From c7ef4cc9fcb5e91c0f402e9dc6c85f8357f2cbfc Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Fri, 12 Feb 2010 09:43:37 +0000
Subject: [PATCH] * Updated the cost matrix normalization proceedure to better
 handle infinite costs. * Enabled R1/R2 application for nodes with infinite
 spill costs in the Briggs heuristic (made safe by the changes to the
 normalization proceedure). * Removed a redundant header.

llvm-svn: 95973
---
 llvm/lib/CodeGen/PBQP/HeuristicSolver.h   | 25 ++++++++++++++++++-----
 llvm/lib/CodeGen/PBQP/Heuristics/Briggs.h |  9 +-------
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/CodeGen/PBQP/HeuristicSolver.h b/llvm/lib/CodeGen/PBQP/HeuristicSolver.h
index b48f548950d9..c156264fae0f 100644
--- a/llvm/lib/CodeGen/PBQP/HeuristicSolver.h
+++ b/llvm/lib/CodeGen/PBQP/HeuristicSolver.h
@@ -18,7 +18,6 @@
 
 #include "Graph.h"
 #include "Solution.h"
-#include "llvm/Support/raw_ostream.h"
 #include <vector>
 #include <limits>
 
@@ -494,14 +493,23 @@ namespace PBQP {
 
     bool tryNormaliseEdgeMatrix(Graph::EdgeItr &eItr) {
 
+      const PBQPNum infinity = std::numeric_limits<PBQPNum>::infinity();
+
       Matrix &edgeCosts = g.getEdgeCosts(eItr);
       Vector &uCosts = g.getNodeCosts(g.getEdgeNode1(eItr)),
              &vCosts = g.getNodeCosts(g.getEdgeNode2(eItr));
 
       for (unsigned r = 0; r < edgeCosts.getRows(); ++r) {
-        PBQPNum rowMin = edgeCosts.getRowMin(r);
+        PBQPNum rowMin = infinity;
+
+        for (unsigned c = 0; c < edgeCosts.getCols(); ++c) {
+          if (vCosts[c] != infinity && edgeCosts[r][c] < rowMin)
+            rowMin = edgeCosts[r][c];
+        }
+
         uCosts[r] += rowMin;
-        if (rowMin != std::numeric_limits<PBQPNum>::infinity()) {
+
+        if (rowMin != infinity) {
           edgeCosts.subFromRow(r, rowMin);
         }
         else {
@@ -510,9 +518,16 @@ namespace PBQP {
       }
 
       for (unsigned c = 0; c < edgeCosts.getCols(); ++c) {
-        PBQPNum colMin = edgeCosts.getColMin(c);
+        PBQPNum colMin = infinity;
+
+        for (unsigned r = 0; r < edgeCosts.getRows(); ++r) {
+          if (uCosts[r] != infinity && edgeCosts[r][c] < colMin)
+            colMin = edgeCosts[r][c];
+        }
+
         vCosts[c] += colMin;
-        if (colMin != std::numeric_limits<PBQPNum>::infinity()) {
+
+        if (colMin != infinity) {
           edgeCosts.subFromCol(c, colMin);
         }
         else {
diff --git a/llvm/lib/CodeGen/PBQP/Heuristics/Briggs.h b/llvm/lib/CodeGen/PBQP/Heuristics/Briggs.h
index c09ad74b198a..30d34d9e3e92 100644
--- a/llvm/lib/CodeGen/PBQP/Heuristics/Briggs.h
+++ b/llvm/lib/CodeGen/PBQP/Heuristics/Briggs.h
@@ -128,14 +128,7 @@ namespace PBQP {
       /// selected for heuristic reduction instead.
       bool shouldOptimallyReduce(Graph::NodeItr nItr) {
         if (getSolver().getSolverDegree(nItr) < 3) {
-          if (getGraph().getNodeCosts(nItr)[0] !=
-                std::numeric_limits<PBQPNum>::infinity()) {
-            return true;
-          }
-          // Otherwise we have an infinite spill cost node.
-          initializeNode(nItr);
-          NodeData &nd = getHeuristicNodeData(nItr);
-          return nd.isAllocable;
+          return true;
         }
         // else
         return false;