From ed74551f2ec100d55b767a32b4cf2e96f4073cc1 Mon Sep 17 00:00:00 2001
From: Yi LIU <yi@quantstamp.com>
Date: Wed, 11 Feb 2026 13:18:42 +0800
Subject: [PATCH] Fix updateSymbol calls misplaced inside loop in
 copyFunctionWithoutAdd

The updateSymbol calls for prologLocation and epilogLocation were inside
the for loop over debugLocations instead of outside. This caused them to
be skipped when debugLocations was empty, and double-remapped when it
had multiple entries.
---
 src/ir/module-utils.cpp   |  4 +--
 test/gtest/source-map.cpp | 68 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/src/ir/module-utils.cpp b/src/ir/module-utils.cpp
index cf08205191b..cc13101b717 100644
--- a/src/ir/module-utils.cpp
+++ b/src/ir/module-utils.cpp
@@ -93,9 +93,9 @@ copyFunctionWithoutAdd(Function* func,
             (*symbolNameIndexMap)[*(iter.second->symbolNameIndex)];
         }
       }
-      updateSymbol(ret->prologLocation, *symbolNameIndexMap);
-      updateSymbol(ret->epilogLocation, *symbolNameIndexMap);
     }
+    updateSymbol(ret->prologLocation, *symbolNameIndexMap);
+    updateSymbol(ret->epilogLocation, *symbolNameIndexMap);
   }
   ret->module = func->module;
   ret->base = func->base;
diff --git a/test/gtest/source-map.cpp b/test/gtest/source-map.cpp
index a01d064eda6..2e60075fdf1 100644
--- a/test/gtest/source-map.cpp
+++ b/test/gtest/source-map.cpp
@@ -15,7 +15,9 @@
  */
 
 #include "source-map.h"
+#include "ir/module-utils.h"
 #include "print-test.h"
+#include "wasm-builder.h"
 #include "gmock/gmock-matchers.h"
 #include "gtest/gtest.h"
 
@@ -232,3 +234,69 @@ TEST_F(SourceMapTest, SourcesContent) {
             "#include <stdio.h> int main()\\n{ printf(\\\"Gr\\u00fc\\u00df "
             "Gott, Welt!\\\"); return 0;}");
 }
+
+// Regression test: updateSymbol calls for prologLocation/epilogLocation were
+// inside the debugLocations loop instead of outside. When debugLocations is
+// empty, the loop never executes and the locations are not updated.
+TEST(SourceMapCopyTest, UpdateSymbolOutsideLoop) {
+  Module srcModule;
+  Module dstModule;
+  Builder builder(srcModule);
+
+  auto func = builder.makeFunction(
+    "test", {}, Signature(Type::none, Type::none), {}, builder.makeNop());
+
+  // Set prologLocation and epilogLocation with symbolNameIndex values,
+  // but leave debugLocations empty.
+  func->prologLocation =
+    Function::DebugLocation{0, 1, 1, std::optional<BinaryLocation>(0)};
+  func->epilogLocation =
+    Function::DebugLocation{0, 2, 1, std::optional<BinaryLocation>(1)};
+
+  // Symbol name index map: 0->10, 1->11.
+  std::vector<Index> symbolNameIndexMap = {10, 11};
+
+  auto copied = ModuleUtils::copyFunctionWithoutAdd(
+    func.get(), dstModule, Name(), std::nullopt, symbolNameIndexMap);
+
+  ASSERT_TRUE(copied->prologLocation.has_value());
+  ASSERT_TRUE(copied->prologLocation->symbolNameIndex.has_value());
+  EXPECT_EQ(*copied->prologLocation->symbolNameIndex, 10u);
+
+  ASSERT_TRUE(copied->epilogLocation.has_value());
+  ASSERT_TRUE(copied->epilogLocation->symbolNameIndex.has_value());
+  EXPECT_EQ(*copied->epilogLocation->symbolNameIndex, 11u);
+}
+
+// When debugLocations has multiple entries, updateSymbol should only run once
+// per location, not once per loop iteration (which would double-remap).
+TEST(SourceMapCopyTest, UpdateSymbolNotDoubleRemapped) {
+  Module srcModule;
+  Module dstModule;
+  Builder builder(srcModule);
+
+  auto func = builder.makeFunction(
+    "test", {}, Signature(Type::none, Type::none), {}, builder.makeNop());
+
+  func->prologLocation =
+    Function::DebugLocation{0, 1, 1, std::optional<BinaryLocation>(0)};
+
+  // Add multiple debug locations so the loop runs multiple times.
+  auto* nop1 = srcModule.allocator.alloc<Nop>();
+  auto* nop2 = srcModule.allocator.alloc<Nop>();
+  func->debugLocations[nop1] =
+    Function::DebugLocation{0, 10, 1, std::optional<BinaryLocation>(0)};
+  func->debugLocations[nop2] =
+    Function::DebugLocation{0, 11, 1, std::optional<BinaryLocation>(1)};
+
+  // Map: 0->5, 1->6.
+  std::vector<Index> symbolNameIndexMap = {5, 6};
+
+  auto copied = ModuleUtils::copyFunctionWithoutAdd(
+    func.get(), dstModule, Name(), std::nullopt, symbolNameIndexMap);
+
+  // Should be remapped exactly once: 0 -> 5.
+  ASSERT_TRUE(copied->prologLocation.has_value());
+  ASSERT_TRUE(copied->prologLocation->symbolNameIndex.has_value());
+  EXPECT_EQ(*copied->prologLocation->symbolNameIndex, 5u);
+}