From 7311e389a691293b4cb6742ef2f77d11e9f2c07d Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Tue, 23 Jul 2002 22:03:41 +0000
Subject: [PATCH] Cleanup and simplify code

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3036 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/DeadTypeElimination.cpp | 81 ++++++----------------
 1 file changed, 22 insertions(+), 59 deletions(-)

diff --git a/lib/Transforms/IPO/DeadTypeElimination.cpp b/lib/Transforms/IPO/DeadTypeElimination.cpp
index 34440f5004e..f276ca7c000 100644
--- a/lib/Transforms/IPO/DeadTypeElimination.cpp
+++ b/lib/Transforms/IPO/DeadTypeElimination.cpp
@@ -1,58 +1,41 @@
-//===- CleanupGCCOutput.cpp - Cleanup GCC Output --------------------------===//
+//===- DeadTypeElimination.cpp - Eliminate unused types for symbol table --===//
 //
-// This pass is used to cleanup the output of GCC.  GCC's output is
-// unneccessarily gross for a couple of reasons. This pass does the following
-// things to try to clean it up:
-//
-// * Eliminate names for GCC types that we know can't be needed by the user.
-// * Eliminate names for types that are unused in the entire translation unit
-// * Fix various problems that we might have in PHI nodes and casts
-//
-// Note:  This code produces dead declarations, it is a good idea to run DCE
-//        after this pass.
+// This pass is used to cleanup the output of GCC.  It eliminate names for types
+// that are unused in the entire translation unit, using the FindUsedTypes pass.
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/CleanupGCCOutput.h"
+#include "llvm/Transforms/IPO.h"
 #include "llvm/Analysis/FindUsedTypes.h"
 #include "llvm/Module.h"
 #include "llvm/SymbolTable.h"
 #include "llvm/DerivedTypes.h"
 #include "Support/StatisticReporter.h"
 
-static Statistic<> NumTypeSymtabEntriesKilled("cleangcc\t- Number of unused typenames removed from symtab");
-
 using std::vector;
 
 namespace {
-  struct CleanupGCCOutput : public FunctionPass {
+  struct DTE : public Pass {
     // doPassInitialization - For this pass, it removes global symbol table
     // entries for primitive types.  These are never used for linking in GCC and
     // they make the output uglier to look at, so we nuke them.
     //
     // Also, initialize instance variables.
     //
-    bool doInitialization(Module &M);
+    bool run(Module &M);
 
-    // FIXME:
-    // FIXME: This FunctionPass should be a PASS!
-    // FIXME:
-    bool runOnFunction(Function &F) { return false; }
-    
-    // doPassFinalization - Strip out type names that are unused by the program
-    bool doFinalization(Module &M);
-    
     // getAnalysisUsage - This function needs FindUsedTypes to do its job...
     //
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addRequired(FindUsedTypes::ID);
     }
   };
-  RegisterPass<CleanupGCCOutput> X("cleangcc", "Cleanup GCC Output");
+  RegisterPass<DTE> X("deadtypeelim", "Dead Type Elimination");
+  Statistic<> NumKilled("deadtypeelim\t- Number of unused typenames removed from symtab");
 }
 
-Pass *createCleanupGCCOutputPass() {
-  return new CleanupGCCOutput();
+Pass *createDeadTypeEliminationPass() {
+  return new DTE();
 }
 
 
@@ -71,14 +54,18 @@ static inline bool ShouldNukeSymtabEntry(const std::pair<std::string,Value*>&E){
   return false;
 }
 
-// doInitialization - For this pass, it removes global symbol table
-// entries for primitive types.  These are never used for linking in GCC and
-// they make the output uglier to look at, so we nuke them.
+// run - For this pass, it removes global symbol table entries for primitive
+// types.  These are never used for linking in GCC and they make the output
+// uglier to look at, so we nuke them.  Also eliminate types that are never used
+// in the entire program as indicated by FindUsedTypes.
 //
-bool CleanupGCCOutput::doInitialization(Module &M) {
+bool DTE::run(Module &M) {
   bool Changed = false;
 
   if (SymbolTable *ST = M.getSymbolTable()) {
+    const std::set<const Type *> &UsedTypes =
+      getAnalysis<FindUsedTypes>().getTypes();
+
     // Check the symbol table for superfluous type entries...
     //
     // Grab the 'type' plane of the module symbol...
@@ -94,46 +81,22 @@ bool CleanupGCCOutput::doInitialization(Module &M) {
           Plane.erase(PI);          // Alas, GCC 2.95.3 doesn't  *SIGH*
           PI = Plane.begin();
 #endif
-          ++NumTypeSymtabEntriesKilled;
+          ++NumKilled;
           Changed = true;
-        } else {
-          ++PI;
-        }
-    }
-  }
-
-  return Changed;
-}
-
-
-bool CleanupGCCOutput::doFinalization(Module &M) {
-  bool Changed = false;
-
-  if (SymbolTable *ST = M.getSymbolTable()) {
-    const std::set<const Type *> &UsedTypes =
-      getAnalysis<FindUsedTypes>().getTypes();
-
-    // Check the symbol table for superfluous type entries that aren't used in
-    // the program
-    //
-    // Grab the 'type' plane of the module symbol...
-    SymbolTable::iterator STI = ST->find(Type::TypeTy);
-    if (STI != ST->end()) {
-      // Loop over all entries in the type plane...
-      SymbolTable::VarMap &Plane = STI->second;
-      for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();)
-        if (!UsedTypes.count(cast<Type>(PI->second))) {
+        } else if (!UsedTypes.count(cast<Type>(PI->second))) {
 #if MAP_IS_NOT_BRAINDEAD
           PI = Plane.erase(PI);     // STD C++ Map should support this!
 #else
           Plane.erase(PI);          // Alas, GCC 2.95.3 doesn't  *SIGH*
           PI = Plane.begin();       // N^2 algorithms are fun.  :(
 #endif
+          ++NumKilled;
           Changed = true;
         } else {
           ++PI;
         }
     }
   }
+
   return Changed;
 }