optimization/4280: Misplaced warnings with optimized `foo / 0.0'

[Hallvard B Furuseth <h.b.furuseth@usit.uio.no>]

>Number:         4280
>Category:       optimization
>Synopsis:       Misplaced warnings with optimized `foo / 0.0'
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Sep 09 17:16:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Hallvard B Furuseth
>Release:        3.0.1
>Organization:
University of Oslo
>Environment:
System: SunOS bombur.uio.no 5.8 Generic_108528-03 sun4u sparc SUNW,Ultra-5_10
Architecture: sun4

	
host: sparc-sun-solaris2.8
build: sparc-sun-solaris2.8
target: sparc-sun-solaris2.8
configured with: ../gcc-3.0.1/configure --prefix=/usit/bombur/hbf --program-suffix=3 --enable-version-specific-runtime-libs --enable-languages=c --quiet
>Description:
	Warnings `division: NaN - producing operation'
	and `division: function singularity' form optimized code
	get the wrong line numbers.  (The line of the closing
	brace of the end of the function.)

	`gcc -W' produces some correctly placed warnings.

	`gcc -W -O' produces some additional misplaced warnings.
	The warnings which `gcc -W' also produced, are not misplaced.

>How-To-Repeat:
	$ cat a.c
double a, b, c, d, e, f;
void y()
{
  double zero = 0.0;

  /* Misplaced warnings: */
  a = zero / zero;	/* "line 15" NaN */
  b = 0.0  / zero;	/* "line 15" NaN */
  c = zero / 0.0;	/* "line 15" NaN */
  d = 1.0  / zero;	/* "line 15" singularity */

  /* Correctly placed warnings: */
  e = 0.0  / 0.0;	/* line 13  NaN */
  f = 1.0  / 0.0;	/* line 14 singularity */
}			/* line 15 */

/* Correctly placed warnings: */
double g = 0.0 / 0.0;	/* line 18 NaN */
double h = 1.0 / 0.0;	/* line 19 singularity */

	$ gcc3 -W -S a.c
a.c: In function `y':
a.c:13: warning: division: NaN - producing operation
a.c:14: warning: division: function singularity
a.c: At top level:
a.c:18: warning: division: NaN - producing operation
a.c:19: warning: division: function singularity

	$ gcc3 -W -O -S a.c
a.c: In function `y':
a.c:13: warning: division: NaN - producing operation
a.c:14: warning: division: function singularity
a.c:15: warning: division: NaN - producing operation
a.c:15: warning: division: NaN - producing operation
a.c:15: warning: division: NaN - producing operation
a.c:15: warning: division: function singularity
a.c: At top level:
a.c:18: warning: division: NaN - producing operation
a.c:19: warning: division: function singularity
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: