path: root/gcc/match.pd

/* Match-and-simplify patterns for shared GENERIC and GIMPLE folding.
   This file is consumed by genmatch which produces gimple-match.c
   and generic-match.c from it.

   Copyright (C) 2014 Free Software Foundation, Inc.
   Contributed by Richard Biener <rguenther@suse.de>
   and Prathamesh Kulkarni  <bilbotheelffriend@gmail.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */


/* Generic tree predicates we inherit.  */
(define_predicates
   integer_onep integer_zerop integer_all_onesp integer_minus_onep
   integer_each_onep
   real_zerop real_onep real_minus_onep
   CONSTANT_CLASS_P
   tree_expr_nonnegative_p)


/* Simplifications of operations with one constant operand and
   simplifications to constants or single values.  */

(for op (plus pointer_plus minus bit_ior bit_xor)
  (simplify
    (op @0 integer_zerop)
    (non_lvalue @0)))

/* 0 +p index -> (type)index */
(simplify
 (pointer_plus integer_zerop @1)
 (non_lvalue (convert @1)))

/* Simplify x - x.
   This is unsafe for certain floats even in non-IEEE formats.
   In IEEE, it is unsafe because it does wrong for NaNs.
   Also note that operand_equal_p is always false if an operand
   is volatile.  */
(simplify
  (minus @0 @0)
  (if (!FLOAT_TYPE_P (type) || !HONOR_NANS (TYPE_MODE (type)))
   { build_zero_cst (type); }))

(simplify
  (mult @0 integer_zerop@1)
  @1)

/* Make sure to preserve divisions by zero.  This is the reason why
   we don't simplify x / x to 1 or 0 / x to 0.  */
(for op (mult trunc_div ceil_div floor_div round_div exact_div)
  (simplify
    (op @0 integer_onep)
    (non_lvalue @0)))

/* Same applies to modulo operations, but fold is inconsistent here
   and simplifies 0 % x to 0, only preserving literal 0 % 0.  */
(for op (ceil_mod floor_mod round_mod trunc_mod)
 /* 0 % X is always zero.  */
 (simplify
  (op integer_zerop@0 @1)
  /* But not for 0 % 0 so that we can get the proper warnings and errors.  */
  (if (!integer_zerop (@1))
   @0))
 /* X % 1 is always zero.  */
 (simplify
  (op @0 integer_onep)
  { build_zero_cst (type); }))

/* x | ~0 -> ~0  */
(simplify
  (bit_ior @0 integer_all_onesp@1)
  @1)

/* x & 0 -> 0  */
(simplify
  (bit_and @0 integer_zerop@1)
  @1)

/* x ^ x -> 0 */
(simplify
  (bit_xor @0 @0)
  { build_zero_cst (type); })

/* Canonicalize X ^ ~0 to ~X.  */
(simplify
  (bit_xor @0 integer_all_onesp@1)
  (bit_not @0))

/* x & ~0 -> x  */
(simplify
 (bit_and @0 integer_all_onesp)
  (non_lvalue @0))

/* x & x -> x,  x | x -> x  */
(for bitop (bit_and bit_ior)
 (simplify
  (bitop @0 @0)
  (non_lvalue @0)))

(simplify
 (abs (negate @0))
 (abs @0))
(simplify
 (abs tree_expr_nonnegative_p@0)
 @0)


/* Try to fold (type) X op CST -> (type) (X op ((type-x) CST))
   when profitable.
   For bitwise binary operations apply operand conversions to the
   binary operation result instead of to the operands.  This allows
   to combine successive conversions and bitwise binary operations.
   We combine the above two cases by using a conditional convert.  */
(for bitop (bit_and bit_ior bit_xor)
 (simplify
  (bitop (convert @0) (convert? @1))
  (if (((TREE_CODE (@1) == INTEGER_CST
	 && INTEGRAL_TYPE_P (TREE_TYPE (@0))
	 && int_fits_type_p (@1, TREE_TYPE (@0)))
	|| (GIMPLE && types_compatible_p (TREE_TYPE (@0), TREE_TYPE (@1)))
	|| (GENERIC && TREE_TYPE (@0) == TREE_TYPE (@1)))
       /* ???  This transform conflicts with fold-const.c doing
	  Convert (T)(x & c) into (T)x & (T)c, if c is an integer
	  constants (if x has signed type, the sign bit cannot be set
	  in c).  This folds extension into the BIT_AND_EXPR.
	  Restrict it to GIMPLE to avoid endless recursions.  */
       && (bitop != BIT_AND_EXPR || GIMPLE)
       && (/* That's a good idea if the conversion widens the operand, thus
	      after hoisting the conversion the operation will be narrower.  */
	   TYPE_PRECISION (TREE_TYPE (@0)) < TYPE_PRECISION (type)
	   /* It's also a good idea if the conversion is to a non-integer
	      mode.  */
	   || GET_MODE_CLASS (TYPE_MODE (type)) != MODE_INT
	   /* Or if the precision of TO is not the same as the precision
	      of its mode.  */
	   || TYPE_PRECISION (type) != GET_MODE_PRECISION (TYPE_MODE (type))))
   (convert (bitop @0 (convert @1))))))

/* Simplify (A & B) OP0 (C & B) to (A OP0 C) & B. */
(for bitop (bit_and bit_ior bit_xor)
 (simplify
  (bitop (bit_and:c @0 @1) (bit_and @2 @1))
  (bit_and (bitop @0 @2) @1)))

/* (x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2) */
(simplify
  (bit_and (bit_ior @0 CONSTANT_CLASS_P@1) CONSTANT_CLASS_P@2)
  (bit_ior (bit_and @0 @2) (bit_and @1 @2)))

/* Combine successive equal operations with constants.  */
(for bitop (bit_and bit_ior bit_xor)
 (simplify
  (bitop (bitop @0 CONSTANT_CLASS_P@1) CONSTANT_CLASS_P@2)
  (bitop @0 (bitop @1 @2))))

/* Try simple folding for X op !X, and X op X with the help
   of the truth_valued_p and logical_inverted_value predicates.  */
(match truth_valued_p
 @0
 (if (INTEGRAL_TYPE_P (type) && TYPE_PRECISION (type) == 1)))
(for op (lt le eq ne ge gt truth_and truth_andif truth_or truth_orif truth_xor)
 (match truth_valued_p
  (op @0 @1)))
(match truth_valued_p
  (truth_not @0))

(match (logical_inverted_value @0)
 (bit_not truth_valued_p@0))
(match (logical_inverted_value @0)
 (eq @0 integer_zerop)
 (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)))))
(match (logical_inverted_value @0)
 (ne truth_valued_p@0 integer_onep)
 (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)))))
(match (logical_inverted_value @0)
 (bit_xor truth_valued_p@0 integer_onep))

/* X & !X -> 0.  */
(simplify
 (bit_and:c @0 (logical_inverted_value @0))
 { build_zero_cst (type); })
/* X | !X and X ^ !X -> 1, , if X is truth-valued.  */
(for op (bit_ior bit_xor)
 (simplify
  (op:c truth_valued_p@0 (logical_inverted_value @0))
  { build_one_cst (type); }))

(for bitop (bit_and bit_ior)
     rbitop (bit_ior bit_and)
  /* (x | y) & x -> x */
  /* (x & y) | x -> x */
 (simplify
  (bitop:c (rbitop:c @0 @1) @0)
  @0)
 /* (~x | y) & x -> x & y */
 /* (~x & y) | x -> x | y */
 (simplify
  (bitop:c (rbitop:c (bit_not @0) @1) @0)
  (bitop @0 @1)))

/* If arg1 and arg2 are booleans (or any single bit type)
   then try to simplify:

   (~X & Y) -> X < Y
   (X & ~Y) -> Y < X
   (~X | Y) -> X <= Y
   (X | ~Y) -> Y <= X

   But only do this if our result feeds into a comparison as
   this transformation is not always a win, particularly on
   targets with and-not instructions.
   -> simplify_bitwise_binary_boolean */
(simplify
  (ne (bit_and:c (bit_not @0) @1) integer_zerop)
  (if (INTEGRAL_TYPE_P (TREE_TYPE (@1))
       && TYPE_PRECISION (TREE_TYPE (@1)) == 1)
   (lt @0 @1)))
(simplify
  (ne (bit_ior:c (bit_not @0) @1) integer_zerop)
  (if (INTEGRAL_TYPE_P (TREE_TYPE (@1))
       && TYPE_PRECISION (TREE_TYPE (@1)) == 1)
   (le @0 @1)))

/* ~~x -> x */
(simplify
  (bit_not (bit_not @0))
  @0)


/* Associate (p +p off1) +p off2 as (p +p (off1 + off2)).  */
(simplify
  (pointer_plus (pointer_plus @0 @1) @3)
  (pointer_plus @0 (plus @1 @3)))

/* Pattern match
     tem1 = (long) ptr1;
     tem2 = (long) ptr2;
     tem3 = tem2 - tem1;
     tem4 = (unsigned long) tem3;
     tem5 = ptr1 + tem4;
   and produce
     tem5 = ptr2;  */
(simplify
  (pointer_plus @0 (convert?@2 (minus@3 (convert @1) (convert @0))))
  /* Conditionally look through a sign-changing conversion.  */
  (if (TYPE_PRECISION (TREE_TYPE (@2)) == TYPE_PRECISION (TREE_TYPE (@3))
       && ((GIMPLE && useless_type_conversion_p (type, TREE_TYPE (@1)))
	    || (GENERIC && type == TREE_TYPE (@1))))
   @1))

/* Pattern match
     tem = (sizetype) ptr;
     tem = tem & algn;
     tem = -tem;
     ... = ptr p+ tem;
   and produce the simpler and easier to analyze with respect to alignment
     ... = ptr & ~algn;  */
(simplify
  (pointer_plus @0 (negate (bit_and (convert @0) INTEGER_CST@1)))
  (with { tree algn = wide_int_to_tree (TREE_TYPE (@0), wi::bit_not (@1)); }
   (bit_and @0 { algn; })))


/* We can't reassociate at all for saturating types.  */
(if (!TYPE_SATURATING (type))

 /* Contract negates.  */
 /* A + (-B) -> A - B */
 (simplify
  (plus:c (convert1? @0) (convert2? (negate @1)))
  /* Apply STRIP_NOPS on @0 and the negate.  */
  (if (tree_nop_conversion_p (type, TREE_TYPE (@0))
       && tree_nop_conversion_p (type, TREE_TYPE (@1))
       && (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0)
   (minus (convert @0) (convert @1))))
 /* A - (-B) -> A + B */
 (simplify
  (minus (convert1? @0) (convert2? (negate @1)))
  (if (tree_nop_conversion_p (type, TREE_TYPE (@0))
       && tree_nop_conversion_p (type, TREE_TYPE (@1)))
   (plus (convert @0) (convert @1))))
 /* -(-A) -> A */
 (simplify
  (negate (convert? (negate @1)))
  (if (tree_nop_conversion_p (type, TREE_TYPE (@1))
       && (TYPE_OVERFLOW_WRAPS (type)
	   || (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0))
   (convert @1)))

 /* We can't reassociate floating-point or fixed-point plus or minus
    because of saturation to +-Inf.  */
 (if (!FLOAT_TYPE_P (type) && !FIXED_POINT_TYPE_P (type))

  /* Match patterns that allow contracting a plus-minus pair
     irrespective of overflow issues.  */
  /* (A +- B) - A       ->  +- B */
  /* (A +- B) -+ B      ->  A */
  /* A - (A +- B)       -> -+ B */
  /* A +- (B -+ A)      ->  +- B */
  (simplify
    (minus (plus:c @0 @1) @0)
    @1)
  (simplify
    (minus (minus @0 @1) @0)
    (negate @1))
  (simplify
    (plus:c (minus @0 @1) @1)
    @0)
  (simplify
   (minus @0 (plus:c @0 @1))
   (negate @1))
  (simplify
   (minus @0 (minus @0 @1))
   @1)

  /* (A +- CST) +- CST -> A + CST  */
  (for outer_op (plus minus)
   (for inner_op (plus minus)
    (simplify
     (outer_op (inner_op @0 CONSTANT_CLASS_P@1) CONSTANT_CLASS_P@2)
     /* If the constant operation overflows we cannot do the transform
	as we would introduce undefined overflow, for example
	with (a - 1) + INT_MIN.  */
     (with { tree cst = fold_binary (outer_op == inner_op
				     ? PLUS_EXPR : MINUS_EXPR, type, @1, @2); }
      (if (cst && !TREE_OVERFLOW (cst))
       (inner_op @0 { cst; } ))))))

  /* (CST - A) +- CST -> CST - A  */
  (for outer_op (plus minus)
   (simplify
    (outer_op (minus CONSTANT_CLASS_P@1 @0) CONSTANT_CLASS_P@2)
    (with { tree cst = fold_binary (outer_op, type, @1, @2); }
     (if (cst && !TREE_OVERFLOW (cst))
      (minus { cst; } @0)))))

  /* ~A + A -> -1 */
  (simplify
   (plus:c (bit_not @0) @0)
   (if (!TYPE_OVERFLOW_TRAPS (type))
    { build_all_ones_cst (type); }))

  /* ~A + 1 -> -A */
  (simplify
   (plus (bit_not @0) integer_each_onep)
   (negate @0))

  /* (T)(P + A) - (T)P -> (T) A */
  (for add (plus pointer_plus)
   (simplify
    (minus (convert (add @0 @1))
     (convert @0))
    (if (TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@1))
	 /* For integer types, if A has a smaller type
	    than T the result depends on the possible
	    overflow in P + A.
	    E.g. T=size_t, A=(unsigned)429497295, P>0.
	    However, if an overflow in P + A would cause
	    undefined behavior, we can assume that there
	    is no overflow.  */
	 || (INTEGRAL_TYPE_P (TREE_TYPE (@0))
	     && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
	 /* For pointer types, if the conversion of A to the
	    final type requires a sign- or zero-extension,
	    then we have to punt - it is not defined which
	    one is correct.  */
	 || (POINTER_TYPE_P (TREE_TYPE (@0))
	     && TREE_CODE (@1) == INTEGER_CST
	     && tree_int_cst_sign_bit (@1) == 0))
     (convert @1))))))



/* Simplifications of conversions.  */

/* Basic strip-useless-type-conversions / strip_nops.  */
(for cvt (convert view_convert float fix_trunc)
 (simplify
  (cvt @0)
  (if ((GIMPLE && useless_type_conversion_p (type, TREE_TYPE (@0)))
       || (GENERIC && type == TREE_TYPE (@0)))
   @0)))

/* Contract view-conversions.  */
(simplify
  (view_convert (view_convert @0))
  (view_convert @0))

/* For integral conversions with the same precision or pointer
   conversions use a NOP_EXPR instead.  */
(simplify
  (view_convert @0)
  (if ((INTEGRAL_TYPE_P (type) || POINTER_TYPE_P (type))
       && (INTEGRAL_TYPE_P (TREE_TYPE (@0)) || POINTER_TYPE_P (TREE_TYPE (@0)))
       && TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (@0)))
   (convert @0)))

/* Strip inner integral conversions that do not change precision or size.  */
(simplify
  (view_convert (convert@0 @1))
  (if ((INTEGRAL_TYPE_P (TREE_TYPE (@0)) || POINTER_TYPE_P (TREE_TYPE (@0)))
       && (INTEGRAL_TYPE_P (TREE_TYPE (@1)) || POINTER_TYPE_P (TREE_TYPE (@1)))
       && (TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (TREE_TYPE (@1)))
       && (TYPE_SIZE (TREE_TYPE (@0)) == TYPE_SIZE (TREE_TYPE (@1))))
   (view_convert @1)))

/* Re-association barriers around constants and other re-association
   barriers can be removed.  */
(simplify
 (paren CONSTANT_CLASS_P@0)
 @0)
(simplify
 (paren (paren@1 @0))
 @1)

/* Handle cases of two conversions in a row.  */
(for ocvt (convert float fix_trunc)
 (for icvt (convert float)
  (simplify
   (ocvt (icvt@1 @0))
   (with
    {
      tree inside_type = TREE_TYPE (@0);
      tree inter_type = TREE_TYPE (@1);
      int inside_int = INTEGRAL_TYPE_P (inside_type);
      int inside_ptr = POINTER_TYPE_P (inside_type);
      int inside_float = FLOAT_TYPE_P (inside_type);
      int inside_vec = TREE_CODE (inside_type) == VECTOR_TYPE;
      unsigned int inside_prec = TYPE_PRECISION (inside_type);
      int inside_unsignedp = TYPE_UNSIGNED (inside_type);
      int inter_int = INTEGRAL_TYPE_P (inter_type);
      int inter_ptr = POINTER_TYPE_P (inter_type);
      int inter_float = FLOAT_TYPE_P (inter_type);
      int inter_vec = TREE_CODE (inter_type) == VECTOR_TYPE;
      unsigned int inter_prec = TYPE_PRECISION (inter_type);
      int inter_unsignedp = TYPE_UNSIGNED (inter_type);
      int final_int = INTEGRAL_TYPE_P (type);
      int final_ptr = POINTER_TYPE_P (type);
      int final_float = FLOAT_TYPE_P (type);
      int final_vec = TREE_CODE (type) == VECTOR_TYPE;
      unsigned int final_prec = TYPE_PRECISION (type);
      int final_unsignedp = TYPE_UNSIGNED (type);
    }
   /* In addition to the cases of two conversions in a row
      handled below, if we are converting something to its own
      type via an object of identical or wider precision, neither
      conversion is needed.  */
   (if (((GIMPLE && useless_type_conversion_p (type, inside_type))
	 || (GENERIC
	     && TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (inside_type)))
	&& (((inter_int || inter_ptr) && final_int)
	    || (inter_float && final_float))
	&& inter_prec >= final_prec)
    (ocvt @0))

   /* Likewise, if the intermediate and initial types are either both
      float or both integer, we don't need the middle conversion if the
      former is wider than the latter and doesn't change the signedness
      (for integers).  Avoid this if the final type is a pointer since
      then we sometimes need the middle conversion.  Likewise if the
      final type has a precision not equal to the size of its mode.  */
   (if (((inter_int && inside_int)
	 || (inter_float && inside_float)
	 || (inter_vec && inside_vec))
	&& inter_prec >= inside_prec
	&& (inter_float || inter_vec
	    || inter_unsignedp == inside_unsignedp)
	&& ! (final_prec != GET_MODE_PRECISION (TYPE_MODE (type))
	      && TYPE_MODE (type) == TYPE_MODE (inter_type))
	&& ! final_ptr
	&& (! final_vec || inter_prec == inside_prec))
    (ocvt @0))

   /* If we have a sign-extension of a zero-extended value, we can
      replace that by a single zero-extension.  Likewise if the
      final conversion does not change precision we can drop the
      intermediate conversion.  */
   (if (inside_int && inter_int && final_int
	&& ((inside_prec < inter_prec && inter_prec < final_prec
	     && inside_unsignedp && !inter_unsignedp)
	    || final_prec == inter_prec))
    (ocvt @0))

   /* Two conversions in a row are not needed unless:
	- some conversion is floating-point (overstrict for now), or
	- some conversion is a vector (overstrict for now), or
	- the intermediate type is narrower than both initial and
	  final, or
	- the intermediate type and innermost type differ in signedness,
	  and the outermost type is wider than the intermediate, or
	- the initial type is a pointer type and the precisions of the
	  intermediate and final types differ, or
	- the final type is a pointer type and the precisions of the
	  initial and intermediate types differ.  */
   (if (! inside_float && ! inter_float && ! final_float
	&& ! inside_vec && ! inter_vec && ! final_vec
	&& (inter_prec >= inside_prec || inter_prec >= final_prec)
	&& ! (inside_int && inter_int
	      && inter_unsignedp != inside_unsignedp
	      && inter_prec < final_prec)
	&& ((inter_unsignedp && inter_prec > inside_prec)
	    == (final_unsignedp && final_prec > inter_prec))
	&& ! (inside_ptr && inter_prec != final_prec)
	&& ! (final_ptr && inside_prec != inter_prec)
	&& ! (final_prec != GET_MODE_PRECISION (TYPE_MODE (type))
	      && TYPE_MODE (type) == TYPE_MODE (inter_type)))
    (ocvt @0))

   /* A truncation to an unsigned type (a zero-extension) should be
      canonicalized as bitwise and of a mask.  */
   (if (final_int && inter_int && inside_int
	&& final_prec == inside_prec
	&& final_prec > inter_prec
	&& inter_unsignedp)
    (convert (bit_and @0 { wide_int_to_tree
	                     (inside_type,
			      wi::mask (inter_prec, false,
					TYPE_PRECISION (inside_type))); })))

   /* If we are converting an integer to a floating-point that can
      represent it exactly and back to an integer, we can skip the
      floating-point conversion.  */
   (if (inside_int && inter_float && final_int &&
	(unsigned) significand_size (TYPE_MODE (inter_type))
	>= inside_prec - !inside_unsignedp)
    (convert @0))))))

/* If we have a narrowing conversion to an integral type that is fed by a
   BIT_AND_EXPR, we might be able to remove the BIT_AND_EXPR if it merely
   masks off bits outside the final type (and nothing else).  */
(simplify
  (convert (bit_and @0 INTEGER_CST@1))
  (if (INTEGRAL_TYPE_P (type)
       && INTEGRAL_TYPE_P (TREE_TYPE (@0))
       && TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@0))
       && operand_equal_p (@1, build_low_bits_mask (TREE_TYPE (@1),
						    TYPE_PRECISION (type)), 0))
   (convert @0)))


/* (X /[ex] A) * A -> X.  */
(simplify
  (mult (convert? (exact_div @0 @1)) @1)
  /* Look through a sign-changing conversion.  */
  (if (TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (type))
   (convert @0)))