RE: [PATCH-1v4, expand] Enable vector mode for compare_by_pieces [PR111449]

["Jiang, Haochen" <haochen.jiang@intel.com>]

It seems that the mail got caught elsewhere and did not send into gcc-patches
mailing thread. Resending that.

Thx,
Haochen

-----Original Message-----
From: Jiang, Haochen 
Sent: Tuesday, October 24, 2023 4:43 PM
To: HAO CHEN GUI <guihaoc@linux.ibm.com>; Richard Sandiford <richard.sandiford@arm.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>
Subject: RE: [PATCH-1v4, expand] Enable vector mode for compare_by_pieces [PR111449]

Hi Haochen Gui,

It seems that the commit caused lots of test case fail on x86 platforms:

https://gcc.gnu.org/pipermail/gcc-regression/2023-October/078379.html
https://gcc.gnu.org/pipermail/gcc-regression/2023-October/078380.html
https://gcc.gnu.org/pipermail/gcc-regression/2023-October/078381.html
https://gcc.gnu.org/pipermail/gcc-regression/2023-October/078382.html
https://gcc.gnu.org/pipermail/gcc-regression/2023-October/078383.html
https://gcc.gnu.org/pipermail/gcc-regression/2023-October/078384.html

Please help verify that if we need some testcase change or we get bug here.

A simple reproducer under build folder is:

make check RUNTESTFLAGS="i386.exp=g++.target/i386/pr80566-2.C --target_board='unix{-m64\ -march=cascadelake,-m32\ -march=cascadelake,-m32,-m64}'"

Thx,
Haochen

> -----Original Message-----
> From: HAO CHEN GUI <guihaoc@linux.ibm.com>
> Sent: Monday, October 23, 2023 9:30 AM
> To: Richard Sandiford <richard.sandiford@arm.com>
> Cc: gcc-patches <gcc-patches@gcc.gnu.org>
> Subject: Re: [PATCH-1v4, expand] Enable vector mode for 
> compare_by_pieces [PR111449]
> 
> Committed as r14-4835.
> 
> https://gcc.gnu.org/g:f08ca5903c7a02b450b93143467f70b9fd8e0085
> 
> Thanks
> Gui Haochen
> 
> 在 2023/10/20 16:49, Richard Sandiford 写道:
> > HAO CHEN GUI <guihaoc@linux.ibm.com> writes:
> >> Hi,
> >>   Vector mode instructions are efficient for compare on some targets.
> >> This patch enables vector mode for compare_by_pieces. Two help 
> >> functions are added to check if vector mode is available for 
> >> certain by pieces operations and if if optabs exists for the mode 
> >> and certain by pieces operations. One member is added in class 
> >> op_by_pieces_d to record the type of operations.
> >>
> >>   The test case is in the second patch which is rs6000 specific.
> >>
> >>   Compared to last version, the main change is to add a target hook 
> >> check - scalar_mode_supported_p when retrieving the available 
> >> scalar modes. The mode which is not supported for a target should be skipped.
> >> (e.g. TImode on ppc). Also some function names and comments are 
> >> refined according to reviewer's advice.
> >>
> >>   Bootstrapped and tested on x86 and powerpc64-linux BE and LE with 
> >> no regressions.
> >>
> >> Thanks
> >> Gui Haochen
> >>
> >> ChangeLog
> >> Expand: Enable vector mode for by pieces compares
> >>
> >> Vector mode compare instructions are efficient for equality compare 
> >> on rs6000. This patch refactors the codes of by pieces operation to 
> >> enable vector mode for compare.
> >>
> >> gcc/
> >> 	PR target/111449
> >> 	* expr.cc (can_use_qi_vectors): New function to return true if
> >> 	we know how to implement OP using vectors of bytes.
> >> 	(qi_vector_mode_supported_p): New function to check if optabs
> >> 	exists for the mode and certain by pieces operations.
> >> 	(widest_fixed_size_mode_for_size): Replace the second argument
> >> 	with the type of by pieces operations.  Call can_use_qi_vectors
> >> 	and qi_vector_mode_supported_p to do the check.  Call
> >> 	scalar_mode_supported_p to check if the scalar mode is supported.
> >> 	(by_pieces_ninsns): Pass the type of by pieces operation to
> >> 	widest_fixed_size_mode_for_size.
> >> 	(class op_by_pieces_d): Remove m_qi_vector_mode.  Add m_op to
> >> 	record the type of by pieces operations.
> >> 	(op_by_pieces_d::op_by_pieces_d): Change last argument to the
> >> 	type of by pieces operations, initialize m_op with it.  Pass
> >> 	m_op to function widest_fixed_size_mode_for_size.
> >> 	(op_by_pieces_d::get_usable_mode): Pass m_op to function
> >> 	widest_fixed_size_mode_for_size.
> >> 	(op_by_pieces_d::smallest_fixed_size_mode_for_size): Call
> >> 	can_use_qi_vectors and qi_vector_mode_supported_p to do the
> >> 	check.
> >> 	(op_by_pieces_d::run): Pass m_op to function
> >> 	widest_fixed_size_mode_for_size.
> >> 	(move_by_pieces_d::move_by_pieces_d): Set m_op to
> MOVE_BY_PIECES.
> >> 	(store_by_pieces_d::store_by_pieces_d): Set m_op with the op.
> >> 	(can_store_by_pieces): Pass the type of by pieces operations to
> >> 	widest_fixed_size_mode_for_size.
> >> 	(clear_by_pieces): Initialize class store_by_pieces_d with
> >> 	CLEAR_BY_PIECES.
> >> 	(compare_by_pieces_d::compare_by_pieces_d): Set m_op to
> >> 	COMPARE_BY_PIECES.
> >
> > OK, thanks.  And thanks for your patience.
> >
> > Richard
> >
> >> patch.diff
> >> diff --git a/gcc/expr.cc b/gcc/expr.cc index 
> >> 2c9930ec674..ad5f9dd8ec2 100644
> >> --- a/gcc/expr.cc
> >> +++ b/gcc/expr.cc
> >> @@ -988,18 +988,44 @@ alignment_for_piecewise_move (unsigned int
> max_pieces, unsigned int align)
> >>    return align;
> >>  }
> >>
> >> -/* Return the widest QI vector, if QI_MODE is true, or integer mode
> >> -   that is narrower than SIZE bytes.  */
> >> +/* Return true if we know how to implement OP using vectors of 
> >> +bytes.  */ static bool can_use_qi_vectors (by_pieces_operation op) 
> >> +{
> >> +  return (op == COMPARE_BY_PIECES
> >> +	  || op == SET_BY_PIECES
> >> +	  || op == CLEAR_BY_PIECES);
> >> +}
> >> +
> >> +/* Return true if optabs exists for the mode and certain by pieces
> >> +   operations.  */
> >> +static bool
> >> +qi_vector_mode_supported_p (fixed_size_mode mode,
> by_pieces_operation op)
> >> +{
> >> +  if ((op == SET_BY_PIECES || op == CLEAR_BY_PIECES)
> >> +      && optab_handler (vec_duplicate_optab, mode) !=
> CODE_FOR_nothing)
> >> +    return true;
> >> +
> >> +  if (op == COMPARE_BY_PIECES
> >> +      && optab_handler (mov_optab, mode) != CODE_FOR_nothing
> >> +      && can_compare_p (EQ, mode, ccp_jump))
> >> +    return true;
> >>
> >> +  return false;
> >> +}
> >> +
> >> +/* Return the widest mode that can be used to perform part of an
> >> +   operation OP on SIZE bytes.  Try to use QI vector modes where
> >> +   possible.  */
> >>  static fixed_size_mode
> >> -widest_fixed_size_mode_for_size (unsigned int size, bool 
> >> qi_vector)
> >> +widest_fixed_size_mode_for_size (unsigned int size, 
> >> +by_pieces_operation
> op)
> >>  {
> >>    fixed_size_mode result = NARROWEST_INT_MODE;
> >>
> >>    gcc_checking_assert (size > 1);
> >>
> >>    /* Use QI vector only if size is wider than a WORD.  */
> >> -  if (qi_vector && size > UNITS_PER_WORD)
> >> +  if (can_use_qi_vectors (op) && size > UNITS_PER_WORD)
> >>      {
> >>        machine_mode mode;
> >>        fixed_size_mode candidate;
> >> @@ -1009,8 +1035,7 @@ widest_fixed_size_mode_for_size (unsigned int
> size, bool qi_vector)
> >>  	  {
> >>  	    if (GET_MODE_SIZE (candidate) >= size)
> >>  	      break;
> >> -	    if (optab_handler (vec_duplicate_optab, candidate)
> >> -		!= CODE_FOR_nothing)
> >> +	    if (qi_vector_mode_supported_p (candidate, op))
> >>  	      result = candidate;
> >>  	  }
> >>
> >> @@ -1019,9 +1044,14 @@ widest_fixed_size_mode_for_size (unsigned
> int size, bool qi_vector)
> >>      }
> >>
> >>    opt_scalar_int_mode tmode;
> >> +  scalar_int_mode mode;
> >>    FOR_EACH_MODE_IN_CLASS (tmode, MODE_INT)
> >> -    if (GET_MODE_SIZE (tmode.require ()) < size)
> >> -      result = tmode.require ();
> >> +    {
> >> +      mode = tmode.require ();
> >> +      if (GET_MODE_SIZE (mode) < size
> >> +	  && targetm.scalar_mode_supported_p (mode))
> >> +      result = mode;
> >> +    }
> >>
> >>    return result;
> >>  }
> >> @@ -1061,8 +1091,7 @@ by_pieces_ninsns (unsigned HOST_WIDE_INT l,
> unsigned int align,
> >>      {
> >>        /* NB: Round up L and ALIGN to the widest integer mode for
> >>  	 MAX_SIZE.  */
> >> -      mode = widest_fixed_size_mode_for_size (max_size,
> >> -					      op == SET_BY_PIECES);
> >> +      mode = widest_fixed_size_mode_for_size (max_size, op);
> >>        if (optab_handler (mov_optab, mode) != CODE_FOR_nothing)
> >>  	{
> >>  	  unsigned HOST_WIDE_INT up = ROUND_UP (l, GET_MODE_SIZE
> (mode));
> >> @@ -1076,8 +1105,7 @@ by_pieces_ninsns (unsigned HOST_WIDE_INT l,
> unsigned int align,
> >>
> >>    while (max_size > 1 && l > 0)
> >>      {
> >> -      mode = widest_fixed_size_mode_for_size (max_size,
> >> -					      op == SET_BY_PIECES);
> >> +      mode = widest_fixed_size_mode_for_size (max_size, op);
> >>        enum insn_code icode;
> >>
> >>        unsigned int modesize = GET_MODE_SIZE (mode); @@ -1317,8 
> >> +1345,8 @@ class op_by_pieces_d
> >>    bool m_push;
> >>    /* True if targetm.overlap_op_by_pieces_p () returns true.  */
> >>    bool m_overlap_op_by_pieces;
> >> -  /* True if QI vector mode can be used.  */
> >> -  bool m_qi_vector_mode;
> >> +  /* The type of operation that we're performing.  */  
> >> + by_pieces_operation m_op;
> >>
> >>    /* Virtual functions, overriden by derived classes for the specific
> >>       operation.  */
> >> @@ -1331,7 +1359,7 @@ class op_by_pieces_d
> >>   public:
> >>    op_by_pieces_d (unsigned int, rtx, bool, rtx, bool, by_pieces_constfn,
> >>  		  void *, unsigned HOST_WIDE_INT, unsigned int, bool,
> >> -		  bool = false);
> >> +		  by_pieces_operation);
> >>    void run ();
> >>  };
> >>
> >> @@ -1349,11 +1377,11 @@ op_by_pieces_d::op_by_pieces_d (unsigned
> int max_pieces, rtx to,
> >>  				void *from_cfn_data,
> >>  				unsigned HOST_WIDE_INT len,
> >>  				unsigned int align, bool push,
> >> -				bool qi_vector_mode)
> >> +				by_pieces_operation op)
> >>    : m_to (to, to_load, NULL, NULL),
> >>      m_from (from, from_load, from_cfn, from_cfn_data),
> >>      m_len (len), m_max_size (max_pieces + 1),
> >> -    m_push (push), m_qi_vector_mode (qi_vector_mode)
> >> +    m_push (push), m_op (op)
> >>  {
> >>    int toi = m_to.get_addr_inc ();
> >>    int fromi = m_from.get_addr_inc (); @@ -1375,8 +1403,7 @@ 
> >> op_by_pieces_d::op_by_pieces_d (unsigned int
> max_pieces, rtx to,
> >>      {
> >>        /* Find the mode of the largest comparison.  */
> >>        fixed_size_mode mode
> >> -	= widest_fixed_size_mode_for_size (m_max_size,
> >> -					   m_qi_vector_mode);
> >> +	= widest_fixed_size_mode_for_size (m_max_size, m_op);
> >>
> >>        m_from.decide_autoinc (mode, m_reverse, len);
> >>        m_to.decide_autoinc (mode, m_reverse, len); @@ -1401,7 
> >> +1428,7 @@ op_by_pieces_d::get_usable_mode
> (fixed_size_mode mode, unsigned int len)
> >>        if (len >= size && prepare_mode (mode, m_align))
> >>  	break;
> >>        /* widest_fixed_size_mode_for_size checks SIZE > 1.  */
> >> -      mode = widest_fixed_size_mode_for_size (size, m_qi_vector_mode);
> >> +      mode = widest_fixed_size_mode_for_size (size, m_op);
> >>      }
> >>    while (1);
> >>    return mode;
> >> @@ -1414,7 +1441,7 @@ fixed_size_mode  
> >> op_by_pieces_d::smallest_fixed_size_mode_for_size (unsigned int 
> >> size)  {
> >>    /* Use QI vector only for > size of WORD.  */
> >> -  if (m_qi_vector_mode && size > UNITS_PER_WORD)
> >> +  if (can_use_qi_vectors (m_op) && size > UNITS_PER_WORD)
> >>      {
> >>        machine_mode mode;
> >>        fixed_size_mode candidate;
> >> @@ -1427,8 +1454,7 @@
> op_by_pieces_d::smallest_fixed_size_mode_for_size (unsigned int size)
> >>  	      break;
> >>
> >>  	    if (GET_MODE_SIZE (candidate) >= size
> >> -		&& (optab_handler (vec_duplicate_optab, candidate)
> >> -		    != CODE_FOR_nothing))
> >> +		&& qi_vector_mode_supported_p (candidate, m_op))
> >>  	      return candidate;
> >>  	  }
> >>      }
> >> @@ -1451,7 +1477,7 @@ op_by_pieces_d::run ()
> >>
> >>    /* widest_fixed_size_mode_for_size checks M_MAX_SIZE > 1.  */
> >>    fixed_size_mode mode
> >> -    = widest_fixed_size_mode_for_size (m_max_size, m_qi_vector_mode);
> >> +    = widest_fixed_size_mode_for_size (m_max_size, m_op);
> >>    mode = get_usable_mode (mode, length);
> >>
> >>    by_pieces_prev to_prev = { nullptr, mode }; @@ -1516,8 +1542,7 
> >> @@ op_by_pieces_d::run ()
> >>        else
> >>  	{
> >>  	  /* widest_fixed_size_mode_for_size checks SIZE > 1.  */
> >> -	  mode = widest_fixed_size_mode_for_size (size,
> >> -						  m_qi_vector_mode);
> >> +	  mode = widest_fixed_size_mode_for_size (size, m_op);
> >>  	  mode = get_usable_mode (mode, length);
> >>  	}
> >>      }
> >> @@ -1543,7 +1568,7 @@ class move_by_pieces_d : public
> op_by_pieces_d
> >>    move_by_pieces_d (rtx to, rtx from, unsigned HOST_WIDE_INT len,
> >>  		    unsigned int align)
> >>      : op_by_pieces_d (MOVE_MAX_PIECES, to, false, from, true, NULL,
> >> -		      NULL, len, align, PUSHG_P (to))
> >> +		      NULL, len, align, PUSHG_P (to), MOVE_BY_PIECES)
> >>    {
> >>    }
> >>    rtx finish_retmode (memop_ret);
> >> @@ -1632,15 +1657,16 @@ move_by_pieces (rtx to, rtx from, unsigned
> HOST_WIDE_INT len,
> >>  class store_by_pieces_d : public op_by_pieces_d  {
> >>    insn_gen_fn m_gen_fun;
> >> +
> >>    void generate (rtx, rtx, machine_mode) final override;
> >>    bool prepare_mode (machine_mode, unsigned int) final override;
> >>
> >>   public:
> >>    store_by_pieces_d (rtx to, by_pieces_constfn cfn, void *cfn_data,
> >>  		     unsigned HOST_WIDE_INT len, unsigned int align,
> >> -		     bool qi_vector_mode)
> >> +		     by_pieces_operation op)
> >>      : op_by_pieces_d (STORE_MAX_PIECES, to, false, NULL_RTX, true, cfn,
> >> -		      cfn_data, len, align, false, qi_vector_mode)
> >> +		      cfn_data, len, align, false, op)
> >>    {
> >>    }
> >>    rtx finish_retmode (memop_ret);
> >> @@ -1729,8 +1755,8 @@ can_store_by_pieces (unsigned
> HOST_WIDE_INT len,
> >>        max_size = STORE_MAX_PIECES + 1;
> >>        while (max_size > 1 && l > 0)
> >>  	{
> >> -	  fixed_size_mode mode
> >> -	    = widest_fixed_size_mode_for_size (max_size, memsetp);
> >> +	  auto op = memsetp ? SET_BY_PIECES : STORE_BY_PIECES;
> >> +	  auto mode = widest_fixed_size_mode_for_size (max_size, op);
> >>
> >>  	  icode = optab_handler (mov_optab, mode);
> >>  	  if (icode != CODE_FOR_nothing
> >> @@ -1793,7 +1819,7 @@ store_by_pieces (rtx to, unsigned
> HOST_WIDE_INT len,
> >>  		 optimize_insn_for_speed_p ()));
> >>
> >>    store_by_pieces_d data (to, constfun, constfundata, len, align,
> >> -			  memsetp);
> >> +			  memsetp ? SET_BY_PIECES : STORE_BY_PIECES);
> >>    data.run ();
> >>
> >>    if (retmode != RETURN_BEGIN)
> >> @@ -1814,7 +1840,7 @@ clear_by_pieces (rtx to, unsigned
> HOST_WIDE_INT len, unsigned int align)
> >>    /* Use builtin_memset_read_str to support vector mode broadcast.  */
> >>    char c = 0;
> >>    store_by_pieces_d data (to, builtin_memset_read_str, &c, len, align,
> >> -			  true);
> >> +			  CLEAR_BY_PIECES);
> >>    data.run ();
> >>  }
> >>
> >> @@ -1832,12 +1858,13 @@ class compare_by_pieces_d : public
> op_by_pieces_d
> >>    void generate (rtx, rtx, machine_mode) final override;
> >>    bool prepare_mode (machine_mode, unsigned int) final override;
> >>    void finish_mode (machine_mode) final override;
> >> +
> >>   public:
> >>    compare_by_pieces_d (rtx op0, rtx op1, by_pieces_constfn op1_cfn,
> >>  		       void *op1_cfn_data, HOST_WIDE_INT len, int align,
> >>  		       rtx_code_label *fail_label)
> >>      : op_by_pieces_d (COMPARE_MAX_PIECES, op0, true, op1, true,
> op1_cfn,
> >> -		      op1_cfn_data, len, align, false)
> >> +		      op1_cfn_data, len, align, false, COMPARE_BY_PIECES)
> >>    {
> >>      m_fail_label = fail_label;
> >>    }