src/share/vm/opto/output.cpp

*** 497,509 ****
          uint bnum = block->non_connector_successor(0)->_pre_order;
          int offset = blk_starts[bnum] - br_offs;
          if (bnum > i) { // adjust following block's offset
            offset -= adjust_block_start;
          }
          // In the following code a nop could be inserted before
          // the branch which will increase the backward distance.
!         bool needs_padding = ((uint)br_offs == last_may_be_short_branch_adr);
          if (needs_padding && offset <= 0)
            offset -= nop_size;
  
          if (_matcher->is_short_branch_offset(mach->rule(), br_size, offset)) {
            // We've got a winner.  Replace this branch.
--- 497,519 ----
          uint bnum = block->non_connector_successor(0)->_pre_order;
          int offset = blk_starts[bnum] - br_offs;
          if (bnum > i) { // adjust following block's offset
            offset -= adjust_block_start;
          }
+ 
+         // This block can be a loop header, account for the padding
+         // in the previous block.
+         int prev_block_loop_pad = block->code_alignment() - relocInfo::addr_unit();
+         if (i > 0 && prev_block_loop_pad > 0) {
+           assert(br_offs >= prev_block_loop_pad, "Should have at least a padding on top");
+         } else {
+           // First block or not a loop
+           prev_block_loop_pad = 0;
+         }
          // In the following code a nop could be inserted before
          // the branch which will increase the backward distance.
!         bool needs_padding = ((uint)(br_offs - prev_block_loop_pad) == last_may_be_short_branch_adr);
          if (needs_padding && offset <= 0)
            offset -= nop_size;
  
          if (_matcher->is_short_branch_offset(mach->rule(), br_size, offset)) {
            // We've got a winner.  Replace this branch.