Added comment to decode_fast.h.

upb/decode_fast.c

@@ -491,6 +491,7 @@ static const char *fastdecode_varint(UPB_PARSE_PARAMS, int tagbytes,
  * {s,o,r,p} x {b1,v4,z4,v8,z8} x {1bt,2bt} */
 
 #define F(card, type, valbytes, tagbytes)                                      \
+  UPB_NOINLINE                                                                 \
   const char *upb_p##card##type##valbytes##_##tagbytes##bt(UPB_PARSE_PARAMS) { \
     return fastdecode_varint(UPB_PARSE_ARGS, tagbytes, valbytes, CARD_##card,  \
                              type##_ZZ,                                        \
@@ -621,7 +622,7 @@ static const char *fastdecode_packedfixed(UPB_PARSE_PARAMS, int tagbytes,
   return fastdecode_dispatch(d, ptr + size, msg, table, hasbits);
 }
 
-
+UPB_FORCEINLINE
 static const char *fastdecode_fixed(UPB_PARSE_PARAMS, int tagbytes,
                                     int valbytes, upb_card card,
                                     _upb_field_parser *unpacked,
@@ -638,6 +639,7 @@ static const char *fastdecode_fixed(UPB_PARSE_PARAMS, int tagbytes,
  * {s,o,r,p} x {f4,f8} x {1bt,2bt} */
 
 #define F(card, valbytes, tagbytes)                                          \
+  UPB_NOINLINE                                                               \
   const char *upb_p##card##f##valbytes##_##tagbytes##bt(UPB_PARSE_PARAMS) {  \
     return fastdecode_fixed(UPB_PARSE_ARGS, tagbytes, valbytes, CARD_##card, \
                             &upb_ppf##valbytes##_##tagbytes##bt,             \

upb/decode_fast.h

@@ -1,8 +1,31 @@
 // These are the specialized field parser functions for the fast parser.
 // Generated tables will refer to these by name.
 //
-// Here we follow the same pattern of macros used in decode_fast.c to declare
-// all of the variants.
+// The function names are encoded with names like:
+//
+//   //  123
+//   upb_pss_1bt();   // Parse singular string, 1 byte tag.
+//
+// In position 1:
+//   - 'p' for parse, most function use this
+//   - 'c' for copy, for when we are copying strings instead of aliasing
+//
+// In position 2 (cardinality):
+//   - 's' for singular, with or without hasbit
+//   - 'o' for oneof
+//   - 'r' for non-packed repeated
+//   - 'p' for packed repeated
+//
+// In position 3 (type):
+//   - 'b1' for bool
+//   - 'v4' for 4-byte varint
+//   - 'v8' for 8-byte varint
+//   - 'z4' for zig-zag-encoded 4-byte varint
+//   - 'z8' for zig-zag-encoded 8-byte varint
+//   - 'f4' for 4-byte fixed
+//   - 'f8' for 8-byte fixed
+//   - 'm' for sub-message
+//   - 's' for string
 
 #ifndef UPB_DECODE_FAST_H_
 #define UPB_DECODE_FAST_H_