util: prevent optimizer from removing endian-swapped writes

libraries/libstratosphere/include/stratosphere/ncm/ncm_content_meta_extended_data.hpp

@@ -843,7 +843,7 @@ namespace ams::ncm {
                 R_SUCCEED_IF(m_header.has_value());
 
                 /* Get our header. */
-                PatchMetaExtendedDataHeader header;
+                PatchMetaExtendedDataHeader header{};
                 R_TRY(this->GetHeader(std::addressof(header)));
 
                 /* Set our header. */

libraries/libstratosphere/libstratosphere.mk

@@ -148,6 +148,8 @@ init_libnx_shim.os.horizon.o: CXXFLAGS += -fno-lto
 
 result_get_name.o: CXXFLAGS += -fno-lto
 
+crypto_sha256_generator.o: CXXFLAGS += -fno-lto
+
 spl_secure_monitor_api.os.generic.o: CXXFLAGS += -I$(ATMOSPHERE_LIBRARIES_DIR)/libexosphere/include
 fs_id_string_impl.os.generic.o: CXXFLAGS += -I$(ATMOSPHERE_LIBRARIES_DIR)/libexosphere/include
 

libraries/libvapours/include/vapours/crypto/crypto_sha256_generator.hpp

@@ -47,9 +47,9 @@ namespace ams::crypto {
             };
             static constexpr size_t Asn1IdentifierSize = util::size(Asn1Identifier);
         private:
-            Impl m_impl;
+            Impl m_impl{};
         public:
-            Sha256Generator() { /* ... */ }
+            Sha256Generator() = default;
 
             void Initialize() {
                 m_impl.Initialize();

libraries/libvapours/include/vapours/util/util_endian.hpp

@@ -144,12 +144,12 @@ namespace ams::util {
 
     template<std::integral T>
     constexpr ALWAYS_INLINE void StoreBigEndian(T *ptr, T val) {
-        *ptr = ConvertToBigEndian<T>(val);
+        *static_cast<volatile T *>(ptr) = ConvertToBigEndian<T>(val);
     }
 
     template<std::integral T>
     constexpr ALWAYS_INLINE void StoreLittleEndian(T *ptr, T val) {
-        *ptr = ConvertToLittleEndian<T>(val);
+        *static_cast<volatile T *>(ptr) = ConvertToLittleEndian<T>(val);
     }
 
 }

libraries/libvapours/source/crypto/crypto_sha256_generator.cpp

@@ -18,7 +18,7 @@
 namespace ams::crypto {
 
     void GenerateSha256(void *dst, size_t dst_size, const void *src, size_t src_size) {
-        Sha256Generator gen;
+        Sha256Generator gen{};
 
         gen.Initialize();
         gen.Update(src, src_size);