optimization/8750: Cygwin prolog generation erroneously emitting __alloca as regular function call

[Danny Smith]

The following reply was made to PR optimization/8750; it has been noted by GNATS.

From: =?iso-8859-1?q?Danny=20Smith?= <danny_r_smith_2001@yahoo.co.nz>
To: hercules-390@yahoogroups.com, gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org,
  zHercules@yahoogroups.com, gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org,
  fish@infidels.org
Cc:  
Subject: Re: optimization/8750: Cygwin prolog generation erroneously emitting __alloca as regular function call
Date: Fri, 20 Dec 2002 06:06:43 +1100 (EST)

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8750
 
 The followin fixes PR optimization/8750, a serious regression from 2.95
 on W32 targets (which set TARGET_STACK_PROBE) 
 
 Tested on 3.2 and 3.3 branches with i386-pc-mingw32.
 
 Can someone with more knowledge of 1386 backend please review and
 perhaps suggest less naive fix.
 
 ChangeLog
 
 2002-12-19  Danny Smith  <dannysmith@users.sourceforge.net>
 
 	PR optimization/8750
 	* config/i386/i386.c (ix86_expand_prologue): Don't allow
 	scheduling pass to move insns across __alloca call.
 
 
 Index: i386.c
 ===================================================================
 RCS file: /cvs/gcc/gcc/gcc/config/i386/i386.c,v
 retrieving revision 1.495
 diff -c -3 -p -r1.495 i386.c
 *** i386.c	9 Dec 2002 23:53:59 -0000	1.495
 --- i386.c	19 Dec 2002 10:44:08 -0000
 *************** ix86_expand_prologue ()
 *** 4516,4521 ****
 --- 4516,4525 ----
         CALL_INSN_FUNCTION_USAGE (insn)
   	= gen_rtx_EXPR_LIST (VOIDmode, gen_rtx_USE (VOIDmode, arg0),
   			     CALL_INSN_FUNCTION_USAGE (insn));
 + 
 +       /* Don't allow scheduling pass to move insns across __alloca
 +          call.  */
 +       emit_insn (gen_blockage (const0_rtx));
       }
     if (use_mov)
       {
 
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