Aren/NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Use a more efficient PIC_PROLOG().

Browse Source
This commit is contained in:
eeh 2002-01-14 16:37:36 +00:00
parent 79cc3b0d73
commit cc61f43486
1 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
sys/arch/sparc64/include/asm.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: asm.h,v 1.16 2001/11/03 20:24:43 thorpej Exp $ */
/* $NetBSD: asm.h,v 1.17 2002/01/14 16:37:36 eeh Exp $ */
/*
* Copyright (c) 1994 Allen Briggs
@ -76,14 +76,23 @@
/*
* PIC_PROLOGUE() is akin to the compiler generated function prologue for
* PIC code. It leaves the address of the Global Offset Table in DEST,
* clobbering register TMP in the process. Using the temporary enables us
* to work without a stack frame (doing so requires saving %o7) .
* clobbering register TMP in the process.
*
* We can use two code sequences. We can read the %pc or use the call
* instruction that saves the pc in %o7. Call requires the branch unit and
* IEU1, and clobbers %o7 which needs to be restored. This instruction
* sequence takes about 4 cycles due to instruction interdependence. Reading
* the pc takes 4 cycles to dispatch and is always dispatched alone. That
* sequence takes 7 cycles.
*/
#define PIC_PROLOGUE(dest,tmp) \
mov %o7, tmp; \
sethi %hi(_GLOBAL_OFFSET_TABLE_-4),dest; \
rd %pc, tmp; \
or dest,%lo(_GLOBAL_OFFSET_TABLE_+4),dest; \
add dest,tmp,dest
call 0f; \
or dest,%lo(_GLOBAL_OFFSET_TABLE_+4),dest; \
0: \
add dest,%o7,dest; \
mov tmp, %o7
/*
* PICCY_SET() does the equivalent of a `set var, %dest' instruction in