From 6d0b5d92c2956501a37dcf32fbcf4b87beaafbf9 Mon Sep 17 00:00:00 2001
From: Max Graey <maxgraey@gmail.com>
Date: Tue, 17 Apr 2018 00:02:55 +0300
Subject: [PATCH] Minor string comparision optimizations (#77)

---
 std/assembly/string.ts                        |   9 +-
 tests/compiler/std/array-access.optimized.wat |   2 +-
 tests/compiler/std/array-access.untouched.wat |   2 +-
 tests/compiler/std/array.optimized.wat        |  23 +--
 tests/compiler/std/array.untouched.wat        |  35 ++--
 tests/compiler/std/string.optimized.wat       |  91 ++++-----
 tests/compiler/std/string.untouched.wat       | 179 +++++++++---------
 7 files changed, 172 insertions(+), 169 deletions(-)

diff --git a/std/assembly/string.ts b/std/assembly/string.ts
index e8ca36b7..3d97250d 100644
--- a/std/assembly/string.ts
+++ b/std/assembly/string.ts
@@ -111,8 +111,7 @@ export class String {
   @operator("==")
   private static __eq(left: String, right: String): bool {
     if (left === right) return true;
-    if (left === null)  return right === null;
-    if (right === null) return false;
+    if (left === null || right === null) return false;
 
     var leftLength = left.length;
     if (leftLength != right.length) return false;
@@ -150,8 +149,7 @@ export class String {
   @operator(">=")
   private static __gte(left: String, right: String): bool {
     if (left === right) return true;
-    if (left === null)  return right === null;
-    if (right === null) return false;
+    if (left === null || right === null) return false;
 
     var leftLength  = left.length;
     var rightLength = right.length;
@@ -188,8 +186,7 @@ export class String {
   @operator("<=")
   private static __lte(left: String, right: String): bool {
     if (left === right) return true;
-    if (left === null)  return right === null;
-    if (right === null) return false;
+    if (left === null || right === null) return false;
 
     var leftLength  = left.length;
     var rightLength = right.length;
diff --git a/tests/compiler/std/array-access.optimized.wat b/tests/compiler/std/array-access.optimized.wat
index 037310b6..dc63f443 100644
--- a/tests/compiler/std/array-access.optimized.wat
+++ b/tests/compiler/std/array-access.optimized.wat
@@ -140,7 +140,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 40)
-     (i32.const 234)
+     (i32.const 231)
      (i32.const 4)
     )
     (unreachable)
diff --git a/tests/compiler/std/array-access.untouched.wat b/tests/compiler/std/array-access.untouched.wat
index 211da89b..aa42c1ba 100644
--- a/tests/compiler/std/array-access.untouched.wat
+++ b/tests/compiler/std/array-access.untouched.wat
@@ -293,7 +293,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 40)
-     (i32.const 234)
+     (i32.const 231)
      (i32.const 4)
     )
     (unreachable)
diff --git a/tests/compiler/std/array.optimized.wat b/tests/compiler/std/array.optimized.wat
index 9bc411e2..aaabc73e 100644
--- a/tests/compiler/std/array.optimized.wat
+++ b/tests/compiler/std/array.optimized.wat
@@ -5320,18 +5320,19 @@
    )
   )
   (if
-   (i32.eqz
-    (get_local $0)
-   )
-   (return
-    (i32.eqz
-     (get_local $1)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eqz
+       (get_local $0)
+      )
+     )
+     (get_local $2)
+     (i32.eqz
+      (get_local $1)
+     )
     )
-   )
-  )
-  (if
-   (i32.eqz
-    (get_local $1)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
diff --git a/tests/compiler/std/array.untouched.wat b/tests/compiler/std/array.untouched.wat
index 144e0b8e..e5dfdc0f 100644
--- a/tests/compiler/std/array.untouched.wat
+++ b/tests/compiler/std/array.untouched.wat
@@ -10378,6 +10378,7 @@
  )
  (func $~lib/string/String.__eq (; 106 ;) (type $iii) (param $0 i32) (param $1 i32) (result i32)
   (local $2 i32)
+  (local $3 i32)
   (if
    (i32.eq
     (get_local $0)
@@ -10388,34 +10389,34 @@
    )
   )
   (if
-   (i32.eq
-    (get_local $0)
-    (i32.const 0)
-   )
-   (return
-    (i32.eq
-     (get_local $1)
-     (i32.const 0)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eq
+       (get_local $0)
+       (i32.const 0)
+      )
+     )
+     (get_local $2)
+     (i32.eq
+      (get_local $1)
+      (i32.const 0)
+     )
     )
-   )
-  )
-  (if
-   (i32.eq
-    (get_local $1)
-    (i32.const 0)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
    )
   )
-  (set_local $2
+  (set_local $3
    (i32.load
     (get_local $0)
    )
   )
   (if
    (i32.ne
-    (get_local $2)
+    (get_local $3)
     (i32.load
      (get_local $1)
     )
@@ -10436,7 +10437,7 @@
       (i32.const 4)
      )
      (i32.shl
-      (get_local $2)
+      (get_local $3)
       (i32.const 1)
      )
     )
diff --git a/tests/compiler/std/string.optimized.wat b/tests/compiler/std/string.optimized.wat
index a535b7d7..ad017436 100644
--- a/tests/compiler/std/string.optimized.wat
+++ b/tests/compiler/std/string.optimized.wat
@@ -161,7 +161,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 234)
+     (i32.const 231)
      (i32.const 4)
     )
     (unreachable)
@@ -381,7 +381,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 213)
+     (i32.const 210)
      (i32.const 4)
     )
     (unreachable)
@@ -1092,7 +1092,7 @@
               (call $abort
                (i32.const 0)
                (i32.const 72)
-               (i32.const 469)
+               (i32.const 466)
                (i32.const 10)
               )
               (unreachable)
@@ -3293,18 +3293,19 @@
    )
   )
   (if
-   (i32.eqz
-    (get_local $0)
-   )
-   (return
-    (i32.eqz
-     (get_local $1)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eqz
+       (get_local $0)
+      )
+     )
+     (get_local $2)
+     (i32.eqz
+      (get_local $1)
+     )
     )
-   )
-  )
-  (if
-   (i32.eqz
-    (get_local $1)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
@@ -3447,31 +3448,32 @@
    )
   )
   (if
-   (i32.eqz
-    (get_local $0)
-   )
-   (return
-    (i32.eqz
-     (get_local $1)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eqz
+       (get_local $0)
+      )
+     )
+     (get_local $2)
+     (i32.eqz
+      (get_local $1)
+     )
     )
-   )
-  )
-  (if
-   (i32.eqz
-    (get_local $1)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
    )
   )
-  (set_local $2
+  (set_local $3
    (i32.load
     (get_local $1)
    )
   )
   (if
    (i32.eqz
-    (tee_local $3
+    (tee_local $2
      (i32.load
       (get_local $0)
      )
@@ -3479,13 +3481,13 @@
    )
    (return
     (i32.eqz
-     (get_local $2)
+     (get_local $3)
     )
    )
   )
   (if
    (i32.eqz
-    (get_local $2)
+    (get_local $3)
    )
    (return
     (i32.const 1)
@@ -3503,11 +3505,11 @@
     )
     (i32.shl
      (select
-      (get_local $3)
       (get_local $2)
+      (get_local $3)
       (i32.lt_s
-       (get_local $3)
        (get_local $2)
+       (get_local $3)
       )
      )
      (i32.const 1)
@@ -3613,18 +3615,19 @@
    )
   )
   (if
-   (i32.eqz
-    (get_local $0)
-   )
-   (return
-    (i32.eqz
-     (get_local $1)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eqz
+       (get_local $0)
+      )
+     )
+     (get_local $2)
+     (i32.eqz
+      (get_local $1)
+     )
     )
-   )
-  )
-  (if
-   (i32.eqz
-    (get_local $1)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
@@ -3694,7 +3697,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 386)
+     (i32.const 383)
      (i32.const 4)
     )
     (unreachable)
@@ -3729,7 +3732,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 391)
+     (i32.const 388)
      (i32.const 6)
     )
     (unreachable)
diff --git a/tests/compiler/std/string.untouched.wat b/tests/compiler/std/string.untouched.wat
index c7133f22..d182e190 100644
--- a/tests/compiler/std/string.untouched.wat
+++ b/tests/compiler/std/string.untouched.wat
@@ -211,7 +211,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 234)
+     (i32.const 231)
      (i32.const 4)
     )
     (unreachable)
@@ -469,7 +469,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 213)
+     (i32.const 210)
      (i32.const 4)
     )
     (unreachable)
@@ -1271,7 +1271,7 @@
                  (call $abort
                   (i32.const 0)
                   (i32.const 72)
-                  (i32.const 469)
+                  (i32.const 466)
                   (i32.const 10)
                  )
                  (unreachable)
@@ -3770,6 +3770,7 @@
  )
  (func $~lib/string/String.__eq (; 22 ;) (type $iii) (param $0 i32) (param $1 i32) (result i32)
   (local $2 i32)
+  (local $3 i32)
   (if
    (i32.eq
     (get_local $0)
@@ -3780,34 +3781,34 @@
    )
   )
   (if
-   (i32.eq
-    (get_local $0)
-    (i32.const 0)
-   )
-   (return
-    (i32.eq
-     (get_local $1)
-     (i32.const 0)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eq
+       (get_local $0)
+       (i32.const 0)
+      )
+     )
+     (get_local $2)
+     (i32.eq
+      (get_local $1)
+      (i32.const 0)
+     )
     )
-   )
-  )
-  (if
-   (i32.eq
-    (get_local $1)
-    (i32.const 0)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
    )
   )
-  (set_local $2
+  (set_local $3
    (i32.load
     (get_local $0)
    )
   )
   (if
    (i32.ne
-    (get_local $2)
+    (get_local $3)
     (i32.load
      (get_local $1)
     )
@@ -3828,7 +3829,7 @@
       (i32.const 4)
      )
      (i32.shl
-      (get_local $2)
+      (get_local $3)
       (i32.const 1)
      )
     )
@@ -3960,64 +3961,64 @@
    )
   )
   (if
-   (i32.eq
-    (get_local $0)
-    (i32.const 0)
-   )
-   (return
-    (i32.eq
-     (get_local $1)
-     (i32.const 0)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eq
+       (get_local $0)
+       (i32.const 0)
+      )
+     )
+     (get_local $2)
+     (i32.eq
+      (get_local $1)
+      (i32.const 0)
+     )
     )
-   )
-  )
-  (if
-   (i32.eq
-    (get_local $1)
-    (i32.const 0)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
    )
   )
-  (set_local $2
-   (i32.load
-    (get_local $0)
-   )
-  )
   (set_local $3
    (i32.load
-    (get_local $1)
+    (get_local $0)
    )
   )
-  (if
-   (i32.eqz
-    (get_local $2)
-   )
-   (return
-    (i32.eqz
-     (get_local $3)
-    )
+  (set_local $4
+   (i32.load
+    (get_local $1)
    )
   )
   (if
    (i32.eqz
     (get_local $3)
    )
+   (return
+    (i32.eqz
+     (get_local $4)
+    )
+   )
+  )
+  (if
+   (i32.eqz
+    (get_local $4)
+   )
    (return
     (i32.const 1)
    )
   )
   (set_local $6
    (select
-    (tee_local $4
-     (get_local $2)
-    )
-    (tee_local $5
+    (tee_local $2
      (get_local $3)
     )
-    (i32.lt_s
+    (tee_local $5
      (get_local $4)
+    )
+    (i32.lt_s
+     (get_local $2)
      (get_local $5)
     )
    )
@@ -4157,64 +4158,64 @@
    )
   )
   (if
-   (i32.eq
-    (get_local $0)
-    (i32.const 0)
-   )
-   (return
-    (i32.eq
-     (get_local $1)
-     (i32.const 0)
+   (i32.and
+    (if (result i32)
+     (tee_local $2
+      (i32.eq
+       (get_local $0)
+       (i32.const 0)
+      )
+     )
+     (get_local $2)
+     (i32.eq
+      (get_local $1)
+      (i32.const 0)
+     )
     )
-   )
-  )
-  (if
-   (i32.eq
-    (get_local $1)
-    (i32.const 0)
+    (i32.const 1)
    )
    (return
     (i32.const 0)
    )
   )
-  (set_local $2
-   (i32.load
-    (get_local $0)
-   )
-  )
   (set_local $3
+   (i32.load
+    (get_local $0)
+   )
+  )
+  (set_local $4
    (i32.load
     (get_local $1)
    )
   )
+  (if
+   (i32.eqz
+    (get_local $4)
+   )
+   (return
+    (i32.eqz
+     (get_local $3)
+    )
+   )
+  )
   (if
    (i32.eqz
     (get_local $3)
    )
-   (return
-    (i32.eqz
-     (get_local $2)
-    )
-   )
-  )
-  (if
-   (i32.eqz
-    (get_local $2)
-   )
    (return
     (i32.const 1)
    )
   )
   (set_local $6
    (select
-    (tee_local $4
-     (get_local $2)
-    )
-    (tee_local $5
+    (tee_local $2
      (get_local $3)
     )
-    (i32.lt_s
+    (tee_local $5
      (get_local $4)
+    )
+    (i32.lt_s
+     (get_local $2)
      (get_local $5)
     )
    )
@@ -4256,7 +4257,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 386)
+     (i32.const 383)
      (i32.const 4)
     )
     (unreachable)
@@ -4294,7 +4295,7 @@
     (call $abort
      (i32.const 0)
      (i32.const 72)
-     (i32.const 391)
+     (i32.const 388)
      (i32.const 6)
     )
     (unreachable)