>Number:         5248
>Category:       port-mips
>Synopsis:       user profiling is broken on mips
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    gnats-admin (GNATS administrator)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Apr  2 20:35:00 1998
>Last-Modified:
>Originator:     Noriyuki Shiota
>Organization:
Ricoh Co., Ltd.
>Release:        NetBSD-1.3
>Environment:
original port based on NetBSD-1.3-pmax
>Description:
	Profiled object dumps core.
>How-To-Repeat:
	Excute object compiled with -pg and linked with gcrt0.o.
>Fix:
On profiling, gcc inserts the following code at the beginning of procedure:

	move	$at, $ra
	jal	_mcount
	subu	$sp, $sp, 8

"subu" instruction is placed on the delayed slot of "jal".
But gas produces the following for "jal _mcount" on .abicalls case:

	lw	$t9, -32680($gp)	; _mcount
	nop
	jalr	$t9
	nop
	lw	$gp,16($sp)
	nop

In this case, "jalr" and "subu" are not excuted in intended order.

*** gnu/usr.bin/gcc/arch/mips/mips.h	1998/02/20 13:15:16	1.1
--- gnu/usr.bin/gcc/arch/mips/mips.h	1998/02/20 13:15:35
***************
*** 2070,2082 ****
    fprintf (FILE, "\t.set\tnoat\n");					\
    fprintf (FILE, "\tmove\t%s,%s\t\t# save current return address\n",	\
  	   reg_names[GP_REG_FIRST + 1], reg_names[GP_REG_FIRST + 31]);	\
-   fprintf (FILE, "\tjal\t_mcount\n");					\
    fprintf (FILE,							\
  	   "\t%s\t%s,%s,%d\t\t# _mcount pops 2 words from  stack\n",	\
  	   TARGET_64BIT ? "dsubu" : "subu",				\
  	   reg_names[STACK_POINTER_REGNUM],				\
  	   reg_names[STACK_POINTER_REGNUM],				\
  	   TARGET_LONG64 ? 16 : 8);					\
    fprintf (FILE, "\t.set\treorder\n");					\
    fprintf (FILE, "\t.set\tat\n");					\
  }
--- 2070,2083 ----
    fprintf (FILE, "\t.set\tnoat\n");					\
    fprintf (FILE, "\tmove\t%s,%s\t\t# save current return address\n",	\
  	   reg_names[GP_REG_FIRST + 1], reg_names[GP_REG_FIRST + 31]);	\
    fprintf (FILE,							\
  	   "\t%s\t%s,%s,%d\t\t# _mcount pops 2 words from  stack\n",	\
  	   TARGET_64BIT ? "dsubu" : "subu",				\
  	   reg_names[STACK_POINTER_REGNUM],				\
  	   reg_names[STACK_POINTER_REGNUM],				\
  	   TARGET_LONG64 ? 16 : 8);					\
+   fprintf (FILE, "\tjal\t_mcount\n");					\
+   fprintf (FILE, "\tnop\n");						\
    fprintf (FILE, "\t.set\treorder\n");					\
    fprintf (FILE, "\t.set\tat\n");					\
  }
>Audit-Trail:
>Unformatted: