On Sat, 2023-10-21 at 15:32 +0800, chenglulu wrote: > > + /* If we are performing LTO for a final link, and we have the linker > > + plugin so we know the resolution of the symbols, then all GOT > > + references are binding to external symbols or preemptable symbols. > > + So the linker cannot relax them. */ > > + return (in_lto_p > > + && !flag_incremental_link > > I don’t quite understand this condition "!flag_incremental_link". Can > you explain it? Others LGTM. > > Thanks.
If we have two (or several) .o files containing LTO bytecode, GCC supports "LTO incremental linking" with: gcc a.o b.o -o ab.o -O2 -flto -flinker-output=nolto-rel The resulted ab.o will include data and code in a.o and b.o, but it contains machine code instead of LTO bytecode. Now if ab.o refers to an external symbol c, the linker may relax "la.global c" to "la.local c" (if ab.o is linked together with another file c.o which contains the definition of c) or not. As we cannot exclude the possibility of a relaxation on la.global for incremental linking, just emit la.global and let the linker to do the correct thing. -- Xi Ruoyao <xry...@xry111.site> School of Aerospace Science and Technology, Xidian University
