From ff08995589871d57a15207a24aeaa8959933c896 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sat, 2 May 2009 18:29:22 +0000 Subject: Previously, RecursivelyDeleteDeadInstructions provided an option of returning a list of pointers to Values that are deleted. This was unsafe, because the pointers in the list are, by nature of what RecursivelyDeleteDeadInstructions does, always dangling. Replace this with a simple callback mechanism. This may eventually be removed if all clients can reasonably be expected to use CallbackVH. Use this to factor out the dead-phi-cycle-elimination code from LSR utility function, and generalize it to use the RecursivelyDeleteTriviallyDeadInstructions utility function. This makes LSR more aggressive about eliminating dead PHI cycles; adjust tests to either be less trivial or to simply expect fewer instructions. llvm-svn: 70636 --- llvm/lib/Transforms/Utils/BasicBlockUtils.cpp | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'llvm/lib/Transforms/Utils/BasicBlockUtils.cpp') diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp index 97460bf1add..076f89e3374 100644 --- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp +++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp @@ -22,6 +22,8 @@ #include "llvm/Analysis/LoopInfo.h" #include "llvm/Analysis/Dominators.h" #include "llvm/Target/TargetData.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/Support/ValueHandle.h" #include using namespace llvm; @@ -73,6 +75,24 @@ void llvm::FoldSingleEntryPHINodes(BasicBlock *BB) { } +/// 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. If a +/// ValueDeletionListener is specified, it is notified of the deletions. +void llvm::DeleteDeadPHIs(BasicBlock *BB, ValueDeletionListener *VDL) { + // 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 PHIs; + for (BasicBlock::iterator I = BB->begin(); + PHINode *PN = dyn_cast(I); ++I) + PHIs.push_back(PN); + + for (unsigned i = 0, e = PHIs.size(); i != e; ++i) + if (PHINode *PN = dyn_cast_or_null(PHIs[i].operator Value*())) + RecursivelyDeleteDeadPHINode(PN, VDL); +} + /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, /// if possible. The return value indicates success or failure. bool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) { -- cgit v1.2.3