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Make RecursivelyDeleteTriviallyDeadInstructions,
RecursivelyDeleteDeadPHINode, and DeleteDeadPHIs return a flag indicating whether they made any changes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92732 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -40,8 +40,9 @@ void FoldSingleEntryPHINodes(BasicBlock *BB);
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/// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it
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/// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it
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/// is dead. Also recursively delete any operands that become dead as
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/// is dead. Also recursively delete any operands that become dead as
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/// a result. This includes tracing the def-use list from the PHI to see if
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/// a result. This includes tracing the def-use list from the PHI to see if
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/// it is ultimately unused or if it reaches an unused cycle.
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/// it is ultimately unused or if it reaches an unused cycle. Return true
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void DeleteDeadPHIs(BasicBlock *BB);
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/// if any PHIs were deleted.
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bool DeleteDeadPHIs(BasicBlock *BB);
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/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
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/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
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/// if possible. The return value indicates success or failure.
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/// if possible. The return value indicates success or failure.
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@ -63,15 +63,16 @@ bool isInstructionTriviallyDead(Instruction *I);
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/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
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/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
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/// trivially dead instruction, delete it. If that makes any of its operands
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/// trivially dead instruction, delete it. If that makes any of its operands
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/// trivially dead, delete them too, recursively.
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/// trivially dead, delete them too, recursively. Return true if any
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void RecursivelyDeleteTriviallyDeadInstructions(Value *V);
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/// instructions were deleted.
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bool RecursivelyDeleteTriviallyDeadInstructions(Value *V);
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/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
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/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
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/// dead PHI node, due to being a def-use chain of single-use nodes that
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/// dead PHI node, due to being a def-use chain of single-use nodes that
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/// either forms a cycle or is terminated by a trivially dead instruction,
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/// either forms a cycle or is terminated by a trivially dead instruction,
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/// delete it. If that makes any of its operands trivially dead, delete them
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/// delete it. If that makes any of its operands trivially dead, delete them
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/// too, recursively.
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/// too, recursively. Return true if the PHI node is actually deleted.
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void RecursivelyDeleteDeadPHINode(PHINode *PN);
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bool RecursivelyDeleteDeadPHINode(PHINode *PN);
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//===----------------------------------------------------------------------===//
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//===----------------------------------------------------------------------===//
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// Control Flow Graph Restructuring.
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// Control Flow Graph Restructuring.
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@ -78,7 +78,7 @@ void llvm::FoldSingleEntryPHINodes(BasicBlock *BB) {
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/// is dead. Also recursively delete any operands that become dead as
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/// is dead. Also recursively delete any operands that become dead as
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/// a result. This includes tracing the def-use list from the PHI to see if
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/// a result. This includes tracing the def-use list from the PHI to see if
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/// it is ultimately unused or if it reaches an unused cycle.
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/// it is ultimately unused or if it reaches an unused cycle.
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void llvm::DeleteDeadPHIs(BasicBlock *BB) {
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bool llvm::DeleteDeadPHIs(BasicBlock *BB) {
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// Recursively deleting a PHI may cause multiple PHIs to be deleted
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// Recursively deleting a PHI may cause multiple PHIs to be deleted
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// or RAUW'd undef, so use an array of WeakVH for the PHIs to delete.
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// or RAUW'd undef, so use an array of WeakVH for the PHIs to delete.
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SmallVector<WeakVH, 8> PHIs;
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SmallVector<WeakVH, 8> PHIs;
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@ -86,9 +86,12 @@ void llvm::DeleteDeadPHIs(BasicBlock *BB) {
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PHINode *PN = dyn_cast<PHINode>(I); ++I)
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PHINode *PN = dyn_cast<PHINode>(I); ++I)
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PHIs.push_back(PN);
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PHIs.push_back(PN);
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bool Changed = false;
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for (unsigned i = 0, e = PHIs.size(); i != e; ++i)
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for (unsigned i = 0, e = PHIs.size(); i != e; ++i)
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if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*()))
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if (PHINode *PN = dyn_cast_or_null<PHINode>(PHIs[i].operator Value*()))
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RecursivelyDeleteDeadPHINode(PN);
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Changed |= RecursivelyDeleteDeadPHINode(PN);
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return Changed;
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}
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}
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/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
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/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
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@ -268,11 +268,12 @@ bool llvm::isInstructionTriviallyDead(Instruction *I) {
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/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
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/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
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/// trivially dead instruction, delete it. If that makes any of its operands
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/// trivially dead instruction, delete it. If that makes any of its operands
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/// trivially dead, delete them too, recursively.
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/// trivially dead, delete them too, recursively. Return true if any
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void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
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/// instructions were deleted.
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bool llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
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Instruction *I = dyn_cast<Instruction>(V);
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
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if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
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return;
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return false;
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SmallVector<Instruction*, 16> DeadInsts;
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SmallVector<Instruction*, 16> DeadInsts;
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DeadInsts.push_back(I);
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DeadInsts.push_back(I);
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@ -298,21 +299,24 @@ void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V) {
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I->eraseFromParent();
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I->eraseFromParent();
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}
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}
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return true;
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}
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}
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/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
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/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
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/// dead PHI node, due to being a def-use chain of single-use nodes that
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/// dead PHI node, due to being a def-use chain of single-use nodes that
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/// either forms a cycle or is terminated by a trivially dead instruction,
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/// either forms a cycle or is terminated by a trivially dead instruction,
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/// delete it. If that makes any of its operands trivially dead, delete them
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/// delete it. If that makes any of its operands trivially dead, delete them
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/// too, recursively.
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/// too, recursively. Return true if the PHI node is actually deleted.
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void
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bool
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llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
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llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
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// We can remove a PHI if it is on a cycle in the def-use graph
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// We can remove a PHI if it is on a cycle in the def-use graph
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// where each node in the cycle has degree one, i.e. only one use,
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// where each node in the cycle has degree one, i.e. only one use,
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// and is an instruction with no side effects.
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// and is an instruction with no side effects.
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if (!PN->hasOneUse())
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if (!PN->hasOneUse())
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return;
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return false;
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bool Changed = false;
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SmallPtrSet<PHINode *, 4> PHIs;
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SmallPtrSet<PHINode *, 4> PHIs;
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PHIs.insert(PN);
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PHIs.insert(PN);
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for (Instruction *J = cast<Instruction>(*PN->use_begin());
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for (Instruction *J = cast<Instruction>(*PN->use_begin());
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@ -324,9 +328,10 @@ llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
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if (!PHIs.insert(cast<PHINode>(JP))) {
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if (!PHIs.insert(cast<PHINode>(JP))) {
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// Break the cycle and delete the PHI and its operands.
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// Break the cycle and delete the PHI and its operands.
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JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
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JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
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RecursivelyDeleteTriviallyDeadInstructions(JP);
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Changed |= RecursivelyDeleteTriviallyDeadInstructions(JP);
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break;
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break;
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}
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}
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return Changed;
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}
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}
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//===----------------------------------------------------------------------===//
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//===----------------------------------------------------------------------===//
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