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comparison src/share/vm/opto/output.cpp @ 14509:b3e1a903b6e8

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8035283: Second phase of branch shortening doesn't account for loop alignment Summary: added missing check for loop padding case. Reviewed-by: kvn, jrose
author iveresov
date Wed, 26 Feb 2014 16:45:15 -0800
parents abec000618bf
children d8041d695d19
comparison
equal deleted inserted replaced
14508:78112be27ba0 14509:b3e1a903b6e8
342 uint nblocks = _cfg->number_of_blocks(); 342 uint nblocks = _cfg->number_of_blocks();
343 343
344 uint* jmp_offset = NEW_RESOURCE_ARRAY(uint,nblocks); 344 uint* jmp_offset = NEW_RESOURCE_ARRAY(uint,nblocks);
345 uint* jmp_size = NEW_RESOURCE_ARRAY(uint,nblocks); 345 uint* jmp_size = NEW_RESOURCE_ARRAY(uint,nblocks);
346 int* jmp_nidx = NEW_RESOURCE_ARRAY(int ,nblocks); 346 int* jmp_nidx = NEW_RESOURCE_ARRAY(int ,nblocks);
347
348 // Collect worst case block paddings
349 int* block_worst_case_pad = NEW_RESOURCE_ARRAY(int, nblocks);
350 memset(block_worst_case_pad, 0, nblocks * sizeof(int));
351
347 DEBUG_ONLY( uint *jmp_target = NEW_RESOURCE_ARRAY(uint,nblocks); ) 352 DEBUG_ONLY( uint *jmp_target = NEW_RESOURCE_ARRAY(uint,nblocks); )
348 DEBUG_ONLY( uint *jmp_rule = NEW_RESOURCE_ARRAY(uint,nblocks); ) 353 DEBUG_ONLY( uint *jmp_rule = NEW_RESOURCE_ARRAY(uint,nblocks); )
349 354
350 bool has_short_branch_candidate = false; 355 bool has_short_branch_candidate = false;
351 356
458 } 463 }
459 if (last_avoid_back_to_back_adr == blk_starts[i]+blk_size) { 464 if (last_avoid_back_to_back_adr == blk_starts[i]+blk_size) {
460 last_avoid_back_to_back_adr += max_loop_pad; 465 last_avoid_back_to_back_adr += max_loop_pad;
461 } 466 }
462 blk_size += max_loop_pad; 467 blk_size += max_loop_pad;
468 block_worst_case_pad[i + 1] = max_loop_pad;
463 } 469 }
464 } 470 }
465 471
466 // Save block size; update total method size 472 // Save block size; update total method size
467 blk_starts[i+1] = blk_starts[i]+blk_size; 473 blk_starts[i+1] = blk_starts[i]+blk_size;
497 uint bnum = block->non_connector_successor(0)->_pre_order; 503 uint bnum = block->non_connector_successor(0)->_pre_order;
498 int offset = blk_starts[bnum] - br_offs; 504 int offset = blk_starts[bnum] - br_offs;
499 if (bnum > i) { // adjust following block's offset 505 if (bnum > i) { // adjust following block's offset
500 offset -= adjust_block_start; 506 offset -= adjust_block_start;
501 } 507 }
508
509 // This block can be a loop header, account for the padding
510 // in the previous block.
511 int block_padding = block_worst_case_pad[i];
512 assert(i == 0 || block_padding == 0 || br_offs >= block_padding, "Should have at least a padding on top");
502 // In the following code a nop could be inserted before 513 // In the following code a nop could be inserted before
503 // the branch which will increase the backward distance. 514 // the branch which will increase the backward distance.
504 bool needs_padding = ((uint)br_offs == last_may_be_short_branch_adr); 515 bool needs_padding = ((uint)(br_offs - block_padding) == last_may_be_short_branch_adr);
516 assert(!needs_padding || jmp_offset[i] == 0, "padding only branches at the beginning of block");
517
505 if (needs_padding && offset <= 0) 518 if (needs_padding && offset <= 0)
506 offset -= nop_size; 519 offset -= nop_size;
507 520
508 if (_matcher->is_short_branch_offset(mach->rule(), br_size, offset)) { 521 if (_matcher->is_short_branch_offset(mach->rule(), br_size, offset)) {
509 // We've got a winner. Replace this branch. 522 // We've got a winner. Replace this branch.