From 0722d7c2ac52b343e895b0726fd08ec8e9677c04 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 21 Feb 2012 15:45:17 -0800 Subject: [PATCH] Explain why we don't make use of RDPC in the sparc PIC register setup. * sysdeps/unix/sparc/sysdep.h: Document why we don't use "rd %pc" in the PIC register setup sequences. --- ChangeLog | 3 +++ sysdeps/unix/sparc/sysdep.h | 3 +++ 2 files changed, 6 insertions(+) diff --git a/ChangeLog b/ChangeLog index 5f966e8..c125719 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,8 @@ 2012-02-20 David S. Miller + * sysdeps/unix/sparc/sysdep.h: Document why we don't use + "rd %pc" in the PIC register setup sequences. + * sysdeps/sparc/crti.S: Try to use GOTDATA relocs. * sysdeps/sparc/sparc32/dl-machine.h (RTLD_START): Likewise. * sysdeps/sparc/sparc32/elf/start.S: Likewise. diff --git a/sysdeps/unix/sparc/sysdep.h b/sysdeps/unix/sparc/sysdep.h index 10d561e..1a095cc 100644 --- a/sysdeps/unix/sparc/sysdep.h +++ b/sysdeps/unix/sparc/sysdep.h @@ -39,6 +39,9 @@ __sparc_get_pc_thunk.reg: \ .previous; \ .endif; +/* Even when v9 we use a call sequence instead of using "rd %pc" because + RDPC is extremely expensive and incurs a full pipeline flush. */ + #define SETUP_PIC_REG(reg) \ SPARC_PIC_THUNK(reg) \ sethi %hi(_GLOBAL_OFFSET_TABLE_-4), %##reg; \ -- 2.7.4