commit c3b6ffc431bbf01f615c6695a0dc1b9368102cad
author Chris Lattner <sabre@nondot.org> Fri Feb 12 18:17:23 2010 +0000
committer Chris Lattner <sabre@nondot.org> Fri Feb 12 18:17:23 2010 +0000
tree 35c30443f188f65f61d9345ee9ff82309370790a
parent 4b2657a404b58e193f84ae7c38ea6ba705d5071d

1. modernize the constantmerge pass, using densemap/smallvector.
2. don't bother trying to merge globals in non-default sections,
   doing so is quite dubious at best anyway.
3. fix a bug reported by Arnaud de Grandmaison where we'd try to
   merge two globals in different address spaces.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95995 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/ConstantMerge.cpp

diff --git a/lib/Transforms/IPO/ConstantMerge.cpp b/lib/Transforms/IPO/ConstantMerge.cpp
index 4972687..3c05f88 100644
--- a/lib/Transforms/IPO/ConstantMerge.cpp
+++ b/lib/Transforms/IPO/ConstantMerge.cpp
@@ -19,10 +19,11 @@
 
 #define DEBUG_TYPE "constmerge"
 #include "llvm/Transforms/IPO.h"
+#include "llvm/DerivedTypes.h"
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Statistic.h"
-#include <map>
 using namespace llvm;
 
 STATISTIC(NumMerged, "Number of global constants merged");
@@ -48,10 +49,10 @@
 bool ConstantMerge::runOnModule(Module &M) {
   // Map unique constant/section pairs to globals.  We don't want to merge
   // globals in different sections.
-  std::map<std::pair<Constant*, std::string>, GlobalVariable*> CMap;
+  DenseMap<Constant*, GlobalVariable*> CMap;
 
   // Replacements - This vector contains a list of replacements to perform.
-  std::vector<std::pair<GlobalVariable*, GlobalVariable*> > Replacements;
+  SmallVector<std::pair<GlobalVariable*, GlobalVariable*>, 32> Replacements;
 
   bool MadeChange = false;
 
@@ -76,19 +77,21 @@
         continue;
       }
       
-      // Only process constants with initializers.
-      if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
-        Constant *Init = GV->getInitializer();
+      // Only process constants with initializers in the default addres space.
+      if (!GV->isConstant() ||!GV->hasDefinitiveInitializer() ||
+          GV->getType()->getAddressSpace() != 0 || !GV->getSection().empty())
+        continue;
+      
+      Constant *Init = GV->getInitializer();
 
-        // Check to see if the initializer is already known.
-        GlobalVariable *&Slot = CMap[std::make_pair(Init, GV->getSection())];
+      // Check to see if the initializer is already known.
+      GlobalVariable *&Slot = CMap[Init];
 
-        if (Slot == 0) {    // Nope, add it to the map.
-          Slot = GV;
-        } else if (GV->hasLocalLinkage()) {    // Yup, this is a duplicate!
-          // Make all uses of the duplicate constant use the canonical version.
-          Replacements.push_back(std::make_pair(GV, Slot));
-        }
+      if (Slot == 0) {    // Nope, add it to the map.
+        Slot = GV;
+      } else if (GV->hasLocalLinkage()) {    // Yup, this is a duplicate!
+        // Make all uses of the duplicate constant use the canonical version.
+        Replacements.push_back(std::make_pair(GV, Slot));
       }
     }
 
@@ -100,11 +103,11 @@
     // now.  This avoid invalidating the pointers in CMap, which are unneeded
     // now.
     for (unsigned i = 0, e = Replacements.size(); i != e; ++i) {
-      // Eliminate any uses of the dead global...
+      // Eliminate any uses of the dead global.
       Replacements[i].first->replaceAllUsesWith(Replacements[i].second);
 
-      // Delete the global value from the module...
-      M.getGlobalList().erase(Replacements[i].first);
+      // Delete the global value from the module.
+      Replacements[i].first->eraseFromParent();
     }
 
     NumMerged += Replacements.size();