Subversion Repositories Open64

Last modification

• Rev 3735 2011-09-10 02:42:57 GMT
• Author: yug

• Log message:

  A new implementation for the open64's support for DSP Zero-Delay-Loop(ZDL) feature. This ZDL contribution is a co-operational approach of global scalar optimizer WOPT and the Code Generation component CG. The common ZDL features, i.e, the loop counting mechanism hidden and bottom loop condition abstracted are implemented in WOPT with minimized changes while keeping the maximum optimizing result. A pseudo branch op method is introduced to expand ZDL WHIRL operator and delay the ZDL hardware instruction generation to the very last phase of CG loop optimization. This lazy implementation helps keeping the compatibility with other CG loop optimizations to produce the most optimal code. With the new ZDL implementation, open64 provides the equal expressibility to gcc's doloop_begin, doloop_end and decrement_and_branch_until_zero patterns.
  
  Pragma:
  #pragma zdl off
  
  Flags:
  WOPT_Enable_ZDL
  OPT_Lower_ZDL
  WOPT_Enable_ZDL_Early_Exit
  WOPT_ZDL_Innermost_Only
  CG_zdl_enabled_level[SL]
  
  retargeting macro:
  ZDL_TARG
  
  retargeting interface:
  INT CG_LOOP_ZDL_Gen(LOOP_DESCR*); //cg_loop.cxx
  void Emit_Phase_Validity_Check(void); //cgemit.cxx
  void Target_Specific_ZDLBR_Expansion(TN* target_tn); //whirl2ops.cxx
  
  provided options
  -WOPT:zdl
  -WOPT:zdl_skip_a
  -WOPT:zdl_skip_b
  -WOPT:zdl_skip_e
  -OPT:lower_zdl
  -CG:zdl_enabled_level[SL]
  
  Code Review: Fred Chow, Lai Jianxin and Sun Chan.