Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!PRINCETON.EDU!ney
From: ney@PRINCETON.EDU (Neal Young)
Newsgroups: gnu.gcc.bug
Subject: gcc bug
Message-ID: <8905292137.AA23435@notecnirp.Princeton.EDU>
Date: 29 May 89 21:37:03 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 36


I think I've run across a gcc bug involving floating point constants.
Here is a .c file and a shell session demonstrating the bug.
(I'm running on a fairly large vax...)

tmp.c
-------------------------------------------------------------
main()
{
  float i;
  i = 1.0;
  printf("%g is %s greater than zero\n", i, i > 0.0 ? "" : "not" );
}
-------------------------------------------------------------

Shell session:
-------------------------------------------------------------
notecnirp> gcc -v -o tmp tmp.c
gcc version 1.35
 /usr/local/gnu/lib/gcc-cpp -v -undef -D__GNUC__ -Dvax -Dunix -D__vax__ -D__unix__ tmp.c /tmp/cc023377.cpp
GNU CPP version 1.35
 /usr/local/gnu/lib/gcc-cc1 /tmp/cc023377.cpp -quiet -dumpbase tmp.c -version -o /tmp/cc023377.s
GNU C version 1.35 (vax) compiled by GNU C version 1.35.
tmp.c: In function main:
tmp.c:4: magnitude of constant too large for `float'
notecnirp> 
----------------------------------------------------------------

I've also had problems with "gas" involving floating points.  In
particular, the above program on one of our Suns compiles but the
assignment "i = 1.0" sets i to zero, so the program outputs "0 is not
greater than zero".  I documented this form of the problem, which
seemed to be an assembler bug from examining the code produced etc.
and sent it to hack@gnu.ai.mit.edu.

  Neal Young (ney@notecnirp.princeton.edu)