On Thu, Apr 5, 2012 at 3:49 PM, William J. Schmidt
<wschm...@linux.vnet.ibm.com> wrote:
> On Thu, 2012-04-05 at 11:23 +0200, Richard Guenther wrote:
>> On Wed, Apr 4, 2012 at 9:15 PM, William J. Schmidt
>> <wschm...@linux.vnet.ibm.com> wrote:
>> >
>> > Unfortunately this seems to be necessary if I name the two passes
>> > "reassoc1" and "reassoc2". If I try to name both of them "reassoc" I
>> > get failures in other tests like gfortran.dg/reassoc_4, where
>> > -fdump-tree-reassoc1 doesn't work. Unless I'm missing something
>> > obvious, I think I need to keep that change.
>>
>> Hm, naming them "reassoc1" and "reassoc2" is a hack. Naming both
>> "reassoc" will not trigger re-naming them to reassoc1 and reassoc2
>> I think. How ugly. Especially that -fdump-tree-reassoc will no longer
>> work. Maybe instead of using two pass structs resort to using
>> the existing hack with using first_pass_instance and
>> TODO_mark_first_instance.
>
> OK, that seems to be the best among evils. Using the
> first_pass_instance hack, the patch is transformed as below.
> Regstrapped on powerpc64-linux, no additional failures. OK for trunk?
Ok.
Thanks,
Richard.
> Thanks,
> Bill
>
>
> gcc:
>
> 2012-04-05 Bill Schmidt <wschm...@linux.vnet.ibm.com>
>
> PR tree-optimization/18589
> * tree-ssa-reassoc.c (reassociate_stats): Add two fields.
> (operand_entry): Add count field.
> (add_repeat_to_ops_vec): New function.
> (completely_remove_stmt): Likewise.
> (remove_def_if_absorbed_call): Likewise.
> (remove_visited_stmt_chain): Remove feeding builtin pow/powi calls.
> (acceptable_pow_call): New function.
> (linearize_expr_tree): Look for builtin pow/powi calls and add operand
> entries with repeat counts when found.
> (repeat_factor_d): New struct and associated typedefs.
> (repeat_factor_vec): New static vector variable.
> (compare_repeat_factors): New function.
> (get_reassoc_pow_ssa_name): Likewise.
> (attempt_builtin_powi): Likewise.
> (reassociate_bb): Call attempt_builtin_powi.
> (fini_reassoc): Two new calls to statistics_counter_event.
>
> gcc/testsuite:
>
> 2012-04-05 Bill Schmidt <wschm...@linux.vnet.ibm.com>
>
> PR tree-optimization/18589
> * gcc.dg/tree-ssa/pr18589-1.c: New test.
> * gcc.dg/tree-ssa/pr18589-2.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-3.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-4.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-5.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-6.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-7.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-8.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-9.c: Likewise.
> * gcc.dg/tree-ssa/pr18589-10.c: Likewise.
>
>
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-4.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-4.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-4.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y, double z, double u)
> +{
> + return x * x * y * y * y * z * z * z * z * u;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 6 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-5.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-5.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-5.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y, double z, double u)
> +{
> + return x * x * x * y * y * y * z * z * z * z * u * u * u * u;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 6 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-6.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-6.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-6.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y)
> +{
> + return __builtin_pow (x, 3.0) * __builtin_pow (y, 4.0);
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 4 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-7.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-7.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-7.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +float baz (float x, float y)
> +{
> + return x * x * x * x * y * y * y * y;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 3 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-8.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-8.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-8.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +long double baz (long double x, long double y)
> +{
> + return x * x * x * x * y * y * y * y;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 3 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-9.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-9.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-9.c (revision 0)
> @@ -0,0 +1,11 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y, double z)
> +{
> + return (__builtin_pow (x, 3.0) * __builtin_pow (y, 2.0)
> + * __builtin_pow (z, 5.0));
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 6 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-10.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-10.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-10.c (revision 0)
> @@ -0,0 +1,11 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y, double z)
> +{
> + return (__builtin_pow (x, 4.0) * __builtin_pow (y, 2.0)
> + * __builtin_pow (z, 4.0));
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 5 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-1.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-1.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-1.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y)
> +{
> + return x * x * x * x * y * y * y * y;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 3 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-2.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-2.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-2.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y)
> +{
> + return x * y * y * x * y * x * x * y;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 3 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/pr18589-3.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/pr18589-3.c (revision 0)
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr18589-3.c (revision 0)
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ffast-math -fdump-tree-optimized" } */
> +
> +double baz (double x, double y, double z)
> +{
> + return x * x * y * y * y * z * z * z * z;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " \\* " 5 "optimized" } } */
> +/* { dg-final { cleanup-tree-dump "optimized" } } */
> Index: gcc/tree-ssa-reassoc.c
> ===================================================================
> --- gcc/tree-ssa-reassoc.c (revision 186108)
> +++ gcc/tree-ssa-reassoc.c (working copy)
> @@ -61,6 +61,10 @@ along with GCC; see the file COPYING3. If not see
> 3. Optimization of the operand lists, eliminating things like a +
> -a, a & a, etc.
>
> + 3a. Combine repeated factors with the same occurrence counts
> + into a __builtin_powi call that will later be optimized into
> + an optimal number of multiplies.
> +
> 4. Rewrite the expression trees we linearized and optimized so
> they are in proper rank order.
>
> @@ -169,6 +173,8 @@ static struct
> int constants_eliminated;
> int ops_eliminated;
> int rewritten;
> + int pows_encountered;
> + int pows_created;
> } reassociate_stats;
>
> /* Operator, rank pair. */
> @@ -177,6 +183,7 @@ typedef struct operand_entry
> unsigned int rank;
> int id;
> tree op;
> + unsigned int count;
> } *operand_entry_t;
>
> static alloc_pool operand_entry_pool;
> @@ -515,9 +522,28 @@ add_to_ops_vec (VEC(operand_entry_t, heap) **ops,
> oe->op = op;
> oe->rank = get_rank (op);
> oe->id = next_operand_entry_id++;
> + oe->count = 1;
> VEC_safe_push (operand_entry_t, heap, *ops, oe);
> }
>
> +/* Add an operand entry to *OPS for the tree operand OP with repeat
> + count REPEAT. */
> +
> +static void
> +add_repeat_to_ops_vec (VEC(operand_entry_t, heap) **ops, tree op,
> + HOST_WIDE_INT repeat)
> +{
> + operand_entry_t oe = (operand_entry_t) pool_alloc (operand_entry_pool);
> +
> + oe->op = op;
> + oe->rank = get_rank (op);
> + oe->id = next_operand_entry_id++;
> + oe->count = repeat;
> + VEC_safe_push (operand_entry_t, heap, *ops, oe);
> +
> + reassociate_stats.pows_encountered++;
> +}
> +
> /* Return true if STMT is reassociable operation containing a binary
> operation with tree code CODE, and is inside LOOP. */
>
> @@ -2049,6 +2075,32 @@ is_phi_for_stmt (gimple stmt, tree operand)
> return false;
> }
>
> +/* Remove STMT, unlink its virtual defs, and release its SSA defs. */
> +
> +static inline void
> +completely_remove_stmt (gimple stmt)
> +{
> + gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
> + gsi_remove (&gsi, true);
> + unlink_stmt_vdef (stmt);
> + release_defs (stmt);
> +}
> +
> +/* If OP is defined by a builtin call that has been absorbed by
> + reassociation, remove its defining statement completely. */
> +
> +static inline void
> +remove_def_if_absorbed_call (tree op)
> +{
> + gimple stmt;
> +
> + if (TREE_CODE (op) == SSA_NAME
> + && has_zero_uses (op)
> + && is_gimple_call ((stmt = SSA_NAME_DEF_STMT (op)))
> + && gimple_visited_p (stmt))
> + completely_remove_stmt (stmt);
> +}
> +
> /* Remove def stmt of VAR if VAR has zero uses and recurse
> on rhs1 operand if so. */
>
> @@ -2057,19 +2109,31 @@ remove_visited_stmt_chain (tree var)
> {
> gimple stmt;
> gimple_stmt_iterator gsi;
> + tree var2;
>
> while (1)
> {
> if (TREE_CODE (var) != SSA_NAME || !has_zero_uses (var))
> return;
> stmt = SSA_NAME_DEF_STMT (var);
> - if (!is_gimple_assign (stmt)
> - || !gimple_visited_p (stmt))
> + if (is_gimple_assign (stmt) && gimple_visited_p (stmt))
> + {
> + var = gimple_assign_rhs1 (stmt);
> + var2 = gimple_assign_rhs2 (stmt);
> + gsi = gsi_for_stmt (stmt);
> + gsi_remove (&gsi, true);
> + release_defs (stmt);
> + /* A multiply whose operands are both fed by builtin pow/powi
> + calls must check whether to remove rhs2 as well. */
> + remove_def_if_absorbed_call (var2);
> + }
> + else if (is_gimple_call (stmt) && gimple_visited_p (stmt))
> + {
> + completely_remove_stmt (stmt);
> + return;
> + }
> + else
> return;
> - var = gimple_assign_rhs1 (stmt);
> - gsi = gsi_for_stmt (stmt);
> - gsi_remove (&gsi, true);
> - release_defs (stmt);
> }
> }
>
> @@ -2564,6 +2628,75 @@ break_up_subtract (gimple stmt, gimple_stmt_iterat
> update_stmt (stmt);
> }
>
> +/* Determine whether STMT is a builtin call that raises an SSA name
> + to an integer power and has only one use. If so, and this is early
> + reassociation and unsafe math optimizations are permitted, place
> + the SSA name in *BASE and the exponent in *EXPONENT, and return TRUE.
> + If any of these conditions does not hold, return FALSE. */
> +
> +static bool
> +acceptable_pow_call (gimple stmt, tree *base, HOST_WIDE_INT *exponent)
> +{
> + tree fndecl, arg1;
> + REAL_VALUE_TYPE c, cint;
> +
> + if (!first_pass_instance
> + || !flag_unsafe_math_optimizations
> + || !is_gimple_call (stmt)
> + || !has_single_use (gimple_call_lhs (stmt)))
> + return false;
> +
> + fndecl = gimple_call_fndecl (stmt);
> +
> + if (!fndecl
> + || DECL_BUILT_IN_CLASS (fndecl) != BUILT_IN_NORMAL)
> + return false;
> +
> + switch (DECL_FUNCTION_CODE (fndecl))
> + {
> + CASE_FLT_FN (BUILT_IN_POW):
> + *base = gimple_call_arg (stmt, 0);
> + arg1 = gimple_call_arg (stmt, 1);
> +
> + if (TREE_CODE (arg1) != REAL_CST)
> + return false;
> +
> + c = TREE_REAL_CST (arg1);
> +
> + if (REAL_EXP (&c) > HOST_BITS_PER_WIDE_INT)
> + return false;
> +
> + *exponent = real_to_integer (&c);
> + real_from_integer (&cint, VOIDmode, *exponent,
> + *exponent < 0 ? -1 : 0, 0);
> + if (!real_identical (&c, &cint))
> + return false;
> +
> + break;
> +
> + CASE_FLT_FN (BUILT_IN_POWI):
> + *base = gimple_call_arg (stmt, 0);
> + arg1 = gimple_call_arg (stmt, 1);
> +
> + if (!host_integerp (arg1, 0))
> + return false;
> +
> + *exponent = TREE_INT_CST_LOW (arg1);
> + break;
> +
> + default:
> + return false;
> + }
> +
> + /* Expanding negative exponents is generally unproductive, so we don't
> + complicate matters with those. Exponents of zero and one should
> + have been handled by expression folding. */
> + if (*exponent < 2 || TREE_CODE (*base) != SSA_NAME)
> + return false;
> +
> + return true;
> +}
> +
> /* Recursively linearize a binary expression that is the RHS of STMT.
> Place the operands of the expression tree in the vector named OPS. */
>
> @@ -2573,11 +2706,13 @@ linearize_expr_tree (VEC(operand_entry_t, heap) **
> {
> tree binlhs = gimple_assign_rhs1 (stmt);
> tree binrhs = gimple_assign_rhs2 (stmt);
> - gimple binlhsdef, binrhsdef;
> + gimple binlhsdef = NULL, binrhsdef = NULL;
> bool binlhsisreassoc = false;
> bool binrhsisreassoc = false;
> enum tree_code rhscode = gimple_assign_rhs_code (stmt);
> struct loop *loop = loop_containing_stmt (stmt);
> + tree base = NULL_TREE;
> + HOST_WIDE_INT exponent = 0;
>
> if (set_visited)
> gimple_set_visited (stmt, true);
> @@ -2615,8 +2750,26 @@ linearize_expr_tree (VEC(operand_entry_t, heap) **
>
> if (!binrhsisreassoc)
> {
> - add_to_ops_vec (ops, binrhs);
> - add_to_ops_vec (ops, binlhs);
> + if (rhscode == MULT_EXPR
> + && TREE_CODE (binrhs) == SSA_NAME
> + && acceptable_pow_call (binrhsdef, &base, &exponent))
> + {
> + add_repeat_to_ops_vec (ops, base, exponent);
> + gimple_set_visited (binrhsdef, true);
> + }
> + else
> + add_to_ops_vec (ops, binrhs);
> +
> + if (rhscode == MULT_EXPR
> + && TREE_CODE (binlhs) == SSA_NAME
> + && acceptable_pow_call (binlhsdef, &base, &exponent))
> + {
> + add_repeat_to_ops_vec (ops, base, exponent);
> + gimple_set_visited (binlhsdef, true);
> + }
> + else
> + add_to_ops_vec (ops, binlhs);
> +
> return;
> }
>
> @@ -2655,7 +2808,16 @@ linearize_expr_tree (VEC(operand_entry_t, heap) **
> rhscode, loop));
> linearize_expr_tree (ops, SSA_NAME_DEF_STMT (binlhs),
> is_associative, set_visited);
> - add_to_ops_vec (ops, binrhs);
> +
> + if (rhscode == MULT_EXPR
> + && TREE_CODE (binrhs) == SSA_NAME
> + && acceptable_pow_call (SSA_NAME_DEF_STMT (binrhs), &base, &exponent))
> + {
> + add_repeat_to_ops_vec (ops, base, exponent);
> + gimple_set_visited (SSA_NAME_DEF_STMT (binrhs), true);
> + }
> + else
> + add_to_ops_vec (ops, binrhs);
> }
>
> /* Repropagate the negates back into subtracts, since no other pass
> @@ -2815,6 +2977,347 @@ break_up_subtract_bb (basic_block bb)
> break_up_subtract_bb (son);
> }
>
> +/* Used for repeated factor analysis. */
> +struct repeat_factor_d
> +{
> + /* An SSA name that occurs in a multiply chain. */
> + tree factor;
> +
> + /* Cached rank of the factor. */
> + unsigned rank;
> +
> + /* Number of occurrences of the factor in the chain. */
> + HOST_WIDE_INT count;
> +
> + /* An SSA name representing the product of this factor and
> + all factors appearing later in the repeated factor vector. */
> + tree repr;
> +};
> +
> +typedef struct repeat_factor_d repeat_factor, *repeat_factor_t;
> +typedef const struct repeat_factor_d *const_repeat_factor_t;
> +
> +DEF_VEC_O (repeat_factor);
> +DEF_VEC_ALLOC_O (repeat_factor, heap);
> +
> +static VEC (repeat_factor, heap) *repeat_factor_vec;
> +
> +/* Used for sorting the repeat factor vector. Sort primarily by
> + ascending occurrence count, secondarily by descending rank. */
> +
> +static int
> +compare_repeat_factors (const void *x1, const void *x2)
> +{
> + const_repeat_factor_t rf1 = (const_repeat_factor_t) x1;
> + const_repeat_factor_t rf2 = (const_repeat_factor_t) x2;
> +
> + if (rf1->count != rf2->count)
> + return rf1->count - rf2->count;
> +
> + return rf2->rank - rf1->rank;
> +}
> +
> +/* Get a new SSA name for register variable *TARGET of type TYPE.
> + If *TARGET is null or incompatible with TYPE, create the variable
> + first. */
> +
> +static tree
> +get_reassoc_pow_ssa_name (tree *target, tree type)
> +{
> + if (!*target || !types_compatible_p (type, TREE_TYPE (*target)))
> + {
> + *target = create_tmp_reg (type, "reassocpow");
> + add_referenced_var (*target);
> + }
> +
> + return make_ssa_name (*target, NULL);
> +}
> +
> +/* Look for repeated operands in OPS in the multiply tree rooted at
> + STMT. Replace them with an optimal sequence of multiplies and powi
> + builtin calls, and remove the used operands from OPS. Push new
> + SSA names onto OPS that represent the introduced multiplies and
> + builtin calls. */
> +
> +static void
> +attempt_builtin_powi (gimple stmt, VEC(operand_entry_t, heap) **ops,
> + tree *target)
> +{
> + unsigned i, j, vec_len;
> + int ii;
> + operand_entry_t oe;
> + repeat_factor_t rf1, rf2;
> + repeat_factor rfnew;
> + tree target_ssa, iter_result;
> + tree type = TREE_TYPE (gimple_get_lhs (stmt));
> + tree powi_fndecl = mathfn_built_in (type, BUILT_IN_POWI);
> + gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
> + gimple mul_stmt, pow_stmt;
> +
> + /* Nothing to do if BUILT_IN_POWI doesn't exist for this type and
> + target. */
> + if (!powi_fndecl)
> + return;
> +
> + /* Allocate the repeated factor vector. */
> + repeat_factor_vec = VEC_alloc (repeat_factor, heap, 10);
> +
> + /* Scan the OPS vector for all SSA names in the product and build
> + up a vector of occurrence counts for each factor. */
> + FOR_EACH_VEC_ELT (operand_entry_t, *ops, i, oe)
> + {
> + if (TREE_CODE (oe->op) == SSA_NAME)
> + {
> + FOR_EACH_VEC_ELT (repeat_factor, repeat_factor_vec, j, rf1)
> + {
> + if (rf1->factor == oe->op)
> + {
> + rf1->count += oe->count;
> + break;
> + }
> + }
> +
> + if (j >= VEC_length (repeat_factor, repeat_factor_vec))
> + {
> + rfnew.factor = oe->op;
> + rfnew.rank = oe->rank;
> + rfnew.count = oe->count;
> + rfnew.repr = NULL_TREE;
> + VEC_safe_push (repeat_factor, heap, repeat_factor_vec, &rfnew);
> + }
> + }
> + }
> +
> + /* Sort the repeated factor vector by (a) increasing occurrence count,
> + and (b) decreasing rank. */
> + VEC_qsort (repeat_factor, repeat_factor_vec, compare_repeat_factors);
> +
> + /* It is generally best to combine as many base factors as possible
> + into a product before applying __builtin_powi to the result.
> + However, the sort order chosen for the repeated factor vector
> + allows us to cache partial results for the product of the base
> + factors for subsequent use. When we already have a cached partial
> + result from a previous iteration, it is best to make use of it
> + before looking for another __builtin_pow opportunity.
> +
> + As an example, consider x * x * y * y * y * z * z * z * z.
> + We want to first compose the product x * y * z, raise it to the
> + second power, then multiply this by y * z, and finally multiply
> + by z. This can be done in 5 multiplies provided we cache y * z
> + for use in both expressions:
> +
> + t1 = y * z
> + t2 = t1 * x
> + t3 = t2 * t2
> + t4 = t1 * t3
> + result = t4 * z
> +
> + If we instead ignored the cached y * z and first multiplied by
> + the __builtin_pow opportunity z * z, we would get the inferior:
> +
> + t1 = y * z
> + t2 = t1 * x
> + t3 = t2 * t2
> + t4 = z * z
> + t5 = t3 * t4
> + result = t5 * y */
> +
> + vec_len = VEC_length (repeat_factor, repeat_factor_vec);
> +
> + /* Repeatedly look for opportunities to create a builtin_powi call. */
> + while (true)
> + {
> + HOST_WIDE_INT power;
> +
> + /* First look for the largest cached product of factors from
> + preceding iterations. If found, create a builtin_powi for
> + it if the minimum occurrence count for its factors is at
> + least 2, or just use this cached product as our next
> + multiplicand if the minimum occurrence count is 1. */
> + FOR_EACH_VEC_ELT (repeat_factor, repeat_factor_vec, j, rf1)
> + {
> + if (rf1->repr && rf1->count > 0)
> + break;
> + }
> +
> + if (j < vec_len)
> + {
> + power = rf1->count;
> +
> + if (power == 1)
> + {
> + iter_result = rf1->repr;
> +
> + if (dump_file && (dump_flags & TDF_DETAILS))
> + {
> + unsigned elt;
> + repeat_factor_t rf;
> + fputs ("Multiplying by cached product ", dump_file);
> + for (elt = j; elt < vec_len; elt++)
> + {
> + rf = VEC_index (repeat_factor, repeat_factor_vec, elt);
> + print_generic_expr (dump_file, rf->factor, 0);
> + if (elt < vec_len - 1)
> + fputs (" * ", dump_file);
> + }
> + fputs ("\n", dump_file);
> + }
> + }
> + else
> + {
> + iter_result = get_reassoc_pow_ssa_name (target, type);
> + pow_stmt = gimple_build_call (powi_fndecl, 2, rf1->repr,
> + build_int_cst (integer_type_node,
> + power));
> + gimple_call_set_lhs (pow_stmt, iter_result);
> + gimple_set_location (pow_stmt, gimple_location (stmt));
> + gsi_insert_before (&gsi, pow_stmt, GSI_SAME_STMT);
> +
> + if (dump_file && (dump_flags & TDF_DETAILS))
> + {
> + unsigned elt;
> + repeat_factor_t rf;
> + fputs ("Building __builtin_pow call for cached product (",
> + dump_file);
> + for (elt = j; elt < vec_len; elt++)
> + {
> + rf = VEC_index (repeat_factor, repeat_factor_vec, elt);
> + print_generic_expr (dump_file, rf->factor, 0);
> + if (elt < vec_len - 1)
> + fputs (" * ", dump_file);
> + }
> + fprintf (dump_file, ")^%ld\n", power);
> + }
> + }
> + }
> + else
> + {
> + /* Otherwise, find the first factor in the repeated factor
> + vector whose occurrence count is at least 2. If no such
> + factor exists, there are no builtin_powi opportunities
> + remaining. */
> + FOR_EACH_VEC_ELT (repeat_factor, repeat_factor_vec, j, rf1)
> + {
> + if (rf1->count >= 2)
> + break;
> + }
> +
> + if (j >= vec_len)
> + break;
> +
> + power = rf1->count;
> +
> + if (dump_file && (dump_flags & TDF_DETAILS))
> + {
> + unsigned elt;
> + repeat_factor_t rf;
> + fputs ("Building __builtin_pow call for (", dump_file);
> + for (elt = j; elt < vec_len; elt++)
> + {
> + rf = VEC_index (repeat_factor, repeat_factor_vec, elt);
> + print_generic_expr (dump_file, rf->factor, 0);
> + if (elt < vec_len - 1)
> + fputs (" * ", dump_file);
> + }
> + fprintf (dump_file, ")^%ld\n", power);
> + }
> +
> + reassociate_stats.pows_created++;
> +
> + /* Visit each element of the vector in reverse order (so that
> + high-occurrence elements are visited first, and within the
> + same occurrence count, lower-ranked elements are visited
> + first). Form a linear product of all elements in this order
> + whose occurrencce count is at least that of element J.
> + Record the SSA name representing the product of each element
> + with all subsequent elements in the vector. */
> + if (j == vec_len - 1)
> + rf1->repr = rf1->factor;
> + else
> + {
> + for (ii = vec_len - 2; ii >= (int)j; ii--)
> + {
> + tree op1, op2;
> +
> + rf1 = VEC_index (repeat_factor, repeat_factor_vec, ii);
> + rf2 = VEC_index (repeat_factor, repeat_factor_vec, ii + 1);
> +
> + /* Init the last factor's representative to be itself. */
> + if (!rf2->repr)
> + rf2->repr = rf2->factor;
> +
> + op1 = rf1->factor;
> + op2 = rf2->repr;
> +
> + target_ssa = get_reassoc_pow_ssa_name (target, type);
> + mul_stmt = gimple_build_assign_with_ops (MULT_EXPR,
> + target_ssa,
> + op1, op2);
> + gimple_set_location (mul_stmt, gimple_location (stmt));
> + gsi_insert_before (&gsi, mul_stmt, GSI_SAME_STMT);
> + rf1->repr = target_ssa;
> +
> + /* Don't reprocess the multiply we just introduced. */
> + gimple_set_visited (mul_stmt, true);
> + }
> + }
> +
> + /* Form a call to __builtin_powi for the maximum product
> + just formed, raised to the power obtained earlier. */
> + rf1 = VEC_index (repeat_factor, repeat_factor_vec, j);
> + iter_result = get_reassoc_pow_ssa_name (target, type);
> + pow_stmt = gimple_build_call (powi_fndecl, 2, rf1->repr,
> + build_int_cst (integer_type_node,
> + power));
> + gimple_call_set_lhs (pow_stmt, iter_result);
> + gimple_set_location (pow_stmt, gimple_location (stmt));
> + gsi_insert_before (&gsi, pow_stmt, GSI_SAME_STMT);
> + }
> +
> + /* Append the result of this iteration to the ops vector. */
> + add_to_ops_vec (ops, iter_result);
> +
> + /* Decrement the occurrence count of each element in the product
> + by the count found above, and remove this many copies of each
> + factor from OPS. */
> + for (i = j; i < vec_len; i++)
> + {
> + unsigned k = power;
> + unsigned n;
> +
> + rf1 = VEC_index (repeat_factor, repeat_factor_vec, i);
> + rf1->count -= power;
> +
> + FOR_EACH_VEC_ELT_REVERSE (operand_entry_t, *ops, n, oe)
> + {
> + if (oe->op == rf1->factor)
> + {
> + if (oe->count <= k)
> + {
> + VEC_ordered_remove (operand_entry_t, *ops, n);
> + k -= oe->count;
> +
> + if (k == 0)
> + break;
> + }
> + else
> + {
> + oe->count -= k;
> + break;
> + }
> + }
> + }
> + }
> + }
> +
> + /* At this point all elements in the repeated factor vector have a
> + remaining occurrence count of 0 or 1, and those with a count of 1
> + don't have cached representatives. Re-sort the ops vector and
> + clean up. */
> + VEC_qsort (operand_entry_t, *ops, sort_by_operand_rank);
> + VEC_free (repeat_factor, heap, repeat_factor_vec);
> +}
> +
> /* Reassociate expressions in basic block BB and its post-dominator as
> children. */
>
> @@ -2823,6 +3326,7 @@ reassociate_bb (basic_block bb)
> {
> gimple_stmt_iterator gsi;
> basic_block son;
> + tree target = NULL_TREE;
>
> for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
> {
> @@ -2904,6 +3408,11 @@ reassociate_bb (basic_block bb)
> if (rhs_code == BIT_IOR_EXPR || rhs_code == BIT_AND_EXPR)
> optimize_range_tests (rhs_code, &ops);
>
> + if (first_pass_instance
> + && rhs_code == MULT_EXPR
> + && flag_unsafe_math_optimizations)
> + attempt_builtin_powi (stmt, &ops, &target);
> +
> if (VEC_length (operand_entry_t, ops) == 1)
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
> @@ -3054,6 +3563,10 @@ fini_reassoc (void)
> reassociate_stats.ops_eliminated);
> statistics_counter_event (cfun, "Statements rewritten",
> reassociate_stats.rewritten);
> + statistics_counter_event (cfun, "Built-in pow[i] calls encountered",
> + reassociate_stats.pows_encountered);
> + statistics_counter_event (cfun, "Built-in powi calls created",
> + reassociate_stats.pows_created);
>
> pointer_map_destroy (operand_rank);
> free_alloc_pool (operand_entry_pool);
>
>
