From 9da02b844f7fe2ddae936b029fcdb34d74706b22 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Thu, 3 Jul 2008 17:21:41 +0000
Subject: [PATCH] Remove the ability for ADCE to remove unreachable blocks in
 loop nests, because, as Eli pointed out, SimplifyCFG already does this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53104 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/ADCE.cpp                | 38 -------------------
 .../Transforms/ADCE/2008-07-02-Unreachable.ll | 37 ------------------
 2 files changed, 75 deletions(-)
 delete mode 100644 test/Transforms/ADCE/2008-07-02-Unreachable.ll

diff --git a/lib/Transforms/Scalar/ADCE.cpp b/lib/Transforms/Scalar/ADCE.cpp
index c5561995deb..aef16f7f1ce 100644
--- a/lib/Transforms/Scalar/ADCE.cpp
+++ b/lib/Transforms/Scalar/ADCE.cpp
@@ -53,44 +53,6 @@ bool ADCE::runOnFunction(Function& F) {
   SmallPtrSet<Instruction*, 128> alive;
   SmallVector<Instruction*, 128> worklist;
   
-  SmallPtrSet<BasicBlock*, 64> reachable;
-  SmallVector<BasicBlock*, 16> unreachable;
-  
-  // First, collect the set of reachable blocks ...
-  for (df_ext_iterator<BasicBlock*, SmallPtrSet<BasicBlock*, 64> >
-       DI = df_ext_begin(&F.getEntryBlock(), reachable),
-       DE = df_ext_end(&F.getEntryBlock(), reachable); DI != DE; ++DI)
-    ; // Deliberately empty, df_ext_iterator will fill in the set.
-  
-  // ... and then invert it into the list of unreachable ones.  These
-  // blocks will be removed from the function.
-  for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
-    if (!reachable.count(FI))
-      unreachable.push_back(FI);
-  
-  // Prepare to remove blocks by removing the PHI node entries for those blocks
-  // in their successors, and remove them from reference counting.
-  for (SmallVector<BasicBlock*, 16>::iterator UI = unreachable.begin(),
-       UE = unreachable.end(); UI != UE; ++UI) {
-    BasicBlock* BB = *UI;
-    for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
-         SI != SE; ++SI) {
-      BasicBlock* succ = *SI;
-      BasicBlock::iterator succ_inst = succ->begin();
-      while (PHINode* P = dyn_cast<PHINode>(succ_inst)) {
-        P->removeIncomingValue(BB);
-        ++succ_inst;
-      }
-    }
-    
-    BB->dropAllReferences();
-  }
-  
-  // Finally, erase the unreachable blocks.
-  for (SmallVector<BasicBlock*, 16>::iterator UI = unreachable.begin(),
-       UE = unreachable.end(); UI != UE; ++UI)
-    (*UI)->eraseFromParent();
-  
   // Collect the set of "root" instructions that are known live.
   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
     if (isa<TerminatorInst>(I.getInstructionIterator()) ||
diff --git a/test/Transforms/ADCE/2008-07-02-Unreachable.ll b/test/Transforms/ADCE/2008-07-02-Unreachable.ll
deleted file mode 100644
index 60f0020cd15..00000000000
--- a/test/Transforms/ADCE/2008-07-02-Unreachable.ll
+++ /dev/null
@@ -1,37 +0,0 @@
-; RUN: llvm-as < %s | opt -adce -simplifycfg | llvm-dis | not grep forcond
-; PR2509
-
-target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
-target triple = "i686-apple-darwin9.3.0"
-@g_3 = external global i8		; <i8*> [#uses=2]
-
-define i32 @func_1() nounwind  {
-entry:
-	br i1 false, label %ifelse, label %ifthen
-
-ifthen:		; preds = %entry
-	br label %ifend
-
-ifelse:		; preds = %entry
-	%tmp3 = load i8* @g_3		; <i8> [#uses=0]
-	br label %forcond.thread
-
-forcond.thread:		; preds = %ifelse
-	br label %afterfor
-
-forcond:		; preds = %forinc
-	br i1 false, label %afterfor, label %forbody
-
-forbody:		; preds = %forcond
-	br label %forinc
-
-forinc:		; preds = %forbody
-	br label %forcond
-
-afterfor:		; preds = %forcond, %forcond.thread
-	%tmp10 = load i8* @g_3		; <i8> [#uses=0]
-	br label %ifend
-
-ifend:		; preds = %afterfor, %ifthen
-	ret i32 0
-}
-- 
2.34.1