https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85216
--- Comment #2 from Timothy Pearson <tpearson at raptorengineering dot com> --- (In reply to David Edelsohn from comment #1) > What two additional instructions? x86 is a CISC architecture and Power is a > RISC architecture. x86 has an instruction that directly performs an > indirect call through a pointer. Power must explicitly load the pointer and > move it to the appropriate register to perform an indirect branch. > > One can comment / questions that the *SEQUENCE* appears to require more time > on Power than the equivalent sequence on x86. But directly comparing > instructions and counting instructions in two different ISAs without context > is not meaningful. That is in fact what I am concerned with, the fact that the sequence is taking longer than the equivalent sequence on x86. I am aware that the two instruction sequences accomplish the same goal, but for some reason the x86 one is fast enough that it doesn't even show up in the perf output as a hot instruction, while the ppc64 sequence stalls twice (two hot instructions), once on the load and once on the register move.
