From f09733a8766aaa331d7e5196ea36cd9c6bb82100 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Fri, 15 Mar 2002 20:35:21 +0000
Subject: [PATCH] Remove code designed to compensate for a bug in GCC.  The bug
 has since been fixed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1881 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/DeadTypeElimination.cpp | 62 ++--------------------
 1 file changed, 5 insertions(+), 57 deletions(-)

diff --git a/lib/Transforms/IPO/DeadTypeElimination.cpp b/lib/Transforms/IPO/DeadTypeElimination.cpp
index 801cdffb7e7..f8a9b6e1dda 100644
--- a/lib/Transforms/IPO/DeadTypeElimination.cpp
+++ b/lib/Transforms/IPO/DeadTypeElimination.cpp
@@ -393,7 +393,6 @@ static inline bool FixCastsAndPHIs(BasicBlock *BB) {
     }
   }
 
-
   return Changed;
 }
 
@@ -436,33 +435,10 @@ static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) {
 }
 
 
-// CheckIncomingValueFor - Make sure that the specified PHI node has an entry
-// for the provided basic block.  If it doesn't, add one and return true.
-//
-static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) {
-  if (PN->getBasicBlockIndex(BB) != -1) return;  // Already has value
-
-  Value      *NewVal = 0;
-  const Type *Ty = PN->getType();
-
-  if (const PointerType *PT = dyn_cast<PointerType>(Ty))
-    NewVal = ConstantPointerNull::get(PT);
-  else if (Ty == Type::BoolTy)
-    NewVal = ConstantBool::True;
-  else if (Ty == Type::FloatTy || Ty == Type::DoubleTy)
-    NewVal = ConstantFP::get(Ty, 42);
-  else if (Ty->isIntegral())
-    NewVal = ConstantInt::get(Ty, 42);
-
-  assert(NewVal && "Unknown PHI node type!");
-  PN->addIncoming(NewVal, BB);
-} 
-
 // fixLocalProblems - Loop through the method and fix problems with the PHI
-// nodes in the current method.  The two problems that are handled are:
-//
-//  1. PHI nodes with multiple entries for the same predecessor.  GCC sometimes
-//     generates code that looks like this:
+// nodes in the current method.  The problem is that PHI nodes might exist with
+// multiple entries for the same predecessor.  GCC sometimes generates code
+// that looks like this:
 //
 //  bb7:  br bool %cond1004, label %bb8, label %bb8
 //  bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ]
@@ -475,18 +451,6 @@ static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) {
 //  bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ]
 //
 //
-//  2. PHI nodes with fewer arguments than predecessors.
-//     These can be generated by GCC if a variable is uninitalized over a path
-//     in the CFG.  We fix this by adding an entry for the missing predecessors
-//     that is initialized to either 42 for a numeric/FP value, or null if it's
-//     a pointer value. This problem can be generated by code that looks like
-//     this:
-//         int foo(int y) {
-//           int X;
-//           if (y) X = 1;
-//           return X;
-//         }
-//
 static bool fixLocalProblems(Method *M) {
   bool Changed = false;
   // Don't use iterators because invalidation gets messy...
@@ -498,8 +462,8 @@ static bool fixLocalProblems(Method *M) {
     if (isa<PHINode>(BB->front())) {
       const vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
 
-      // Handle Problem #1.  Sort the list of predecessors so that it is easy to
-      // decide whether or not duplicate predecessors exist.
+      // Handle the problem.  Sort the list of predecessors so that it is easy
+      // to decide whether or not duplicate predecessors exist.
       vector<BasicBlock*> SortedPreds(Preds);
       sort(SortedPreds.begin(), SortedPreds.end());
 
@@ -512,22 +476,6 @@ static bool fixLocalProblems(Method *M) {
         }
         LastOne = SortedPreds[i];
       }
-
-      // Loop over all of the PHI nodes in the current BB.  These PHI nodes are
-      // guaranteed to be at the beginning of the basic block.
-      //
-      for (BasicBlock::iterator I = BB->begin(); 
-           PHINode *PN = dyn_cast<PHINode>(*I); ++I) {
-        
-        // Handle problem #2.
-        if (PN->getNumIncomingValues() != Preds.size()) {
-          assert(PN->getNumIncomingValues() <= Preds.size() &&
-                 "Can't handle extra arguments to PHI nodes!");
-          for (unsigned i = 0; i < Preds.size(); ++i)
-            CheckIncomingValueFor(PN, Preds[i]);
-          Changed = true;
-        }
-      }
     }
   }
   return Changed;