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From: OSKAR BERRETEAGA <oskarb AT fagorautomation DOT es>
To: "'cygwin AT sourceware DOT cygnus DOT com'" <cygwin AT sourceware DOT cygnus DOT com>
Subject: Double alignment trouble
Date: Mon, 8 Feb 1999 10:21:25 +0100
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Hi, all,

I've been trying to change the way gcc aligns double type variables but
with no possitive result. This is the test file I've used:

-------------------------------------> Source file begins
struct mystr_st
{
	char onebyte;
	double onedouble;
};
typedef struct mystr_st MYSTR;

MYSTR myvar;

void foo(void)
{
  myvar.onebyte = 1;
  myvar.onedouble = 0.0;
}
-------------------------------------> End of source file

These are the options I've set with gcc: -malign-double (alone or with
one of the following -march='pentium' -m386 -m486) and the full command
line is: gcc -c test.c -malign-double -o test.o
I've even used the  __attribute__((aligned(2))) for both the struct and
the double var but, again, it seems it has no effect on double
alignment.
>
>Everytime I get the following assembler listing file without regard to
>the options I set:
>
>---------------------------------------------> Listing file begins
>
>GAS LISTING C:\WINDOWS\TEMP\ccWk6MAE.s 			page 1
>
>
>   1              		.file	"test.c"
>   2              	gcc2_compiled.:
>   3              	___gnu_compiled_c:
>   4              	.text
>   5              		.align 4
>   6              	.globl _foo
>   7              		.def	_foo;	.scl	2;	.type	32;	.endef
>   8              	_foo:
>   9 0000 55       		pushl %ebp
>  10 0001 89E5     		movl %esp,%ebp
>  11 0003 C6050000 		movb $1,_myvar
>  11      000001
>  12 000a C7050800 		movl $0,_myvar+8
>  12      00000000 
>  12      0000
>  13 0014 C7050C00 		movl $0,_myvar+12
>  13      00000000 
>  13      0000
>  14              	L1:
>  15 001e 89EC     		movl %ebp,%esp
>  16 0020 5D       		popl %ebp
>  17 0021 C3       		ret
>  18              		.comm	_myvar, 16	 # 16
>
>------------------------------------------> End of listing file
>
>I somehow expected to see a '+4' in line 12 when moving to the double
>var. Is there anyway to change it or am I missing something?
>Thanks in advance.
>
>Oskar Berreteaga Castro
>Depto. I+D Software
>e-mail: oskarb AT fagorautomation DOT es
>
>----------------------------------------------------
>Fagor Automation, S.Coop.
>Barrio San Andres, s/n - P.O. Box. 144
>Mondragon 20500 - SPAIN
>
>Tfno:	+34-943 79 95 11
>Fax:	+34-943 79 17 12
>http://www.fagorautomation.mcc.es
>----------------------------------------------------
>


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