From 7cad3cf44819449e1b3450f74adca4193bb9cff2 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sat, 10 Feb 2007 06:09:41 +0000
Subject: [PATCH] Make the ModuleLevel datastructure more sane.  When a
 function-local value is inserted into the table, it remembers that the value
 needs to be popped off.  This makes purgeFunction much faster, speeding up
 bcwriting of 447.dealII from 6.8->4.6s (47%).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34133 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Bytecode/Writer/SlotCalculator.cpp | 41 +++++++++++---------------
 lib/Bytecode/Writer/SlotCalculator.h   | 11 +------
 2 files changed, 19 insertions(+), 33 deletions(-)

diff --git a/lib/Bytecode/Writer/SlotCalculator.cpp b/lib/Bytecode/Writer/SlotCalculator.cpp
index 00df27f7c69..8e22a18aa54 100644
--- a/lib/Bytecode/Writer/SlotCalculator.cpp
+++ b/lib/Bytecode/Writer/SlotCalculator.cpp
@@ -64,7 +64,6 @@ void SlotCalculator::insertPrimitives() {
 
 SlotCalculator::SlotCalculator(const Module *M) {
   assert(M);
-  ModuleTypeLevel = 0;
   TheModule = M;
 
   insertPrimitives();
@@ -182,11 +181,8 @@ void SlotCalculator::processModule() {
   }
 
     
-  // Compute the ModuleLevel entries.
-  ModuleLevel.resize(getNumPlanes());
-  for (unsigned i = 0, e = getNumPlanes(); i != e; ++i)
-    ModuleLevel[i] = getPlane(i).size();
-  ModuleTypeLevel = Types.size();
+  // Initialize the ModuleLevel entries.
+  ModuleLevel.resize(getNumPlanes(), -1);
     
   SC_DEBUG("end processModule!\n");
 }
@@ -222,9 +218,6 @@ void SlotCalculator::CreateSlotIfNeeded(const Value *V) {
       // Do not index the characters that make up constant strings.  We emit
       // constant strings as special entities that don't require their
       // individual characters to be emitted.
-      assert(ModuleLevel.empty() &&
-             "How can a constant string be directly accessed in a function?");
-      // Otherwise, this IS a string: remember it.
       if (!C->isNullValue())
         ConstantStrings.push_back(cast<ConstantArray>(C));
     } else {
@@ -313,16 +306,16 @@ void SlotCalculator::purgeFunction() {
   
   // Next, remove values from existing type planes
   for (unsigned i = 0; i != NumModuleTypes; ++i) {
-    // Size of plane before function came
-    unsigned ModuleLev = getModuleLevel(i);
-    assert(int(ModuleLev) >= 0 && "BAD!");
+    // If this type is not used by this function, ignore it.
+    int ModuleLev = ModuleLevel[i];
+    if (ModuleLev == -1) continue;
     
+    ModuleLevel[i] = -1;  // Reset for next function.
+
+    // Pop all function-local values in this type-plane off of Table.
     TypePlane &Plane = getPlane(i);
-    
-    assert(ModuleLev <= Plane.size() && "module levels higher than elements?");
-    while (Plane.size() != ModuleLev) {
-      assert(!isa<GlobalValue>(Plane.back()) &&
-             "Functions cannot define globals!");
+    assert(ModuleLev < Plane.size() && "module levels higher than elements?");
+    for (unsigned i = ModuleLev, e = Plane.size(); i != e; ++i) {
       NodeMap.erase(Plane.back());       // Erase from nodemap
       Plane.pop_back();                  // Shrink plane
     }
@@ -333,12 +326,8 @@ void SlotCalculator::purgeFunction() {
     TypePlane &Plane = Table.back();
     SC_DEBUG("Removing Plane " << (Table.size()-1) << " of size "
              << Plane.size() << "\n");
-    while (Plane.size()) {
-      assert(!isa<GlobalValue>(Plane.back()) &&
-             "Functions cannot define globals!");
-      NodeMap.erase(Plane.back());   // Erase from nodemap
-      Plane.pop_back();              // Shrink plane
-    }
+    for (unsigned i = 0, e = Plane.size(); i != e; ++i)
+      NodeMap.erase(Plane[i]);   // Erase from nodemap
     
     Table.pop_back();                // Nuke the plane, we don't like it.
   }
@@ -357,6 +346,12 @@ void SlotCalculator::CreateFunctionValueSlot(const Value *V) {
   if (Table.size() <= TyPlane)    // Make sure we have the type plane allocated.
     Table.resize(TyPlane+1, TypePlane());
   
+  // If this is the first value noticed of this type within this function,
+  // remember the module level for this type plane in ModuleLevel.  This reminds
+  // us to remove the values in purgeFunction and tells us how many to remove.
+  if (TyPlane < ModuleLevel.size() && ModuleLevel[TyPlane] == -1)
+    ModuleLevel[TyPlane] = Table[TyPlane].size();
+  
   // If this is the first value to get inserted into the type plane, make sure
   // to insert the implicit null value.
   if (Table[TyPlane].empty()) {
diff --git a/lib/Bytecode/Writer/SlotCalculator.h b/lib/Bytecode/Writer/SlotCalculator.h
index 229715936ef..d39635b1076 100644
--- a/lib/Bytecode/Writer/SlotCalculator.h
+++ b/lib/Bytecode/Writer/SlotCalculator.h
@@ -54,7 +54,7 @@ class SlotCalculator {
   /// ModuleLevel - Used to keep track of which values belong to the module,
   /// and which values belong to the currently incorporated function.
   ///
-  std::vector<unsigned> ModuleLevel;
+  std::vector<int> ModuleLevel;
   unsigned ModuleTypeLevel;
 
   SlotCalculator(const SlotCalculator &);  // DO NOT IMPLEMENT
@@ -80,15 +80,6 @@ public:
   inline unsigned getNumPlanes() const { return Table.size(); }
   inline unsigned getNumTypes() const { return Types.size(); }
 
-  inline unsigned getModuleLevel(unsigned Plane) const {
-    return Plane < ModuleLevel.size() ? ModuleLevel[Plane] : 0;
-  }
-
-  /// Returns the number of types in the type list that are at module level
-  inline unsigned getModuleTypeLevel() const {
-    return ModuleTypeLevel;
-  }
-
   TypePlane &getPlane(unsigned Plane) {
     // Okay we are just returning an entry out of the main Table.  Make sure the
     // plane exists and return it.