--- a/src/hotspot/share/opto/loopTransform.cpp Mon Dec 31 14:38:16 2018 +0100
+++ b/src/hotspot/share/opto/loopTransform.cpp Fri Dec 14 11:22:26 2018 +0100
@@ -2039,13 +2039,20 @@
//------------------------------adjust_limit-----------------------------------
// Helper function for add_constraint().
-Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl) {
+Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl, bool round_up) {
// Compute "I :: (limit-offset)/scale"
Node *con = new SubINode(rc_limit, offset);
register_new_node(con, pre_ctrl);
Node *X = new DivINode(0, con, scale);
register_new_node(X, pre_ctrl);
+ // When the absolute value of scale is greater than one, the integer
+ // division may round limit down so add one to the limit.
+ if (round_up) {
+ X = new AddINode(X, _igvn.intcon(1));
+ register_new_node(X, pre_ctrl);
+ }
+
// Adjust loop limit
loop_limit = (stride_con > 0)
? (Node*)(new MinINode(loop_limit, X))
@@ -2086,7 +2093,7 @@
// (upper_limit-offset) may overflow or underflow.
// But it is fine since main loop will either have
// less iterations or will be skipped in such case.
- *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl);
+ *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl, false);
// The underflow limit: low_limit <= scale*I+offset.
// For pre-loop compute
@@ -2121,7 +2128,8 @@
// max(pre_limit, original_limit) is used in do_range_check().
}
// Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
- *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl);
+ *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl,
+ scale_con > 1 && stride_con > 0);
} else { // stride_con*scale_con < 0
// For negative stride*scale pre-loop checks for overflow and
@@ -2147,7 +2155,8 @@
Node *plus_one = new AddINode(offset, one);
register_new_node( plus_one, pre_ctrl );
// Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
- *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl);
+ *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl,
+ scale_con < -1 && stride_con > 0);
if (low_limit->get_int() == -max_jint) {
// We need this guard when scale*main_limit+offset >= limit
@@ -2181,7 +2190,8 @@
// I > (low_limit-(offset+1))/scale
// )
- *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl);
+ *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl,
+ false);
}
}