Fix UBSan on CI (#7173)

The UBSan builder started failing with an error about a misaligned store
in wasm-ctor-eval.cpp. The store was already done via `memcpy` to avoid
alignment issues, but apparently this is no longer enough. Use `void*`
as the destination type to further avoid giving the impression of
guaranteed alignment.

Also fix UB when executing std::abs on minimum negative integers in
literal.cpp.

2 files changed, 13 insertions, 7 deletions

diff --git a/src/tools/wasm-ctor-eval.cpp b/src/tools/wasm-ctor-eval.cpp
index 89727d012..17927f5a6 100644
--- a/src/tools/wasm-ctor-eval.cpp
+++ b/src/tools/wasm-ctor-eval.cpp
@@ -462,30 +462,30 @@ private:
   const size_t MaximumMemory = 100 * 1024 * 1024;
 
   // TODO: handle unaligned too, see shell-interface
-  template<typename T> T* getMemory(Address address, Name memoryName) {
+  void* getMemory(Address address, Name memoryName, size_t size) {
     auto it = memories.find(memoryName);
     assert(it != memories.end());
     auto& memory = it->second;
     // resize the memory buffer as needed.
-    auto max = address + sizeof(T);
+    auto max = address + size;
     if (max > memory.size()) {
       if (max > MaximumMemory) {
         throw FailToEvalException("excessively high memory address accessed");
       }
       memory.resize(max);
     }
-    return (T*)(&memory[address]);
+    return &memory[address];
   }
 
   template<typename T> void doStore(Address address, T value, Name memoryName) {
-    // do a memcpy to avoid undefined behavior if unaligned
-    memcpy(getMemory<T>(address, memoryName), &value, sizeof(T));
+    // Use memcpy to avoid UB if unaligned.
+    memcpy(getMemory(address, memoryName, sizeof(T)), &value, sizeof(T));
   }
 
   template<typename T> T doLoad(Address address, Name memoryName) {
-    // do a memcpy to avoid undefined behavior if unaligned
+    // Use memcpy to avoid UB if unaligned.
     T ret;
-    memcpy(&ret, getMemory<T>(address, memoryName), sizeof(T));
+    memcpy(&ret, getMemory(address, memoryName, sizeof(T)), sizeof(T));
     return ret;
   }
 
diff --git a/src/wasm/literal.cpp b/src/wasm/literal.cpp
index b53378cfa..05027ee6b 100644
--- a/src/wasm/literal.cpp
+++ b/src/wasm/literal.cpp
@@ -978,8 +978,14 @@ Literal Literal::neg() const {
 Literal Literal::abs() const {
   switch (type.getBasic()) {
     case Type::i32:
+      if (i32 == std::numeric_limits<int32_t>::min()) {
+        return *this;
+      }
       return Literal(std::abs(i32));
     case Type::i64:
+      if (i64 == std::numeric_limits<int64_t>::min()) {
+        return *this;
+      }
       return Literal(std::abs(i64));
     case Type::f32:
       return Literal(i32 & 0x7fffffff).castToF32();