Improved common subexpression elimination support.

1 files changed, 0 insertions, 175 deletions

diff --git a/Tools/CodeGen/CodeGen.m b/Tools/CodeGen/CodeGen.m
index e8175a1..197c6af 100644
--- a/Tools/CodeGen/CodeGen.m
+++ b/Tools/CodeGen/CodeGen.m
@@ -121,7 +121,6 @@ CommaNewlineSeparated::usage = ""; (* This should not really be in CodeGen *)
 CommaSeparated::usage = "";
 ReplacePowers::usage = "";
 CFormHideStrings::usage = "";
-CSE::usage = "";
 BoundaryLoop::usage = "";
 BoundaryWithGhostsLoop::usage = "";
 GenericGridLoop::usage = "";
@@ -926,180 +925,6 @@ CFormHideStrings[x_, opts___] := StringReplace[ToString[CForm[x,opts]], "\"" ->
 
 
 
-(* Debug output *)
-DebugCSE = True;
-
-(* Eliminate common subexpressions in a code sequence *)
-CSE[code_] := Module[
-  {expr, optexpr,
-   decomposed, locals, block,
-   block1, block2, temps1, stmts1, stmts2, stmts3,
-   replacevar,
-   stmts4,
-   stmts5, stmts6, stmts7},
-  if [DebugCSE, Print["code\n", code, "\nendcode\n"]];
-  
-  (* The code is passed in as list of {lhs,rhs} tuples.  Turn this
-     list into a single expression, so that it can be optimised.  *)
-  expr = code //. {a_, b__} -> CSequence[a, {b}]
-              //. {a_} -> a
-              //. (a_ -> b_) -> CAssign[a, b];
-  If [DebugCSE, Print["expr\n", expr, "\nendexpr\n"]];
-  
-  (* Optimise this expression *)
-  optexpr = Experimental`OptimizeExpression[expr];
-  If [DebugCSE, Print["optexpr\n", optexpr, "\nendoptexpr\n"]];
-  
-  (* This expression is a Mathematica expression.  Decompose it into
-     the set of newly introduced local variables and the optimised
-     expression itself.  *)
-  decomposed =
-    ReleaseHold[(Hold @@ optexpr)
-                /. Verbatim[Block][vars_, seq_] :> {vars, Hold[seq]}];
-  
-  If[decomposed[[0]] =!= List,
-    (* If the optimiser didn't create a Block expression, we assume it
-       didn't do anything useful and return the original.  *)
-    code,
-    
-    {locals, block} = decomposed;
-    If [DebugCSE, Print["locals\n", locals, "\nendlocals\n"]];
-    If [DebugCSE, Print["block\n", block, "\nendblock\n"]];
-    
-    block1 = block /. Hold[CompoundExpression[seq__]] :> Hold[{seq}];
-    If [DebugCSE, Print["block1\n", block1, "\nendblock1\n"]];
-    block2 = First[block1 //. Hold[{a___Hold, b_, c___}]
-                              /; Head[Unevaluated[b]] =!= Hold
-                              :> Hold[{a, Hold[b], c}]];
-    If [DebugCSE, Print["block2\n", block2, "\nendblock2\n"]];
-    
-    (* Temporaries, including a fake declaration for them *)
-    temps1 = Most[block2] //. Hold[lhs_ = rhs_] -> CAssign[CDeclare[lhs], rhs];
-    If [DebugCSE, Print["temps1\n", temps1, "\nendtemps1\n"]];
-    
-    (* Expression *)
-    stmts1 = ReleaseHold[Last[block2]];
-    If [DebugCSE, Print["stmts1\n", stmts1, "\nendstmts1\n"]];
-    
-    (* Turn CSequence back into a list *)
-    stmts2 = Flatten[{stmts1} //. CSequence[a_,b_] -> {a,b}];
-    If [DebugCSE, Print["stmts2\n", stmts2, "\nendstmts2\n"]];
-    
-    (* Combine temporaries and expression *)
-    stmts3 = Join[temps1, stmts2];
-    If [DebugCSE, Print["stmts3\n", stmts3, "\nendstmts3\n"]];
-    
-    (* Replace the internal names of the newly generated temporaries
-       with legal C names *)
-    replacevar =
-      Rule @@@ Transpose[{(*ToString[CForm[#]] & /@*) locals,
-        Symbol[
-          StringReplace[StringReplace[ToString[#], {__ ~~ "`" ~~ a_ :> a}],
-            "$" -> "T"]] & /@ locals}];
-    If [DebugCSE, Print["replacevar\n", replacevar, "\nendreplacevar\n"]];
-    
-    stmts4 = stmts3 //. replacevar;
-    If [DebugCSE, Print["stmts4\n", stmts4, "\nendstmts4\n"]];
-    
-    (* Sort statements topologically *)
-(*
-    stmts5 = stmts4;
-*)
-    If [DebugCSE, Print["A\n"]];
-    stmts5 =
-      Module[{debug,
-              tmpVars, newVars, i,
-              stmtsLeft, stmtsDone,
-              lhs, rhs, any, contains, containsAny,
-              canDoStmts, cannotDoStmts,
-              selfStmts, selfVars, allVars, nonSelfVars},
-        debug = False;
-        stmtsLeft = stmts4;
-        If [DebugCSE, Print["B\n"]];
-        stmtsDone = {};
-        If [DebugCSE, Print["C\n"]];
-        (* lhs[x_] := x[[1]]; *)
-        lhs[x_] := x /. (CAssign[lhs_, rhs_] -> lhs);
-        If [DebugCSE, Print["D\n"]];
-        (* rhs[x_] := x[[2]]; *)
-        rhs[x_] := x /. (CAssign[lhs_, rhs_] -> rhs);
-        If [DebugCSE, Print["E\n"]];
-        (* any[xs_] := Fold[Or, False, xs]; *)
-        any[xs_] := MemberQ[xs, True];
-        If [DebugCSE, Print["F\n"]];
-        (* contains[e_, x_] := (e /. x -> {}) =!= e; *)
-        (* contains[e_, x_] := Count[{e}, x, Infinity] > 0; *)
-        contains[e_, x_] := MemberQ[{e}, x, Infinity];
-        If [DebugCSE, Print["G\n"]];
-        containsAny[e_, xs_] := any[Map[contains[e,#]&, xs]];
-        If [DebugCSE, Print["H\n"]];
-        getVars[stmts_] := Map[lhs, stmts] //. (CDeclare[lhs_] -> lhs);
-
-        (* Rename temporary variables deterministically *)
-        tmpVars = Select[getVars[stmtsLeft],
-                         StringMatchQ[ToString[#], "TT"~~__]&];
-        newVars = Table[Symbol["T"<>ToString[1000000+i]],
-                        {i, 1, Length[tmpVars]}];
-        stmtsLeft = stmtsLeft /. MapThread[(#1->#2)&, {tmpVars, newVars}];
-
-        allVars = getVars[stmtsLeft];
-        While[stmtsLeft =!= {},
-          If[debug, Print["stmtsLeft = \n", stmtsLeft]];
-          If[debug, Print["stmtsDone = \n", stmtsDone]];
-          allVars = getVars[stmtsLeft];
-          If[debug, Print["allVars = \n", allVars]];
-          canDoStmts =
-            Select[stmtsLeft, Not[containsAny[rhs[#], allVars]] &];
-          cannotDoStmts =
-            Select[stmtsLeft,     containsAny[rhs[#], allVars]  &];
-          If[debug, Print["canDoStmts = \n", canDoStmts]];
-          If[debug, Print["cannotDoStmts = \n", cannotDoStmts]];
-          If[False && canDoStmts == {},
-            (* Handle assignment where LHS and RHS access the same variables
-               (hopefully without taking derivatives!) *)
-            selfStmts = Select[stmtsLeft, contains[rhs[#], lhs[#]]];
-            selfVars = getVars[selfStmts];
-            nonSelfVars = Select[allVars, Not[contains[selfVars, #]] &];
-            canDoStmts =
-              Select[stmtsLeft, Not[containsAny[rhs[#], nonSelfVars]] &];
-            cannotDoStmts =
-              Select[stmtsLeft,     containsAny[rhs[#], nonSelfVars]  &];
-            If[debug, Print["nonself/canDoStmts = \n", canDoStmts]];
-            If[debug, Print["nonself/cannotDoStmts = \n", cannotDoStmts]];
-          ];
-          If[canDoStmts == {},
-            (* Accept the first statement *)
-            canDoStmts = {First[stmtsLeft]};
-            cannotDoStmts = Rest[stmtsLeft];
-            If[debug, Print["takeone/canDoStmts = \n", canDoStmts]];
-            If[debug, Print["takeone/cannotDoStmts = \n", cannotDoStmts]];
-          ];
-          If[canDoStmts == {}, ThrowError["canDoStmts == {}"]];
-          stmtsDone = Join[stmtsDone, canDoStmts];
-          If [DebugCSE, Print["I\n"]];
-          stmtsLeft = cannotDoStmts;
-          If [DebugCSE, Print["J\n"]];
-        ];
-        If[debug, Print["stmtsLeft\n", stmtsLeft]];
-        If[debug, Print["stmtsDone\n", stmtsDone]];
-      stmtsDone];
-    If [DebugCSE, Print["Z\n"]];
-    
-    (* Turn CAssign statements back into (->) tuples *)
-    stmts6 = stmts5 //. CAssign[lhs_,rhs_] -> (lhs -> rhs);
-    If [DebugCSE, Print["stmts6\n", stmts6, "\nendstmts6\n"]];
-    
-    (* Turn CDeclare statements into "faked" declarations *)
-    stmts7 = stmts6
-      //. CDeclare[var_]
-          :> "const " <>
-             StringReplace[ToString[var], __ ~~ "`" -> ""];
-    If [DebugCSE, Print["stmts7\n", stmts7, "\nendstmts7\n"]];
-    
-    stmts7
-  ]
-];
-
 Quote[x_] := {"\"", x, "\""};
 
 End[];