RE: [PATCH 1/4]middle-end Support not decomposing specific divisions during vectorization.

[Tamar Christina <Tamar.Christina@arm.com>]

Ping.

> -----Original Message-----
> From: Tamar Christina
> Sent: Monday, October 31, 2022 11:35 AM
> To: Richard Biener <rguenther@suse.de>
> Cc: gcc-patches@gcc.gnu.org; nd <nd@arm.com>; jeffreyalaw@gmail.com
> Subject: RE: [PATCH 1/4]middle-end Support not decomposing specific
> divisions during vectorization.
> 
> >
> > The type of the expression should be available via the mode and the
> > signedness, no?  So maybe to avoid having both RTX and TREE on the
> > target hook pass it a wide_int instead for the divisor?
> >
> 
> Done.
> 
> Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
> and no issues.
> 
> Ok for master?
> 
> Thanks,
> Tamar
> 
> gcc/ChangeLog:
> 
> 	* expmed.h (expand_divmod): Pass tree operands down in addition
> to RTX.
> 	* expmed.cc (expand_divmod): Likewise.
> 	* explow.cc (round_push, align_dynamic_address): Likewise.
> 	* expr.cc (force_operand, expand_expr_divmod): Likewise.
> 	* optabs.cc (expand_doubleword_mod,
> expand_doubleword_divmod):
> 	Likewise.
> 	* target.h: Include tree-core.
> 	* target.def (can_special_div_by_const): New.
> 	* targhooks.cc (default_can_special_div_by_const): New.
> 	* targhooks.h (default_can_special_div_by_const): New.
> 	* tree-vect-generic.cc (expand_vector_operation): Use it.
> 	* doc/tm.texi.in: Document it.
> 	* doc/tm.texi: Regenerate.
> 	* tree-vect-patterns.cc (vect_recog_divmod_pattern): Check for
> support.
> 	* tree-vect-stmts.cc (vectorizable_operation): Likewise.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/vect/vect-div-bitmask-1.c: New test.
> 	* gcc.dg/vect/vect-div-bitmask-2.c: New test.
> 	* gcc.dg/vect/vect-div-bitmask-3.c: New test.
> 	* gcc.dg/vect/vect-div-bitmask.h: New file.
> 
> --- inline copy of patch ---
> 
> diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index
> 92bda1a7e14a3c9ea63e151e4a49a818bf4d1bdb..a29f5c39be3f0927f8ef6e094
> c7a712c0604fb77 100644
> --- a/gcc/doc/tm.texi
> +++ b/gcc/doc/tm.texi
> @@ -6112,6 +6112,22 @@ instruction pattern.  There is no need for the hook
> to handle these two  implementation approaches itself.
>  @end deftypefn
> 
> +@deftypefn {Target Hook} bool
> TARGET_VECTORIZE_CAN_SPECIAL_DIV_BY_CONST
> +(enum @var{tree_code}, tree @var{vectype}, wide_int @var{constant}, rtx
> +*@var{output}, rtx @var{in0}, rtx @var{in1}) This hook is used to test
> +whether the target has a special method of division of vectors of type
> +@var{vectype} using the value @var{constant}, and producing a vector of
> type @var{vectype}.  The division will then not be decomposed by the and
> kept as a div.
> +
> +When the hook is being used to test whether the target supports a
> +special divide, @var{in0}, @var{in1}, and @var{output} are all null.
> +When the hook is being used to emit a division, @var{in0} and @var{in1}
> +are the source vectors of type @var{vecttype} and @var{output} is the
> +destination vector of type @var{vectype}.
> +
> +Return true if the operation is possible, emitting instructions for it
> +if rtxes are provided and updating @var{output}.
> +@end deftypefn
> +
>  @deftypefn {Target Hook} tree
> TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned
> @var{code}, tree @var{vec_type_out}, tree @var{vec_type_in})  This hook
> should return the decl of a function that implements the  vectorized variant
> of the function with the @code{combined_fn} code diff --git
> a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in index
> 112462310b134705d860153294287cfd7d4af81d..d5a745a02acdf051ea1da1b04
> 076d058c24ce093 100644
> --- a/gcc/doc/tm.texi.in
> +++ b/gcc/doc/tm.texi.in
> @@ -4164,6 +4164,8 @@ address;  but often a machine-dependent strategy
> can generate better code.
> 
>  @hook TARGET_VECTORIZE_VEC_PERM_CONST
> 
> +@hook TARGET_VECTORIZE_CAN_SPECIAL_DIV_BY_CONST
> +
>  @hook TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION
> 
>  @hook TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION
> diff --git a/gcc/explow.cc b/gcc/explow.cc index
> ddb4d6ae3600542f8d2bb5617cdd3933a9fae6c0..568e0eb1a158c696458ae678f
> 5e346bf34ba0036 100644
> --- a/gcc/explow.cc
> +++ b/gcc/explow.cc
> @@ -1037,7 +1037,7 @@ round_push (rtx size)
>       TRUNC_DIV_EXPR.  */
>    size = expand_binop (Pmode, add_optab, size, alignm1_rtx,
>  		       NULL_RTX, 1, OPTAB_LIB_WIDEN);
> -  size = expand_divmod (0, TRUNC_DIV_EXPR, Pmode, size, align_rtx,
> +  size = expand_divmod (0, TRUNC_DIV_EXPR, Pmode, NULL, NULL, size,
> + align_rtx,
>  			NULL_RTX, 1);
>    size = expand_mult (Pmode, size, align_rtx, NULL_RTX, 1);
> 
> @@ -1203,7 +1203,7 @@ align_dynamic_address (rtx target, unsigned
> required_align)
>  			 gen_int_mode (required_align / BITS_PER_UNIT - 1,
>  				       Pmode),
>  			 NULL_RTX, 1, OPTAB_LIB_WIDEN);
> -  target = expand_divmod (0, TRUNC_DIV_EXPR, Pmode, target,
> +  target = expand_divmod (0, TRUNC_DIV_EXPR, Pmode, NULL, NULL,
> target,
>  			  gen_int_mode (required_align / BITS_PER_UNIT,
>  					Pmode),
>  			  NULL_RTX, 1);
> diff --git a/gcc/expmed.h b/gcc/expmed.h index
> 0b2538c4c6bd51dfdc772ef70bdf631c0bed8717..0db2986f11ff4a4b10b59501c6
> f33cb3595659b5 100644
> --- a/gcc/expmed.h
> +++ b/gcc/expmed.h
> @@ -708,8 +708,9 @@ extern rtx expand_variable_shift (enum tree_code,
> machine_mode,  extern rtx expand_shift (enum tree_code, machine_mode,
> rtx, poly_int64, rtx,
>  			 int);
>  #ifdef GCC_OPTABS_H
> -extern rtx expand_divmod (int, enum tree_code, machine_mode, rtx, rtx,
> -			  rtx, int, enum optab_methods =
> OPTAB_LIB_WIDEN);
> +extern rtx expand_divmod (int, enum tree_code, machine_mode, tree,
> tree,
> +			  rtx, rtx, rtx, int,
> +			  enum optab_methods = OPTAB_LIB_WIDEN);
>  #endif
>  #endif
> 
> diff --git a/gcc/expmed.cc b/gcc/expmed.cc index
> 8d7418be418406e72a895ecddf2dc7fdb950c76c..bab020c07222afa38305ef8d7
> 333f271b1965b78 100644
> --- a/gcc/expmed.cc
> +++ b/gcc/expmed.cc
> @@ -4222,8 +4222,8 @@ expand_sdiv_pow2 (scalar_int_mode mode, rtx
> op0, HOST_WIDE_INT d)
> 
>  rtx
>  expand_divmod (int rem_flag, enum tree_code code, machine_mode
> mode,
> -	       rtx op0, rtx op1, rtx target, int unsignedp,
> -	       enum optab_methods methods)
> +	       tree treeop0, tree treeop1, rtx op0, rtx op1, rtx target,
> +	       int unsignedp, enum optab_methods methods)
>  {
>    machine_mode compute_mode;
>    rtx tquotient;
> @@ -4375,6 +4375,17 @@ expand_divmod (int rem_flag, enum tree_code
> code, machine_mode mode,
> 
>    last_div_const = ! rem_flag && op1_is_constant ? INTVAL (op1) : 0;
> 
> +  /* Check if the target has specific expansions for the division.  */
> +  tree cst;
> +  if (treeop0
> +      && treeop1
> +      && (cst = uniform_integer_cst_p (treeop1))
> +      && targetm.vectorize.can_special_div_by_const (code, TREE_TYPE
> (treeop0),
> +						     wi::to_wide (cst),
> +						     &target, op0, op1))
> +    return target;
> +
> +
>    /* Now convert to the best mode to use.  */
>    if (compute_mode != mode)
>      {
> @@ -4618,8 +4629,8 @@ expand_divmod (int rem_flag, enum tree_code
> code, machine_mode mode,
>  			    || (optab_handler (sdivmod_optab, int_mode)
>  				!= CODE_FOR_nothing)))
>  		      quotient = expand_divmod (0, TRUNC_DIV_EXPR,
> -						int_mode, op0,
> -						gen_int_mode (abs_d,
> +						int_mode, treeop0, treeop1,
> +						op0, gen_int_mode (abs_d,
>  							      int_mode),
>  						NULL_RTX, 0);
>  		    else
> @@ -4808,8 +4819,8 @@ expand_divmod (int rem_flag, enum tree_code
> code, machine_mode mode,
>  				      size - 1, NULL_RTX, 0);
>  		t3 = force_operand (gen_rtx_MINUS (int_mode, t1, nsign),
>  				    NULL_RTX);
> -		t4 = expand_divmod (0, TRUNC_DIV_EXPR, int_mode, t3,
> op1,
> -				    NULL_RTX, 0);
> +		t4 = expand_divmod (0, TRUNC_DIV_EXPR, int_mode,
> treeop0,
> +				    treeop1, t3, op1, NULL_RTX, 0);
>  		if (t4)
>  		  {
>  		    rtx t5;
> diff --git a/gcc/expr.cc b/gcc/expr.cc
> index
> 80bb1b8a4c5b8350fb1b8f57a99fd52e5882fcb6..b786f1d75e25f3410c0640cd96
> a8abc055fa34d9 100644
> --- a/gcc/expr.cc
> +++ b/gcc/expr.cc
> @@ -8028,16 +8028,17 @@ force_operand (rtx value, rtx target)
>  	    return expand_divmod (0,
>  				  FLOAT_MODE_P (GET_MODE (value))
>  				  ? RDIV_EXPR : TRUNC_DIV_EXPR,
> -				  GET_MODE (value), op1, op2, target, 0);
> +				  GET_MODE (value), NULL, NULL, op1, op2,
> +				  target, 0);
>  	case MOD:
> -	  return expand_divmod (1, TRUNC_MOD_EXPR, GET_MODE (value),
> op1, op2,
> -				target, 0);
> +	  return expand_divmod (1, TRUNC_MOD_EXPR, GET_MODE (value),
> NULL, NULL,
> +				op1, op2, target, 0);
>  	case UDIV:
> -	  return expand_divmod (0, TRUNC_DIV_EXPR, GET_MODE (value),
> op1, op2,
> -				target, 1);
> +	  return expand_divmod (0, TRUNC_DIV_EXPR, GET_MODE (value),
> NULL, NULL,
> +				op1, op2, target, 1);
>  	case UMOD:
> -	  return expand_divmod (1, TRUNC_MOD_EXPR, GET_MODE (value),
> op1, op2,
> -				target, 1);
> +	  return expand_divmod (1, TRUNC_MOD_EXPR, GET_MODE (value),
> NULL, NULL,
> +				op1, op2, target, 1);
>  	case ASHIFTRT:
>  	  return expand_simple_binop (GET_MODE (value), code, op1, op2,
>  				      target, 0, OPTAB_LIB_WIDEN);
> @@ -8990,11 +8991,13 @@ expand_expr_divmod (tree_code code,
> machine_mode mode, tree treeop0,
>        bool speed_p = optimize_insn_for_speed_p ();
>        do_pending_stack_adjust ();
>        start_sequence ();
> -      rtx uns_ret = expand_divmod (mod_p, code, mode, op0, op1, target, 1);
> +      rtx uns_ret = expand_divmod (mod_p, code, mode, treeop0, treeop1,
> +				   op0, op1, target, 1);
>        rtx_insn *uns_insns = get_insns ();
>        end_sequence ();
>        start_sequence ();
> -      rtx sgn_ret = expand_divmod (mod_p, code, mode, op0, op1, target, 0);
> +      rtx sgn_ret = expand_divmod (mod_p, code, mode, treeop0, treeop1,
> +				   op0, op1, target, 0);
>        rtx_insn *sgn_insns = get_insns ();
>        end_sequence ();
>        unsigned uns_cost = seq_cost (uns_insns, speed_p); @@ -9016,7 +9019,8
> @@ expand_expr_divmod (tree_code code, machine_mode mode, tree
> treeop0,
>        emit_insn (sgn_insns);
>        return sgn_ret;
>      }
> -  return expand_divmod (mod_p, code, mode, op0, op1, target, unsignedp);
> +  return expand_divmod (mod_p, code, mode, treeop0, treeop1,
> +			op0, op1, target, unsignedp);
>  }
> 
>  rtx
> diff --git a/gcc/optabs.cc b/gcc/optabs.cc index
> 165f8d1fa22432b96967c69a58dbb7b4bf18120d..cff37ccb0dfc3dd79b97d0abfd
> 872f340855dc96 100644
> --- a/gcc/optabs.cc
> +++ b/gcc/optabs.cc
> @@ -1104,8 +1104,9 @@ expand_doubleword_mod (machine_mode mode,
> rtx op0, rtx op1, bool unsignedp)
>  		return NULL_RTX;
>  	    }
>  	}
> -      rtx remainder = expand_divmod (1, TRUNC_MOD_EXPR, word_mode,
> sum,
> -				     gen_int_mode (INTVAL (op1),
> word_mode),
> +      rtx remainder = expand_divmod (1, TRUNC_MOD_EXPR, word_mode,
> NULL, NULL,
> +				     sum, gen_int_mode (INTVAL (op1),
> +							word_mode),
>  				     NULL_RTX, 1, OPTAB_DIRECT);
>        if (remainder == NULL_RTX)
>  	return NULL_RTX;
> @@ -1208,8 +1209,8 @@ expand_doubleword_divmod (machine_mode
> mode, rtx op0, rtx op1, rtx *rem,
> 
>    if (op11 != const1_rtx)
>      {
> -      rtx rem2 = expand_divmod (1, TRUNC_MOD_EXPR, mode, quot1, op11,
> -				NULL_RTX, unsignedp, OPTAB_DIRECT);
> +      rtx rem2 = expand_divmod (1, TRUNC_MOD_EXPR, mode, NULL, NULL,
> quot1,
> +				op11, NULL_RTX, unsignedp,
> OPTAB_DIRECT);
>        if (rem2 == NULL_RTX)
>  	return NULL_RTX;
> 
> @@ -1223,8 +1224,8 @@ expand_doubleword_divmod (machine_mode
> mode, rtx op0, rtx op1, rtx *rem,
>        if (rem2 == NULL_RTX)
>  	return NULL_RTX;
> 
> -      rtx quot2 = expand_divmod (0, TRUNC_DIV_EXPR, mode, quot1, op11,
> -				 NULL_RTX, unsignedp, OPTAB_DIRECT);
> +      rtx quot2 = expand_divmod (0, TRUNC_DIV_EXPR, mode, NULL, NULL,
> quot1,
> +				 op11, NULL_RTX, unsignedp,
> OPTAB_DIRECT);
>        if (quot2 == NULL_RTX)
>  	return NULL_RTX;
> 
> diff --git a/gcc/target.def b/gcc/target.def index
> 2a7fa68f83dd15dcdd2c332e8431e6142ec7d305..f491e2233cf18760631f148dac
> f18d0e0b133e4c 100644
> --- a/gcc/target.def
> +++ b/gcc/target.def
> @@ -1902,6 +1902,25 @@ implementation approaches itself.",
>  	const vec_perm_indices &sel),
>   NULL)
> 
> +DEFHOOK
> +(can_special_div_by_const,
> + "This hook is used to test whether the target has a special method
> +of\n\ division of vectors of type @var{vectype} using the value
> +@var{constant},\n\ and producing a vector of type @var{vectype}.  The
> +division\n\ will then not be decomposed by the and kept as a div.\n\
> +\n\ When the hook is being used to test whether the target supports a
> +special\n\ divide, @var{in0}, @var{in1}, and @var{output} are all null.
> +When the hook\n\ is being used to emit a division, @var{in0} and
> +@var{in1} are the source\n\ vectors of type @var{vecttype} and
> +@var{output} is the destination vector of\n\ type @var{vectype}.\n\ \n\
> +Return true if the operation is possible, emitting instructions for
> +it\n\ if rtxes are provided and updating @var{output}.",  bool, (enum
> +tree_code, tree vectype, wide_int constant, rtx *output,
> +	rtx in0, rtx in1),
> + default_can_special_div_by_const)
> +
>  /* Return true if the target supports misaligned store/load of a
>     specific factor denoted in the third parameter.  The last parameter
>     is true if the access is defined in a packed struct.  */ diff --git a/gcc/target.h
> b/gcc/target.h index
> d6fa6931499d15edff3e5af3e429540d001c7058..c836036ac7fa7910d62bd3da56
> f39c061f68b665 100644
> --- a/gcc/target.h
> +++ b/gcc/target.h
> @@ -51,6 +51,7 @@
>  #include "insn-codes.h"
>  #include "tm.h"
>  #include "hard-reg-set.h"
> +#include "tree-core.h"
> 
>  #if CHECKING_P
> 
> diff --git a/gcc/targhooks.h b/gcc/targhooks.h index
> ecce55ebe797cedc940620e8d89816973a045d49..c8df2af02b9d8c41d953b7887
> dd980b1a7c5cf1c 100644
> --- a/gcc/targhooks.h
> +++ b/gcc/targhooks.h
> @@ -207,6 +207,8 @@ extern void default_addr_space_diagnose_usage
> (addr_space_t, location_t);  extern rtx default_addr_space_convert (rtx,
> tree, tree);  extern unsigned int default_case_values_threshold (void);
> extern bool default_have_conditional_execution (void);
> +extern bool default_can_special_div_by_const (enum tree_code, tree,
> wide_int,
> +					      rtx *, rtx, rtx);
> 
>  extern bool default_libc_has_function (enum function_class, tree);  extern
> bool default_libc_has_fast_function (int fcode); diff --git a/gcc/targhooks.cc
> b/gcc/targhooks.cc index
> b15ae19bcb60c59ae8112e67b5f06a241a9bdbf1..f941b1c218d3c4de8b7f780b6
> 9fe04593ae3419e 100644
> --- a/gcc/targhooks.cc
> +++ b/gcc/targhooks.cc
> @@ -1807,6 +1807,14 @@ default_have_conditional_execution (void)
>    return HAVE_conditional_execution;
>  }
> 
> +/* Default that no division by constant operations are special.  */
> +bool default_can_special_div_by_const (enum tree_code, tree, wide_int,
> +rtx *, rtx,
> +				  rtx)
> +{
> +  return false;
> +}
> +
>  /* By default we assume that c99 functions are present at the runtime,
>     but sincos is not.  */
>  bool
> diff --git a/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-1.c
> b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-1.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..472cd710534bc8aa9b1b4916f3
> d7b4d5b64a19b9
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-1.c
> @@ -0,0 +1,25 @@
> +/* { dg-require-effective-target vect_int } */
> +
> +#include <stdint.h>
> +#include "tree-vect.h"
> +
> +#define N 50
> +#define TYPE uint8_t
> +
> +__attribute__((noipa, noinline, optimize("O1"))) void fun1(TYPE*
> +restrict pixel, TYPE level, int n) {
> +  for (int i = 0; i < n; i+=1)
> +    pixel[i] = (pixel[i] * level) / 0xff; }
> +
> +__attribute__((noipa, noinline, optimize("O3"))) void fun2(TYPE*
> +restrict pixel, TYPE level, int n) {
> +  for (int i = 0; i < n; i+=1)
> +    pixel[i] = (pixel[i] * level) / 0xff; }
> +
> +#include "vect-div-bitmask.h"
> +
> +/* { dg-final { scan-tree-dump-not "vect_recog_divmod_pattern:
> +detected" "vect" { target aarch64*-*-* } } } */
> diff --git a/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-2.c
> b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-2.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..e904a71885b2e8487593a2cd3
> db75b3e4112e2cc
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-2.c
> @@ -0,0 +1,25 @@
> +/* { dg-require-effective-target vect_int } */
> +
> +#include <stdint.h>
> +#include "tree-vect.h"
> +
> +#define N 50
> +#define TYPE uint16_t
> +
> +__attribute__((noipa, noinline, optimize("O1"))) void fun1(TYPE*
> +restrict pixel, TYPE level, int n) {
> +  for (int i = 0; i < n; i+=1)
> +    pixel[i] = (pixel[i] * level) / 0xffffU; }
> +
> +__attribute__((noipa, noinline, optimize("O3"))) void fun2(TYPE*
> +restrict pixel, TYPE level, int n) {
> +  for (int i = 0; i < n; i+=1)
> +    pixel[i] = (pixel[i] * level) / 0xffffU; }
> +
> +#include "vect-div-bitmask.h"
> +
> +/* { dg-final { scan-tree-dump-not "vect_recog_divmod_pattern:
> +detected" "vect" { target aarch64*-*-* } } } */
> diff --git a/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-3.c
> b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-3.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..a1418ebbf5ea8731ed4e3e720
> 157701d9d1cf852
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask-3.c
> @@ -0,0 +1,26 @@
> +/* { dg-require-effective-target vect_int } */
> +/* { dg-additional-options "-fno-vect-cost-model" { target aarch64*-*-*
> +} } */
> +
> +#include <stdint.h>
> +#include "tree-vect.h"
> +
> +#define N 50
> +#define TYPE uint32_t
> +
> +__attribute__((noipa, noinline, optimize("O1"))) void fun1(TYPE*
> +restrict pixel, TYPE level, int n) {
> +  for (int i = 0; i < n; i+=1)
> +    pixel[i] = (pixel[i] * (uint64_t)level) / 0xffffffffUL; }
> +
> +__attribute__((noipa, noinline, optimize("O3"))) void fun2(TYPE*
> +restrict pixel, TYPE level, int n) {
> +  for (int i = 0; i < n; i+=1)
> +    pixel[i] = (pixel[i] * (uint64_t)level) / 0xffffffffUL; }
> +
> +#include "vect-div-bitmask.h"
> +
> +/* { dg-final { scan-tree-dump-not "vect_recog_divmod_pattern:
> +detected" "vect" { target aarch64*-*-* } } } */
> diff --git a/gcc/testsuite/gcc.dg/vect/vect-div-bitmask.h
> b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask.h
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..29a16739aa4b706616367bfd1
> 832f28ebd07993e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/vect-div-bitmask.h
> @@ -0,0 +1,43 @@
> +#include <stdio.h>
> +
> +#ifndef N
> +#define N 65
> +#endif
> +
> +#ifndef TYPE
> +#define TYPE uint32_t
> +#endif
> +
> +#ifndef DEBUG
> +#define DEBUG 0
> +#endif
> +
> +#define BASE ((TYPE) -1 < 0 ? -126 : 4)
> +
> +int main ()
> +{
> +  TYPE a[N];
> +  TYPE b[N];
> +
> +  for (int i = 0; i < N; ++i)
> +    {
> +      a[i] = BASE + i * 13;
> +      b[i] = BASE + i * 13;
> +      if (DEBUG)
> +        printf ("%d: 0x%x\n", i, a[i]);
> +    }
> +
> +  fun1 (a, N / 2, N);
> +  fun2 (b, N / 2, N);
> +
> +  for (int i = 0; i < N; ++i)
> +    {
> +      if (DEBUG)
> +        printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
> +
> +      if (a[i] != b[i])
> +        __builtin_abort ();
> +    }
> +  return 0;
> +}
> +
> diff --git a/gcc/tree-vect-generic.cc b/gcc/tree-vect-generic.cc index
> 350129555a0c71c0896c4f1003163f3b3557c11b..6ad6372c55eef94a742a8fa35e7
> 9d66aa24e2f3b 100644
> --- a/gcc/tree-vect-generic.cc
> +++ b/gcc/tree-vect-generic.cc
> @@ -1237,6 +1237,17 @@ expand_vector_operation (gimple_stmt_iterator
> *gsi, tree type, tree compute_type
>  	  tree rhs2 = gimple_assign_rhs2 (assign);
>  	  tree ret;
> 
> +	  /* Check if the target was going to handle it through the special
> +	     division callback hook.  */
> +	  tree cst = uniform_integer_cst_p (rhs2);
> +	  if (cst &&
> +	      targetm.vectorize.can_special_div_by_const (code, type,
> +							  wi::to_wide (cst),
> +							  NULL,
> +							  NULL_RTX,
> NULL_RTX))
> +	    return NULL_TREE;
> +
> +
>  	  if (!optimize
>  	      || !VECTOR_INTEGER_TYPE_P (type)
>  	      || TREE_CODE (rhs2) != VECTOR_CST diff --git a/gcc/tree-vect-
> patterns.cc b/gcc/tree-vect-patterns.cc index
> 09574bb1a2696b3438a4ce9f09f74b42e784aca0..e91bcef56fff931a7a7ba534a0
> affd56e7314370 100644
> --- a/gcc/tree-vect-patterns.cc
> +++ b/gcc/tree-vect-patterns.cc
> @@ -3432,7 +3432,7 @@ vect_recog_divmod_pattern (vec_info *vinfo,
>    gimple *pattern_stmt, *def_stmt;
>    enum tree_code rhs_code;
>    optab optab;
> -  tree q;
> +  tree q, cst;
>    int dummy_int, prec;
> 
>    if (!is_gimple_assign (last_stmt))
> @@ -3596,6 +3596,14 @@ vect_recog_divmod_pattern (vec_info *vinfo,
> 
>        return pattern_stmt;
>      }
> +  else if ((cst = uniform_integer_cst_p (oprnd1))
> +	   && targetm.vectorize.can_special_div_by_const (rhs_code,
> vectype,
> +							  wi::to_wide (cst),
> +							  NULL, NULL_RTX,
> +							  NULL_RTX))
> +    {
> +      return NULL;
> +    }
> 
>    if (prec > HOST_BITS_PER_WIDE_INT
>        || integer_zerop (oprnd1))
> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc index
> c9dab217f059f17e91e9a7582523e627d7a45b66..1399c22ba0df75f582887d7e8
> 3b67e3ea53d25f4 100644
> --- a/gcc/tree-vect-stmts.cc
> +++ b/gcc/tree-vect-stmts.cc
> @@ -6260,6 +6260,14 @@ vectorizable_operation (vec_info *vinfo,
>  	}
>        target_support_p = (optab_handler (optab, vec_mode)
>  			  != CODE_FOR_nothing);
> +      tree cst;
> +      if (!target_support_p
> +	  && (cst = uniform_integer_cst_p (op1)))
> +	target_support_p
> +	  = targetm.vectorize.can_special_div_by_const (code, vectype,
> +							wi::to_wide (cst),
> +							NULL, NULL_RTX,
> +							NULL_RTX);
>      }
> 
>    bool using_emulated_vectors_p = vect_emulated_vector_p (vectype);