DCE even in -O0 (#884)

9 files changed, 5 insertions, 69 deletions

diff --git a/src/asm2wasm.h b/src/asm2wasm.h
index d8a2053be..77be6aad2 100644
--- a/src/asm2wasm.h
+++ b/src/asm2wasm.h
@@ -1029,8 +1029,10 @@ void Asm2WasmBuilder::processAsm(Ref ast) {
     passRunner.add("remove-unused-brs");
     passRunner.add("optimize-instructions");
     passRunner.add("post-emscripten");
-    passRunner.add("dce"); // make sure to not emit unreachable code
   }
+  // make sure to not emit unreachable code at all, even in -O0, as wasm rules for it are complex
+  // and changing.
+  passRunner.add("dce");
   passRunner.run();
 
   // apply memory growth, if relevant
diff --git a/test/emcc_hello_world.fromasm.imprecise.no-opts b/test/emcc_hello_world.fromasm.imprecise.no-opts
index 9488b62c2..b4dcbcaa3 100644
--- a/test/emcc_hello_world.fromasm.imprecise.no-opts
+++ b/test/emcc_hello_world.fromasm.imprecise.no-opts
@@ -5982,7 +5982,6 @@
                       (i32.const 9)
                     )
                     (br $label$break$L9)
-                    (br $switch)
                   )
                 )
                 (block
@@ -5993,7 +5992,6 @@
                     (get_local $$incdec$ptr169274)
                   )
                   (br $label$break$L9)
-                  (br $switch)
                 )
               )
               (nop)
@@ -7881,7 +7879,6 @@
                                                                             (get_local $$l10n$3)
                                                                           )
                                                                           (br $label$continue$L1)
-                                                                          (br $switch18)
                                                                         )
                                                                       )
                                                                       (block
@@ -7907,7 +7904,6 @@
                                                                           (get_local $$l10n$3)
                                                                         )
                                                                         (br $label$continue$L1)
-                                                                        (br $switch18)
                                                                       )
                                                                     )
                                                                     (block
@@ -7967,7 +7963,6 @@
                                                                         (get_local $$l10n$3)
                                                                       )
                                                                       (br $label$continue$L1)
-                                                                      (br $switch18)
                                                                     )
                                                                   )
                                                                   (block
@@ -7999,7 +7994,6 @@
                                                                       (get_local $$l10n$3)
                                                                     )
                                                                     (br $label$continue$L1)
-                                                                    (br $switch18)
                                                                   )
                                                                 )
                                                                 (block
@@ -8031,7 +8025,6 @@
                                                                     (get_local $$l10n$3)
                                                                   )
                                                                   (br $label$continue$L1)
-                                                                  (br $switch18)
                                                                 )
                                                               )
                                                               (block
@@ -8057,7 +8050,6 @@
                                                                   (get_local $$l10n$3)
                                                                 )
                                                                 (br $label$continue$L1)
-                                                                (br $switch18)
                                                               )
                                                             )
                                                             (block
@@ -8117,7 +8109,6 @@
                                                                 (get_local $$l10n$3)
                                                               )
                                                               (br $label$continue$L1)
-                                                              (br $switch18)
                                                             )
                                                           )
                                                           (block
@@ -8136,7 +8127,6 @@
                                                             (br $label$continue$L1)
                                                           )
                                                         )
-                                                        (br $switch17)
                                                       )
                                                     )
                                                     (block
@@ -13145,7 +13135,6 @@
                   (get_local $$l10n$3)
                 )
                 (br $label$continue$L1)
-                (br $switch17)
               )
             )
             (block
@@ -14766,7 +14755,6 @@
                                     (get_local $$6)
                                   )
                                   (br $label$break$L1)
-                                  (br $switch)
                                 )
                               )
                               (block
@@ -14883,7 +14871,6 @@
                                   (get_local $$15)
                                 )
                                 (br $label$break$L1)
-                                (br $switch)
                               )
                             )
                             (block
@@ -14985,7 +14972,6 @@
                                 (i32.const 0)
                               )
                               (br $label$break$L1)
-                              (br $switch)
                             )
                           )
                           (block
@@ -15107,7 +15093,6 @@
                               (get_local $$42)
                             )
                             (br $label$break$L1)
-                            (br $switch)
                           )
                         )
                         (block
@@ -15239,7 +15224,6 @@
                             (get_local $$56)
                           )
                           (br $label$break$L1)
-                          (br $switch)
                         )
                       )
                       (block
@@ -15347,7 +15331,6 @@
                           (i32.const 0)
                         )
                         (br $label$break$L1)
-                        (br $switch)
                       )
                     )
                     (block
@@ -15479,7 +15462,6 @@
                         (get_local $$81)
                       )
                       (br $label$break$L1)
-                      (br $switch)
                     )
                   )
                   (block
@@ -15587,7 +15569,6 @@
                       (i32.const 0)
                     )
                     (br $label$break$L1)
-                    (br $switch)
                   )
                 )
                 (block
@@ -15670,7 +15651,6 @@
                     (get_local $$103)
                   )
                   (br $label$break$L1)
-                  (br $switch)
                 )
               )
               (block
@@ -15753,7 +15733,6 @@
                   (get_local $$110)
                 )
                 (br $label$break$L1)
-                (br $switch)
               )
             )
             (br $label$break$L1)
diff --git a/test/emcc_hello_world.fromasm.no-opts b/test/emcc_hello_world.fromasm.no-opts
index e12ecdb96..10cae59e8 100644
--- a/test/emcc_hello_world.fromasm.no-opts
+++ b/test/emcc_hello_world.fromasm.no-opts
@@ -5988,7 +5988,6 @@
                       (i32.const 9)
                     )
                     (br $label$break$L9)
-                    (br $switch)
                   )
                 )
                 (block
@@ -5999,7 +5998,6 @@
                     (get_local $$incdec$ptr169274)
                   )
                   (br $label$break$L9)
-                  (br $switch)
                 )
               )
               (nop)
@@ -7887,7 +7885,6 @@
                                                                             (get_local $$l10n$3)
                                                                           )
                                                                           (br $label$continue$L1)
-                                                                          (br $switch18)
                                                                         )
                                                                       )
                                                                       (block
@@ -7913,7 +7910,6 @@
                                                                           (get_local $$l10n$3)
                                                                         )
                                                                         (br $label$continue$L1)
-                                                                        (br $switch18)
                                                                       )
                                                                     )
                                                                     (block
@@ -7973,7 +7969,6 @@
                                                                         (get_local $$l10n$3)
                                                                       )
                                                                       (br $label$continue$L1)
-                                                                      (br $switch18)
                                                                     )
                                                                   )
                                                                   (block
@@ -8005,7 +8000,6 @@
                                                                       (get_local $$l10n$3)
                                                                     )
                                                                     (br $label$continue$L1)
-                                                                    (br $switch18)
                                                                   )
                                                                 )
                                                                 (block
@@ -8037,7 +8031,6 @@
                                                                     (get_local $$l10n$3)
                                                                   )
                                                                   (br $label$continue$L1)
-                                                                  (br $switch18)
                                                                 )
                                                               )
                                                               (block
@@ -8063,7 +8056,6 @@
                                                                   (get_local $$l10n$3)
                                                                 )
                                                                 (br $label$continue$L1)
-                                                                (br $switch18)
                                                               )
                                                             )
                                                             (block
@@ -8123,7 +8115,6 @@
                                                                 (get_local $$l10n$3)
                                                               )
                                                               (br $label$continue$L1)
-                                                              (br $switch18)
                                                             )
                                                           )
                                                           (block
@@ -8142,7 +8133,6 @@
                                                             (br $label$continue$L1)
                                                           )
                                                         )
-                                                        (br $switch17)
                                                       )
                                                     )
                                                     (block
@@ -13151,7 +13141,6 @@
                   (get_local $$l10n$3)
                 )
                 (br $label$continue$L1)
-                (br $switch17)
               )
             )
             (block
@@ -14772,7 +14761,6 @@
                                     (get_local $$6)
                                   )
                                   (br $label$break$L1)
-                                  (br $switch)
                                 )
                               )
                               (block
@@ -14889,7 +14877,6 @@
                                   (get_local $$15)
                                 )
                                 (br $label$break$L1)
-                                (br $switch)
                               )
                             )
                             (block
@@ -14991,7 +14978,6 @@
                                 (i32.const 0)
                               )
                               (br $label$break$L1)
-                              (br $switch)
                             )
                           )
                           (block
@@ -15113,7 +15099,6 @@
                               (get_local $$42)
                             )
                             (br $label$break$L1)
-                            (br $switch)
                           )
                         )
                         (block
@@ -15245,7 +15230,6 @@
                             (get_local $$56)
                           )
                           (br $label$break$L1)
-                          (br $switch)
                         )
                       )
                       (block
@@ -15353,7 +15337,6 @@
                           (i32.const 0)
                         )
                         (br $label$break$L1)
-                        (br $switch)
                       )
                     )
                     (block
@@ -15485,7 +15468,6 @@
                         (get_local $$81)
                       )
                       (br $label$break$L1)
-                      (br $switch)
                     )
                   )
                   (block
@@ -15593,7 +15575,6 @@
                       (i32.const 0)
                     )
                     (br $label$break$L1)
-                    (br $switch)
                   )
                 )
                 (block
@@ -15676,7 +15657,6 @@
                     (get_local $$103)
                   )
                   (br $label$break$L1)
-                  (br $switch)
                 )
               )
               (block
@@ -15759,7 +15739,6 @@
                   (get_local $$110)
                 )
                 (br $label$break$L1)
-                (br $switch)
               )
             )
             (br $label$break$L1)
diff --git a/test/two_sides.fromasm.imprecise.no-opts b/test/two_sides.fromasm.imprecise.no-opts
index 2abda5dca..94bca7245 100644
--- a/test/two_sides.fromasm.imprecise.no-opts
+++ b/test/two_sides.fromasm.imprecise.no-opts
@@ -79,8 +79,5 @@
         )
       )
     )
-    (return
-      (i32.const 0)
-    )
   )
 )
diff --git a/test/two_sides.fromasm.no-opts b/test/two_sides.fromasm.no-opts
index f49fc79b3..0976e4c90 100644
--- a/test/two_sides.fromasm.no-opts
+++ b/test/two_sides.fromasm.no-opts
@@ -81,8 +81,5 @@
         )
       )
     )
-    (return
-      (i32.const 0)
-    )
   )
 )
diff --git a/test/unit.fromasm.imprecise.no-opts b/test/unit.fromasm.imprecise.no-opts
index 0dbdd7b50..eafbb32f7 100644
--- a/test/unit.fromasm.imprecise.no-opts
+++ b/test/unit.fromasm.imprecise.no-opts
@@ -301,7 +301,6 @@
           (loop $while-in
             (block $while-out
               (br $while-out)
-              (br $while-in)
             )
           )
           (br $label$break$Lout)
@@ -311,10 +310,8 @@
         (loop $while-in8
           (block $while-out7
             (br $label$break$Lout)
-            (br $while-in8)
           )
         )
-        (br $label$break$Lout)
       )
     )
     (loop $label$continue$L1
@@ -335,7 +332,6 @@
                     )
                     (block
                       (br $label$break$L1)
-                      (br $switch10)
                     )
                   )
                   (block
@@ -347,7 +343,6 @@
                 )
                 (block
                   (br $label$break$L3)
-                  (br $switch10)
                 )
               )
               (br $label$break$L1)
@@ -1736,7 +1731,6 @@
           (i32.const 14)
         )
         (br $while-out)
-        (br $while-in)
       )
     )
     (if
diff --git a/test/unit.fromasm.no-opts b/test/unit.fromasm.no-opts
index af5daebe0..29fede80c 100644
--- a/test/unit.fromasm.no-opts
+++ b/test/unit.fromasm.no-opts
@@ -307,7 +307,6 @@
           (loop $while-in
             (block $while-out
               (br $while-out)
-              (br $while-in)
             )
           )
           (br $label$break$Lout)
@@ -317,10 +316,8 @@
         (loop $while-in8
           (block $while-out7
             (br $label$break$Lout)
-            (br $while-in8)
           )
         )
-        (br $label$break$Lout)
       )
     )
     (loop $label$continue$L1
@@ -341,7 +338,6 @@
                     )
                     (block
                       (br $label$break$L1)
-                      (br $switch10)
                     )
                   )
                   (block
@@ -353,7 +349,6 @@
                 )
                 (block
                   (br $label$break$L3)
-                  (br $switch10)
                 )
               )
               (br $label$break$L1)
@@ -1742,7 +1737,6 @@
           (i32.const 14)
         )
         (br $while-out)
-        (br $while-in)
       )
     )
     (if
diff --git a/test/wasm-only.fromasm.imprecise.no-opts b/test/wasm-only.fromasm.imprecise.no-opts
index 4db467f47..4e05d6bd3 100644
--- a/test/wasm-only.fromasm.imprecise.no-opts
+++ b/test/wasm-only.fromasm.imprecise.no-opts
@@ -732,10 +732,7 @@
         (block
           (if
             (get_local $$2)
-            (block
-              (br $label$break$L1)
-              (return)
-            )
+            (br $label$break$L1)
           )
           (i32.store
             (get_local $$0)
diff --git a/test/wasm-only.fromasm.no-opts b/test/wasm-only.fromasm.no-opts
index e71e6b2b2..eae9c4597 100644
--- a/test/wasm-only.fromasm.no-opts
+++ b/test/wasm-only.fromasm.no-opts
@@ -780,10 +780,7 @@
         (block
           (if
             (get_local $$2)
-            (block
-              (br $label$break$L1)
-              (return)
-            )
+            (br $label$break$L1)
           )
           (i32.store
             (get_local $$0)