optimize ne of 0 in a boolean context (#808)

9 files changed, 64 insertions, 75 deletions

diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 84f126ae9..6454d3510 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -352,14 +352,24 @@ struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions,
   }
 
 private:
-
+  // Optimize given that the expression is flowing into a boolean context
   Expression* optimizeBoolean(Expression* boolean) {
-    auto* condition = boolean->dynCast<Unary>();
-    if (condition && condition->op == EqZInt32) {
-      auto* condition2 = condition->value->dynCast<Unary>();
-      if (condition2 && condition2->op == EqZInt32) {
-        // double eqz
-        return condition2->value;
+    if (auto* unary = boolean->dynCast<Unary>()) {
+      if (unary && unary->op == EqZInt32) {
+        auto* unary2 = unary->value->dynCast<Unary>();
+        if (unary2 && unary2->op == EqZInt32) {
+          // double eqz
+          return unary2->value;
+        }
+      }
+    } else if (auto* binary = boolean->dynCast<Binary>()) {
+      // x != 0 is just x if it's used as a bool
+      if (binary->op == NeInt32) {
+        if (auto* num = binary->right->dynCast<Const>()) {
+          if (num->value.geti32() == 0) {
+            return binary->left;
+          }
+        }
       }
     }
     return boolean;
diff --git a/test/emcc_O2_hello_world.fromasm b/test/emcc_O2_hello_world.fromasm
index 8b7d2cffd..78428e1ce 100644
--- a/test/emcc_O2_hello_world.fromasm
+++ b/test/emcc_O2_hello_world.fromasm
@@ -1973,10 +1973,7 @@
                       )
                     )
                     (i32.const 0)
-                    (i32.ne
-                      (get_local $12)
-                      (i32.const 0)
-                    )
+                    (get_local $12)
                   )
                   (block
                     (if
@@ -3123,13 +3120,10 @@
     )
     (if
       (if i32
-        (i32.ne
-          (tee_local $10
-            (i32.load
-              (i32.const 616)
-            )
+        (tee_local $10
+          (i32.load
+            (i32.const 616)
           )
-          (i32.const 0)
         )
         (i32.or
           (i32.le_u
@@ -3399,10 +3393,7 @@
                                       )
                                     )
                                     (i32.const 0)
-                                    (i32.ne
-                                      (get_local $5)
-                                      (i32.const 0)
-                                    )
+                                    (get_local $5)
                                   )
                                 )
                                 (if
@@ -3695,13 +3686,10 @@
                     )
                   )
                   (br_if $do-in
-                    (i32.ne
-                      (tee_local $3
-                        (i32.load offset=8
-                          (get_local $3)
-                        )
+                    (tee_local $3
+                      (i32.load offset=8
+                        (get_local $3)
                       )
-                      (i32.const 0)
                     )
                   )
                 )
diff --git a/test/emcc_O2_hello_world.fromasm.imprecise b/test/emcc_O2_hello_world.fromasm.imprecise
index 8fc101afc..0cd471b28 100644
--- a/test/emcc_O2_hello_world.fromasm.imprecise
+++ b/test/emcc_O2_hello_world.fromasm.imprecise
@@ -1971,10 +1971,7 @@
                       )
                     )
                     (i32.const 0)
-                    (i32.ne
-                      (get_local $12)
-                      (i32.const 0)
-                    )
+                    (get_local $12)
                   )
                   (block
                     (if
@@ -3121,13 +3118,10 @@
     )
     (if
       (if i32
-        (i32.ne
-          (tee_local $10
-            (i32.load
-              (i32.const 616)
-            )
+        (tee_local $10
+          (i32.load
+            (i32.const 616)
           )
-          (i32.const 0)
         )
         (i32.or
           (i32.le_u
@@ -3397,10 +3391,7 @@
                                       )
                                     )
                                     (i32.const 0)
-                                    (i32.ne
-                                      (get_local $5)
-                                      (i32.const 0)
-                                    )
+                                    (get_local $5)
                                   )
                                 )
                                 (if
@@ -3693,13 +3684,10 @@
                     )
                   )
                   (br_if $do-in
-                    (i32.ne
-                      (tee_local $3
-                        (i32.load offset=8
-                          (get_local $3)
-                        )
+                    (tee_local $3
+                      (i32.load offset=8
+                        (get_local $3)
                       )
-                      (i32.const 0)
                     )
                   )
                 )
diff --git a/test/emcc_hello_world.fromasm b/test/emcc_hello_world.fromasm
index cb6e15b30..7443cdaff 100644
--- a/test/emcc_hello_world.fromasm
+++ b/test/emcc_hello_world.fromasm
@@ -2146,10 +2146,7 @@
     (select
       (get_local $2)
       (i32.const 0)
-      (i32.ne
-        (get_local $0)
-        (i32.const 0)
-      )
+      (get_local $0)
     )
   )
   (func $___syscall_ret (param $0 i32) (result i32)
@@ -4060,10 +4057,7 @@
                                         )
                                       )
                                       (i32.const 4101)
-                                      (i32.ne
-                                        (get_local $9)
-                                        (i32.const 0)
-                                      )
+                                      (get_local $9)
                                     )
                                   )
                                   (br $jumpthreading$inner$4)
diff --git a/test/emcc_hello_world.fromasm.imprecise b/test/emcc_hello_world.fromasm.imprecise
index d34035bf2..b3ce6e84e 100644
--- a/test/emcc_hello_world.fromasm.imprecise
+++ b/test/emcc_hello_world.fromasm.imprecise
@@ -2139,10 +2139,7 @@
     (select
       (get_local $2)
       (i32.const 0)
-      (i32.ne
-        (get_local $0)
-        (i32.const 0)
-      )
+      (get_local $0)
     )
   )
   (func $___syscall_ret (param $0 i32) (result i32)
@@ -4052,10 +4049,7 @@
                                         )
                                       )
                                       (i32.const 4101)
-                                      (i32.ne
-                                        (get_local $9)
-                                        (i32.const 0)
-                                      )
+                                      (get_local $9)
                                     )
                                   )
                                   (br $jumpthreading$inner$4)
diff --git a/test/memorygrowth.fromasm b/test/memorygrowth.fromasm
index dd14ea0bf..d2c814e8d 100644
--- a/test/memorygrowth.fromasm
+++ b/test/memorygrowth.fromasm
@@ -3728,13 +3728,10 @@
                     )
                   )
                   (br_if $do-in41
-                    (i32.ne
-                      (tee_local $2
-                        (i32.load offset=8
-                          (get_local $2)
-                        )
+                    (tee_local $2
+                      (i32.load offset=8
+                        (get_local $2)
                       )
-                      (i32.const 0)
                     )
                   )
                 )
diff --git a/test/memorygrowth.fromasm.imprecise b/test/memorygrowth.fromasm.imprecise
index a6af9df0e..f9fa51bce 100644
--- a/test/memorygrowth.fromasm.imprecise
+++ b/test/memorygrowth.fromasm.imprecise
@@ -3726,13 +3726,10 @@
                     )
                   )
                   (br_if $do-in41
-                    (i32.ne
-                      (tee_local $2
-                        (i32.load offset=8
-                          (get_local $2)
-                        )
+                    (tee_local $2
+                      (i32.load offset=8
+                        (get_local $2)
                       )
-                      (i32.const 0)
                     )
                   )
                 )
diff --git a/test/passes/optimize-instructions.txt b/test/passes/optimize-instructions.txt
index c93c7d1fa..1bd410822 100644
--- a/test/passes/optimize-instructions.txt
+++ b/test/passes/optimize-instructions.txt
@@ -1,6 +1,7 @@
 (module
   (type $0 (func (param i32 i64)))
   (type $1 (func))
+  (type $2 (func (result i32)))
   (memory $0 0)
   (func $f (type $0) (param $i1 i32) (param $i2 i64)
     (if
@@ -363,4 +364,15 @@
       )
     )
   )
+  (func $ne0 (type $2) (result i32)
+    (if
+      (call $ne0)
+      (nop)
+    )
+    (if
+      (call $ne0)
+      (nop)
+    )
+    (i32.const 1)
+  )
 )
diff --git a/test/passes/optimize-instructions.wast b/test/passes/optimize-instructions.wast
index 99e77ea9e..56e9d08fb 100644
--- a/test/passes/optimize-instructions.wast
+++ b/test/passes/optimize-instructions.wast
@@ -287,4 +287,13 @@
     (drop (i32.div_s (unreachable) (i32.const 1))) ;; not ok
     (drop (i32.div_s (i32.const 1) (unreachable)))
   )
+  (func $ne0 (result i32)
+    (if (i32.ne (call $ne0) (i32.const 0))
+      (nop)
+    )
+    (if (i32.ne (i32.const 0) (call $ne0))
+      (nop)
+    )
+    (i32.const 1)
+  )
 )