Add a clear() method to PriorityQueue.

[oota-llvm.git] / lib / Transforms / IPO / GlobalDCE.cpp

diff --git a/lib/Transforms/IPO/GlobalDCE.cpp b/lib/Transforms/IPO/GlobalDCE.cpp
index 07296cfa5e456ec56694ac3bba35839994730278..98202eb0b34583c813d923d51e005f2e072c225c 100644 (file)
--- a/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/lib/Transforms/IPO/GlobalDCE.cpp
@@ -2,8 +2,8 @@
 //
 //                     The LLVM Compiler Infrastructure
 //
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
@@ -15,19 +15,24 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define DEBUG_TYPE "globaldce"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Constants.h"
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Support/Compiler.h"
 #include <set>
 using namespace llvm;
 
-namespace {
-  Statistic<> NumFunctions("globaldce","Number of functions removed");
-  Statistic<> NumVariables("globaldce","Number of global variables removed");
+STATISTIC(NumFunctions, "Number of functions removed");
+STATISTIC(NumVariables, "Number of global variables removed");
 
-  struct GlobalDCE : public ModulePass {
+namespace {
+  struct VISIBILITY_HIDDEN GlobalDCE : public ModulePass {
+    static char ID; // Pass identification, replacement for typeid
+    GlobalDCE() : ModulePass((intptr_t)&ID) {}
+ 
     // run - Do the GlobalDCE pass on the specified module, optionally updating
     // the specified callgraph to reflect the changes.
     //
@@ -44,9 +49,11 @@ namespace {
     bool SafeToDestroyConstant(Constant* C);
     bool RemoveUnusedGlobalValue(GlobalValue &GV);
   };
-  RegisterPass<GlobalDCE> X("globaldce", "Dead Global Elimination");
 }
 
+char GlobalDCE::ID = 0;
+static RegisterPass<GlobalDCE> X("globaldce", "Dead Global Elimination");
+
 ModulePass *llvm::createGlobalDCEPass() { return new GlobalDCE(); }
 
 bool GlobalDCE::runOnModule(Module &M) {
@@ -56,20 +63,27 @@ bool GlobalDCE::runOnModule(Module &M) {
     Changed |= RemoveUnusedGlobalValue(*I);
     // Functions with external linkage are needed if they have a body
     if ((!I->hasInternalLinkage() && !I->hasLinkOnceLinkage()) &&
-        !I->isExternal())
+        !I->isDeclaration())
       GlobalIsNeeded(I);
   }
 
-  for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I) {
+  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
+       I != E; ++I) {
     Changed |= RemoveUnusedGlobalValue(*I);
     // Externally visible & appending globals are needed, if they have an
     // initializer.
     if ((!I->hasInternalLinkage() && !I->hasLinkOnceLinkage()) &&
-        !I->isExternal())
+        !I->isDeclaration())
       GlobalIsNeeded(I);
   }
 
 
+  for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
+       I != E; ++I) {
+    // Aliases are always needed even if they are not used.
+    MarkUsedGlobalsAsNeeded(I->getAliasee());
+  }
+
   // Now that all globals which are needed are in the AliveGlobals set, we loop
   // through the program, deleting those which are not alive.
   //
@@ -88,7 +102,7 @@ bool GlobalDCE::runOnModule(Module &M) {
   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
     if (!AliveGlobals.count(I)) {
       DeadFunctions.push_back(I);         // Keep track of dead globals
-      if (!I->isExternal())
+      if (!I->isDeclaration())
         I->deleteBody();
     }
 
@@ -133,7 +147,7 @@ void GlobalDCE::GlobalIsNeeded(GlobalValue *G) {
     // referenced by the initializer to the alive set.
     if (GV->hasInitializer())
       MarkUsedGlobalsAsNeeded(GV->getInitializer());
-  } else {
+  } else if (!isa<GlobalAlias>(G)) {
     // Otherwise this must be a function object.  We have to scan the body of
     // the function looking for constants and global values which are used as
     // operands.  Any operands of these types must be processed to ensure that