[phc-internals] [phc commit] r1832 - in branches/dataflow/src: generated generated_src optimize optimize/ssa

[codesite-noreply at google.com]

Author: paul.biggar
Date: Tue Oct 28 13:40:34 2008
New Revision: 1832

Modified:
    branches/dataflow/src/generated/MIR.cpp
    branches/dataflow/src/generated/MIR.h
    branches/dataflow/src/generated_src/mir.tea
    branches/dataflow/src/optimize/Def_use.cpp
    branches/dataflow/src/optimize/ssa/HSSA.cpp

Log:
when going out of SSA form, only create assignments for phi nodes if the  
phi arg is a literal, and just drop ssa indices.


Modified: branches/dataflow/src/generated/MIR.cpp
==============================================================================
--- branches/dataflow/src/generated/MIR.cpp	(original)
+++ branches/dataflow/src/generated/MIR.cpp	Tue Oct 28 13:40:34 2008
@@ -10090,6 +10090,15 @@
  	}
  }

+void VARIABLE_NAME::drop_ssa_index()
+{
+    {
+		assert (this->in_ssa);
+		in_ssa = false;
+		this->version = 0;
+	}
+}
+
  VARIABLE_NAME* VARIABLE_NAME::clone()
  {
      {

Modified: branches/dataflow/src/generated/MIR.h
==============================================================================
--- branches/dataflow/src/generated/MIR.h	(original)
+++ branches/dataflow/src/generated/MIR.h	Tue Oct 28 13:40:34 2008
@@ -2704,6 +2704,7 @@
      VARIABLE_NAME(String* name);
      VARIABLE_NAME(const char* name);
      void convert_to_ssa_name(int version);
+    void drop_ssa_index();
      VARIABLE_NAME* clone();
      void set_version(int version);
      bool operator<(MIR ::VARIABLE_NAME& other);

Modified: branches/dataflow/src/generated_src/mir.tea
==============================================================================
--- branches/dataflow/src/generated_src/mir.tea	(original)
+++ branches/dataflow/src/generated_src/mir.tea	Tue Oct 28 13:40:34 2008
@@ -478,6 +478,13 @@
  		this->is_virtual = false;
  	}

+	void drop_ssa_index ()
+	{
+		assert (this->in_ssa);
+		in_ssa = false;
+		this->version = 0;
+	}
+
  	VARIABLE_NAME* clone ()
  	{
  		String* value = new String(*this->value);

Modified: branches/dataflow/src/optimize/Def_use.cpp
==============================================================================
--- branches/dataflow/src/optimize/Def_use.cpp	(original)
+++ branches/dataflow/src/optimize/Def_use.cpp	Tue Oct 28 13:40:34 2008
@@ -152,7 +152,12 @@
  }


-
+/*
+ * Calculate the def-use web
+ * TODO: this probably needs to be integrated with alias-analysis, or at
+ * least with mu/chi calculation. Its not enough to say a def creates a  
load
+ * of may-defs.
+ */
  void
  Def_use_web::add_use (MIR::Rvalue* def, SSA_op* use)
  {

Modified: branches/dataflow/src/optimize/ssa/HSSA.cpp
==============================================================================
--- branches/dataflow/src/optimize/ssa/HSSA.cpp	(original)
+++ branches/dataflow/src/optimize/ssa/HSSA.cpp	Tue Oct 28 13:40:34 2008
@@ -134,11 +134,36 @@
  		bb->remove_mu_nodes ();
  		bb->remove_virtual_phis ();

+		// There are two problems when coming out of SSA form:
+		//		1.) variable-variables: i_0 is not the same as i
+		//		2.) CHI nodes update variable indices, but when you drop the chi
+		//		nodes, you lose the relationship between them. Renumbering is
+		//		possible, I suppose, but not as good as:
+		//
+		//	The solution is to drop the indices when coming out of SSA form.
+		//	(Warning, this could hide bugs unfortunately). The only real problem
+		//	is to make sure that variables with overlapping live ranges are not
+		//	created. This could happen in copy-propagation, value numbering, or
+		//	PRE. I suspect the latter two can be avoided by using the HSSA
+		//	algorithms. For copy-propagation, I'll just have to be careful.
+
+		// TODO: Add a check that there aren't overlapping live ranges.
  		foreach (VARIABLE_NAME* phi_lhs, *bb->get_phi_lhss ())
  		{
  			BB_list* preds = bb->get_predecessors ();
  			foreach (Rvalue* rval, *bb->get_phi_args (phi_lhs))
  			{
+				if (isa<VARIABLE_NAME> (rval))
+				{
+					VARIABLE_NAME* var = dyc<VARIABLE_NAME> (rval);
+
+					// We've dropped the indices, so make sure the varaibles are
+					// equal (if they arent, perhaps if we've added copy
+					// propagation, we should add an assignment).
+					assert (*var->value == *phi_lhs->value);
+					continue;
+				}
+
  				Assign_var* copy = new Assign_var (
  					phi_lhs->clone (),
  					false,
@@ -157,7 +182,21 @@
  			}
  		}
  		bb->remove_phi_nodes ();
+
  	}
+
+
+	// Drop variable indices
+	rebuild_ssa_form (); // we only care about DUW
+	foreach (Basic_block* bb, *cfg->get_all_bbs ())
+	{
+		foreach (VARIABLE_NAME* var, *cfg->duw->get_nonphi_uses (bb))
+			var->drop_ssa_index();
+
+		foreach (VARIABLE_NAME* var, *cfg->duw->get_nonphi_defs (bb))
+			var->drop_ssa_index();
+	}
+