Selectively enable -O3 for gcc for some functions (use auto vectorization).

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/rawconverter.cc

@@ -33,8 +33,8 @@ template<int BIT_DEPTH, RawFormat::Endian ENDIAN, RawFormat::Encoding ENCODING>
 class RawConverterImpl : public RawConverter
 {
 public:
-  void to_raw (const std::vector<float>& samples, std::vector<unsigned char>& bytes);
-  void from_raw (const std::vector<unsigned char>& bytes, std::vector<float>& samples);
+  void to_raw (const std::vector<float>& samples, std::vector<unsigned char>& bytes) AUDIOWMARK_EXTRA_OPT;
+  void from_raw (const std::vector<unsigned char>& bytes, std::vector<float>& samples) AUDIOWMARK_EXTRA_OPT;
 };
 
 template<int BIT_DEPTH, RawFormat::Endian ENDIAN>

src/sfinputstream.cc

@@ -155,7 +155,7 @@ SFInputStream::read_frames (vector<float>& samples, size_t count)
        * used during read and write are identical
        */
       samples.resize (r_count * m_n_channels);
-      const double norm = 1.0 / 0x80000000LL;
+      const float norm = 1.0 / 0x80000000LL;
       for (size_t i = 0; i < samples.size(); i++)
         samples[i] = isamples[i] * norm;
     }

src/sfinputstream.hh

@@ -61,7 +61,7 @@ public:
 
   Error               open (const std::string& filename);
   Error               open (const std::vector<unsigned char> *data);
-  Error               read_frames (std::vector<float>& samples, size_t count) override;
+  Error               read_frames (std::vector<float>& samples, size_t count) override AUDIOWMARK_EXTRA_OPT;
   void                close();
 
   int

src/utils.hh

@@ -39,8 +39,10 @@ bound (const T& min_value, const T& value, const T& max_value)
 // detect compiler
 #if __clang__
   #define AUDIOWMARK_COMP_CLANG
+  #define AUDIOWMARK_EXTRA_OPT
 #elif __GNUC__ > 2
   #define AUDIOWMARK_COMP_GCC
+  #define AUDIOWMARK_EXTRA_OPT __attribute__((optimize("-O3"))) /* enable auto vectorization, some functions benefit a lot from this */
 #else
   #error "unsupported compiler"
 #endif