/* ss.c: STACK SCANNING
*
* $Id: //info.ravenbrook.com/project/mps/master/code/ss.c#11 $
* Copyright (c) 2001-2020 Ravenbrook Limited. See end of file for license.
*
* This scans the mutator's stack and fixes the registers that may
* contain roots. <design/stack-scan>.
*
* This is a generic implementation, but it makes assumptions that,
* while true on all the platforms we currently (version 1.115)
* support, may not be true on all platforms. See
* <design/stack-scan#.sol.platform>.
*
* .assume.desc: The stack is descending (and so stackHot is a lower
* address than stackCold).
*
* .assume.full: The stack convention is "full" (and so we must scan
* the word pointed to by stackHot but not the word pointed to by
* stackCold).
*/
#include "mpm.h"
SRCID(ss, "$Id: //info.ravenbrook.com/project/mps/master/code/ss.c#11 $");
/* StackHot -- capture a hot stack pointer
*
* On all supported platforms, the arguments are pushed on to the
* stack by the caller below its other local data, so as long as
* it does not use something like alloca, the address of the argument
* is a hot stack pointer. <design/ss#.sol.stack.hot>.
*/
ATTRIBUTE_NOINLINE
void StackHot(void **stackOut)
{
*stackOut = &stackOut;
}
/* StackScan -- scan the mutator's stack and registers */
Res StackScan(ScanState ss, void *stackCold,
mps_area_scan_t scan_area, void *closure)
{
StackContextStruct scStruct;
Arena arena;
/* Avoid the error "variable might be clobbered by 'longjmp'" from
GCC by specifying volatile. See job004113. */
void * volatile warmest;
AVERT(ScanState, ss);
arena = ss->arena;
AVER(arena->stackWarm != NULL);
warmest = arena->stackWarm;
if (warmest == NULL) {
/* Somehow missed saving the context at the entry point
<design/stack-scan#.sol.entry-points.fragile>: do it now. */
warmest = &scStruct;
STACK_CONTEXT_SAVE(&scStruct);
}
AVER(warmest < stackCold); /* .assume.desc */
return TraceScanArea(ss, warmest, stackCold, scan_area, closure);
}
/* C. COPYRIGHT AND LICENSE
*
* Copyright (C) 2001-2020 Ravenbrook Limited <https://www.ravenbrook.com/>.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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