[EH] Fix nested pops when GTO removes a GC operation (WebAssembly#7242)

Author: kripken

src/passes/GlobalTypeOptimization.cpp

@@ -22,6 +22,7 @@
 //  * Fields that are never read from can be removed entirely.
 //
 
+#include "ir/eh-utils.h"
 #include "ir/localize.h"
 #include "ir/module-utils.h"
 #include "ir/ordering.h"
@@ -453,6 +454,8 @@ struct GlobalTypeOptimization : public Pass {
         return std::make_unique<FieldRemover>(parent);
       }
 
+      bool needEHFixups = false;
+
       void visitStructNew(StructNew* curr) {
         if (curr->type == Type::unreachable) {
           return;
@@ -476,6 +479,8 @@ struct GlobalTypeOptimization : public Pass {
         ChildLocalizer localizer(
           curr, getFunction(), *getModule(), getPassOptions());
         replaceCurrent(localizer.getReplacement());
+        // Adding a block here requires EH fixups.
+        needEHFixups = true;
 
         // Remove and reorder operands.
         Index removed = 0;
@@ -519,6 +524,7 @@ struct GlobalTypeOptimization : public Pass {
                                            getFunction(),
                                            getModule(),
                                            getPassOptions());
+          needEHFixups = true;
           Expression* replacement =
             builder.makeDrop(builder.makeRefAs(RefAsNonNull, flipped));
           if (curr->order == MemoryOrder::SeqCst) {
@@ -545,6 +551,12 @@ struct GlobalTypeOptimization : public Pass {
         curr->index = newIndex;
       }
 
+      void visitFunction(Function* curr) {
+        if (needEHFixups) {
+          EHUtils::handleBlockNestedPops(curr, *getModule());
+        }
+      }
+
     private:
       Index getNewIndex(HeapType type, Index index) {
         auto iter = parent.indexesAfterRemovals.find(type);

test/lit/passes/gto-removals.wast

@@ -1627,3 +1627,55 @@
     )
   )
 )
+
+;; A struct with a pop, which requires EH fixups to avoid popping in a nested
+;; block.
+(module
+  (type $i32 (func (param i32)))
+
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $struct (struct))
+  (type $struct (struct (field (mut i32))))
+
+  ;; CHECK:       (type $1 (func))
+
+  ;; CHECK:       (type $i32 (func (param i32)))
+
+  ;; CHECK:      (tag $tag (type $i32) (param i32))
+  (tag $tag (type $i32) (param i32))
+
+  ;; CHECK:      (func $func (type $1)
+  ;; CHECK-NEXT:  (local $0 i32)
+  ;; CHECK-NEXT:  (local $1 i32)
+  ;; CHECK-NEXT:  (try
+  ;; CHECK-NEXT:   (do
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:   (catch $tag
+  ;; CHECK-NEXT:    (local.set $1
+  ;; CHECK-NEXT:     (pop i32)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:    (drop
+  ;; CHECK-NEXT:     (block (result (ref $struct))
+  ;; CHECK-NEXT:      (local.set $0
+  ;; CHECK-NEXT:       (local.get $1)
+  ;; CHECK-NEXT:      )
+  ;; CHECK-NEXT:      (struct.new_default $struct)
+  ;; CHECK-NEXT:     )
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $func
+    (try
+      (do
+      )
+      (catch $tag
+        (drop
+          (struct.new $struct
+            (pop i32)
+          )
+        )
+      )
+    )
+  )
+)