Mercurial > hg > truffle
changeset 308:756b58154237
6611837: block frequency is zero
Summary: insert_goto_at should set frequency for newly created blocks
Reviewed-by: never
author | rasbold |
---|---|
date | Thu, 28 Aug 2008 10:22:12 -0700 |
parents | 892493c3d862 |
children | eaf496ad4a14 |
files | src/share/vm/opto/block.cpp src/share/vm/opto/gcm.cpp |
diffstat | 2 files changed, 30 insertions(+), 1 deletions(-) [+] |
line wrap: on
line diff
--- a/src/share/vm/opto/block.cpp Wed Aug 27 16:33:34 2008 -0700 +++ b/src/share/vm/opto/block.cpp Thu Aug 28 10:22:12 2008 -0700 @@ -467,6 +467,10 @@ // get successor block succ_no assert(succ_no < in->_num_succs, "illegal successor number"); Block* out = in->_succs[succ_no]; + // Compute frequency of the new block. Do this before inserting + // new block in case succ_prob() needs to infer the probability from + // surrounding blocks. + float freq = in->_freq * in->succ_prob(succ_no); // get ProjNode corresponding to the succ_no'th successor of the in block ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj(); // create region for basic block @@ -491,6 +495,8 @@ } // remap predecessor's successor to new block in->_succs.map(succ_no, block); + // Set the frequency of the new block + block->_freq = freq; // add new basic block to basic block list _blocks.insert(block_no + 1, block); _num_blocks++;
--- a/src/share/vm/opto/gcm.cpp Wed Aug 27 16:33:34 2008 -0700 +++ b/src/share/vm/opto/gcm.cpp Thu Aug 28 10:22:12 2008 -0700 @@ -1609,7 +1609,30 @@ float Block::succ_prob(uint i) { int eidx = end_idx(); Node *n = _nodes[eidx]; // Get ending Node - int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode(); + + int op = n->Opcode(); + if (n->is_Mach()) { + if (n->is_MachNullCheck()) { + // Can only reach here if called after lcm. The original Op_If is gone, + // so we attempt to infer the probability from one or both of the + // successor blocks. + assert(_num_succs == 2, "expecting 2 successors of a null check"); + // If either successor has only one predecessor, then the + // probabiltity estimate can be derived using the + // relative frequency of the successor and this block. + if (_succs[i]->num_preds() == 2) { + return _succs[i]->_freq / _freq; + } else if (_succs[1-i]->num_preds() == 2) { + return 1 - (_succs[1-i]->_freq / _freq); + } else { + // Estimate using both successor frequencies + float freq = _succs[i]->_freq; + return freq / (freq + _succs[1-i]->_freq); + } + } + op = n->as_Mach()->ideal_Opcode(); + } + // Switch on branch type switch( op ) {