Fix translator handling of basic block indices.

src/IceCfg.cpp

Index: src/IceCfg.cpp
diff --git a/src/IceCfg.cpp b/src/IceCfg.cpp
index 847563cc809654d7e1435d6d7e925d08ce264c92..268240cff525c6cfac317747ab9c45396e0b36e4 100644
--- a/src/IceCfg.cpp
+++ b/src/IceCfg.cpp
@@ -61,6 +61,12 @@ CfgNode *Cfg::makeNode() {
   return Node;
 }
 
+void Cfg::replaceNodes(const NodeList &NewNodes) {
+  Nodes = NewNodes;

[John, 2015/08/06 17:22:54]

The CL description mentions "large numbers." So, I assume NewNodes is
potentially very large.

NodeList is not a list, is a std::vector, so copying is not super efficient. The
calls to replaceNodes below don't care about what happens to NewNodes. Why not
turning NewNodes into a non-const pointer, and using swap?

[Karl, 2015/08/06 18:55:52]

Done.

+  for (size_t i = 0, sz = Nodes.size(); i < sz; ++i)

[Jim Stichnoth, 2015/08/06 17:24:33]

for (SizeT I = 0, NumNodes = getNumNodes(); I < NumNodes; ++I)

(sorry, I don't like the capitalization either)

[Karl, 2015/08/06 18:55:52]

Done.

+    Nodes[i]->resetIndex(i);
+}
+
 void Cfg::addArg(Variable *Arg) {
   Arg->setIsArg();
   Args.push_back(Arg);
@@ -361,14 +367,12 @@ void Cfg::reorderNodes() {
   }
 
   // Reorder Nodes according to the built-up lists.
-  SizeT OldSize = Nodes.size();
-  (void)OldSize;
-  Nodes.clear();
+  NodeList Reordered;

[John, 2015/08/06 17:22:54]

Reordered.reserve(Placed.size() + Unreachable.size())?

[Karl, 2015/08/06 18:55:52]

Done.

   for (CfgNode *Node : Placed)
-    Nodes.push_back(Node);
+    Reordered.push_back(Node);
   for (CfgNode *Node : Unreachable)
-    Nodes.push_back(Node);
-  assert(Nodes.size() == OldSize);

[Jim Stichnoth, 2015/08/06 17:24:33]

Can you preserve the size assert?  This is to make sure we haven't lost (or
gained...) any nodes during the reordering.  Here and below.

[Karl, 2015/08/06 18:55:51]

Added assert back.

+    Reordered.push_back(Node);
+  replaceNodes(Reordered);
 }
 
 namespace {
@@ -403,15 +407,12 @@ void Cfg::shuffleNodes() {
     if (ToVisit[Node->getIndex()])
       Unreachable.push_back(Node);
   // Copy the layout list to the Nodes.
-  SizeT OldSize = Nodes.size();
-  (void)OldSize;
-  Nodes.clear();
+  NodeList Shuffled;
   for (CfgNode *Node : reverse_range(ReversedReachable))
-    Nodes.emplace_back(Node);
-  for (CfgNode *Node : Unreachable) {
-    Nodes.emplace_back(Node);
-  }
-  assert(Nodes.size() == OldSize);
+    Shuffled.push_back(Node);
+  for (CfgNode *Node : Unreachable)
+    Shuffled.push_back(Node);
+  replaceNodes(Shuffled);
 
   dump("After basic block shuffling");
 }