Temporarily revert r62487. It's causing this error during a release bootstrap of

llvm-gcc. Most likely, it's miscompiling one of the "gen*" programs:

/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm-gcc.obj/./prev-gcc/xgcc -B/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm-gcc.obj/./prev-gcc/ -B/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm-gcc.install/i386-apple-darwin9.6.0/bin/ -c -g -O2 -mdynamic-no-pic -DIN_GCC -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -mdynamic-no-pic -DHAVE_CONFIG_H -DGENERATOR_FILE -I. -Ibuild -I../../llvm-gcc.src/gcc -I../../llvm-gcc.src/gcc/build -I../../llvm-gcc.src/gcc/../include -I./../intl -I../../llvm-gcc.src/gcc/../libcpp/include  -I../../llvm-gcc.src/gcc/../libdecnumber -I../libdecnumber -I/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.obj/include -I/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/include -DENABLE_LLVM -I/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.obj/../llvm.src/include  -D_DEBUG  -D_GNU_SOURCE -D__STDC_LIMIT_MACROS -D__STDC_CONSTANT_MACROS   -o build/gencondmd.o build/gencondmd.c
../../llvm-gcc.src/gcc/config/i386/mmx.md:926: error: expected '}' before ')' token
../../llvm-gcc.src/gcc/config/i386/mmx.md:926: warning: excess elements in struct initializer
../../llvm-gcc.src/gcc/config/i386/mmx.md:926: warning: (near initialization for 'insn_conditions[4]')
../../llvm-gcc.src/gcc/config/i386/mmx.md:926: error: expected '}' before ')' token
../../llvm-gcc.src/gcc/config/i386/mmx.md:926: error: expected ',' or ';' before ')' token
../../llvm-gcc.src/gcc/config/i386/mmx.md:927: error: expected identifier or '(' before ',' token
../../llvm-gcc.src/gcc/config/i386/sse.md:3458: error: expected identifier or '(' before ',' token
...

llvm-svn: 62506

1 files changed, 2 insertions, 77 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index fd3ca9e8439..b0feadffadd 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -21,7 +21,6 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/Statistic.h"
@@ -173,74 +172,6 @@ static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
   return true;
 }
 
-/// BlockIsReachableFrom - Return true if there is a path from StartBB to
-/// DestBB.  We do this by recursively walking the CFG from DestBB up to StartBB
-/// unwind we either reach StartBB or find an unreachable chunk of the CFG.
-/// 
-/// Each entry in VisitedBlocks is either 0 -> not visited, 1 -> known reachable
-/// 2 -> known unreachable, 3 -> visitation in progress.
-static bool BlockIsReachableFrom(BasicBlock *StartBB, BasicBlock *DestBB,
-                               DenseMap<BasicBlock*, unsigned> &VisitedBlocks) {
-  if (StartBB == DestBB) return true;
-  
-  unsigned &BlockEntry = VisitedBlocks[DestBB];
-  if (BlockEntry == 1) return true;       // Known reachable!
-  if (BlockEntry == 2 ||                  // Known unreachable.
-      BlockEntry == 3)                    // Found a loop.
-    return false;
-  
-  // If BlockEntry is 0, this is the first time we've seen this block.  Mark it
-  // as being visited and recurse up predecessors.
-  BlockEntry = 3;
-  
-  for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
-       ++PI) {
-    if (BlockIsReachableFrom(StartBB, *PI, VisitedBlocks)) {
-      VisitedBlocks[DestBB] = 1;
-      return true;
-    }
-  }
-  
-  // If we scanned all of our predecessors and we couldn't find a path to 
-  // StartBB, then this block must be unreachable for sure.  Record this to
-  // prevent visitation of this block in the future.
-  VisitedBlocks[DestBB] = 2;
-  return false;
-}
-
-/// RemoveUnreachableUsersOf - For each user of Inst, scan up the CFG until we
-/// find Inst.  If Inst is found, then the user is live, otherwise it is dead.
-/// Remove dead users.  This is basically a poor-man's dominance query, and is
-/// worst-case linear time in the number of blocks in the function.
-static void RemoveUnreachableUsersOf(Instruction *Inst) {
-  DenseMap<BasicBlock*, unsigned> VisitedBlocks;
-  
-  BasicBlock *InstBB = Inst->getParent();
-  for (Instruction::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
-       UI != E;) {
-    Instruction *User = cast<Instruction>(*UI);
-    Use &TheUse = UI.getUse();
-    
-    if (PHINode *PN = dyn_cast<PHINode>(User)) {
-      unsigned UseOp = UI.getOperandNo();
-      ++UI;
-      
-      if (BlockIsReachableFrom(InstBB, PN->getIncomingBlock(UseOp/2),
-                               VisitedBlocks))
-        continue;
-    } else {
-      ++UI;
-      if (BlockIsReachableFrom(InstBB, User->getParent(),
-                               VisitedBlocks))
-        continue;
-    }
-    // If there is no path from Inst to this User, then this user is in dead
-    // code.  Just replace uses of Inst with undef.
-    TheUse = UndefValue::get(Inst->getType());
-  }
-}
-
-
 /// TryToSimplifyUncondBranchFromEmptyBlock - BB contains an unconditional
 /// branch to Succ, and contains no instructions other than PHI nodes and the
 /// branch.  If possible, eliminate BB.
@@ -285,18 +216,12 @@ static bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
   }
   
   if (isa<PHINode>(&BB->front())) {
-    SmallVector<BasicBlock*, 16> OldSuccPreds(pred_begin(Succ),
-                                              pred_end(Succ));
+    SmallVector<BasicBlock*, 16>
+    OldSuccPreds(pred_begin(Succ), pred_end(Succ));
     
     // Move all PHI nodes in BB to Succ if they are alive, otherwise
     // delete them.
     while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
-      // The algorithm below will not work if there are users of PN that are in
-      // unreachable blocks.  These users will not be properly dominated by the
-      // instruction, but the IR is valid because dead code does not need to
-      // obey dominance properties.
-      RemoveUnreachableUsersOf(PN);
-      
       if (PN->use_empty()) {
         // Just remove the dead phi.  This happens if Succ's PHIs were the only
         // users of the PHI nodes.