return true;
}
+/* Return true when the induction variable IV is simple enough to be
+ re-synthesized. */
+static bool
+can_duplicate_iv (tree iv, struct loop *loop)
+{
+ tree scev = instantiate_parameters
+ (loop, analyze_scalar_evolution (loop, iv));
+
+ if (!automatically_generated_chrec_p (scev))
+ {
+ tree step = evolution_part_in_loop_num (scev, loop->num);
+
+ if (step && step != chrec_dont_know && TREE_CODE (step) == INTEGER_CST)
+ return true;
+ }
+
+ return false;
+}
+
+/* If this is a scalar operation that can be put back into the inner
+ loop, or after the inner loop, through copying, then do so. This
+ works on the theory that any amount of scalar code we have to
+ reduplicate into or after the loops is less expensive that the win
+ we get from rearranging the memory walk the loop is doing so that
+ it has better cache behavior. */
+
+static bool
+cannot_convert_modify_to_perfect_nest (tree stmt, struct loop *loop)
+{
+
+ use_operand_p use_a, use_b;
+ imm_use_iterator imm_iter;
+ ssa_op_iter op_iter, op_iter1;
+ tree op0 = GIMPLE_STMT_OPERAND (stmt, 0);
+
+ /* The statement should not define a variable used in the inner
+ loop. */
+ if (TREE_CODE (op0) == SSA_NAME
+ && !can_duplicate_iv (op0, loop))
+ FOR_EACH_IMM_USE_FAST (use_a, imm_iter, op0)
+ if (bb_for_stmt (USE_STMT (use_a))->loop_father
+ == loop->inner)
+ return true;
+
+ FOR_EACH_SSA_USE_OPERAND (use_a, stmt, op_iter, SSA_OP_USE)
+ {
+ tree node, op = USE_FROM_PTR (use_a);
+
+ /* The variables should not be used in both loops. */
+ if (!can_duplicate_iv (op, loop))
+ FOR_EACH_IMM_USE_FAST (use_b, imm_iter, op)
+ if (bb_for_stmt (USE_STMT (use_b))->loop_father
+ == loop->inner)
+ return true;
+
+ /* The statement should not use the value of a scalar that was
+ modified in the loop. */
+ node = SSA_NAME_DEF_STMT (op);
+ if (TREE_CODE (node) == PHI_NODE)
+ FOR_EACH_PHI_ARG (use_b, node, op_iter1, SSA_OP_USE)
+ {
+ tree arg = USE_FROM_PTR (use_b);
+
+ if (TREE_CODE (arg) == SSA_NAME)
+ {
+ tree arg_stmt = SSA_NAME_DEF_STMT (arg);
+
+ if (bb_for_stmt (arg_stmt)
+ && (bb_for_stmt (arg_stmt)->loop_father
+ == loop->inner))
+ return true;
+ }
+ }
+ }
+
+ return false;
+}
+
+/* Return true when BB contains statements that can harm the transform
+ to a perfect loop nest. */
+
+static bool
+cannot_convert_bb_to_perfect_nest (basic_block bb, struct loop *loop)
+{
+ block_stmt_iterator bsi;
+ tree exit_condition = get_loop_exit_condition (loop);
+
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ {
+ tree stmt = bsi_stmt (bsi);
+
+ if (stmt == exit_condition
+ || not_interesting_stmt (stmt)
+ || stmt_is_bumper_for_loop (loop, stmt))
+ continue;
+
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+ {
+ if (cannot_convert_modify_to_perfect_nest (stmt, loop))
+ return true;
+
+ if (can_duplicate_iv (GIMPLE_STMT_OPERAND (stmt, 0), loop))
+ continue;
+
+ if (can_put_in_inner_loop (loop->inner, stmt)
+ || can_put_after_inner_loop (loop, stmt))
+ continue;
+ }
+
+ /* If the bb of a statement we care about isn't dominated by the
+ header of the inner loop, then we can't handle this case
+ right now. This test ensures that the statement comes
+ completely *after* the inner loop. */
+ if (!dominated_by_p (CDI_DOMINATORS,
+ bb_for_stmt (stmt),
+ loop->inner->header))
+ return true;
+ }
+
+ return false;
+}
/* Return TRUE if LOOP is an imperfect nest that we can convert to a
perfect one. At the moment, we only handle imperfect nests of
can_convert_to_perfect_nest (struct loop *loop)
{
basic_block *bbs;
- tree exit_condition, phi;
+ tree phi;
size_t i;
- block_stmt_iterator bsi;
- basic_block exitdest;
/* Can't handle triply nested+ loops yet. */
if (!loop->inner || loop->inner->inner)
return false;
bbs = get_loop_body (loop);
- exit_condition = get_loop_exit_condition (loop);
for (i = 0; i < loop->num_nodes; i++)
- {
- if (bbs[i]->loop_father == loop)
- {
- for (bsi = bsi_start (bbs[i]); !bsi_end_p (bsi); bsi_next (&bsi))
- {
- tree stmt = bsi_stmt (bsi);
-
- if (stmt == exit_condition
- || not_interesting_stmt (stmt)
- || stmt_is_bumper_for_loop (loop, stmt))
- continue;
-
- /* If this is a scalar operation that can be put back
- into the inner loop, or after the inner loop, through
- copying, then do so. This works on the theory that
- any amount of scalar code we have to reduplicate
- into or after the loops is less expensive that the
- win we get from rearranging the memory walk
- the loop is doing so that it has better
- cache behavior. */
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
- {
- use_operand_p use_a, use_b;
- imm_use_iterator imm_iter;
- ssa_op_iter op_iter, op_iter1;
- tree op0 = GIMPLE_STMT_OPERAND (stmt, 0);
- tree scev = instantiate_parameters
- (loop, analyze_scalar_evolution (loop, op0));
-
- /* If the IV is simple, it can be duplicated. */
- if (!automatically_generated_chrec_p (scev))
- {
- tree step = evolution_part_in_loop_num (scev, loop->num);
- if (step && step != chrec_dont_know
- && TREE_CODE (step) == INTEGER_CST)
- continue;
- }
-
- /* The statement should not define a variable used
- in the inner loop. */
- if (TREE_CODE (op0) == SSA_NAME)
- FOR_EACH_IMM_USE_FAST (use_a, imm_iter, op0)
- if (bb_for_stmt (USE_STMT (use_a))->loop_father
- == loop->inner)
- goto fail;
-
- FOR_EACH_SSA_USE_OPERAND (use_a, stmt, op_iter, SSA_OP_USE)
- {
- tree node, op = USE_FROM_PTR (use_a);
-
- /* The variables should not be used in both loops. */
- FOR_EACH_IMM_USE_FAST (use_b, imm_iter, op)
- if (bb_for_stmt (USE_STMT (use_b))->loop_father
- == loop->inner)
- goto fail;
-
- /* The statement should not use the value of a
- scalar that was modified in the loop. */
- node = SSA_NAME_DEF_STMT (op);
- if (TREE_CODE (node) == PHI_NODE)
- FOR_EACH_PHI_ARG (use_b, node, op_iter1, SSA_OP_USE)
- {
- tree arg = USE_FROM_PTR (use_b);
-
- if (TREE_CODE (arg) == SSA_NAME)
- {
- tree arg_stmt = SSA_NAME_DEF_STMT (arg);
-
- if (bb_for_stmt (arg_stmt)
- && (bb_for_stmt (arg_stmt)->loop_father
- == loop->inner))
- goto fail;
- }
- }
- }
-
- if (can_put_in_inner_loop (loop->inner, stmt)
- || can_put_after_inner_loop (loop, stmt))
- continue;
- }
-
- /* Otherwise, if the bb of a statement we care about isn't
- dominated by the header of the inner loop, then we can't
- handle this case right now. This test ensures that the
- statement comes completely *after* the inner loop. */
- if (!dominated_by_p (CDI_DOMINATORS,
- bb_for_stmt (stmt),
- loop->inner->header))
- goto fail;
- }
- }
- }
+ if (bbs[i]->loop_father == loop
+ && cannot_convert_bb_to_perfect_nest (bbs[i], loop))
+ goto fail;
/* We also need to make sure the loop exit only has simple copy phis in it,
- otherwise we don't know how to transform it into a perfect nest right
- now. */
- exitdest = single_exit (loop)->dest;
-
- for (phi = phi_nodes (exitdest); phi; phi = PHI_CHAIN (phi))
+ otherwise we don't know how to transform it into a perfect nest. */
+ for (phi = phi_nodes (single_exit (loop)->dest); phi; phi = PHI_CHAIN (phi))
if (PHI_NUM_ARGS (phi) != 1)
goto fail;
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