optimization/8128: gcc 3.1 reports "Internal compiler error in subst, at combine.c:3546"

[chambers at cs dot washington dot edu]

>Number:         8128
>Category:       optimization
>Synopsis:       gcc 3.1 reports "Internal compiler error in subst, at combine.c:3546"
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          ice-on-legal-code
>Submitter-Id:   net
>Arrival-Date:   Wed Oct 02 16:56:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     
>Release:        3.1
>Organization:
University of Washington
>Environment:
System: SunOS rousseau 5.8 Generic_108528-14 sun4u sparc SUNW,Sun-Blade-1000
Architecture: sun4

	
host: sparc-sun-solaris2.8
build: sparc-sun-solaris2.8
target: sparc-sun-solaris2.8
configured with: ../configure --with-as=/usr/ccs/bin/as --with-ld=/usr/ccs/bin/ld --disable-nls
>Description:
gcc 3.1 reports "Internal compiler error in subst, at combine.c:3546"
>How-To-Repeat:

Put this into a file, e.g. t.c:

float m() {
  union {
    double d;
    float f; 
    int i;
  } u;
  u.i = -1;
  return u.f;
}

(The double d; declaration is required to trigger the problem.)

Then compile w/ -O, e.g.
% gcc -O -c t.c

>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: