Sriraman Tallam <tmsri...@google.com> writes: > > This comes with caveats. This cannot be generally done for all > functions marked extern as it is impossible for the compiler to say if > a function is "truly extern" (defined in a shared library). If a > function is not truly extern(ends up defined in the final executable), > then calling it indirectly is a performance penalty as it could have > been a direct call. Further, the newly created GOT entries are fixed > up at start-up and do not get lazily bound.
This means you need to make it depend on -fno-semantic-interposition ? > Given this, I propose adding a new option called > -fno-plt=<function-name> to the compiler. This tells the compiler > that we know that the function is truly extern and we want the > indirect call only for these call-sites. I have attached a patch that > adds -fno-plt= to GCC. Any number of "-fno-plt=" can be specified and > all call-sites corresponding to these named functions will be done > indirectly using the mechanism described above without the use of a > PLT stub. The argument seems awkward. The command line may get very long. Better an attribute? Longer term it would be probably better to support it properly in the linker. -Andi -- a...@linux.intel.com -- Speaking for myself only
