static gphi * single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1) { gimple_stmt_iterator i; gphi *phi = NULL; if (gimple_seq_singleton_p (seq)) return as_a <gphi *> (gsi_stmt (gsi_start (seq))); for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i)) { gphi *p = as_a <gphi *> (gsi_stmt (i)); /* If the PHI arguments are equal then we can skip this PHI. */ if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p, e0->dest_idx), gimple_phi_arg_def (p, e1->dest_idx))) continue; /* If we already have a PHI that has the two edge arguments are different, then return it is not a singleton for these PHIs. */ if (phi) return NULL; phi = p; } return phi; }
static bool minmax_replacement (basic_block cond_bb, basic_block middle_bb, edge e0, edge e1, gimple phi, tree arg0, tree arg1) { tree result, type; gimple cond, new_stmt; edge true_edge, false_edge; enum tree_code cmp, minmax, ass_code; tree smaller, larger, arg_true, arg_false; gimple_stmt_iterator gsi, gsi_from; type = TREE_TYPE (PHI_RESULT (phi)); /* The optimization may be unsafe due to NaNs. */ if (HONOR_NANS (TYPE_MODE (type))) return false; cond = last_stmt (cond_bb); cmp = gimple_cond_code (cond); result = PHI_RESULT (phi); /* This transformation is only valid for order comparisons. Record which operand is smaller/larger if the result of the comparison is true. */ if (cmp == LT_EXPR || cmp == LE_EXPR) { smaller = gimple_cond_lhs (cond); larger = gimple_cond_rhs (cond); } else if (cmp == GT_EXPR || cmp == GE_EXPR) { smaller = gimple_cond_rhs (cond); larger = gimple_cond_lhs (cond); } else return false; /* We need to know which is the true edge and which is the false edge so that we know if have abs or negative abs. */ extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); /* Forward the edges over the middle basic block. */ if (true_edge->dest == middle_bb) true_edge = EDGE_SUCC (true_edge->dest, 0); if (false_edge->dest == middle_bb) false_edge = EDGE_SUCC (false_edge->dest, 0); if (true_edge == e0) { gcc_assert (false_edge == e1); arg_true = arg0; arg_false = arg1; } else { gcc_assert (false_edge == e0); gcc_assert (true_edge == e1); arg_true = arg1; arg_false = arg0; } if (empty_block_p (middle_bb)) { if (operand_equal_for_phi_arg_p (arg_true, smaller) && operand_equal_for_phi_arg_p (arg_false, larger)) { /* Case if (smaller < larger) rslt = smaller; else rslt = larger; */ minmax = MIN_EXPR; } else if (operand_equal_for_phi_arg_p (arg_false, smaller) && operand_equal_for_phi_arg_p (arg_true, larger)) minmax = MAX_EXPR; else return false; } else { /* Recognize the following case, assuming d <= u: if (a <= u) b = MAX (a, d); x = PHI <b, u> This is equivalent to b = MAX (a, d); x = MIN (b, u); */ gimple assign = last_and_only_stmt (middle_bb); tree lhs, op0, op1, bound; if (!assign || gimple_code (assign) != GIMPLE_ASSIGN) return false; lhs = gimple_assign_lhs (assign); ass_code = gimple_assign_rhs_code (assign); if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) return false; op0 = gimple_assign_rhs1 (assign); op1 = gimple_assign_rhs2 (assign); if (true_edge->src == middle_bb) { /* We got here if the condition is true, i.e., SMALLER < LARGER. */ if (!operand_equal_for_phi_arg_p (lhs, arg_true)) return false; if (operand_equal_for_phi_arg_p (arg_false, larger)) { /* Case if (smaller < larger) { r' = MAX_EXPR (smaller, bound) } r = PHI <r', larger> --> to be turned to MIN_EXPR. */ if (ass_code != MAX_EXPR) return false; minmax = MIN_EXPR; if (operand_equal_for_phi_arg_p (op0, smaller)) bound = op1; else if (operand_equal_for_phi_arg_p (op1, smaller)) bound = op0; else return false; /* We need BOUND <= LARGER. */ if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, bound, larger))) return false; } else if (operand_equal_for_phi_arg_p (arg_false, smaller)) { /* Case if (smaller < larger) { r' = MIN_EXPR (larger, bound) } r = PHI <r', smaller> --> to be turned to MAX_EXPR. */ if (ass_code != MIN_EXPR) return false; minmax = MAX_EXPR; if (operand_equal_for_phi_arg_p (op0, larger)) bound = op1; else if (operand_equal_for_phi_arg_p (op1, larger)) bound = op0; else return false; /* We need BOUND >= SMALLER. */ if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, bound, smaller))) return false; } else return false; } else { /* We got here if the condition is false, i.e., SMALLER > LARGER. */ if (!operand_equal_for_phi_arg_p (lhs, arg_false)) return false; if (operand_equal_for_phi_arg_p (arg_true, larger)) { /* Case if (smaller > larger) { r' = MIN_EXPR (smaller, bound) } r = PHI <r', larger> --> to be turned to MAX_EXPR. */ if (ass_code != MIN_EXPR) return false; minmax = MAX_EXPR; if (operand_equal_for_phi_arg_p (op0, smaller)) bound = op1; else if (operand_equal_for_phi_arg_p (op1, smaller)) bound = op0; else return false; /* We need BOUND >= LARGER. */ if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, bound, larger))) return false; } else if (operand_equal_for_phi_arg_p (arg_true, smaller)) { /* Case if (smaller > larger) { r' = MAX_EXPR (larger, bound) } r = PHI <r', smaller> --> to be turned to MIN_EXPR. */ if (ass_code != MAX_EXPR) return false; minmax = MIN_EXPR; if (operand_equal_for_phi_arg_p (op0, larger)) bound = op1; else if (operand_equal_for_phi_arg_p (op1, larger)) bound = op0; else return false; /* We need BOUND <= SMALLER. */ if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, bound, smaller))) return false; } else return false; } /* Move the statement from the middle block. */ gsi = gsi_last_bb (cond_bb); gsi_from = gsi_last_bb (middle_bb); gsi_move_before (&gsi_from, &gsi); } /* Emit the statement to compute min/max. */ result = duplicate_ssa_name (PHI_RESULT (phi), NULL); new_stmt = gimple_build_assign_with_ops (minmax, result, arg0, arg1); gsi = gsi_last_bb (cond_bb); gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); replace_phi_edge_with_variable (cond_bb, e1, phi, result); return true; }
static bool value_replacement (basic_block cond_bb, basic_block middle_bb, edge e0, edge e1, gimple phi, tree arg0, tree arg1) { gimple cond; edge true_edge, false_edge; enum tree_code code; /* If the type says honor signed zeros we cannot do this optimization. */ if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) return false; if (!empty_block_p (middle_bb)) return false; cond = last_stmt (cond_bb); code = gimple_cond_code (cond); /* This transformation is only valid for equality comparisons. */ if (code != NE_EXPR && code != EQ_EXPR) return false; /* We need to know which is the true edge and which is the false edge so that we know if have abs or negative abs. */ extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); /* At this point we know we have a COND_EXPR with two successors. One successor is BB, the other successor is an empty block which falls through into BB. The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR. There is a single PHI node at the join point (BB) with two arguments. We now need to verify that the two arguments in the PHI node match the two arguments to the equality comparison. */ if ((operand_equal_for_phi_arg_p (arg0, gimple_cond_lhs (cond)) && operand_equal_for_phi_arg_p (arg1, gimple_cond_rhs (cond))) || (operand_equal_for_phi_arg_p (arg1, gimple_cond_lhs (cond)) && operand_equal_for_phi_arg_p (arg0, gimple_cond_rhs (cond)))) { edge e; tree arg; /* For NE_EXPR, we want to build an assignment result = arg where arg is the PHI argument associated with the true edge. For EQ_EXPR we want the PHI argument associated with the false edge. */ e = (code == NE_EXPR ? true_edge : false_edge); /* Unfortunately, E may not reach BB (it may instead have gone to OTHER_BLOCK). If that is the case, then we want the single outgoing edge from OTHER_BLOCK which reaches BB and represents the desired path from COND_BLOCK. */ if (e->dest == middle_bb) e = single_succ_edge (e->dest); /* Now we know the incoming edge to BB that has the argument for the RHS of our new assignment statement. */ if (e0 == e) arg = arg0; else arg = arg1; replace_phi_edge_with_variable (cond_bb, e1, phi, arg); /* Note that we optimized this PHI. */ return true; } return false; }