1.1 --- a/src/share/vm/opto/loopTransform.cpp Wed May 04 22:41:17 2011 -0700
1.2 +++ b/src/share/vm/opto/loopTransform.cpp Thu May 05 21:06:14 2011 -0700
1.3 @@ -1229,6 +1229,19 @@
1.4 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1.5 set_ctrl(new_limit, C->root());
1.6 } else {
1.7 + // Limit is not constant.
1.8 + {
1.9 + // Separate limit by Opaque node in case it is an incremented
1.10 + // variable from previous loop to avoid using pre-incremented
1.11 + // value which could increase register pressure.
1.12 + // Otherwise reorg_offsets() optimization will create a separate
1.13 + // Opaque node for each use of trip-counter and as result
1.14 + // zero trip guard limit will be different from loop limit.
1.15 + assert(has_ctrl(opaq), "should have it");
1.16 + Node* opaq_ctrl = get_ctrl(opaq);
1.17 + limit = new (C, 2) Opaque2Node( C, limit );
1.18 + register_new_node( limit, opaq_ctrl );
1.19 + }
1.20 if (stride_con > 0 && ((limit_type->_lo - stride_con) < limit_type->_lo) ||
1.21 stride_con < 0 && ((limit_type->_hi - stride_con) > limit_type->_hi)) {
1.22 // No underflow.
1.23 @@ -1278,24 +1291,19 @@
1.24 register_new_node(new_limit, ctrl);
1.25 }
1.26 assert(new_limit != NULL, "");
1.27 - if (limit->outcnt() == 2) {
1.28 - // Replace old limit if it is used only in loop tests.
1.29 - _igvn.replace_node(limit, new_limit);
1.30 - } else {
1.31 - // Replace in loop test.
1.32 - _igvn.hash_delete(cmp);
1.33 - cmp->set_req(2, new_limit);
1.34 + // Replace in loop test.
1.35 + _igvn.hash_delete(cmp);
1.36 + cmp->set_req(2, new_limit);
1.37
1.38 - // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1.39 - // Make it a 1-trip test (means at least 2 trips).
1.40 + // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1.41 + // Make it a 1-trip test (means at least 2 trips).
1.42
1.43 - // Guard test uses an 'opaque' node which is not shared. Hence I
1.44 - // can edit it's inputs directly. Hammer in the new limit for the
1.45 - // minimum-trip guard.
1.46 - assert(opaq->outcnt() == 1, "");
1.47 - _igvn.hash_delete(opaq);
1.48 - opaq->set_req(1, new_limit);
1.49 - }
1.50 + // Guard test uses an 'opaque' node which is not shared. Hence I
1.51 + // can edit it's inputs directly. Hammer in the new limit for the
1.52 + // minimum-trip guard.
1.53 + assert(opaq->outcnt() == 1, "");
1.54 + _igvn.hash_delete(opaq);
1.55 + opaq->set_req(1, new_limit);
1.56 }
1.57
1.58 // Adjust max trip count. The trip count is intentionally rounded
