[EH] Fix pops in newly-added blocks in ReFinalize (#8114)

Author: kripken

src/ir/ReFinalize.cpp

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include "ir/eh-utils.h"
 #include "ir/utils.h"
 
 namespace wasm {
@@ -137,7 +138,10 @@ void ReFinalize::visitRethrow(Rethrow* curr) { curr->finalize(); }
 void ReFinalize::visitThrowRef(ThrowRef* curr) { curr->finalize(); }
 void ReFinalize::visitNop(Nop* curr) { curr->finalize(); }
 void ReFinalize::visitUnreachable(Unreachable* curr) { curr->finalize(); }
-void ReFinalize::visitPop(Pop* curr) { curr->finalize(); }
+void ReFinalize::visitPop(Pop* curr) {
+  curr->finalize();
+  seenPop = true;
+}
 void ReFinalize::visitTupleMake(TupleMake* curr) { curr->finalize(); }
 void ReFinalize::visitTupleExtract(TupleExtract* curr) { curr->finalize(); }
 void ReFinalize::visitRefI31(RefI31* curr) { curr->finalize(); }
@@ -210,6 +214,11 @@ void ReFinalize::visitDataSegment(DataSegment* curr) {
   WASM_UNREACHABLE("unimp");
 }
 void ReFinalize::visitTag(Tag* curr) { WASM_UNREACHABLE("unimp"); }
+void ReFinalize::visitFunction(Function* curr) {
+  if (seenPop && addedBlock) {
+    EHUtils::handleBlockNestedPops(curr, *getModule());
+  }
+}
 void ReFinalize::visitModule(Module* curr) { WASM_UNREACHABLE("unimp"); }
 
 void ReFinalize::updateBreakValueType(Name name, Type type) {
@@ -232,6 +241,7 @@ void ReFinalize::replaceUntaken(Expression* value, Expression* otherChild) {
       otherChild = builder.makeDrop(otherChild);
     }
     replaceCurrent(builder.makeBlock({value, otherChild}, Type::unreachable));
+    addedBlock = true;
   } else if (value) {
     replaceCurrent(value);
   } else {

src/ir/utils.h

@@ -145,6 +145,7 @@ struct ReFinalize
   void visitMemory(Memory* curr);
   void visitDataSegment(DataSegment* curr);
   void visitTag(Tag* curr);
+  void visitFunction(Function* curr);
   void visitModule(Module* curr);
 
 private:
@@ -153,6 +154,10 @@ struct ReFinalize
   // Replace an untaken branch/switch with an unreachable value.
   // A condition may also exist and may or may not be unreachable.
   void replaceUntaken(Expression* value, Expression* condition);
+
+  // If we see a pop and also add a block, we need to do EH fixups.
+  bool seenPop = false;
+  bool addedBlock = false;
 };
 
 // Re-finalize a single node. This is slow, if you want to refinalize

test/lit/passes/vacuum-eh-pop.wast

@@ -0,0 +1,65 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
+;; RUN: wasm-opt %s --vacuum -all -S -o - | filecheck %s
+
+(module
+ ;; CHECK:      (type $func (func (param i32)))
+ (type $func (func (param i32)))
+
+ ;; CHECK:      (import "fuzzing-support" "log-i32" (func $import (type $func) (param i32)))
+ (import "fuzzing-support" "log-i32" (func $import (param i32)))
+
+ ;; CHECK:      (tag $tag (type $func) (param i32))
+ (tag $tag (type $func) (param i32))
+
+ ;; CHECK:      (func $test (type $1) (result i32)
+ ;; CHECK-NEXT:  (local $0 i32)
+ ;; CHECK-NEXT:  (block $block (result i32)
+ ;; CHECK-NEXT:   (try
+ ;; CHECK-NEXT:    (do
+ ;; CHECK-NEXT:     (call $import
+ ;; CHECK-NEXT:      (i32.const 0)
+ ;; CHECK-NEXT:     )
+ ;; CHECK-NEXT:    )
+ ;; CHECK-NEXT:    (catch $tag
+ ;; CHECK-NEXT:     (local.set $0
+ ;; CHECK-NEXT:      (pop i32)
+ ;; CHECK-NEXT:     )
+ ;; CHECK-NEXT:     (drop
+ ;; CHECK-NEXT:      (block
+ ;; CHECK-NEXT:       (drop
+ ;; CHECK-NEXT:        (local.get $0)
+ ;; CHECK-NEXT:       )
+ ;; CHECK-NEXT:       (unreachable)
+ ;; CHECK-NEXT:      )
+ ;; CHECK-NEXT:     )
+ ;; CHECK-NEXT:    )
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:   (i32.const 1)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $test (result i32)
+  (block $block (result i32)
+   ;; Vacuum cannot simplify the body here, but it will make a change to the
+   ;; unreachable br_if, replacing it with its dropped children (as the branch
+   ;; is untaken, and we want to remove that reference to $block). While doing
+   ;; so we must update the IR to handle the pop.
+   (try
+    (do
+     (call $import
+      (i32.const 0)
+     )
+    )
+    (catch $tag
+     (drop
+      (br_if $block
+       (pop i32)
+       (unreachable)
+      )
+     )
+    )
+   )
+   (i32.const 1)
+  )
+ )
+)
+