Message-Id: <199906082242.RAA19006@mercury.xraylith.wisc.edu>
To: Andris Pavenis <andris AT stargate DOT astr DOT lu DOT lv>
cc: djgpp-workers AT delorie DOT com, egcs-bugs AT egcs DOT cygnus DOT com
Subject: Re: problem with data alignment with egcs-19990602 
In-Reply-To: Your message of "Tue, 08 Jun 1999 10:27:08 -0000."
             <99060810411500 DOT 00968 AT hal> 
Date: Tue, 08 Jun 1999 17:42:16 -0500
From: Mumit Khan <khan AT xraylith DOT wisc DOT EDU>
Reply-To: djgpp-workers AT delorie DOT com

Andris Pavenis <andris AT stargate DOT astr DOT lu DOT lv> writes:
> Problem seems to be related with use of #pragma pack():
> 	I had to put definition of some structures between
> 		#pragma pack(1)
> 	and
> 		#pragma pack()
> 
> It looks that with gcc 2.95 tree the second line (#pragma pack())
> is ignored and as result I'm getting wrong code.
> 	- using __attribute__(packed) instead fixes the problem
> 	- no changes needed for egcs-1.1.2 (#pragma pack() works
> 	   as I expect)
> 
> Below is simple test example that ilustrates the problem
> 
> ----------------------------------------------------
> #include <stdio.h>
> #include <assert.h>
> 
> 
> #pragma pack(1)
> #pragma pack()
> 
> 
> class  Test1
>   {
>   public:
>       char a;
>       long b;
>       Test1 (void)
>         {
> 	    printf ("%p\n",(((char *) & b)-((char *) & a)));
> 	}
>   };
>   
>   
> int main (void)
>   {
>       Test1 x;
>       return 0;
>   }
>   
> ----------------------------------------------------		
> With gcc-1.1.2 I'm getting output 4
> With gcc-2.95 prerelease I'm getting 1
> 
> So we should either have a warning from compiler that #pragma pack()
> should not be used or this problem must be fixed
> 

The alignment should revert to the default when `#pragma pack()' is 
encountered (ie., without an token between the '(' and ')').

Does the following fix it?

Tue Jun  8 17:31:18 1999  Mumit Khan  <khan AT xraylith DOT wisc DOT edu>

	* c-pragma.c (handle_pragma_token): Handle `#pragma pack()'
	correctly.

Index: c-pragma.c
===================================================================
RCS file: /cvs/egcs/egcs/gcc/c-pragma.c,v
retrieving revision 1.16
diff -u -3 -p -r1.16 c-pragma.c
--- c-pragma.c	1999/04/26 21:18:07	1.16
+++ c-pragma.c	1999/06/08 23:37:49
@@ -383,8 +383,15 @@ handle_pragma_token (string, token)
     case ps_left:
 
       if (token == NULL_TREE)
-	state = (strcmp (string, ")") ? ps_bad : ps_right);
-
+	{
+	  if (strcmp (string, ")") == 0)
+	    {
+	      align = 0;
+	      state = ps_right;
+	    }
+	  else
+	    state = ps_bad;
+	}
       else if (TREE_CODE (token) == INTEGER_CST)
 	goto handle_align;
 
Regards,
Mumit