[llvm-commits] [llvm] r92732 - in /llvm/trunk: include/llvm/Transforms/Utils/BasicBlockUtils.h include/llvm/Transforms/Utils/Local.h lib/Transforms/Utils/BasicBlockUtils.cpp lib/Transforms/Utils/Local.cpp

[Dan Gohman]

Author: djg
Date: Tue Jan  5 09:45:31 2010
New Revision: 92732

URL: http://llvm.org/viewvc/llvm-project?rev=92732&view=rev
Log:
Make RecursivelyDeleteTriviallyDeadInstructions,
RecursivelyDeleteDeadPHINode, and DeleteDeadPHIs return a flag
indicating whether they made any changes.

Modified:
    llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
    llvm/trunk/include/llvm/Transforms/Utils/Local.h
    llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
    llvm/trunk/lib/Transforms/Utils/Local.cpp

Modified: llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h?rev=92732&r1=92731&r2=92732&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Tue Jan  5 09:45:31 2010
@@ -40,8 +40,9 @@
 /// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it
 /// is dead. Also recursively delete any operands that become dead as
 /// a result. This includes tracing the def-use list from the PHI to see if
-/// it is ultimately unused or if it reaches an unused cycle.
-void DeleteDeadPHIs(BasicBlock *BB);
+/// it is ultimately unused or if it reaches an unused cycle. Return true
+/// if any PHIs were deleted.
+bool DeleteDeadPHIs(BasicBlock *BB);
 
 /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
 /// if possible.  The return value indicates success or failure.

Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/Local.h?rev=92732&r1=92731&r2=92732&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Tue Jan  5 09:45:31 2010
@@ -63,15 +63,16 @@
 
 /// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
 /// trivially dead instruction, delete it.  If that makes any of its operands
-/// trivially dead, delete them too, recursively.
-void RecursivelyDeleteTriviallyDeadInstructions(Value *V);
+/// trivially dead, delete them too, recursively.  Return true if any
+/// instructions were deleted.
+bool RecursivelyDeleteTriviallyDeadInstructions(Value *V);
 
 /// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
 /// dead PHI node, due to being a def-use chain of single-use nodes that
 /// either forms a cycle or is terminated by a trivially dead instruction,
 /// delete it.  If that makes any of its operands trivially dead, delete them
-/// too, recursively.
-void RecursivelyDeleteDeadPHINode(PHINode *PN);
+/// too, recursively.  Return true if the PHI node is actually deleted.
+bool RecursivelyDeleteDeadPHINode(PHINode *PN);
 
 //===----------------------------------------------------------------------===//
 //  Control Flow Graph Restructuring.

Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=92732&r1=92731&r2=92732&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Tue Jan  5 09:45:31 2010
@@ -78,7 +78,7 @@
 /// is dead. Also recursively delete any operands that become dead as
 /// a result. This includes tracing the def-use list from the PHI to see if
 /// it is ultimately unused or if it reaches an unused cycle.
-void llvm::DeleteDeadPHIs(BasicBlock *BB) {
+bool llvm::DeleteDeadPHIs(BasicBlock *BB) {
   // Recursively deleting a PHI may cause multiple PHIs to be deleted
   // or RAUW'd undef, so use an array of WeakVH for the PHIs to delete.
   SmallVector<WeakVH, 8> PHIs;
@@ -86,9 +86,12 @@
        PHINode *PN = dyn_cast<PHINode>(I); ++I)
     PHIs.push_back(PN);
 
+  bool Changed = false;
   for (unsigned i = 0, e = PHIs.size(); i != e; ++i)
     if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*()))
-      RecursivelyDeleteDeadPHINode(PN);
+      Changed |= RecursivelyDeleteDeadPHINode(PN);
+
+  return Changed;
 }
 
 /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,

Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=92732&r1=92731&r2=92732&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Local.cpp Tue Jan  5 09:45:31 2010
@@ -268,11 +268,12 @@
 
 /// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
 /// trivially dead instruction, delete it.  If that makes any of its operands
-/// trivially dead, delete them too, recursively.
-void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
+/// trivially dead, delete them too, recursively.  Return true if any
+/// instructions were deleted.
+bool llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
   Instruction *I = dyn_cast<Instruction>(V);
   if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
-    return;
+    return false;
   
   SmallVector<Instruction*, 16> DeadInsts;
   DeadInsts.push_back(I);
@@ -298,21 +299,24 @@
     
     I->eraseFromParent();
   }
+
+  return true;
 }
 
 /// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
 /// dead PHI node, due to being a def-use chain of single-use nodes that
 /// either forms a cycle or is terminated by a trivially dead instruction,
 /// delete it.  If that makes any of its operands trivially dead, delete them
-/// too, recursively.
-void
+/// too, recursively.  Return true if the PHI node is actually deleted.
+bool
 llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
   // We can remove a PHI if it is on a cycle in the def-use graph
   // where each node in the cycle has degree one, i.e. only one use,
   // and is an instruction with no side effects.
   if (!PN->hasOneUse())
-    return;
+    return false;
 
+  bool Changed = false;
   SmallPtrSet<PHINode *, 4> PHIs;
   PHIs.insert(PN);
   for (Instruction *J = cast<Instruction>(*PN->use_begin());
@@ -324,9 +328,10 @@
       if (!PHIs.insert(cast<PHINode>(JP))) {
         // Break the cycle and delete the PHI and its operands.
         JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
-        RecursivelyDeleteTriviallyDeadInstructions(JP);
+        Changed |= RecursivelyDeleteTriviallyDeadInstructions(JP);
         break;
       }
+  return Changed;
 }
 
 //===----------------------------------------------------------------------===//