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/* S/390-specific implementation of profiling support.
Copyright (C) 2000-2017 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, see
<http://www.gnu.org/licenses/>. */
#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.
*/
.globl C_SYMBOL_NAME(_mcount)
.type C_SYMBOL_NAME(_mcount), @function
cfi_startproc
.align ALIGNARG(4)
C_LABEL(_mcount)
/* Save the caller-clobbered registers. */
ahi %r15,-128
cfi_adjust_cfa_offset (128)
stm %r14,%r5,96(%r15)
cfi_offset (r14, 0)
cfi_offset (r15, 4)
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
cfi_adjust_cfa_offset (-128)
br %r14
cfi_endproc
ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(_mcount))
#undef mcount
weak_alias (_mcount, mcount)
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