Fold i32.eqz(wrap_i64(x)) -> i64.eqz(x) where possible (#3181)

Specifically, when `x` has at most 32 bits so that wrapping doesn't change its value.

3 files changed, 99 insertions, 0 deletions

diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 1f65ae609..36d92e81f 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -330,6 +330,18 @@ struct OptimizeInstructions
           return un;
         }
       }
+      {
+        // i32.eqz(i32.wrap_i64(x))  =>  i64.eqz(x)
+        //   where maxBits(x) <= 32
+        Unary* inner;
+        Expression* x;
+        if (matches(curr, unary(EqZInt32, unary(&inner, WrapInt64, any(&x)))) &&
+            Bits::getMaxBits(x, this) <= 32) {
+          inner->op = EqZInt64;
+          inner->value = x;
+          return inner;
+        }
+      }
     }
 
     if (auto* select = curr->dynCast<Select>()) {
diff --git a/test/passes/optimize-instructions_all-features.txt b/test/passes/optimize-instructions_all-features.txt
index 860783f36..873d550d7 100644
--- a/test/passes/optimize-instructions_all-features.txt
+++ b/test/passes/optimize-instructions_all-features.txt
@@ -3516,6 +3516,42 @@
    )
   )
   (drop
+   (i32.eqz
+    (i32.shr_u
+     (local.get $x)
+     (i32.const 31)
+    )
+   )
+  )
+  (drop
+   (i64.eqz
+    (i64.shr_u
+     (local.get $y)
+     (i64.const 63)
+    )
+   )
+  )
+  (drop
+   (i64.eqz
+    (i64.shr_u
+     (local.get $y)
+     (i64.const 63)
+    )
+   )
+  )
+  (drop
+   (i64.eqz
+    (local.get $y)
+   )
+  )
+  (drop
+   (i32.eqz
+    (i32.wrap_i64
+     (local.get $y)
+    )
+   )
+  )
+  (drop
    (i32.wrap_i64
     (i64.and
      (local.get $y)
diff --git a/test/passes/optimize-instructions_all-features.wast b/test/passes/optimize-instructions_all-features.wast
index 1afa3e5b5..59e7e21d8 100644
--- a/test/passes/optimize-instructions_all-features.wast
+++ b/test/passes/optimize-instructions_all-features.wast
@@ -4063,6 +4063,57 @@
       )
       (i64.const 0)
     ))
+    ;; eqz((i32(bool(expr)) != 0) != 0)
+    (drop (i32.eqz
+      (i32.ne
+        (i32.ne
+          (i32.shr_u
+            (local.get $x)
+            (i32.const 31)
+          )
+          (i32.const 0)
+        )
+        (i32.const 0)
+      )
+    ))
+    ;; i32.eqz(wrap(i64(x)))
+    (drop (i32.eqz
+      (i32.wrap_i64
+        (i64.shr_u
+          (local.get $y)
+          (i64.const 63)
+        )
+      )
+    ))
+    ;; eqz((i64(bool(expr)) != 0) != 0)
+    (drop (i32.eqz
+      (i32.ne
+        (i64.ne
+          (i64.shr_u
+            (local.get $y)
+            (i64.const 63)
+          )
+          (i64.const 0)
+        )
+        (i32.const 0)
+      )
+    ))
+    ;; eqz((i64(bool(expr)) != 0) != 0)
+    (drop (i32.eqz
+      (i32.ne
+        (i64.ne
+          (local.get $y)
+          (i64.const 0)
+        )
+        (i32.const 0)
+      )
+    ))
+    ;; i32.eqz(wrap(i64(x))) -> skip
+    (drop (i32.eqz
+      (i32.wrap_i64
+        (local.get $y)
+      )
+    ))
     ;; i64(bool(expr)) == 1 -> i32(bool(expr))
     (drop (i64.eq
       (i64.and