Re: [PATCH 3/3] Misaligned MEM_REF reads

[Richard Guenther <rguenther at suse dot de>]

On Wed, 14 Mar 2012, Martin Jambor wrote:

> Hi,
> 
> On Mon, Mar 12, 2012 at 03:09:04PM +0100, Martin Jambor wrote:
> > Hi,
> > 
> > this patch is very similar to the one I posted before
> > (http://gcc.gnu.org/ml/gcc-patches/2012-02/msg01377.html) except that
> > it is now adjusted to sit on top of the new one before this and does
> > not ignore complex numbers...
> 
> This is the same patch updated to apply on top of the new version of
> the previous one (which I have committed a moment ago).  Again,
> bootstrapped and tested on x86_64-linux (all languages including Ada
> and Java), usparc64-linux (without Java) and ia64-linux (without
> Ada), the i686 compile farm machine was not accessible yesterday so I
> don't have any results from it but will start a test right now.
> 
> OK for trunk?

Ok.

Thanks,
Richard.

> Thanks,
> 
> Martin
> 
> 
> 
> 2012-03-12  Martin Jambor  <mjambor@suse.cz>
> 
> 	* expr.c (expand_expr_real_1): handle misaligned scalar reads from
> 	memory through MEM_REFs by calling extract_bit_field.
> 
> 	* testsuite/gcc.dg/misaligned-expand-1.c: New test.
> 	* testsuite/gcc.dg/misaligned-expand-3.c: Likewise.
> 
> 
> Index: src/gcc/expr.c
> ===================================================================
> --- src.orig/gcc/expr.c
> +++ src/gcc/expr.c
> @@ -9411,21 +9411,27 @@ expand_expr_real_1 (tree exp, rtx target
>  	  MEM_VOLATILE_P (temp) = 1;
>  	if (modifier != EXPAND_WRITE
>  	    && mode != BLKmode
> -	    && align < GET_MODE_ALIGNMENT (mode)
> -	    /* If the target does not have special handling for unaligned
> -	       loads of mode then it can use regular moves for them.  */
> -	    && ((icode = optab_handler (movmisalign_optab, mode))
> -		!= CODE_FOR_nothing))
> +	    && align < GET_MODE_ALIGNMENT (mode))
>  	  {
> -	    struct expand_operand ops[2];
> +	    if ((icode = optab_handler (movmisalign_optab, mode))
> +		!= CODE_FOR_nothing)
> +	      {
> +		struct expand_operand ops[2];
>  
> -	    /* We've already validated the memory, and we're creating a
> -	       new pseudo destination.  The predicates really can't fail,
> -	       nor can the generator.  */
> -	    create_output_operand (&ops[0], NULL_RTX, mode);
> -	    create_fixed_operand (&ops[1], temp);
> -	    expand_insn (icode, 2, ops);
> -	    return ops[0].value;
> +		/* We've already validated the memory, and we're creating a
> +		   new pseudo destination.  The predicates really can't fail,
> +		   nor can the generator.  */
> +		create_output_operand (&ops[0], NULL_RTX, mode);
> +		create_fixed_operand (&ops[1], temp);
> +		expand_insn (icode, 2, ops);
> +		return ops[0].value;
> +	      }
> +	    else if (SLOW_UNALIGNED_ACCESS (mode, align))
> +	      temp = extract_bit_field (temp, GET_MODE_BITSIZE (mode),
> +					0, TYPE_UNSIGNED (TREE_TYPE (exp)),
> +					true, (modifier == EXPAND_STACK_PARM
> +					       ? NULL_RTX : target),
> +					mode, mode);
>  	  }
>  	return temp;
>        }
> Index: src/gcc/testsuite/gcc.dg/misaligned-expand-1.c
> ===================================================================
> --- /dev/null
> +++ src/gcc/testsuite/gcc.dg/misaligned-expand-1.c
> @@ -0,0 +1,41 @@
> +/* Test that expand can generate correct loads of misaligned data even on
> +   strict alignment platforms.  */
> +
> +/* { dg-do run } */
> +/* { dg-options "-O0" } */
> +
> +extern void abort ();
> +
> +typedef unsigned int myint __attribute__((aligned(1)));
> +
> +unsigned int
> +foo (myint *p)
> +{
> +  return *p;
> +}
> +
> +#define cst 0xdeadbeef
> +#define NUM 8
> +
> +struct blah
> +{
> +  char c;
> +  myint i[NUM];
> +};
> +
> +struct blah g;
> +
> +int
> +main (int argc, char **argv)
> +{
> +  int i, k;
> +  for (k = 0; k < NUM; k++)
> +    {
> +      g.i[k] = cst;
> +      i = foo (&g.i[k]);
> +
> +      if (i != cst)
> +	abort ();
> +    }
> +  return 0;
> +}
> Index: src/gcc/testsuite/gcc.dg/misaligned-expand-3.c
> ===================================================================
> --- /dev/null
> +++ src/gcc/testsuite/gcc.dg/misaligned-expand-3.c
> @@ -0,0 +1,43 @@
> +/* Test that expand can generate correct stores to misaligned data of complex
> +   type even on strict alignment platforms.  */
> +
> +/* { dg-do run } */
> +/* { dg-options "-O0" } */
> +
> +extern void abort ();
> +
> +typedef _Complex float mycmplx __attribute__((aligned(1)));
> +
> +void
> +foo (mycmplx *p, float r, float i)
> +{
> +  __real__ *p = r;
> +  __imag__ *p = i;
> +}
> +
> +#define cvr 3.2f
> +#define cvi 2.5f
> +#define NUM 8
> +
> +struct blah
> +{
> +  char c;
> +  mycmplx x[NUM];
> +} __attribute__((packed));
> +
> +struct blah g;
> +
> +int
> +main (int argc, char **argv)
> +{
> +  int k;
> +
> +  for (k = 0; k < NUM; k++)
> +    {
> +      foo (&g.x[k], cvr, cvi);
> +      if (__real__ g.x[k] != cvr
> +	  || __imag__ g.x[k] != cvi)
> +	abort ();
> +    }
> +  return 0;
> +}
> 
> 

-- 
Richard Guenther <rguenther@suse.de>
SUSE / SUSE Labs
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