Move "X +- C1 CMP C2 to X CMP C2 -+ C1" to match.pd

On Fri, 29 Apr 2016, Richard Biener wrote:

> Another option is to move the enum declaration from flag-types.h to
> coretypes.h.  I think I like that best.

This works.

2016-05-02  Marc Glisse  <marc.glisse@inria.fr>

gcc/
 	* flag-types.h (enum warn_strict_overflow_code): Move ...
 	* coretypes.h: ... here.
 	* fold-const.h (fold_overflow_warning): Declare.
 	* fold-const.c (fold_overflow_warning): Make non-static.
 	(fold_comparison): Move the transformation of X +- C1 CMP C2
 	into X CMP C2 -+ C1 ...
 	* match.pd: ... here.
 	* gimple-fold.c (fold_stmt_1): Protect with
 	fold_defer_overflow_warnings.

gcc/testsuite/
 	* gcc.dg/tree-ssa/20040305-1.c: Adjust.

On Fri, Apr 29, 2016 at 7:36 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> On Fri, 29 Apr 2016, Richard Biener wrote:
>
>> Another option is to move the enum declaration from flag-types.h to
>> coretypes.h.  I think I like that best.
>
>
> This works.

Ok.

Thanks,
Richard.

> 2016-05-02  Marc Glisse  <marc.glisse@inria.fr>
>
> gcc/
>         * flag-types.h (enum warn_strict_overflow_code): Move ...
>         * coretypes.h: ... here.
>         * fold-const.h (fold_overflow_warning): Declare.
>         * fold-const.c (fold_overflow_warning): Make non-static.
>         (fold_comparison): Move the transformation of X +- C1 CMP C2
>         into X CMP C2 -+ C1 ...
>         * match.pd: ... here.
>         * gimple-fold.c (fold_stmt_1): Protect with
>
>         fold_defer_overflow_warnings.
>
> gcc/testsuite/
>         * gcc.dg/tree-ssa/20040305-1.c: Adjust.
>
> --
> Marc Glisse
>
> Index: gcc/coretypes.h
> ===================================================================
> --- gcc/coretypes.h     (revision 235644)
> +++ gcc/coretypes.h     (working copy)
> @@ -215,20 +215,44 @@ enum optimization_type {
>  /* Possible initialization status of a variable.   When requested
>     by the user, this information is tracked and recorded in the DWARF
>     debug information, along with the variable's location.  */
>  enum var_init_status
>  {
>    VAR_INIT_STATUS_UNKNOWN,
>    VAR_INIT_STATUS_UNINITIALIZED,
>    VAR_INIT_STATUS_INITIALIZED
>  };
>
> +/* Names for the different levels of -Wstrict-overflow=N.  The numeric
> +   values here correspond to N.  */
> +enum warn_strict_overflow_code
> +{
> +  /* Overflow warning that should be issued with -Wall: a questionable
> +     construct that is easy to avoid even when using macros.  Example:
> +     folding (x + CONSTANT > x) to 1.  */
> +  WARN_STRICT_OVERFLOW_ALL = 1,
> +  /* Overflow warning about folding a comparison to a constant because
> +     of undefined signed overflow, other than cases covered by
> +     WARN_STRICT_OVERFLOW_ALL.  Example: folding (abs (x) >= 0) to 1
> +     (this is false when x == INT_MIN).  */
> +  WARN_STRICT_OVERFLOW_CONDITIONAL = 2,
> +  /* Overflow warning about changes to comparisons other than folding
> +     them to a constant.  Example: folding (x + 1 > 1) to (x > 0).  */
> +  WARN_STRICT_OVERFLOW_COMPARISON = 3,
> +  /* Overflow warnings not covered by the above cases.  Example:
> +     folding ((x * 10) / 5) to (x * 2).  */
> +  WARN_STRICT_OVERFLOW_MISC = 4,
> +  /* Overflow warnings about reducing magnitude of constants in
> +     comparison.  Example: folding (x + 2 > y) to (x + 1 >= y).  */
> +  WARN_STRICT_OVERFLOW_MAGNITUDE = 5
> +};
> +
>  /* The type of an alias set.  Code currently assumes that variables of
>     this type can take the values 0 (the alias set which aliases
>     everything) and -1 (sometimes indicating that the alias set is
>     unknown, sometimes indicating a memory barrier) and -2 (indicating
>     that the alias set should be set to a unique value but has not been
>     set yet).  */
>  typedef int alias_set_type;
>
>  struct edge_def;
>  typedef struct edge_def *edge;
> Index: gcc/flag-types.h
> ===================================================================
> --- gcc/flag-types.h    (revision 235644)
> +++ gcc/flag-types.h    (working copy)
> @@ -171,44 +171,20 @@ enum stack_check_type
>    /* Check the stack and rely on the target configuration files to
>       check the static frame of functions, i.e. use the generic
>       mechanism only for dynamic stack allocations.  */
>    STATIC_BUILTIN_STACK_CHECK,
>
>    /* Check the stack and entirely rely on the target configuration
>       files, i.e. do not use the generic mechanism at all.  */
>    FULL_BUILTIN_STACK_CHECK
>  };
>
> -/* Names for the different levels of -Wstrict-overflow=N.  The numeric
> -   values here correspond to N.  */
> -enum warn_strict_overflow_code
> -{
> -  /* Overflow warning that should be issued with -Wall: a questionable
> -     construct that is easy to avoid even when using macros.  Example:
> -     folding (x + CONSTANT > x) to 1.  */
> -  WARN_STRICT_OVERFLOW_ALL = 1,
> -  /* Overflow warning about folding a comparison to a constant because
> -     of undefined signed overflow, other than cases covered by
> -     WARN_STRICT_OVERFLOW_ALL.  Example: folding (abs (x) >= 0) to 1
> -     (this is false when x == INT_MIN).  */
> -  WARN_STRICT_OVERFLOW_CONDITIONAL = 2,
> -  /* Overflow warning about changes to comparisons other than folding
> -     them to a constant.  Example: folding (x + 1 > 1) to (x > 0).  */
> -  WARN_STRICT_OVERFLOW_COMPARISON = 3,
> -  /* Overflow warnings not covered by the above cases.  Example:
> -     folding ((x * 10) / 5) to (x * 2).  */
> -  WARN_STRICT_OVERFLOW_MISC = 4,
> -  /* Overflow warnings about reducing magnitude of constants in
> -     comparison.  Example: folding (x + 2 > y) to (x + 1 >= y).  */
> -  WARN_STRICT_OVERFLOW_MAGNITUDE = 5
> -};
> -
>  /* Floating-point contraction mode.  */
>  enum fp_contract_mode {
>    FP_CONTRACT_OFF = 0,
>    FP_CONTRACT_ON = 1,
>    FP_CONTRACT_FAST = 2
>  };
>
>  /* Scalar storage order kind.  */
>  enum scalar_storage_order_kind {
>    SSO_NATIVE = 0,
> Index: gcc/fold-const.c
> ===================================================================
> --- gcc/fold-const.c    (revision 235644)
> +++ gcc/fold-const.c    (working copy)
> @@ -290,21 +290,21 @@ fold_undefer_and_ignore_overflow_warning
>
>  bool
>  fold_deferring_overflow_warnings_p (void)
>  {
>    return fold_deferring_overflow_warnings > 0;
>  }
>
>  /* This is called when we fold something based on the fact that signed
>     overflow is undefined.  */
>
> -static void
> +void
>  fold_overflow_warning (const char* gmsgid, enum warn_strict_overflow_code
> wc)
>  {
>    if (fold_deferring_overflow_warnings > 0)
>      {
>        if (fold_deferred_overflow_warning == NULL
>           || wc < fold_deferred_overflow_code)
>         {
>           fold_deferred_overflow_warning = gmsgid;
>           fold_deferred_overflow_code = wc;
>         }
> @@ -8388,89 +8388,20 @@ fold_comparison (location_t loc, enum tr
>  {
>    const bool equality_code = (code == EQ_EXPR || code == NE_EXPR);
>    tree arg0, arg1, tem;
>
>    arg0 = op0;
>    arg1 = op1;
>
>    STRIP_SIGN_NOPS (arg0);
>    STRIP_SIGN_NOPS (arg1);
>
> -  /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1.
> */
> -  if ((TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR)
> -      && (equality_code
> -         || (ANY_INTEGRAL_TYPE_P (TREE_TYPE (arg0))
> -             && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (arg0))))
> -      && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
> -      && !TREE_OVERFLOW (TREE_OPERAND (arg0, 1))
> -      && TREE_CODE (arg1) == INTEGER_CST
> -      && !TREE_OVERFLOW (arg1))
> -    {
> -      const enum tree_code
> -       reverse_op = TREE_CODE (arg0) == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR;
> -      tree const1 = TREE_OPERAND (arg0, 1);
> -      tree const2 = fold_convert_loc (loc, TREE_TYPE (const1), arg1);
> -      tree variable = TREE_OPERAND (arg0, 0);
> -      tree new_const = int_const_binop (reverse_op, const2, const1);
> -
> -      /* If the constant operation overflowed this can be
> -        simplified as a comparison against INT_MAX/INT_MIN.  */
> -      if (TREE_OVERFLOW (new_const)
> -         && !TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0)))
> -       {
> -         int const1_sgn = tree_int_cst_sgn (const1);
> -         enum tree_code code2 = code;
> -
> -         /* Get the sign of the constant on the lhs if the
> -            operation were VARIABLE + CONST1.  */
> -         if (TREE_CODE (arg0) == MINUS_EXPR)
> -           const1_sgn = -const1_sgn;
> -
> -         /* The sign of the constant determines if we overflowed
> -            INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
> -            Canonicalize to the INT_MIN overflow by swapping the comparison
> -            if necessary.  */
> -         if (const1_sgn == -1)
> -           code2 = swap_tree_comparison (code);
> -
> -         /* We now can look at the canonicalized case
> -              VARIABLE + 1  CODE2  INT_MIN
> -            and decide on the result.  */
> -         switch (code2)
> -           {
> -           case EQ_EXPR:
> -           case LT_EXPR:
> -           case LE_EXPR:
> -             return
> -               omit_one_operand_loc (loc, type, boolean_false_node,
> variable);
> -
> -           case NE_EXPR:
> -           case GE_EXPR:
> -           case GT_EXPR:
> -             return
> -               omit_one_operand_loc (loc, type, boolean_true_node,
> variable);
> -
> -           default:
> -             gcc_unreachable ();
> -           }
> -       }
> -      else
> -       {
> -         if (!equality_code)
> -           fold_overflow_warning ("assuming signed overflow does not occur
> "
> -                                  "when changing X +- C1 cmp C2 to "
> -                                  "X cmp C2 -+ C1",
> -                                  WARN_STRICT_OVERFLOW_COMPARISON);
> -         return fold_build2_loc (loc, code, type, variable, new_const);
> -       }
> -    }
> -
>    /* For comparisons of pointers we can decompose it to a compile time
>       comparison of the base objects and the offsets into the object.
>       This requires at least one operand being an ADDR_EXPR or a
>       POINTER_PLUS_EXPR to do more than the operand_equal_p test below.  */
>    if (POINTER_TYPE_P (TREE_TYPE (arg0))
>        && (TREE_CODE (arg0) == ADDR_EXPR
>           || TREE_CODE (arg1) == ADDR_EXPR
>           || TREE_CODE (arg0) == POINTER_PLUS_EXPR
>           || TREE_CODE (arg1) == POINTER_PLUS_EXPR))
>      {
> Index: gcc/fold-const.h
> ===================================================================
> --- gcc/fold-const.h    (revision 235644)
> +++ gcc/fold-const.h    (working copy)
> @@ -79,20 +79,21 @@ extern bool fold_convertible_p (const_tr
>     fold_convert_loc (UNKNOWN_LOCATION, T1, T2)
>  extern tree fold_convert_loc (location_t, tree, tree);
>  extern tree fold_single_bit_test (location_t, enum tree_code, tree, tree,
> tree);
>  extern tree fold_ignored_result (tree);
>  extern tree fold_abs_const (tree, tree);
>  extern tree fold_indirect_ref_1 (location_t, tree, tree);
>  extern void fold_defer_overflow_warnings (void);
>  extern void fold_undefer_overflow_warnings (bool, const gimple *, int);
>  extern void fold_undefer_and_ignore_overflow_warnings (void);
>  extern bool fold_deferring_overflow_warnings_p (void);
> +extern void fold_overflow_warning (const char*, enum
> warn_strict_overflow_code);
>  extern int operand_equal_p (const_tree, const_tree, unsigned int);
>  extern int multiple_of_p (tree, const_tree, const_tree);
>  #define omit_one_operand(T1,T2,T3)\
>     omit_one_operand_loc (UNKNOWN_LOCATION, T1, T2, T3)
>  extern tree omit_one_operand_loc (location_t, tree, tree, tree);
>  #define omit_two_operands(T1,T2,T3,T4)\
>     omit_two_operands_loc (UNKNOWN_LOCATION, T1, T2, T3, T4)
>  extern tree omit_two_operands_loc (location_t, tree, tree, tree, tree);
>  #define invert_truthvalue(T)\
>     invert_truthvalue_loc (UNKNOWN_LOCATION, T)
> Index: gcc/gimple-fold.c
> ===================================================================
> --- gcc/gimple-fold.c   (revision 235644)
> +++ gcc/gimple-fold.c   (working copy)
> @@ -3518,21 +3518,23 @@ maybe_canonicalize_mem_ref_addr (tree *t
>  }
>
>  /* Worker for both fold_stmt and fold_stmt_inplace.  The INPLACE argument
>     distinguishes both cases.  */
>
>  static bool
>  fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize)
> (tree))
>  {
>    bool changed = false;
>    gimple *stmt = gsi_stmt (*gsi);
> +  bool nowarning = gimple_no_warning_p (stmt);
>    unsigned i;
> +  fold_defer_overflow_warnings ();
>
>    /* First do required canonicalization of [TARGET_]MEM_REF addresses
>       after propagation.
>       ???  This shouldn't be done in generic folding but in the
>       propagation helpers which also know whether an address was
>       propagated.
>       Also canonicalize operand order.  */
>    switch (gimple_code (stmt))
>      {
>      case GIMPLE_ASSIGN:
> @@ -3811,20 +3813,21 @@ fold_stmt_1 (gimple_stmt_iterator *gsi,
>         {
>           tree new_lhs = maybe_fold_reference (lhs, true);
>           if (new_lhs)
>             {
>               gimple_set_lhs (stmt, new_lhs);
>               changed = true;
>             }
>         }
>      }
>
> +  fold_undefer_overflow_warnings (changed && !nowarning, stmt, 0);
>    return changed;
>  }
>
>  /* Valueziation callback that ends up not following SSA edges.  */
>
>  tree
>  no_follow_ssa_edges (tree)
>  {
>    return NULL_TREE;
>  }
> Index: gcc/match.pd
> ===================================================================
> --- gcc/match.pd        (revision 235644)
> +++ gcc/match.pd        (working copy)
> @@ -3179,10 +3179,54 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>  (simplify
>   /* signbit(x) -> 0 if x is nonnegative.  */
>   (SIGNBIT tree_expr_nonnegative_p@0)
>   { integer_zero_node; })
>
>  (simplify
>   /* signbit(x) -> x<0 if x doesn't have signed zeros.  */
>   (SIGNBIT @0)
>   (if (!HONOR_SIGNED_ZEROS (@0))
>    (convert (lt @0 { build_real (TREE_TYPE (@0), dconst0); }))))
> +
> +/* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1.  */
> +(for cmp (eq ne)
> + (for op (plus minus)
> +      rop (minus plus)
> +  (simplify
> +   (cmp (op@3 @0 INTEGER_CST@1) INTEGER_CST@2)
> +   (if (!TREE_OVERFLOW (@1) && !TREE_OVERFLOW (@2)
> +       && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@0))
> +       && !TYPE_OVERFLOW_TRAPS (TREE_TYPE (@0))
> +       && !TYPE_SATURATING (TREE_TYPE (@0)))
> +    (with { tree res = int_const_binop (rop, @2, @1); }
> +     (if (TREE_OVERFLOW (res))
> +      { constant_boolean_node (cmp == NE_EXPR, type); }
> +      (if (single_use (@3))
> +       (cmp @0 { res; }))))))))
> +(for cmp (lt le gt ge)
> + (for op (plus minus)
> +      rop (minus plus)
> +  (simplify
> +   (cmp (op@3 @0 INTEGER_CST@1) INTEGER_CST@2)
> +   (if (!TREE_OVERFLOW (@1) && !TREE_OVERFLOW (@2)
> +       && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
> +    (with { tree res = int_const_binop (rop, @2, @1); }
> +     (if (TREE_OVERFLOW (res))
> +      {
> +       fold_overflow_warning (("assuming signed overflow does not occur "
> +                               "when simplifying conditional to constant"),
> +                              WARN_STRICT_OVERFLOW_CONDITIONAL);
> +        bool less = cmp == LE_EXPR || cmp == LT_EXPR;
> +       /* wi::ges_p (@2, 0) should be sufficient for a signed type.  */
> +       bool ovf_high = wi::lt_p (@1, 0, TYPE_SIGN (TREE_TYPE (@1)))
> +                       != (op == MINUS_EXPR);
> +       constant_boolean_node (less == ovf_high, type);
> +      }
> +      (if (single_use (@3))
> +       (with
> +       {
> +         fold_overflow_warning (("assuming signed overflow does not occur "
> +                                 "when changing X +- C1 cmp C2 to "
> +                                 "X cmp C2 -+ C1"),
> +                                WARN_STRICT_OVERFLOW_COMPARISON);
> +       }
> +       (cmp @0 { res; })))))))))
> Index: gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c  (revision 235644)
> +++ gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c  (working copy)
> @@ -16,15 +16,15 @@ void foo(int edx, int eax)
>      }
>    if (eax == 100)
>      {
>        if (-- edx == 0)
>          afred[0] = 2;
>      }
>  }
>
>
>  /* Verify that we did a forward propagation.  */
> -/* { dg-final { scan-tree-dump-times "Replaced" 1 "forwprop1"} } */
> +/* { dg-final { scan-tree-dump-times "gimple_simplified" 1 "forwprop1"} }
> */
>
>  /* After cddce we should have two IF statements remaining as the other
>     two tests can be threaded.  */
>  /* { dg-final { scan-tree-dump-times "if " 2 "cddce2"} } */
>