curr (struct.get $channel $curr (local.get $ch)))
       (local.set $free
          (i32.sub (struct.get $channel $size (local.get $ch)) (local.get $curr)))
       (if (i32.ge_u (local.get $len) (local.get $free))
          (then (local.set $len (local.get $free))))
       (local.set $buf (struct.get $channel $buffer (local.get $ch)))
-      (loop $loop
-         (if (i32.lt_u (local.get $i) (local.get $len))
-            (then
-               (call $ta_set_ui8 (local.get $buf)
-                  (i32.add (local.get $curr) (local.get $i))
-                  (array.get_u $string (local.get $s)
-                     (i32.add (local.get $pos) (local.get $i))))
-               (local.set $i (i32.add (local.get $i) (i32.const 1)))
-               (br $loop))))
+      (call $ta_blit_from_string
+         (local.get $s) (local.get $pos)
+         (local.get $buf) (local.get $curr) (local.get $len))
       (struct.set $channel $curr (local.get $ch)
          (i32.add (local.get $curr) (local.get $len)))
       (if (i32.ge_u (local.get $len) (local.get $free))

runtime/wasm/runtime.js

@@ -222,6 +222,12 @@
     ta_copy: (ta, t, s, n) => ta.copyWithin(t, s, n),
     ta_bytes: (a) =>
       new Uint8Array(a.buffer, a.byteOffset, a.length * a.BYTES_PER_ELEMENT),
+    ta_blit_from_string: (s, p1, a, p2, l) => {
+      for (let i = 0; i < l; i++) a[p2 + i] = string_get(s, p1 + i);
+    },
+    ta_blit_to_string: (a, p1, s, p2, l) => {
+      for (let i = 0; i < l; i++) string_set(s, p2 + i, a[p1 + i]);
+    },
     wrap_callback: (f) =>
       function () {
         var n = arguments.length;
@@ -537,6 +543,8 @@
     caml_handle_uncaught_exception,
     caml_buffer,
     caml_extract_string,
+    string_get,
+    string_set,
     _initialize,
   } = wasmModule.instance.exports;