optimize if(const)

12 files changed, 96 insertions, 167 deletions

diff --git a/src/passes/Vacuum.cpp b/src/passes/Vacuum.cpp
index 03becb04c..c3fed2328 100644
--- a/src/passes/Vacuum.cpp
+++ b/src/passes/Vacuum.cpp
@@ -186,6 +186,21 @@ struct Vacuum : public WalkerPass<ExpressionStackWalker<Vacuum, Visitor<Vacuum>>
   }
 
   void visitIf(If* curr) {
+    // if the condition is a constant, just apply it
+    // we can just return the ifTrue or ifFalse.
+    if (auto* value = curr->condition->dynCast<Const>()) {
+      if (value->value.getInteger()) {
+        replaceCurrent(curr->ifTrue);
+        return;
+      } else {
+        if (curr->ifFalse) {
+          replaceCurrent(curr->ifFalse);
+        } else {
+          ExpressionManipulator::nop(curr);
+        }
+        return;
+      }
+    }
     if (curr->ifFalse) {
       if (curr->ifFalse->is<Nop>()) {
         curr->ifFalse = nullptr;
diff --git a/test/example/c-api-kitchen-sink.txt b/test/example/c-api-kitchen-sink.txt
index 8cc6a0a1c..b66982140 100644
--- a/test/example/c-api-kitchen-sink.txt
+++ b/test/example/c-api-kitchen-sink.txt
@@ -1054,29 +1054,12 @@ optimized:
       (br $shape$0$continue)
     )
   )
-  (func $split (type $v)
-    (call $check
-      (i32.const 0)
-    )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
-      (call $check
-        (i32.const 2)
-      )
-    )
-  )
   (func $if (type $v)
     (call $check
       (i32.const 0)
     )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
+    (call $check
+      (i32.const 1)
     )
     (call $check
       (i32.const 2)
@@ -1086,14 +1069,8 @@ optimized:
     (call $check
       (i32.const 0)
     )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
-      (call $check
-        (i32.const 2)
-      )
+    (call $check
+      (i32.const 1)
     )
     (call $check
       (i32.const 3)
@@ -1108,10 +1085,7 @@ optimized:
         (call $check
           (i32.const 1)
         )
-        (br_if $shape$0$continue
-          (i32.const 10)
-        )
-        (br $block$3$break)
+        (br $shape$0$continue)
       )
     )
     (call $check
@@ -1131,20 +1105,14 @@ optimized:
           (call $check
             (i32.const 2)
           )
-          (br_if $block$4$break
-            (i32.const -6)
-          )
-          (br $shape$1$continue)
+          (br $block$4$break)
         )
       )
       (call $check
         (i32.const 3)
       )
-      (if
-        (i32.const -10)
-        (call $check
-          (i32.const 4)
-        )
+      (call $check
+        (i32.const 4)
       )
       (call $check
         (i32.const 5)
@@ -3093,29 +3061,12 @@ optimized:
       (br $shape$0$continue)
     )
   )
-  (func $split (type $v)
-    (call $check
-      (i32.const 0)
-    )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
-      (call $check
-        (i32.const 2)
-      )
-    )
-  )
   (func $if (type $v)
     (call $check
       (i32.const 0)
     )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
+    (call $check
+      (i32.const 1)
     )
     (call $check
       (i32.const 2)
@@ -3125,14 +3076,8 @@ optimized:
     (call $check
       (i32.const 0)
     )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
-      (call $check
-        (i32.const 2)
-      )
+    (call $check
+      (i32.const 1)
     )
     (call $check
       (i32.const 3)
@@ -3147,10 +3092,7 @@ optimized:
         (call $check
           (i32.const 1)
         )
-        (br_if $shape$0$continue
-          (i32.const 10)
-        )
-        (br $block$3$break)
+        (br $shape$0$continue)
       )
     )
     (call $check
@@ -3170,20 +3112,14 @@ optimized:
           (call $check
             (i32.const 2)
           )
-          (br_if $block$4$break
-            (i32.const -6)
-          )
-          (br $shape$1$continue)
+          (br $block$4$break)
         )
       )
       (call $check
         (i32.const 3)
       )
-      (if
-        (i32.const -10)
-        (call $check
-          (i32.const 4)
-        )
+      (call $check
+        (i32.const 4)
       )
       (call $check
         (i32.const 5)
diff --git a/test/example/c-api-kitchen-sink.txt.txt b/test/example/c-api-kitchen-sink.txt.txt
index 1ce2c903a..b42c1ec34 100644
--- a/test/example/c-api-kitchen-sink.txt.txt
+++ b/test/example/c-api-kitchen-sink.txt.txt
@@ -1047,29 +1047,12 @@
       (br $shape$0$continue)
     )
   )
-  (func $split (type $v)
-    (call $check
-      (i32.const 0)
-    )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
-      (call $check
-        (i32.const 2)
-      )
-    )
-  )
   (func $if (type $v)
     (call $check
       (i32.const 0)
     )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
+    (call $check
+      (i32.const 1)
     )
     (call $check
       (i32.const 2)
@@ -1079,14 +1062,8 @@
     (call $check
       (i32.const 0)
     )
-    (if
-      (i32.const 55)
-      (call $check
-        (i32.const 1)
-      )
-      (call $check
-        (i32.const 2)
-      )
+    (call $check
+      (i32.const 1)
     )
     (call $check
       (i32.const 3)
@@ -1101,10 +1078,7 @@
         (call $check
           (i32.const 1)
         )
-        (br_if $shape$0$continue
-          (i32.const 10)
-        )
-        (br $block$3$break)
+        (br $shape$0$continue)
       )
     )
     (call $check
@@ -1124,20 +1098,14 @@
           (call $check
             (i32.const 2)
           )
-          (br_if $block$4$break
-            (i32.const -6)
-          )
-          (br $shape$1$continue)
+          (br $block$4$break)
         )
       )
       (call $check
         (i32.const 3)
       )
-      (if
-        (i32.const -10)
-        (call $check
-          (i32.const 4)
-        )
+      (call $check
+        (i32.const 4)
       )
       (call $check
         (i32.const 5)
diff --git a/test/passes/precompute.txt b/test/passes/precompute.txt
index 9c3640757..cbf0f23a7 100644
--- a/test/passes/precompute.txt
+++ b/test/passes/precompute.txt
@@ -16,13 +16,6 @@
       (br $in)
     )
     (nop)
-    (if
-      (i32.const 2)
-      (call $x
-        (i32.const 3)
-      )
-    )
-    (nop)
     (block $c
       (nop)
       (call $x
diff --git a/test/passes/precompute.wast b/test/passes/precompute.wast
index ab7f0e3ad..e57522578 100644
--- a/test/passes/precompute.wast
+++ b/test/passes/precompute.wast
@@ -41,8 +41,6 @@
     (loop $in
       (br $in)
     )
-    (if (i32.const 0) (call $x (i32.const 1)))
-    (if (i32.const 2) (call $x (i32.const 3)))
     (block $b
       (br_if $b (i32.const 0))
       (br_if $b (i32.const 1))
diff --git a/test/passes/vacuum.txt b/test/passes/vacuum.txt
index 6b5d63b2a..73be2fea4 100644
--- a/test/passes/vacuum.txt
+++ b/test/passes/vacuum.txt
@@ -143,23 +143,24 @@
       (unreachable)
     )
   )
-  (func $if-drop (type $0)
+  (func $if-drop (type $3) (result i32)
     (block $out
       (if
-        (i32.const 0)
+        (call $if-drop)
         (drop
           (call $int)
         )
         (br $out)
       )
       (if
-        (i32.const 1)
+        (call $if-drop)
         (br $out)
         (drop
           (call $int)
         )
       )
     )
+    (i32.const 1)
   )
   (func $drop-silly (type $0)
     (drop
@@ -210,11 +211,22 @@
   (func $if2drops (type $3) (result i32)
     (drop
       (if
-        (i32.const 1)
+        (call $if2drops)
         (call $if2drops)
         (call $if2drops)
       )
     )
     (i32.const 2)
   )
+  (func $if-const (type $1) (param $x i32)
+    (call $if-const
+      (i32.const 3)
+    )
+    (call $if-const
+      (i32.const 5)
+    )
+    (call $if-const
+      (i32.const 7)
+    )
+  )
 )
diff --git a/test/passes/vacuum.wast b/test/passes/vacuum.wast
index 3584df3ff..559deb971 100644
--- a/test/passes/vacuum.wast
+++ b/test/passes/vacuum.wast
@@ -299,21 +299,22 @@
       (unreachable)
     )
   )
-  (func $if-drop
+  (func $if-drop (result i32)
     (block $out
       (drop
-        (if (i32.const 0)
+        (if (call $if-drop)
           (call $int)
           (br $out)
         )
       )
       (drop
-        (if (i32.const 1)
+        (if (call $if-drop)
           (br $out)
           (call $int)
         )
       )
     )
+    (i32.const 1)
   )
   (func $drop-silly
     (drop
@@ -414,7 +415,7 @@
   )
   (func $if2drops (result i32)
     (if
-      (i32.const 1)
+      (call $if2drops)
       (drop
         (call $if2drops)
       )
@@ -424,4 +425,10 @@
     )
     (i32.const 2)
   )
+  (func $if-const (param $x i32)
+    (if (i32.const 0) (call $if-const (i32.const 1)))
+    (if (i32.const 2) (call $if-const (i32.const 3)))
+    (if (i32.const 0) (call $if-const (i32.const 4)) (call $if-const (i32.const 5)))
+    (if (i32.const 6) (call $if-const (i32.const 7)) (call $if-const (i32.const 8)))
+  )
 )
diff --git a/test/unit.asm.js b/test/unit.asm.js
index 86be4cf2f..c3adb2a3a 100644
--- a/test/unit.asm.js
+++ b/test/unit.asm.js
@@ -266,7 +266,7 @@ function asm(global, env, buffer) {
 
   function smallIf() {
     do {
-      if (2) {
+      if (return_int() | 0) {
         lb(3) | 0;
       } else {
         break;
@@ -328,8 +328,8 @@ function asm(global, env, buffer) {
 
   function conditionalTypeFun() {
     var x = 0, y = +0;
-    x = 1 ? abort(5) | 0 : 2;
-    y = 3 ? +abort(7) : 4.5;
+    x = return_int() | 0 ? abort(5) | 0 : 2;
+    y = return_int() | 0 ? +abort(7) : 4.5;
   }
 
   function loadSigned(x) {
@@ -358,7 +358,7 @@ function asm(global, env, buffer) {
     Int = x;
     globalOpts();
     x = Int;
-    if (1) Int = 20; // but this does interfere
+    if (return_int() | 0) Int = 20; // but this does interfere
     Int = x;
     globalOpts();
     x = Int;
@@ -367,7 +367,7 @@ function asm(global, env, buffer) {
   }
 
   function dropCallImport() {
-    if (1) return_int() | 0;
+    if (return_int() | 0) return_int() | 0;
   }
 
   function loophi(x, y) {
@@ -399,7 +399,7 @@ function asm(global, env, buffer) {
     j = 0;
     while(1) {
      temp = j;
-     if (1) {
+     if (return_int() | 0) {
       if (temp) {
        i$lcssa = i;
        break L7;
diff --git a/test/unit.fromasm b/test/unit.fromasm
index 6d0952bd4..e08babd28 100644
--- a/test/unit.fromasm
+++ b/test/unit.fromasm
@@ -509,7 +509,7 @@
   )
   (func $smallIf
     (if
-      (i32.const 2)
+      (call $return_int)
       (drop
         (call $lb
           (i32.const 3)
@@ -594,7 +594,7 @@
   (func $conditionalTypeFun
     (drop
       (if
-        (i32.const 1)
+        (call $return_int)
         (i32.trunc_s/f64
           (call $abort
             (f64.convert_s/i32
@@ -607,7 +607,7 @@
     )
     (drop
       (if
-        (i32.const 3)
+        (call $return_int)
         (call $abort
           (f64.convert_s/i32
             (i32.const 7)
@@ -696,7 +696,7 @@
       (get_global $Int)
     )
     (if
-      (i32.const 1)
+      (call $return_int)
       (set_global $Int
         (i32.const 20)
       )
@@ -715,7 +715,7 @@
   )
   (func $dropCallImport
     (if
-      (i32.const 1)
+      (call $return_int)
       (drop
         (call $return_int)
       )
@@ -768,7 +768,7 @@
             (get_local $0)
           )
           (if
-            (i32.const 1)
+            (call $return_int)
             (br_if $label$break$L7
               (get_local $2)
             )
diff --git a/test/unit.fromasm.imprecise b/test/unit.fromasm.imprecise
index 1e50ad731..f99b02e82 100644
--- a/test/unit.fromasm.imprecise
+++ b/test/unit.fromasm.imprecise
@@ -490,7 +490,7 @@
   )
   (func $smallIf
     (if
-      (i32.const 2)
+      (call $return_int)
       (drop
         (call $lb
           (i32.const 3)
@@ -575,7 +575,7 @@
   (func $conditionalTypeFun
     (drop
       (if
-        (i32.const 1)
+        (call $return_int)
         (i32.trunc_s/f64
           (call $abort
             (f64.convert_s/i32
@@ -588,7 +588,7 @@
     )
     (drop
       (if
-        (i32.const 3)
+        (call $return_int)
         (call $abort
           (f64.convert_s/i32
             (i32.const 7)
@@ -677,7 +677,7 @@
       (get_global $Int)
     )
     (if
-      (i32.const 1)
+      (call $return_int)
       (set_global $Int
         (i32.const 20)
       )
@@ -696,7 +696,7 @@
   )
   (func $dropCallImport
     (if
-      (i32.const 1)
+      (call $return_int)
       (drop
         (call $return_int)
       )
@@ -749,7 +749,7 @@
             (get_local $0)
           )
           (if
-            (i32.const 1)
+            (call $return_int)
             (br_if $label$break$L7
               (get_local $2)
             )
diff --git a/test/unit.fromasm.imprecise.no-opts b/test/unit.fromasm.imprecise.no-opts
index f851b86c9..16a10861b 100644
--- a/test/unit.fromasm.imprecise.no-opts
+++ b/test/unit.fromasm.imprecise.no-opts
@@ -857,7 +857,7 @@
   (func $smallIf
     (block $do-once$0
       (if
-        (i32.const 2)
+        (call $return_int)
         (drop
           (call $lb
             (i32.const 3)
@@ -986,7 +986,7 @@
     (local $y f64)
     (set_local $x
       (if
-        (i32.const 1)
+        (call $return_int)
         (i32.trunc_s/f64
           (call $abort
             (f64.convert_s/i32
@@ -999,7 +999,7 @@
     )
     (set_local $y
       (if
-        (i32.const 3)
+        (call $return_int)
         (call $abort
           (f64.convert_s/i32
             (i32.const 7)
@@ -1131,7 +1131,7 @@
       (get_global $Int)
     )
     (if
-      (i32.const 1)
+      (call $return_int)
       (set_global $Int
         (i32.const 20)
       )
@@ -1150,7 +1150,7 @@
   )
   (func $dropCallImport
     (if
-      (i32.const 1)
+      (call $return_int)
       (drop
         (call $return_int)
       )
@@ -1219,7 +1219,7 @@
               (get_local $j)
             )
             (if
-              (i32.const 1)
+              (call $return_int)
               (if
                 (get_local $temp)
                 (block
diff --git a/test/unit.fromasm.no-opts b/test/unit.fromasm.no-opts
index a7580f991..58f63e66c 100644
--- a/test/unit.fromasm.no-opts
+++ b/test/unit.fromasm.no-opts
@@ -863,7 +863,7 @@
   (func $smallIf
     (block $do-once$0
       (if
-        (i32.const 2)
+        (call $return_int)
         (drop
           (call $lb
             (i32.const 3)
@@ -992,7 +992,7 @@
     (local $y f64)
     (set_local $x
       (if
-        (i32.const 1)
+        (call $return_int)
         (i32.trunc_s/f64
           (call $abort
             (f64.convert_s/i32
@@ -1005,7 +1005,7 @@
     )
     (set_local $y
       (if
-        (i32.const 3)
+        (call $return_int)
         (call $abort
           (f64.convert_s/i32
             (i32.const 7)
@@ -1137,7 +1137,7 @@
       (get_global $Int)
     )
     (if
-      (i32.const 1)
+      (call $return_int)
       (set_global $Int
         (i32.const 20)
       )
@@ -1156,7 +1156,7 @@
   )
   (func $dropCallImport
     (if
-      (i32.const 1)
+      (call $return_int)
       (drop
         (call $return_int)
       )
@@ -1225,7 +1225,7 @@
               (get_local $j)
             )
             (if
-              (i32.const 1)
+              (call $return_int)
               (if
                 (get_local $temp)
                 (block