mirrors/emacs
1
Fork 0
mirror of git://git.sv.gnu.org/emacs.git synced 2026-04-06 22:31:13 -07:00
Code Issues Projects Releases Wiki Activity

Change.dylan.kinglet.160270: added source for set of callee-saved registers.

Browse source 
Comment on assumptions about __asm__ and code movement/stack discipline.

Copied from Perforce
 Change: 20889
 ServerID: perforce.ravenbrook.com
This commit is contained in:
Martin Simmons 1999-08-11 16:47:28 +01:00
parent 432efc0f5c
commit b4594f2d5e
1 changed files with 23 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

31
mps/src/sslii3.c
View file

@ -1,6 +1,6 @@
/* impl.c.sslii3: LINUX/INTEL STACK SCANNING
*
* $HopeName: $
* $HopeName: MMsrc!sslii3.c(trunk.1) $
* Copyright (C) 1999. Harlequin Group plc. All rights reserved.
*
* This scans the stack and fixes the registers which may contain
@ -10,17 +10,31 @@
* across function calls and therefore may contain roots.
* These are pushed on the stack for scanning.
*
* SOURCES
*
* .source.callees.saves: Set of callee-saved registers taken from
* CALL_USED_REGISTERS in <gcc-sources>/config/i386/i386.h.
*
* ASSUMPTIONS
*
* .align: The stack pointer is assumed to be aligned on a word
* .assume.align: The stack pointer is assumed to be aligned on a word
* boundary.
*
* .assume.asm.stack: The compiler must not do wacky things with the
* stack pointer around a call since we need to ensure that the
* callee-save regs are visible during TraceScanArea.
*
* .assume.asm.order: The volatile modifier should prevent movement
* of code, which might break .assume.asm.stack.
*
*/
#include "mpm.h"
SRCID(sslii3, "$HopeName: $");
SRCID(sslii3, "$HopeName: MMsrc!sslii3.c(trunk.1) $");
/* .assume.asm.order */
#define ASMV(x) __asm__ volatile (x)
@ -29,15 +43,16 @@ Res StackScan(ScanState ss, Addr *stackBot)
Addr *stackTop;
Res res;
ASMV("push %ebx"); /* these registers are the save registers */
/* .assume.asm.stack */
ASMV("push %ebx"); /* These registers are callee-saved */
ASMV("push %esi"); /* and so may contain roots. They are pushed */
ASMV("push %edi"); /* for scanning */
ASMV("mov %%esp, %0" : "=r" (stackTop) :); /* stack pointer */
ASMV("push %edi"); /* for scanning. See .source.callees.saves. */
ASMV("mov %%esp, %0" : "=r" (stackTop) :); /* stackTop = esp */
AVER(AddrIsAligned((Addr)stackTop, sizeof(Addr))); /* .align */
AVER(AddrIsAligned((Addr)stackTop, sizeof(Addr))); /* .assume.align */
res = TraceScanArea(ss, stackTop, stackBot);
ASMV("add $12, %esp"); /* pop 3 registers to restore the stack pointer */
ASMV("add $12, %esp"); /* pop 3 regs to restore the stack pointer */
return res;
}