fix off-by-one error in clz/ctz/popcount used bits computation

Author: kripken

src/passes/OptimizeInstructions.cpp

@@ -228,8 +228,8 @@ Index getMaxBits(Expression* curr, LocalInfoProvider* localInfoProvider) {
     }
   } else if (auto* unary = curr->dynCast<Unary>()) {
     switch (unary->op) {
-      case ClzInt32: case CtzInt32: case PopcntInt32: return 5;
-      case ClzInt64: case CtzInt64: case PopcntInt64: return 6;
+      case ClzInt32: case CtzInt32: case PopcntInt32: return 6;
+      case ClzInt64: case CtzInt64: case PopcntInt64: return 7;
       case EqZInt32: case EqZInt64: return 1;
       case WrapInt64: return std::min(Index(32), getMaxBits(unary->value, localInfoProvider));
       default: {}

test/passes/optimize-instructions.txt

@@ -7,6 +7,7 @@
  (type $5 (func (param i32)))
  (type $6 (func (param i32 i32) (result i32)))
  (type $7 (func (param i64) (result i64)))
+ (type $8 (func (result i64)))
  (memory $0 0)
  (export "load-off-2" (func $load-off-2))
  (func $f (type $0) (param $i1 i32) (param $i2 i64)
@@ -827,11 +828,14 @@
    )
   )
   (drop
-   (i32.shl
-    (i32.clz
-     (i32.const 0)
+   (i32.shr_s
+    (i32.shl
+     (i32.clz
+      (i32.const 0)
+     )
+     (i32.const 26)
     )
-    (i32.const 2)
+    (i32.const 24)
    )
   )
   (drop
@@ -853,13 +857,16 @@
    )
   )
   (drop
-   (i32.shl
-    (i32.wrap/i64
-     (i64.clz
-      (i64.const 0)
+   (i32.shr_s
+    (i32.shl
+     (i32.wrap/i64
+      (i64.clz
+       (i64.const 0)
+      )
      )
+     (i32.const 25)
     )
-    (i32.const 1)
+    (i32.const 24)
    )
   )
   (drop
@@ -2076,4 +2083,41 @@
  (func $less-shifts-than-it-seems (type $3) (param $x i32) (result i32)
   (i32.const 4800)
  )
+ (func $and-popcount32 (type $2) (result i32)
+  (i32.and
+   (i32.popcnt
+    (i32.const -1)
+   )
+   (i32.const 31)
+  )
+ )
+ (func $and-popcount32-big (type $2) (result i32)
+  (i32.popcnt
+   (i32.const -1)
+  )
+ )
+ (func $and-popcount64 (type $8) (result i64)
+  (i64.and
+   (i64.popcnt
+    (i64.const -1)
+   )
+   (i64.const 63)
+  )
+ )
+ (func $and-popcount64-big (type $8) (result i64)
+  (i64.and
+   (i64.popcnt
+    (i64.const -1)
+   )
+   (i64.const 127)
+  )
+ )
+ (func $and-popcount64-bigger (type $8) (result i64)
+  (i64.and
+   (i64.popcnt
+    (i64.const -1)
+   )
+   (i64.const 255)
+  )
+ )
 )

test/passes/optimize-instructions.wast

@@ -2526,4 +2526,44 @@
       )
     )
   )
+  (func $and-popcount32 (result i32)
+    (i32.and
+      (i32.popcnt
+        (i32.const -1)
+      )
+      (i32.const 31)
+    )
+  )
+  (func $and-popcount32-big (result i32)
+    (i32.and
+      (i32.popcnt
+        (i32.const -1)
+      )
+      (i32.const 63)
+    )
+  )
+  (func $and-popcount64 (result i64) ;; these are TODOs
+    (i64.and
+      (i64.popcnt
+        (i64.const -1)
+      )
+      (i64.const 63)
+    )
+  )
+  (func $and-popcount64-big (result i64)
+    (i64.and
+      (i64.popcnt
+        (i64.const -1)
+      )
+      (i64.const 127)
+    )
+  )
+  (func $and-popcount64-bigger (result i64)
+    (i64.and
+      (i64.popcnt
+        (i64.const -1)
+      )
+      (i64.const 255)
+    )
+  )
 )