vacuum dead code after unconditional brs

7 files changed, 31 insertions, 51 deletions

diff --git a/src/passes/Vacuum.cpp b/src/passes/Vacuum.cpp
index 863d78f14..ed868f2f9 100644
--- a/src/passes/Vacuum.cpp
+++ b/src/passes/Vacuum.cpp
@@ -32,14 +32,25 @@ struct Vacuum : public WalkerPass<PostWalker<Vacuum, Visitor<Vacuum>>> {
     int skip = 0;
     auto& list = curr->list;
     size_t size = list.size();
+    bool needResize = false;
     for (size_t z = 0; z < size; z++) {
       if (list[z]->is<Nop>()) {
         skip++;
-      } else if (skip > 0) {
-        list[z - skip] = list[z];
+        needResize = true;
+      } else {
+        if (skip > 0) {
+          list[z - skip] = list[z];
+        }
+        // if this is an unconditional br, the rest is dead code
+        Break* br = list[z - skip]->dynCast<Break>();
+        if (br && !br->condition) {
+          list.resize(z - skip + 1);
+          needResize = false;
+          break;
+        }
       }
     }
-    if (skip > 0) {
+    if (needResize) {
       list.resize(size - skip);
     }
     if (!curr->name.is()) {
diff --git a/test/emcc_hello_world.fromasm b/test/emcc_hello_world.fromasm
index 2d8457313..387da4310 100644
--- a/test/emcc_hello_world.fromasm
+++ b/test/emcc_hello_world.fromasm
@@ -3963,7 +3963,6 @@
                   (i32.const 9)
                 )
                 (br $label$break$L9)
-                (br $switch$2)
               )
               (set_local $$incdec$ptr169276$lcssa
                 (get_local $$incdec$ptr169274)
@@ -3972,7 +3971,6 @@
                 (get_local $$incdec$ptr169274)
               )
               (br $label$break$L9)
-              (br $switch$2)
             )
           )
         )
@@ -5394,7 +5392,6 @@
                                                                           (get_local $$l10n$3)
                                                                         )
                                                                         (br $label$continue$L1)
-                                                                        (br $switch$25)
                                                                       )
                                                                       (i32.store
                                                                         (i32.load
@@ -5415,7 +5412,6 @@
                                                                         (get_local $$l10n$3)
                                                                       )
                                                                       (br $label$continue$L1)
-                                                                      (br $switch$25)
                                                                     )
                                                                     (i32.store
                                                                       (set_local $$76
@@ -5451,7 +5447,6 @@
                                                                       (get_local $$l10n$3)
                                                                     )
                                                                     (br $label$continue$L1)
-                                                                    (br $switch$25)
                                                                   )
                                                                   (i32.store16
                                                                     (i32.load
@@ -5475,7 +5470,6 @@
                                                                     (get_local $$l10n$3)
                                                                   )
                                                                   (br $label$continue$L1)
-                                                                  (br $switch$25)
                                                                 )
                                                                 (i32.store8
                                                                   (i32.load
@@ -5499,7 +5493,6 @@
                                                                   (get_local $$l10n$3)
                                                                 )
                                                                 (br $label$continue$L1)
-                                                                (br $switch$25)
                                                               )
                                                               (i32.store
                                                                 (i32.load
@@ -5520,7 +5513,6 @@
                                                                 (get_local $$l10n$3)
                                                               )
                                                               (br $label$continue$L1)
-                                                              (br $switch$25)
                                                             )
                                                             (i32.store
                                                               (set_local $$86
@@ -5556,7 +5548,6 @@
                                                               (get_local $$l10n$3)
                                                             )
                                                             (br $label$continue$L1)
-                                                            (br $switch$25)
                                                           )
                                                           (set_local $$cnt$0
                                                             (get_local $$cnt$1)
@@ -9328,7 +9319,6 @@
                 (get_local $$l10n$3)
               )
               (br $label$continue$L1)
-              (br $switch$24)
             )
             (set_local $$a$2
               (get_local $$incdec$ptr169275)
@@ -10440,7 +10430,6 @@
                                   (get_local $$6)
                                 )
                                 (br $label$break$L1)
-                                (br $switch$3)
                               )
                               (set_local $$13
                                 (i32.load
@@ -10499,7 +10488,6 @@
                                 )
                               )
                               (br $label$break$L1)
-                              (br $switch$3)
                             )
                             (set_local $$26
                               (i32.load
@@ -10549,7 +10537,6 @@
                               (i32.const 0)
                             )
                             (br $label$break$L1)
-                            (br $switch$3)
                           )
                           (set_local $$39
                             (i32.load
@@ -10606,7 +10593,6 @@
                             (get_local $$42)
                           )
                           (br $label$break$L1)
-                          (br $switch$3)
                         )
                         (set_local $$53
                           (i32.load
@@ -10679,7 +10665,6 @@
                           (get_local $$56)
                         )
                         (br $label$break$L1)
-                        (br $switch$3)
                       )
                       (set_local $$67
                         (i32.load
@@ -10732,7 +10717,6 @@
                         (i32.const 0)
                       )
                       (br $label$break$L1)
-                      (br $switch$3)
                     )
                     (set_local $$78
                       (i32.load
@@ -10805,7 +10789,6 @@
                       (get_local $$81)
                     )
                     (br $label$break$L1)
-                    (br $switch$3)
                   )
                   (set_local $$92
                     (i32.load
@@ -10858,7 +10841,6 @@
                     (i32.const 0)
                   )
                   (br $label$break$L1)
-                  (br $switch$3)
                 )
                 (set_local $$103
                   (f64.load
@@ -10902,7 +10884,6 @@
                   (get_local $$103)
                 )
                 (br $label$break$L1)
-                (br $switch$3)
               )
               (set_local $$110
                 (f64.load
@@ -10946,7 +10927,6 @@
                 (get_local $$110)
               )
               (br $label$break$L1)
-              (br $switch$3)
             )
             (br $label$break$L1)
           )
diff --git a/test/emcc_hello_world.fromasm.imprecise b/test/emcc_hello_world.fromasm.imprecise
index 71a0412b7..6fcffbf53 100644
--- a/test/emcc_hello_world.fromasm.imprecise
+++ b/test/emcc_hello_world.fromasm.imprecise
@@ -3961,7 +3961,6 @@
                   (i32.const 9)
                 )
                 (br $label$break$L9)
-                (br $switch$2)
               )
               (set_local $$incdec$ptr169276$lcssa
                 (get_local $$incdec$ptr169274)
@@ -3970,7 +3969,6 @@
                 (get_local $$incdec$ptr169274)
               )
               (br $label$break$L9)
-              (br $switch$2)
             )
           )
         )
@@ -5392,7 +5390,6 @@
                                                                           (get_local $$l10n$3)
                                                                         )
                                                                         (br $label$continue$L1)
-                                                                        (br $switch$25)
                                                                       )
                                                                       (i32.store
                                                                         (i32.load
@@ -5413,7 +5410,6 @@
                                                                         (get_local $$l10n$3)
                                                                       )
                                                                       (br $label$continue$L1)
-                                                                      (br $switch$25)
                                                                     )
                                                                     (i32.store
                                                                       (set_local $$76
@@ -5449,7 +5445,6 @@
                                                                       (get_local $$l10n$3)
                                                                     )
                                                                     (br $label$continue$L1)
-                                                                    (br $switch$25)
                                                                   )
                                                                   (i32.store16
                                                                     (i32.load
@@ -5473,7 +5468,6 @@
                                                                     (get_local $$l10n$3)
                                                                   )
                                                                   (br $label$continue$L1)
-                                                                  (br $switch$25)
                                                                 )
                                                                 (i32.store8
                                                                   (i32.load
@@ -5497,7 +5491,6 @@
                                                                   (get_local $$l10n$3)
                                                                 )
                                                                 (br $label$continue$L1)
-                                                                (br $switch$25)
                                                               )
                                                               (i32.store
                                                                 (i32.load
@@ -5518,7 +5511,6 @@
                                                                 (get_local $$l10n$3)
                                                               )
                                                               (br $label$continue$L1)
-                                                              (br $switch$25)
                                                             )
                                                             (i32.store
                                                               (set_local $$86
@@ -5554,7 +5546,6 @@
                                                               (get_local $$l10n$3)
                                                             )
                                                             (br $label$continue$L1)
-                                                            (br $switch$25)
                                                           )
                                                           (set_local $$cnt$0
                                                             (get_local $$cnt$1)
@@ -9326,7 +9317,6 @@
                 (get_local $$l10n$3)
               )
               (br $label$continue$L1)
-              (br $switch$24)
             )
             (set_local $$a$2
               (get_local $$incdec$ptr169275)
@@ -10438,7 +10428,6 @@
                                   (get_local $$6)
                                 )
                                 (br $label$break$L1)
-                                (br $switch$3)
                               )
                               (set_local $$13
                                 (i32.load
@@ -10497,7 +10486,6 @@
                                 )
                               )
                               (br $label$break$L1)
-                              (br $switch$3)
                             )
                             (set_local $$26
                               (i32.load
@@ -10547,7 +10535,6 @@
                               (i32.const 0)
                             )
                             (br $label$break$L1)
-                            (br $switch$3)
                           )
                           (set_local $$39
                             (i32.load
@@ -10604,7 +10591,6 @@
                             (get_local $$42)
                           )
                           (br $label$break$L1)
-                          (br $switch$3)
                         )
                         (set_local $$53
                           (i32.load
@@ -10677,7 +10663,6 @@
                           (get_local $$56)
                         )
                         (br $label$break$L1)
-                        (br $switch$3)
                       )
                       (set_local $$67
                         (i32.load
@@ -10730,7 +10715,6 @@
                         (i32.const 0)
                       )
                       (br $label$break$L1)
-                      (br $switch$3)
                     )
                     (set_local $$78
                       (i32.load
@@ -10803,7 +10787,6 @@
                       (get_local $$81)
                     )
                     (br $label$break$L1)
-                    (br $switch$3)
                   )
                   (set_local $$92
                     (i32.load
@@ -10856,7 +10839,6 @@
                     (i32.const 0)
                   )
                   (br $label$break$L1)
-                  (br $switch$3)
                 )
                 (set_local $$103
                   (f64.load
@@ -10900,7 +10882,6 @@
                   (get_local $$103)
                 )
                 (br $label$break$L1)
-                (br $switch$3)
               )
               (set_local $$110
                 (f64.load
@@ -10944,7 +10925,6 @@
                 (get_local $$110)
               )
               (br $label$break$L1)
-              (br $switch$3)
             )
             (br $label$break$L1)
           )
diff --git a/test/passes/vacuum.txt b/test/passes/vacuum.txt
index bb76b2d82..a6c7f22f0 100644
--- a/test/passes/vacuum.txt
+++ b/test/passes/vacuum.txt
@@ -4,5 +4,12 @@
     (i32.const 50)
     (i32.const 51)
     (i32.const 52)
+    (block $waka1
+      (i32.const 53)
+      (br $waka1)
+    )
+    (block $waka2
+      (br $waka2)
+    )
   )
 )
diff --git a/test/passes/vacuum.wast b/test/passes/vacuum.wast
index 24dc32bcb..dda86804e 100644
--- a/test/passes/vacuum.wast
+++ b/test/passes/vacuum.wast
@@ -7,6 +7,16 @@
     (nop)
     (nop)
     (i32.const 52)
+    (block $waka1
+      (i32.const 53)
+      (br $waka1)
+      (i32.const 54)
+    )
+    (block $waka2
+      (nop)
+      (br $waka2)
+      (i32.const 56)
+    )
   )
 )
 
diff --git a/test/unit.fromasm b/test/unit.fromasm
index 0b43f14fc..412bfcace 100644
--- a/test/unit.fromasm
+++ b/test/unit.fromasm
@@ -222,13 +222,11 @@
           )
           (loop $while-out$10 $while-in$11
             (br $while-out$10)
-            (br $while-in$11)
           )
           (br $label$break$Lout)
         )
         (loop $while-out$13 $while-in$14
           (br $label$break$Lout)
-          (br $while-in$14)
         )
         (br $label$break$Lout)
       )
@@ -249,13 +247,11 @@
                     )
                   )
                   (br $label$break$L1)
-                  (br $switch$17)
                 )
                 (i32.const 1)
                 (br $switch$17)
               )
               (br $label$break$L3)
-              (br $switch$17)
             )
             (br $label$break$L1)
           )
diff --git a/test/unit.fromasm.imprecise b/test/unit.fromasm.imprecise
index f5ba55d90..363131ff3 100644
--- a/test/unit.fromasm.imprecise
+++ b/test/unit.fromasm.imprecise
@@ -216,13 +216,11 @@
           )
           (loop $while-out$10 $while-in$11
             (br $while-out$10)
-            (br $while-in$11)
           )
           (br $label$break$Lout)
         )
         (loop $while-out$13 $while-in$14
           (br $label$break$Lout)
-          (br $while-in$14)
         )
         (br $label$break$Lout)
       )
@@ -243,13 +241,11 @@
                     )
                   )
                   (br $label$break$L1)
-                  (br $switch$17)
                 )
                 (i32.const 1)
                 (br $switch$17)
               )
               (br $label$break$L3)
-              (br $switch$17)
             )
             (br $label$break$L1)
           )