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Re: 2 new testcases



  > 
  > On Tue, Jun 30, 1998 at 08:35:05PM -3100, H.J. Lu wrote:
  > > --- /dev/null	Wed Dec 31 16:00:00 1969
  > > +++ execute/980630-1.c	Tue Jun 30 20:07:49 1998
  > > @@ -0,0 +1,17 @@
  > > +long A [2] = {0};
  > > +long B [2] = {2, 0};
  > > +
  > > +main ()
  > > +{
  > > +  unsigned int i;
  > > +  long long u;
  > > +  for (i = 0; i < 2; i+=2)
  > > +  {
  > > +    u = A [i] + B [i];
  > > +    u = (long long) (*(((long *)&( u ))+1)) + A [i+1] + B [i+1];
  > 
  > This line will fail with big endian or -fstrict-aliasing.
  > 

  Ooops. I forgot about endian. We can move it to gcc.dg and
  test it on little endian machines only, like x86. As for
  -fstrict-aliasing, I have submitted a patch for the bug.
  It works with -fstrict-aliasing.

It may at the moment.  But, your code is not conforming ANSI C, even
assuming the existence of long long.  You are referencing a variable of
type `long long' (namely `u') through a pointer of type `long'.
That's a no-no.  If you want to submit this test case, you should
explicitly add -fno-strict-aliasing to the compiler options.  IMO, you
should write this code differently.  The only even semi-portable way
to do what you are doing is to use type-punning through unions.

-- 
Mark Mitchell 			mark@markmitchell.com
Mark Mitchell Consulting	http://www.markmitchell.com


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