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glibc/sysdeps/s390/s390-32/s390-mcount.S
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/* S/390-specific implemetation of profiling support. | |
Copyright (C) 2000, 2001 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com) | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, write to the Free | |
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
02111-1307 USA. */ | |
#include <sysdep.h> | |
/* | |
* How profiling works on S/390: | |
* On the start of each function _mcount is called with the address of a | |
* data word in %r1 (initialized to 0, used for counting). The compiler | |
* with the option -p generates code of the form: | |
* | |
* STM 6,15,24(15) | |
* BRAS 13,.LTN0_0 | |
* .LT0_0: | |
* .LC12: .long _mcount | |
* .LC13: .long .LP0 | |
* .data | |
* .align 4 | |
* .LP0: .long 0 | |
* .text | |
* # function profiler | |
* st 14,4(15) | |
* l 14,.LC12-.LT0_0(13) | |
* l 1,.LC13-.LT0_0(13) | |
* basr 14,14 | |
* l 14,4(15) | |
* | |
* The _mcount implementation now has to call __mcount_internal with the | |
* address of .LP0 as first parameter and the return address as second | |
* parameter. &.LP0 was loaded to %r1 and the return address is in %r14. | |
* _mcount may not modify any register. | |
*/ | |
ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(_mcount) | |
ASM_TYPE_DIRECTIVE(C_SYMBOL_NAME(_mcount), @function) | |
.align ALIGNARG(4) | |
C_LABEL(_mcount) | |
/* Save the caller-clobbered registers. */ | |
ahi %r15,-128 | |
stm %r14,%r5,96(%r15) | |
l %r2,132(%r15) # callers address = first parameter | |
la %r2,0(%r2) # clear bit 0 | |
la %r3,0(%r14) # callees address = second parameter | |
#ifdef PIC | |
bras %r14,0f | |
.long _GLOBAL_OFFSET_TABLE_-. | |
0: al %r14,0(%r14) | |
l %r14,__mcount_internal@GOT(%r14) | |
#else | |
bras %r14,0f | |
.long __mcount_internal | |
0: l %r14,0(%r14) | |
#endif | |
basr %r14,%r14 | |
/* | |
* Pop the saved registers. Please note that `mcount' has no | |
* return value. | |
*/ | |
lm %r14,%r5,96(%r15) | |
ahi %r15,128 | |
br %r14 | |
ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(_mcount)) | |
#undef mcount | |
weak_alias (_mcount, mcount) |