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94 lines
3.6 KiB
ArmAsm
94 lines
3.6 KiB
ArmAsm
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/*
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(C) Copyright IBM Corp. 2008
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of IBM nor the names of its contributors may be
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used to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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Author: Ken Werner <ken.werner@de.ibm.com>
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*/
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/* _mcount extracts the address of the function just entered and the address
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of the caller of that function and then calls __mcount_internal. The
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prologue calls mcount without saving any registers. The return address is
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stored in $75. The _mcount function has to:
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- create a new stack frame
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- save registers $2 to $75 on the stack
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- copy the two addresses ($0 and $75) into the argument registers $3 and $4
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- call __mcount_internal
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- restore registers
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- return to $75 */
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/* The following two convenience macros assist in the coding of the
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saving and restoring the register.
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saveregs first, last Saves registers from first to the last.
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restoreregs first, last Restores registers from last down to first.
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Note: first must be less than or equal to last. */
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.macro saveregs first, last
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stqd $\first, \first*16($SP)
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.if \last-\first
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saveregs "(\first+1)",\last
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.endif
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.endm
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.macro restoreregs first, last
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lqd $\last, \last*16($SP)
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.if \last-\first
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restoreregs \first,"(\last-1)"
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.endif
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.endm
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/* _mcount needs to be resident since the overlay manager uses the scratch
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registers too. */
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.text
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.align 3 /* 8 byte alignment. */
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.global _mcount
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.type _mcount, @function
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_mcount:
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stqd $lr, 16($sp) /* Save link register in the callers stack frame. */
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stqd $lr, -1216($sp) /* Store back pointer. */
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il $lr, -1216 /* Push a new stack frame. */
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a $sp, $sp, $lr /* Frame size: 16 * (74 + 2) = 1216. */
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/* Save registers $2 to $75 on the stack. */
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saveregs 2, 75
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/* Bring the __mcount_internal arguments in place. */
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lqd $3, 1232($sp) /* frompc (the link register). */
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ori $4, $75, 0 /* selfpc (the gcc prologue puts "brsl $75, _mcount" in
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front of every function). */
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brsl $lr, __mcount_internal
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/* Restore register $2 to $75 from the stack. */
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restoreregs 2, 75
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il $lr, 1216
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a $sp, $sp, $lr /* Pop the stack frame. */
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lqd $lr, 16($sp) /* Restore link register. */
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bi $75 /* Branch to the called function. */
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