Simplified the pack macros in Portability.h

Removed NANOLOG_PACK_ATTR and changed the NANOLOG_PACK_PUSH/POP macros
to define _Pragma's for GCC. This unifies the structure between the
MSC and GCC macros and simplifies usage across the code base.

Author: syang0

runtime/Log.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2016-2018 Stanford University
+/* Copyright (c) 2016-2020 Stanford University
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -226,7 +226,7 @@ namespace Log {
     struct UnknownHeader {
         uint8_t entryType:2;
         uint8_t other:6;
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
     static_assert(sizeof(UnknownHeader) == 1, "Unknown Header should have a"
@@ -256,7 +256,7 @@ namespace Log {
 
         // Value returned by pack(timestamp)
         uint8_t additionalTimestampBytes:4;
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
     /**
@@ -295,7 +295,7 @@ namespace Log {
         static constexpr uint32_t maxSizeOfHeader() {
             return sizeof(BufferExtent) + sizeof(uint32_t);
         }
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
     /**
@@ -330,7 +330,7 @@ namespace Log {
         // in the log file.
         uint32_t totalMetadataEntries;
 
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
     /**
@@ -351,7 +351,7 @@ namespace Log {
         // Total number of FormatMetadata encountered so far in the log
         // including this fragment (used as a sanity check only).
         uint32_t totalMetadataEntries;
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
     /**
@@ -373,7 +373,7 @@ namespace Log {
         // Length of the format string that is associated with this log
         // invocation and comes after filename.
         uint16_t formatStringLength;
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
     /**
@@ -401,7 +401,7 @@ namespace Log {
 
         // Filename for the original source file containing the LOG statement
         char filename[];
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
     /**
@@ -426,7 +426,7 @@ namespace Log {
         // A fragment of the original LOG statement that contains at most
         // one format specifier.
         char formatFragment[];
-    } NANOLOG_PACK_ATTR;
+    };
     NANOLOG_PACK_POP
 
 

runtime/Packer.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2016-2018 Stanford University
+/* Copyright (c) 2016-2020 Stanford University
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -76,7 +76,7 @@ NANOLOG_PACK_PUSH
 struct TwoNibbles {
     uint8_t first:4;
     uint8_t second:4;
-} NANOLOG_PACK_ATTR;
+};
 NANOLOG_PACK_POP
 
 /**
@@ -285,7 +285,7 @@ unpack(const char **in, uint8_t packNibble) {
     int bytes = packNibble == 0 ? 16 : packNibble;
     std::memcpy(&result, (*in), bytes);
     (*in) += bytes;
-    
+
     return result;
 }
 

runtime/Portability.h

@@ -18,15 +18,12 @@
 #endif
 
 #ifdef _MSC_VER
-#define NANOLOG_PACK_ATTR
 #define NANOLOG_PACK_PUSH __pragma(pack(push, 1))
 #define NANOLOG_PACK_POP __pragma(pack(pop))
 #elif defined(__GNUC__)
-#define NANOLOG_PACK_ATTR __attribute__((__packed__))
-#define NANOLOG_PACK_PUSH
-#define NANOLOG_PACK_POP
+#define NANOLOG_PACK_PUSH _Pragma("pack(push, 1)")
+#define NANOLOG_PACK_POP _Pragma("pack(pop)")
 #else
-#define NANOLOG_PACK_ATTR
 #define NANOLOG_PACK_PUSH
 #define NANOLOG_PACK_POP
 #endif