RE: [PATCH]middle-end: check if target can do extract first for early breaks [PR113199]

[Richard Biener <rguenther@suse.de>]

On Tue, 9 Jan 2024, Tamar Christina wrote:

> > > -
> > > -      gimple_seq_add_seq (&stmts, tem);
> > > -
> > > -      scalar_res = gimple_build (&stmts, CFN_EXTRACT_LAST, scalar_type,
> > > -				 mask, vec_lhs_phi);
> > > +	scalar_res = gimple_build (&stmts, CFN_VEC_EXTRACT, TREE_TYPE
> > (vectype),
> > > +				   vec_lhs_phi, bitstart);
> > 
> > So bitstart is always zero?  I wonder why using CFN_VEC_EXTRACT over
> > BIT_FIELD_REF here which wouldn't need any additional target support.
> > 
> 
> Ok, how about...
> 
> ---
> 
> I was generating the vector reverse mask without checking if the target
> actually supported such an operation.
> 
> This patch changes it to if the bitstart is 0 then use BIT_FIELD_REF instead
> to extract the first element since this is supported by all targets.
> 
> This is good for now since masks always come from whilelo.  But in the future
> when masks can come from other sources we will need the old code back.
> 
> Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
> and no issues with --enable-checking=release --enable-lto
> --with-build-config=bootstrap-O3 --enable-checking=yes,rtl,extra.
> tested on cross cc1 for amdgcn-amdhsa and issue fixed.
> 
> Ok for master?

OK.

> Thanks,
> Tamar
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/113199
> 	* tree-vect-loop.cc (vectorizable_live_operation_1): Use
> 	BIT_FIELD_REF.
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR tree-optimization/113199
> 	* gcc.target/gcn/pr113199.c: New test.
> 
> --- inline copy of patch ---
> 
> diff --git a/gcc/testsuite/gcc.target/gcn/pr113199.c b/gcc/testsuite/gcc.target/gcn/pr113199.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..8a641e5536e80e207ca0163cac66c0f4f6ca93f7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/gcn/pr113199.c
> @@ -0,0 +1,44 @@
> +/* { dg-do compile } */
> +/* { dg-additional-options "-O2" } */
> +
> +typedef long unsigned int size_t;
> +typedef int wchar_t;
> +struct tm
> +{
> +  int tm_mon;
> +  int tm_year;
> +};
> +int abs (int);
> +struct lc_time_T { const char *month[12]; };
> +struct __locale_t * __get_current_locale (void) { }
> +const struct lc_time_T * __get_time_locale (struct __locale_t *locale) { }
> +const wchar_t * __ctloc (wchar_t *buf, const char *elem, size_t *len_ret) { return buf; }
> +size_t
> +__strftime (wchar_t *s, size_t maxsize, const wchar_t *format,
> +     const struct tm *tim_p, struct __locale_t *locale)
> +{
> +  size_t count = 0;
> +  const wchar_t *ctloc;
> +  wchar_t ctlocbuf[256];
> +  size_t i, ctloclen;
> +  const struct lc_time_T *_CurrentTimeLocale = __get_time_locale (locale);
> +    {
> +      switch (*format)
> + {
> + case L'B':
> +   (ctloc = __ctloc (ctlocbuf, _CurrentTimeLocale->month[tim_p->tm_mon], &ctloclen));
> +   for (i = 0; i < ctloclen; i++)
> +     {
> +       if (count < maxsize - 1)
> +  s[count++] = ctloc[i];
> +       else
> +  return 0;
> +       {
> +  int century = tim_p->tm_year >= 0
> +    ? tim_p->tm_year / 100 + 1900 / 100
> +    : abs (tim_p->tm_year + 1900) / 100;
> +       }
> +   }
> + }
> +    }
> +}
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index 37f1be1101ffae779214056a0886411e0683e887..39b1161309d8ff8bfe88ee26df9147df0af0a58c 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -10592,7 +10592,17 @@ vectorizable_live_operation_1 (loop_vec_info loop_vinfo,
>  
>    gimple_seq stmts = NULL;
>    tree new_tree;
> -  if (LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
> +
> +  /* If bitstart is 0 then we can use a BIT_FIELD_REF  */
> +  if (integer_zerop (bitstart))
> +    {
> +      tree scalar_res = gimple_build (&stmts, BIT_FIELD_REF, TREE_TYPE (vectype),
> +				   vec_lhs_phi, bitsize, bitstart);
> +
> +      /* Convert the extracted vector element to the scalar type.  */
> +      new_tree = gimple_convert (&stmts, lhs_type, scalar_res);
> +    }
> +  else if (LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
>      {
>        /* Emit:
>  
> @@ -10618,12 +10628,6 @@ vectorizable_live_operation_1 (loop_vec_info loop_vinfo,
>        tree last_index = gimple_build (&stmts, PLUS_EXPR, TREE_TYPE (len),
>  				     len, bias_minus_one);
>  
> -      /* This needs to implement extraction of the first index, but not sure
> -	 how the LEN stuff works.  At the moment we shouldn't get here since
> -	 there's no LEN support for early breaks.  But guard this so there's
> -	 no incorrect codegen.  */
> -      gcc_assert (!LOOP_VINFO_EARLY_BREAKS (loop_vinfo));
> -
>        /* SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN + BIAS - 1>.  */
>        tree scalar_res
>  	= gimple_build (&stmts, CFN_VEC_EXTRACT, TREE_TYPE (vectype),
> @@ -10648,32 +10652,6 @@ vectorizable_live_operation_1 (loop_vec_info loop_vinfo,
>  				      &LOOP_VINFO_MASKS (loop_vinfo),
>  				      1, vectype, 0);
>        tree scalar_res;
> -
> -      /* For an inverted control flow with early breaks we want EXTRACT_FIRST
> -	 instead of EXTRACT_LAST.  Emulate by reversing the vector and mask. */
> -      if (restart_loop && LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
> -	{
> -	  /* First create the permuted mask.  */
> -	  tree perm_mask = perm_mask_for_reverse (TREE_TYPE (mask));
> -	  tree perm_dest = copy_ssa_name (mask);
> -	  gimple *perm_stmt
> -		= gimple_build_assign (perm_dest, VEC_PERM_EXPR, mask,
> -				       mask, perm_mask);
> -	  vect_finish_stmt_generation (loop_vinfo, stmt_info, perm_stmt,
> -				       &gsi);
> -	  mask = perm_dest;
> -
> -	  /* Then permute the vector contents.  */
> -	  tree perm_elem = perm_mask_for_reverse (vectype);
> -	  perm_dest = copy_ssa_name (vec_lhs_phi);
> -	  perm_stmt
> -		= gimple_build_assign (perm_dest, VEC_PERM_EXPR, vec_lhs_phi,
> -				       vec_lhs_phi, perm_elem);
> -	  vect_finish_stmt_generation (loop_vinfo, stmt_info, perm_stmt,
> -				       &gsi);
> -	  vec_lhs_phi = perm_dest;
> -	}
> -
>        gimple_seq_add_seq (&stmts, tem);
>  
>        scalar_res = gimple_build (&stmts, CFN_EXTRACT_LAST, scalar_type,
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)