From b69b56b65a76c86f22d5375f6259e962f76642f7 Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Thu, 15 Oct 2026 09:08:31 -0700
Subject: [PATCH 1/2] fix

---
 src/passes/OptimizeInstructions.cpp |  4 ++++
 src/wasm-interpreter.h              | 18 +++++++++++-------
 test/lit/exec/memory.grow-huge.wast | 19 +++++++++++++++++++
 3 files changed, 34 insertions(+), 7 deletions(-)
 create mode 100644 test/lit/exec/memory.grow-huge.wast

diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 15926c65b64..2e0562f21b8 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -1589,6 +1589,10 @@ struct OptimizeInstructions
   //    Given the large amount of potential benefit we can get from a successful
   //    optimization in GUFA, any reduction there may be a bad idea, so we
   //    should be very careful and probably *not* remove such casts.
+  //
+  // The only case where we are always ok to remove such casts is when lastOpts
+  // is true, because nothing significant runs after us that can be harmed. That
+  // logic is in the StripRefiningCasts pass.
 
   // If an instruction traps on a null input, there is no need for a
   // ref.as_non_null on that input: we will trap either way (and the binaryen
diff --git a/src/wasm-interpreter.h b/src/wasm-interpreter.h
index d5e358a081d..d4bd349b1b4 100644
--- a/src/wasm-interpreter.h
+++ b/src/wasm-interpreter.h
@@ -4616,14 +4616,18 @@ class ModuleRunnerBase : public ExpressionRunner<SubType> {
     if (newSize > memory->max) {
       return fail;
     }
-    if (!info.interface()->growMemory(
-          info.name, (memorySize << pageSizeLog2), (newSize << pageSizeLog2))) {
-      // We failed to grow the memory in practice, even though it was valid
-      // to try to do so.
-      return fail;
+    // Only grow if we are actually changing the size (otherwise it is wasted
+    // work, and may OOM unnecessarily).
+    if (delta != 0) {
+      if (!info.interface()->growMemory(
+            info.name, (memorySize << pageSizeLog2), (newSize << pageSizeLog2))) {
+        // We failed to grow the memory in practice, even though it was valid
+        // to try to do so.
+        return fail;
+      }
+      memorySize = newSize;
+      info.instance->setMemorySize(info.name, memorySize);
     }
-    memorySize = newSize;
-    info.instance->setMemorySize(info.name, memorySize);
     return ret;
   }
   Flow visitMemoryInit(MemoryInit* curr) {
diff --git a/test/lit/exec/memory.grow-huge.wast b/test/lit/exec/memory.grow-huge.wast
new file mode 100644
index 00000000000..a14b5c3e14a
--- /dev/null
+++ b/test/lit/exec/memory.grow-huge.wast
@@ -0,0 +1,19 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --output=fuzz-exec and should not be edited.
+
+;; RUN: wasm-opt %s -all --fuzz-exec-before -q -o /dev/null 2>&1 | filecheck %s
+
+;; The memory here is over 2GB in size. We grow it by size 0, that is, just
+;; retrieve the size without changing it. We should not error on an OOM here.
+
+(module
+ (memory i64 32769)
+
+ ;; CHECK:      [fuzz-exec] export measure
+ ;; CHECK-NEXT: [fuzz-exec] note result: measure => 32769
+ (func $measure (export "measure") (result i64)
+  ;; This will return the size, 32769, and not -1 to indicate an OOM.
+  (memory.grow
+   (i64.const 0)
+  )
+ )
+)

From 2b9dd1200edb1ecdba152b72db4a0074c0f14ded Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Thu, 15 Oct 2026 09:08:38 -0700
Subject: [PATCH 2/2] format

---
 src/wasm-interpreter.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/wasm-interpreter.h b/src/wasm-interpreter.h
index d4bd349b1b4..733381f958f 100644
--- a/src/wasm-interpreter.h
+++ b/src/wasm-interpreter.h
@@ -4619,8 +4619,9 @@ class ModuleRunnerBase : public ExpressionRunner<SubType> {
     // Only grow if we are actually changing the size (otherwise it is wasted
     // work, and may OOM unnecessarily).
     if (delta != 0) {
-      if (!info.interface()->growMemory(
-            info.name, (memorySize << pageSizeLog2), (newSize << pageSizeLog2))) {
+      if (!info.interface()->growMemory(info.name,
+                                        (memorySize << pageSizeLog2),
+                                        (newSize << pageSizeLog2))) {
         // We failed to grow the memory in practice, even though it was valid
         // to try to do so.
         return fail;