On Thu, 5 May 2022, Jan Hubicka wrote: > Also note that visibility pass is run twice (once at compile time before > early optimizations and then again at LTO). Since LTO linking may > promote public symbols to local/hidden, perhaps we want to do this only > second time the pass is executed?
The first pass appears to be redundant and could be avoided, yes. > What is the reson we avoid using LOCAL_DYNAMIC with !optimize while we > are happy to use LOCAL_EXEC with !optimize !flag_shlib? It follows from how local-dynamic model is defined: we call __tls_get_addr with an argument that identifies the current DSO (not the individual thread-local variable), and then compute the address of the variable with a simple addition, so when there are two or more TLS variables, we can call __tls_get_addr just once (but at -O0 we will end up with redundant calls). There's no such concern for local-exec vs initial-exec promotion. Alexander
