Revert "[OptimizeInstructions] Optimize zero sized bulk memory ops even without "ignoreImplicitTraps" (#4295)" (#4459)

This reverts commit 5cf3521708cfada341285414df2dc7366d7e5454.

1 files changed, 5 insertions, 21 deletions

diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 6187e2879..347ebbbe4 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -3406,16 +3406,6 @@ private:
             // memory.copy(dst, src, 0)  ==>  {drop(dst), drop(src)}
             return builder.makeBlock({builder.makeDrop(memCopy->dest),
                                       builder.makeDrop(memCopy->source)});
-          } else {
-            // memory.copy(dst, src, 0)  ==>  {
-            //   drop(i32.load8_u(dst)),
-            //   drop(i32.load8_u(src))
-            // }
-            return builder.makeBlock(
-              {builder.makeDrop(
-                 builder.makeLoad(1, false, 0, 1, memCopy->dest, Type::i32)),
-               builder.makeDrop(builder.makeLoad(
-                 1, false, 0, 1, memCopy->source, Type::i32))});
           }
           break;
         }
@@ -3478,17 +3468,11 @@ private:
     auto* csize = memFill->size->cast<Const>();
     auto bytes = csize->value.getInteger();
 
-    if (bytes == 0LL) {
-      if (options.ignoreImplicitTraps || options.trapsNeverHappen) {
-        // memory.fill(d, v, 0)  ==>  { drop(d), drop(v) }
-        return builder.makeBlock(
-          {builder.makeDrop(memFill->dest), builder.makeDrop(memFill->value)});
-      } else {
-        // memory.fill(d, v, 0)  ==>  { drop(i32.load8_u(d)), drop(v) }
-        return builder.makeBlock({builder.makeDrop(builder.makeLoad(
-                                    1, false, 0, 1, memFill->dest, Type::i32)),
-                                  builder.makeDrop(memFill->value)});
-      }
+    if (bytes == 0LL &&
+        (options.ignoreImplicitTraps || options.trapsNeverHappen)) {
+      // memory.fill(d, v, 0)  ==>  { drop(d), drop(v) }
+      return builder.makeBlock(
+        {builder.makeDrop(memFill->dest), builder.makeDrop(memFill->value)});
     }
 
     const uint32_t offset = 0, align = 1;