Subzero: Control whether deleted instructions are retained.

src/IceCfg.cpp

 //===- subzero/src/IceCfg.cpp - Control flow graph implementation ---------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 253 matching lines @@
       ++Dest;
     }
   }
   Nodes.resize(Dest);
 
   TimerMarker T(TimerStack::TT_phiValidation, this);
   for (CfgNode *Node : Nodes)
     Node->validatePhis();
 }
 
+/// Renumber the non-deleted instructions in the Cfg.  This needs to be done in
+/// preparation for live range analysis.  The instruction numbers in a block
+/// must be monotonically increasing.  The range of instruction numbers in a
+/// block, from lowest to highest, must not overlap with the range of any other
+/// block.
+///
+/// Also, if the configuration specifies to do so, remove/unlink all deleted
+/// instructions from the Cfg, to speed up later passes over the instructions.

[John, 2016/03/14 13:27:15]

Maybe document the .h file instead?

[Jim Stichnoth, 2016/03/14 13:51:15]

Done.

 void Cfg::renumberInstructions() {
   TimerMarker T(TimerStack::TT_renumberInstructions, this);
   NextInstNumber = Inst::NumberInitial;
   for (CfgNode *Node : Nodes)
     Node->renumberInstructions();
   // Make sure the entry node is the first node and therefore got the lowest
   // instruction numbers, to facilitate live range computation of function
   // arguments.  We want to model function arguments as being live on entry to
   // the function, otherwise an argument whose only use is in the first
   // instruction will be assigned a trivial live range and the register
@@ skipping 854 matching lines @@
     }
   }
   // Print each basic block
   for (CfgNode *Node : Nodes)
     Node->dump(this);
   if (isVerbose(IceV_Instructions))
     Str << "}\n";
 }
 
 } // end of namespace Ice