Following program
cat >test-pg-src.c <<EOF
#include<stdio.h>
int
main(int argc, char **argv)
{
printf("argc: %d argv: %p\n", argc, argv);
return 0;
}
EOF
compiled with "-pg" options
gcc -pg -o test-pg test-pg-src.c
results in following code (disassembled with mdb)
main: leal 0x4(%esp),%ecx
main+4: andl $0xfffffff0,%esp
main+7: pushl -0x4(%ecx)
main+0xa: pushl %ebp
main+0xb: movl %esp,%ebp
main+0xd: pushl %ecx
main+0xe: subl $0x14,%esp
main+0x11: movl $0x8049ed0,%edx
main+0x16: call -0x5d3 <_mcount>
main+0x1b: movl 0x4(%ecx),%eax ; either _mcount should not change ecx
; or the compiler should restore ecx -
; for example "movl 0x14(%esp), %ecx"
; (the number 0x14 is taken from the line
; "main+0xe: subl $0x14,%esp")
main+0x1e: movl %eax,0x8(%esp)
main+0x22: movl (%ecx),%eax
main+0x24: movl %eax,0x4(%esp)
main+0x28: movl $0x8048d6c,(%esp)
main+0x2f: call -0x6c8 <printf>
main+0x34: movl $0x0,%eax
main+0x39: addl $0x14,%esp
main+0x3c: popl %ecx
main+0x3d: popl %ebp
main+0x3e: leal -0x4(%ecx),%esp
main+0x41: ret
After call to mcount register ecx is changed, but commands, following call to
mcount, assume the register ecx unchanged.
--
Summary: mcount in gmon.o change register ecx
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: YLitvinenko at astana dot oilfield dot slb dot com
GCC build triplet: i386-pc-solaris2.11
GCC host triplet: i386-pc-solaris2.11
GCC target triplet: i386-pc-solaris2.11
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38239
