Re: optimization/10315: [3.2/3.3 regression] [powerpc] ICE: in extract_insn, at recog.c:2175

[David Edelsohn <dje@watson.ibm.com>]

The following reply was made to PR optimization/10315; it has been noted by GNATS.

From: David Edelsohn <dje@watson.ibm.com>
To: Geoff Keating <geoffk@geoffk.org>
Cc: s.bosscher@student.tudelft.nl, gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org,
   adconrad@0c3.net, 186299@bugs.debian.org, gcc-patches@gcc.gnu.org
Subject: Re: optimization/10315: [3.2/3.3 regression] [powerpc] ICE: in extract_insn, at recog.c:2175 
Date: Wed, 23 Apr 2003 16:09:59 -0400

 >>>>> Geoff Keating writes:
 
 > In that case, the RTL should never have been generated...
 
 	The original C code appears to be buggy and GCC is not handling
 the error very gracefully.  The C code is:
 
 case 'f': {
         float v;
 
         memcpy(&v, &input[inputpos], sizeof(float));
         add_assoc_double(return_value, n, (double)v);
 
         break;
 }
 
 case 'd': {
         double v;
 
         memcpy(&v, &input[inputpos], sizeof(float));
         add_assoc_double(return_value, n, v);
 
         break;
 }
 
 Notice case 'd' memcpy uses sizeof(float), not sizeof(double).  GCC
 inlines the memcpy(), but only half of "v" is set.
 flow.c:initialize_uninitialized_subregs() simply jams in a zero in the
 entry block for the function:
 
         insn = gen_move_insn (param.retval,
                               CONST0_RTX (GET_MODE (param.retval)));
 
 	If I change sizeof(float) to sizeof(double) for case 'd', the
 function compiles without error.  The sizeof(float) seems to be a typo, so
 my first suggestion is fix the source code.
 
 	GCC probably should not fall on its face when presented with this
 type of error, but I am not sure who sure ensure a valid insn.
 gen_move_insn() should not be called that late?
 
 David