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Diffstat (limited to 'NOTES.txt')
-rw-r--r-- | NOTES.txt | 26 |
1 files changed, 26 insertions, 0 deletions
@@ -28,6 +28,32 @@ Extensions: //===---------------------------------------------------------------------===// +When we go to reimplement <tgmath.h>, we should do it more intelligently than +the GCC-supplied header. EDG has an interesting __generic builtin that provides +overloading for C: +http://www.edg.com/docs/edg_cpp.pdf + +For example, they have: + #define sin(x) __generic(x,,, sin, sinf, sinl, csin, csinf,csinl)(x) + +It's unclear to me why you couldn't just have a builtin like: + __builtin_overload(1, arg1, impl1, impl2, impl3) + __builtin_overload(2, arg1, arg2, impl1, impl2, impl3) + __builtin_overload(3, arg1, arg2, arg3, impl1, impl2, impl3) + +Where the compiler would just pick the right "impl" based on the arguments +provided. One nasty detail is that some arithmetic promotions most be done for +use by the tgmath.h stuff, but it would be nice to be able to handle vectors +etc as well without huge globs of macros. With the above scheme, you could +use: + + #define sin(x) __builtin_overload(1, x, sin, sinf, sinl, csin, csinf,csinl)(x) + +and not need to keep track of which argument to "__generic" corresponds to which +type, etc. + +//===---------------------------------------------------------------------===// + To time GCC preprocessing speed without output, use: "time gcc -MM file" This is similar to -Eonly. |