[llvm-commits] [llvm] r103060 - in /llvm/trunk: include/llvm/CodeGen/MachineSSAUpdater.h include/llvm/Transforms/Utils/SSAUpdater.h include/llvm/Transforms/Utils/SSAUpdaterImpl.h lib/CodeGen/MachineSSAUpdater.cpp lib/Transforms/Utils/SSAUpdater.cpp
Bob Wilson
bob.wilson at apple.com
Tue May 4 16:18:19 PDT 2010
Author: bwilson
Date: Tue May 4 18:18:19 2010
New Revision: 103060
URL: http://llvm.org/viewvc/llvm-project?rev=103060&view=rev
Log:
Combine the implementations of the core part of the SSAUpdater and
MachineSSAUpdater to avoid duplicating all the code.
Added:
llvm/trunk/include/llvm/Transforms/Utils/SSAUpdaterImpl.h
Modified:
llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h
llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h
llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp
llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp
Modified: llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h?rev=103060&r1=103059&r2=103060&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h Tue May 4 18:18:19 2010
@@ -23,6 +23,7 @@
class TargetInstrInfo;
class TargetRegisterClass;
template<typename T> class SmallVectorImpl;
+ template<typename T> class SSAUpdaterTraits;
class BumpPtrAllocator;
/// MachineSSAUpdater - This class updates SSA form for a set of virtual
@@ -30,9 +31,7 @@
/// or another unstructured transformation wants to rewrite a set of uses of one
/// vreg with uses of a set of vregs.
class MachineSSAUpdater {
-public:
- class BBInfo;
- typedef SmallVectorImpl<BBInfo*> BlockListTy;
+ friend class SSAUpdaterTraits<MachineSSAUpdater>;
private:
/// AvailableVals - This keeps track of which value to use on a per-block
@@ -40,11 +39,6 @@
//typedef DenseMap<MachineBasicBlock*, unsigned > AvailableValsTy;
void *AV;
- /// BBMap - The GetValueAtEndOfBlock method maintains this mapping from
- /// basic blocks to BBInfo structures.
- /// typedef DenseMap<MachineBasicBlock*, BBInfo*> BBMapTy;
- void *BM;
-
/// VR - Current virtual register whose uses are being updated.
unsigned VR;
@@ -111,14 +105,6 @@
private:
void ReplaceRegWith(unsigned OldReg, unsigned NewReg);
unsigned GetValueAtEndOfBlockInternal(MachineBasicBlock *BB);
- void BuildBlockList(MachineBasicBlock *BB, BlockListTy *BlockList,
- BumpPtrAllocator *Allocator);
- void FindDominators(BlockListTy *BlockList);
- void FindPHIPlacement(BlockListTy *BlockList);
- void FindAvailableVals(BlockListTy *BlockList);
- void FindExistingPHI(MachineBasicBlock *BB, BlockListTy *BlockList);
- bool CheckIfPHIMatches(MachineInstr *PHI);
- void RecordMatchingPHI(MachineInstr *PHI);
void operator=(const MachineSSAUpdater&); // DO NOT IMPLEMENT
MachineSSAUpdater(const MachineSSAUpdater&); // DO NOT IMPLEMENT
Modified: llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h?rev=103060&r1=103059&r2=103060&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h Tue May 4 18:18:19 2010
@@ -19,8 +19,8 @@
class BasicBlock;
class Use;
class PHINode;
- template<typename T>
- class SmallVectorImpl;
+ template<typename T> class SmallVectorImpl;
+ template<typename T> class SSAUpdaterTraits;
class BumpPtrAllocator;
/// SSAUpdater - This class updates SSA form for a set of values defined in
@@ -28,9 +28,7 @@
/// transformation wants to rewrite a set of uses of one value with uses of a
/// set of values.
class SSAUpdater {
-public:
- class BBInfo;
- typedef SmallVectorImpl<BBInfo*> BlockListTy;
+ friend class SSAUpdaterTraits<SSAUpdater>;
private:
/// AvailableVals - This keeps track of which value to use on a per-block
@@ -42,14 +40,10 @@
/// and a type for PHI nodes.
Value *PrototypeValue;
- /// BBMap - The GetValueAtEndOfBlock method maintains this mapping from
- /// basic blocks to BBInfo structures.
- /// typedef DenseMap<BasicBlock*, BBInfo*> BBMapTy;
- void *BM;
-
/// InsertedPHIs - If this is non-null, the SSAUpdater adds all PHI nodes that
/// it creates to the vector.
SmallVectorImpl<PHINode*> *InsertedPHIs;
+
public:
/// SSAUpdater constructor. If InsertedPHIs is specified, it will be filled
/// in with all PHI Nodes created by rewriting.
@@ -102,14 +96,6 @@
private:
Value *GetValueAtEndOfBlockInternal(BasicBlock *BB);
- void BuildBlockList(BasicBlock *BB, BlockListTy *BlockList,
- BumpPtrAllocator *Allocator);
- void FindDominators(BlockListTy *BlockList);
- void FindPHIPlacement(BlockListTy *BlockList);
- void FindAvailableVals(BlockListTy *BlockList);
- void FindExistingPHI(BasicBlock *BB, BlockListTy *BlockList);
- bool CheckIfPHIMatches(PHINode *PHI);
- void RecordMatchingPHI(PHINode *PHI);
void operator=(const SSAUpdater&); // DO NOT IMPLEMENT
SSAUpdater(const SSAUpdater&); // DO NOT IMPLEMENT
Added: llvm/trunk/include/llvm/Transforms/Utils/SSAUpdaterImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/SSAUpdaterImpl.h?rev=103060&view=auto
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/SSAUpdaterImpl.h (added)
+++ llvm/trunk/include/llvm/Transforms/Utils/SSAUpdaterImpl.h Tue May 4 18:18:19 2010
@@ -0,0 +1,463 @@
+//===-- SSAUpdaterImpl.h - SSA Updater Implementation -----------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides a template that implements the core algorithm for the
+// SSAUpdater and MachineSSAUpdater.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_SSAUPDATERIMPL_H
+#define LLVM_TRANSFORMS_UTILS_SSAUPDATERIMPL_H
+
+namespace llvm {
+
+template<typename T> class SSAUpdaterTraits;
+
+template<typename UpdaterT>
+class SSAUpdaterImpl {
+private:
+ UpdaterT *Updater;
+
+ typedef SSAUpdaterTraits<UpdaterT> Traits;
+ typedef typename Traits::BlkT BlkT;
+ typedef typename Traits::ValT ValT;
+ typedef typename Traits::PhiT PhiT;
+
+ /// BBInfo - Per-basic block information used internally by SSAUpdaterImpl.
+ /// The predecessors of each block are cached here since pred_iterator is
+ /// slow and we need to iterate over the blocks at least a few times.
+ class BBInfo {
+ public:
+ BlkT *BB; // Back-pointer to the corresponding block.
+ ValT AvailableVal; // Value to use in this block.
+ BBInfo *DefBB; // Block that defines the available value.
+ int BlkNum; // Postorder number.
+ BBInfo *IDom; // Immediate dominator.
+ unsigned NumPreds; // Number of predecessor blocks.
+ BBInfo **Preds; // Array[NumPreds] of predecessor blocks.
+ PhiT *PHITag; // Marker for existing PHIs that match.
+
+ BBInfo(BlkT *ThisBB, ValT V)
+ : BB(ThisBB), AvailableVal(V), DefBB(V ? this : 0), BlkNum(0), IDom(0),
+ NumPreds(0), Preds(0), PHITag(0) { }
+ };
+
+ typedef DenseMap<BlkT*, ValT> AvailableValsTy;
+ AvailableValsTy *AvailableVals;
+
+ SmallVectorImpl<PhiT*> *InsertedPHIs;
+
+ typedef SmallVectorImpl<BBInfo*> BlockListTy;
+ typedef DenseMap<BlkT*, BBInfo*> BBMapTy;
+ BBMapTy BBMap;
+ BumpPtrAllocator Allocator;
+
+public:
+ explicit SSAUpdaterImpl(UpdaterT *U, AvailableValsTy *A,
+ SmallVectorImpl<PhiT*> *Ins) :
+ Updater(U), AvailableVals(A), InsertedPHIs(Ins) { }
+
+ /// GetValue - Check to see if AvailableVals has an entry for the specified
+ /// BB and if so, return it. If not, construct SSA form by first
+ /// calculating the required placement of PHIs and then inserting new PHIs
+ /// where needed.
+ ValT GetValue(BlkT *BB) {
+ SmallVector<BBInfo*, 100> BlockList;
+ BuildBlockList(BB, &BlockList);
+
+ // Special case: bail out if BB is unreachable.
+ if (BlockList.size() == 0) {
+ ValT V = Traits::GetUndefVal(BB, Updater);
+ (*AvailableVals)[BB] = V;
+ return V;
+ }
+
+ FindDominators(&BlockList);
+ FindPHIPlacement(&BlockList);
+ FindAvailableVals(&BlockList);
+
+ return BBMap[BB]->DefBB->AvailableVal;
+ }
+
+ /// BuildBlockList - Starting from the specified basic block, traverse back
+ /// through its predecessors until reaching blocks with known values.
+ /// Create BBInfo structures for the blocks and append them to the block
+ /// list.
+ void BuildBlockList(BlkT *BB, BlockListTy *BlockList) {
+ SmallVector<BBInfo*, 10> RootList;
+ SmallVector<BBInfo*, 64> WorkList;
+
+ BBInfo *Info = new (Allocator) BBInfo(BB, 0);
+ BBMap[BB] = Info;
+ WorkList.push_back(Info);
+
+ // Search backward from BB, creating BBInfos along the way and stopping
+ // when reaching blocks that define the value. Record those defining
+ // blocks on the RootList.
+ SmallVector<BlkT*, 10> Preds;
+ while (!WorkList.empty()) {
+ Info = WorkList.pop_back_val();
+ Preds.clear();
+ Traits::FindPredecessorBlocks(Info->BB, &Preds);
+ Info->NumPreds = Preds.size();
+ Info->Preds = static_cast<BBInfo**>
+ (Allocator.Allocate(Info->NumPreds * sizeof(BBInfo*),
+ AlignOf<BBInfo*>::Alignment));
+
+ // Treat an unreachable predecessor as a definition with 'undef'.
+ if (Info->NumPreds == 0) {
+ Info->AvailableVal = Traits::GetUndefVal(Info->BB, Updater);
+ Info->DefBB = Info;
+ RootList.push_back(Info);
+ continue;
+ }
+
+ for (unsigned p = 0; p != Info->NumPreds; ++p) {
+ BlkT *Pred = Preds[p];
+ // Check if BBMap already has a BBInfo for the predecessor block.
+ typename BBMapTy::value_type &BBMapBucket =
+ BBMap.FindAndConstruct(Pred);
+ if (BBMapBucket.second) {
+ Info->Preds[p] = BBMapBucket.second;
+ continue;
+ }
+
+ // Create a new BBInfo for the predecessor.
+ ValT PredVal = AvailableVals->lookup(Pred);
+ BBInfo *PredInfo = new (Allocator) BBInfo(Pred, PredVal);
+ BBMapBucket.second = PredInfo;
+ Info->Preds[p] = PredInfo;
+
+ if (PredInfo->AvailableVal) {
+ RootList.push_back(PredInfo);
+ continue;
+ }
+ WorkList.push_back(PredInfo);
+ }
+ }
+
+ // Now that we know what blocks are backwards-reachable from the starting
+ // block, do a forward depth-first traversal to assign postorder numbers
+ // to those blocks.
+ BBInfo *PseudoEntry = new (Allocator) BBInfo(0, 0);
+ unsigned BlkNum = 1;
+
+ // Initialize the worklist with the roots from the backward traversal.
+ while (!RootList.empty()) {
+ Info = RootList.pop_back_val();
+ Info->IDom = PseudoEntry;
+ Info->BlkNum = -1;
+ WorkList.push_back(Info);
+ }
+
+ while (!WorkList.empty()) {
+ Info = WorkList.back();
+
+ if (Info->BlkNum == -2) {
+ // All the successors have been handled; assign the postorder number.
+ Info->BlkNum = BlkNum++;
+ // If not a root, put it on the BlockList.
+ if (!Info->AvailableVal)
+ BlockList->push_back(Info);
+ WorkList.pop_back();
+ continue;
+ }
+
+ // Leave this entry on the worklist, but set its BlkNum to mark that its
+ // successors have been put on the worklist. When it returns to the top
+ // the list, after handling its successors, it will be assigned a
+ // number.
+ Info->BlkNum = -2;
+
+ // Add unvisited successors to the work list.
+ for (typename Traits::BlkSucc_iterator SI =
+ Traits::BlkSucc_begin(Info->BB),
+ E = Traits::BlkSucc_end(Info->BB); SI != E; ++SI) {
+ BBInfo *SuccInfo = BBMap[*SI];
+ if (!SuccInfo || SuccInfo->BlkNum)
+ continue;
+ SuccInfo->BlkNum = -1;
+ WorkList.push_back(SuccInfo);
+ }
+ }
+ PseudoEntry->BlkNum = BlkNum;
+ }
+
+ /// IntersectDominators - This is the dataflow lattice "meet" operation for
+ /// finding dominators. Given two basic blocks, it walks up the dominator
+ /// tree until it finds a common dominator of both. It uses the postorder
+ /// number of the blocks to determine how to do that.
+ BBInfo *IntersectDominators(BBInfo *Blk1, BBInfo *Blk2) {
+ while (Blk1 != Blk2) {
+ while (Blk1->BlkNum < Blk2->BlkNum) {
+ Blk1 = Blk1->IDom;
+ if (!Blk1)
+ return Blk2;
+ }
+ while (Blk2->BlkNum < Blk1->BlkNum) {
+ Blk2 = Blk2->IDom;
+ if (!Blk2)
+ return Blk1;
+ }
+ }
+ return Blk1;
+ }
+
+ /// FindDominators - Calculate the dominator tree for the subset of the CFG
+ /// corresponding to the basic blocks on the BlockList. This uses the
+ /// algorithm from: "A Simple, Fast Dominance Algorithm" by Cooper, Harvey
+ /// and Kennedy, published in Software--Practice and Experience, 2001,
+ /// 4:1-10. Because the CFG subset does not include any edges leading into
+ /// blocks that define the value, the results are not the usual dominator
+ /// tree. The CFG subset has a single pseudo-entry node with edges to a set
+ /// of root nodes for blocks that define the value. The dominators for this
+ /// subset CFG are not the standard dominators but they are adequate for
+ /// placing PHIs within the subset CFG.
+ void FindDominators(BlockListTy *BlockList) {
+ bool Changed;
+ do {
+ Changed = false;
+ // Iterate over the list in reverse order, i.e., forward on CFG edges.
+ for (typename BlockListTy::reverse_iterator I = BlockList->rbegin(),
+ E = BlockList->rend(); I != E; ++I) {
+ BBInfo *Info = *I;
+
+ // Start with the first predecessor.
+ assert(Info->NumPreds > 0 && "unreachable block");
+ BBInfo *NewIDom = Info->Preds[0];
+
+ // Iterate through the block's other predecessors.
+ for (unsigned p = 1; p != Info->NumPreds; ++p) {
+ BBInfo *Pred = Info->Preds[p];
+ NewIDom = IntersectDominators(NewIDom, Pred);
+ }
+
+ // Check if the IDom value has changed.
+ if (NewIDom != Info->IDom) {
+ Info->IDom = NewIDom;
+ Changed = true;
+ }
+ }
+ } while (Changed);
+ }
+
+ /// IsDefInDomFrontier - Search up the dominator tree from Pred to IDom for
+ /// any blocks containing definitions of the value. If one is found, then
+ /// the successor of Pred is in the dominance frontier for the definition,
+ /// and this function returns true.
+ bool IsDefInDomFrontier(const BBInfo *Pred, const BBInfo *IDom) {
+ for (; Pred != IDom; Pred = Pred->IDom) {
+ if (Pred->DefBB == Pred)
+ return true;
+ }
+ return false;
+ }
+
+ /// FindPHIPlacement - PHIs are needed in the iterated dominance frontiers
+ /// of the known definitions. Iteratively add PHIs in the dom frontiers
+ /// until nothing changes. Along the way, keep track of the nearest
+ /// dominating definitions for non-PHI blocks.
+ void FindPHIPlacement(BlockListTy *BlockList) {
+ bool Changed;
+ do {
+ Changed = false;
+ // Iterate over the list in reverse order, i.e., forward on CFG edges.
+ for (typename BlockListTy::reverse_iterator I = BlockList->rbegin(),
+ E = BlockList->rend(); I != E; ++I) {
+ BBInfo *Info = *I;
+
+ // If this block already needs a PHI, there is nothing to do here.
+ if (Info->DefBB == Info)
+ continue;
+
+ // Default to use the same def as the immediate dominator.
+ BBInfo *NewDefBB = Info->IDom->DefBB;
+ for (unsigned p = 0; p != Info->NumPreds; ++p) {
+ if (IsDefInDomFrontier(Info->Preds[p], Info->IDom)) {
+ // Need a PHI here.
+ NewDefBB = Info;
+ break;
+ }
+ }
+
+ // Check if anything changed.
+ if (NewDefBB != Info->DefBB) {
+ Info->DefBB = NewDefBB;
+ Changed = true;
+ }
+ }
+ } while (Changed);
+ }
+
+ /// FindAvailableVal - If this block requires a PHI, first check if an
+ /// existing PHI matches the PHI placement and reaching definitions computed
+ /// earlier, and if not, create a new PHI. Visit all the block's
+ /// predecessors to calculate the available value for each one and fill in
+ /// the incoming values for a new PHI.
+ void FindAvailableVals(BlockListTy *BlockList) {
+ // Go through the worklist in forward order (i.e., backward through the CFG)
+ // and check if existing PHIs can be used. If not, create empty PHIs where
+ // they are needed.
+ for (typename BlockListTy::iterator I = BlockList->begin(),
+ E = BlockList->end(); I != E; ++I) {
+ BBInfo *Info = *I;
+ // Check if there needs to be a PHI in BB.
+ if (Info->DefBB != Info)
+ continue;
+
+ // Look for an existing PHI.
+ FindExistingPHI(Info->BB, BlockList);
+ if (Info->AvailableVal)
+ continue;
+
+ ValT PHI = Traits::CreateEmptyPHI(Info->BB, Info->NumPreds, Updater);
+ Info->AvailableVal = PHI;
+ (*AvailableVals)[Info->BB] = PHI;
+ }
+
+ // Now go back through the worklist in reverse order to fill in the
+ // arguments for any new PHIs added in the forward traversal.
+ for (typename BlockListTy::reverse_iterator I = BlockList->rbegin(),
+ E = BlockList->rend(); I != E; ++I) {
+ BBInfo *Info = *I;
+
+ if (Info->DefBB != Info) {
+ // Record the available value at join nodes to speed up subsequent
+ // uses of this SSAUpdater for the same value.
+ if (Info->NumPreds > 1)
+ (*AvailableVals)[Info->BB] = Info->DefBB->AvailableVal;
+ continue;
+ }
+
+ // Check if this block contains a newly added PHI.
+ PhiT *PHI = Traits::ValueIsNewPHI(Info->AvailableVal, Updater);
+ if (!PHI)
+ continue;
+
+ // Iterate through the block's predecessors.
+ for (unsigned p = 0; p != Info->NumPreds; ++p) {
+ BBInfo *PredInfo = Info->Preds[p];
+ BlkT *Pred = PredInfo->BB;
+ // Skip to the nearest preceding definition.
+ if (PredInfo->DefBB != PredInfo)
+ PredInfo = PredInfo->DefBB;
+ Traits::AddPHIOperand(PHI, PredInfo->AvailableVal, Pred);
+ }
+
+ DEBUG(dbgs() << " Inserted PHI: " << *PHI << "\n");
+
+ // If the client wants to know about all new instructions, tell it.
+ if (InsertedPHIs) InsertedPHIs->push_back(PHI);
+ }
+ }
+
+ /// FindExistingPHI - Look through the PHI nodes in a block to see if any of
+ /// them match what is needed.
+ void FindExistingPHI(BlkT *BB, BlockListTy *BlockList) {
+ for (typename BlkT::iterator BBI = BB->begin(), BBE = BB->end();
+ BBI != BBE; ++BBI) {
+ PhiT *SomePHI = Traits::InstrIsPHI(BBI);
+ if (!SomePHI)
+ break;
+ if (CheckIfPHIMatches(SomePHI)) {
+ RecordMatchingPHI(SomePHI);
+ break;
+ }
+ // Match failed: clear all the PHITag values.
+ for (typename BlockListTy::iterator I = BlockList->begin(),
+ E = BlockList->end(); I != E; ++I)
+ (*I)->PHITag = 0;
+ }
+ }
+
+ /// CheckIfPHIMatches - Check if a PHI node matches the placement and values
+ /// in the BBMap.
+ bool CheckIfPHIMatches(PhiT *PHI) {
+ SmallVector<PhiT*, 20> WorkList;
+ WorkList.push_back(PHI);
+
+ // Mark that the block containing this PHI has been visited.
+ BBMap[PHI->getParent()]->PHITag = PHI;
+
+ while (!WorkList.empty()) {
+ PHI = WorkList.pop_back_val();
+
+ // Iterate through the PHI's incoming values.
+ for (typename Traits::PHI_iterator I = Traits::PHI_begin(PHI),
+ E = Traits::PHI_end(PHI); I != E; ++I) {
+ ValT IncomingVal = I.getIncomingValue();
+ BBInfo *PredInfo = BBMap[I.getIncomingBlock()];
+ // Skip to the nearest preceding definition.
+ if (PredInfo->DefBB != PredInfo)
+ PredInfo = PredInfo->DefBB;
+
+ // Check if it matches the expected value.
+ if (PredInfo->AvailableVal) {
+ if (IncomingVal == PredInfo->AvailableVal)
+ continue;
+ return false;
+ }
+
+ // Check if the value is a PHI in the correct block.
+ PhiT *IncomingPHIVal = Traits::ValueIsPHI(IncomingVal, Updater);
+ if (!IncomingPHIVal || IncomingPHIVal->getParent() != PredInfo->BB)
+ return false;
+
+ // If this block has already been visited, check if this PHI matches.
+ if (PredInfo->PHITag) {
+ if (IncomingPHIVal == PredInfo->PHITag)
+ continue;
+ return false;
+ }
+ PredInfo->PHITag = IncomingPHIVal;
+
+ WorkList.push_back(IncomingPHIVal);
+ }
+ }
+ return true;
+ }
+
+ /// RecordMatchingPHI - For a PHI node that matches, record it and its input
+ /// PHIs in both the BBMap and the AvailableVals mapping.
+ void RecordMatchingPHI(PhiT *PHI) {
+ SmallVector<PhiT*, 20> WorkList;
+ WorkList.push_back(PHI);
+
+ // Record this PHI.
+ BlkT *BB = PHI->getParent();
+ ValT PHIVal = Traits::GetPHIValue(PHI);
+ (*AvailableVals)[BB] = PHIVal;
+ BBMap[BB]->AvailableVal = PHIVal;
+
+ while (!WorkList.empty()) {
+ PHI = WorkList.pop_back_val();
+
+ // Iterate through the PHI's incoming values.
+ for (typename Traits::PHI_iterator I = Traits::PHI_begin(PHI),
+ E = Traits::PHI_end(PHI); I != E; ++I) {
+ ValT IncomingVal = I.getIncomingValue();
+ PhiT *IncomingPHI = Traits::ValueIsPHI(IncomingVal, Updater);
+ if (!IncomingPHI) continue;
+ BB = IncomingPHI->getParent();
+ BBInfo *Info = BBMap[BB];
+ if (!Info || Info->AvailableVal)
+ continue;
+
+ // Record the PHI and add it to the worklist.
+ (*AvailableVals)[BB] = IncomingVal;
+ Info->AvailableVal = IncomingVal;
+ WorkList.push_back(IncomingPHI);
+ }
+ }
+ }
+};
+
+} // End llvm namespace
+
+#endif
Modified: llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp?rev=103060&r1=103059&r2=103060&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp Tue May 4 18:18:19 2010
@@ -26,39 +26,17 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/SSAUpdaterImpl.h"
using namespace llvm;
-/// BBInfo - Per-basic block information used internally by MachineSSAUpdater.
-class MachineSSAUpdater::BBInfo {
-public:
- MachineBasicBlock *BB; // Back-pointer to the corresponding block.
- unsigned AvailableVal; // Value to use in this block.
- BBInfo *DefBB; // Block that defines the available value.
- int BlkNum; // Postorder number.
- BBInfo *IDom; // Immediate dominator.
- unsigned NumPreds; // Number of predecessor blocks.
- BBInfo **Preds; // Array[NumPreds] of predecessor blocks.
- MachineInstr *PHITag; // Marker for existing PHIs that match.
-
- BBInfo(MachineBasicBlock *ThisBB, unsigned V)
- : BB(ThisBB), AvailableVal(V), DefBB(V ? this : 0), BlkNum(0), IDom(0),
- NumPreds(0), Preds(0), PHITag(0) { }
-};
-
-typedef DenseMap<MachineBasicBlock*, MachineSSAUpdater::BBInfo*> BBMapTy;
-
typedef DenseMap<MachineBasicBlock*, unsigned> AvailableValsTy;
static AvailableValsTy &getAvailableVals(void *AV) {
return *static_cast<AvailableValsTy*>(AV);
}
-static BBMapTy *getBBMap(void *BM) {
- return static_cast<BBMapTy*>(BM);
-}
-
MachineSSAUpdater::MachineSSAUpdater(MachineFunction &MF,
SmallVectorImpl<MachineInstr*> *NewPHI)
- : AV(0), BM(0), InsertedPHIs(NewPHI) {
+ : AV(0), InsertedPHIs(NewPHI) {
TII = MF.getTarget().getInstrInfo();
MRI = &MF.getRegInfo();
}
@@ -134,7 +112,8 @@
MachineInstr *InsertNewDef(unsigned Opcode,
MachineBasicBlock *BB, MachineBasicBlock::iterator I,
const TargetRegisterClass *RC,
- MachineRegisterInfo *MRI, const TargetInstrInfo *TII) {
+ MachineRegisterInfo *MRI,
+ const TargetInstrInfo *TII) {
unsigned NewVR = MRI->createVirtualRegister(RC);
return BuildMI(*BB, I, DebugLoc(), TII->get(Opcode), NewVR);
}
@@ -263,438 +242,131 @@
I->second = NewReg;
}
-/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry
-/// for the specified BB and if so, return it. If not, construct SSA form by
-/// first calculating the required placement of PHIs and then inserting new
-/// PHIs where needed.
-unsigned MachineSSAUpdater::GetValueAtEndOfBlockInternal(MachineBasicBlock *BB){
- AvailableValsTy &AvailableVals = getAvailableVals(AV);
- if (unsigned V = AvailableVals[BB])
- return V;
-
- // Pool allocation used internally by GetValueAtEndOfBlock.
- BumpPtrAllocator Allocator;
- BBMapTy BBMapObj;
- BM = &BBMapObj;
-
- SmallVector<BBInfo*, 100> BlockList;
- BuildBlockList(BB, &BlockList, &Allocator);
-
- // Special case: bail out if BB is unreachable.
- if (BlockList.size() == 0) {
- BM = 0;
+/// MachinePHIiter - Iterator for PHI operands. This is used for the
+/// PHI_iterator in the SSAUpdaterImpl template.
+namespace {
+ class MachinePHIiter {
+ private:
+ MachineInstr *PHI;
+ unsigned idx;
+
+ public:
+ explicit MachinePHIiter(MachineInstr *P) // begin iterator
+ : PHI(P), idx(1) {}
+ MachinePHIiter(MachineInstr *P, bool) // end iterator
+ : PHI(P), idx(PHI->getNumOperands()) {}
+
+ MachinePHIiter &operator++() { idx += 2; return *this; }
+ bool operator==(const MachinePHIiter& x) const { return idx == x.idx; }
+ bool operator!=(const MachinePHIiter& x) const { return !operator==(x); }
+ unsigned getIncomingValue() { return PHI->getOperand(idx).getReg(); }
+ MachineBasicBlock *getIncomingBlock() {
+ return PHI->getOperand(idx+1).getMBB();
+ }
+ };
+}
+
+/// SSAUpdaterTraits<MachineSSAUpdater> - Traits for the SSAUpdaterImpl
+/// template, specialized for MachineSSAUpdater.
+namespace llvm {
+template<>
+class SSAUpdaterTraits<MachineSSAUpdater> {
+public:
+ typedef MachineBasicBlock BlkT;
+ typedef unsigned ValT;
+ typedef MachineInstr PhiT;
+
+ typedef MachineBasicBlock::succ_iterator BlkSucc_iterator;
+ static BlkSucc_iterator BlkSucc_begin(BlkT *BB) { return BB->succ_begin(); }
+ static BlkSucc_iterator BlkSucc_end(BlkT *BB) { return BB->succ_end(); }
+
+ typedef MachinePHIiter PHI_iterator;
+ static inline PHI_iterator PHI_begin(PhiT *PHI) { return PHI_iterator(PHI); }
+ static inline PHI_iterator PHI_end(PhiT *PHI) {
+ return PHI_iterator(PHI, true);
+ }
+
+ /// FindPredecessorBlocks - Put the predecessors of BB into the Preds
+ /// vector.
+ static void FindPredecessorBlocks(MachineBasicBlock *BB,
+ SmallVectorImpl<MachineBasicBlock*> *Preds){
+ for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
+ E = BB->pred_end(); PI != E; ++PI)
+ Preds->push_back(*PI);
+ }
+
+ /// GetUndefVal - Create an IMPLICIT_DEF instruction with a new register.
+ /// Add it into the specified block and return the register.
+ static unsigned GetUndefVal(MachineBasicBlock *BB,
+ MachineSSAUpdater *Updater) {
// Insert an implicit_def to represent an undef value.
MachineInstr *NewDef = InsertNewDef(TargetOpcode::IMPLICIT_DEF,
BB, BB->getFirstTerminator(),
- VRC, MRI, TII);
- unsigned V = NewDef->getOperand(0).getReg();
- AvailableVals[BB] = V;
- return V;
- }
-
- FindDominators(&BlockList);
- FindPHIPlacement(&BlockList);
- FindAvailableVals(&BlockList);
-
- BM = 0;
- return BBMapObj[BB]->DefBB->AvailableVal;
-}
-
-/// FindPredecessorBlocks - Put the predecessors of Info->BB into the Preds
-/// vector, set Info->NumPreds, and allocate space in Info->Preds.
-static void FindPredecessorBlocks(MachineSSAUpdater::BBInfo *Info,
- SmallVectorImpl<MachineBasicBlock*> *Preds,
- BumpPtrAllocator *Allocator) {
- MachineBasicBlock *BB = Info->BB;
- for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
- E = BB->pred_end(); PI != E; ++PI)
- Preds->push_back(*PI);
-
- Info->NumPreds = Preds->size();
- Info->Preds = static_cast<MachineSSAUpdater::BBInfo**>
- (Allocator->Allocate(Info->NumPreds * sizeof(MachineSSAUpdater::BBInfo*),
- AlignOf<MachineSSAUpdater::BBInfo*>::Alignment));
-}
-
-/// BuildBlockList - Starting from the specified basic block, traverse back
-/// through its predecessors until reaching blocks with known values. Create
-/// BBInfo structures for the blocks and append them to the block list.
-void MachineSSAUpdater::BuildBlockList(MachineBasicBlock *BB,
- BlockListTy *BlockList,
- BumpPtrAllocator *Allocator) {
- AvailableValsTy &AvailableVals = getAvailableVals(AV);
- BBMapTy *BBMap = getBBMap(BM);
- SmallVector<BBInfo*, 10> RootList;
- SmallVector<BBInfo*, 64> WorkList;
-
- BBInfo *Info = new (*Allocator) BBInfo(BB, 0);
- (*BBMap)[BB] = Info;
- WorkList.push_back(Info);
-
- // Search backward from BB, creating BBInfos along the way and stopping when
- // reaching blocks that define the value. Record those defining blocks on
- // the RootList.
- SmallVector<MachineBasicBlock*, 10> Preds;
- while (!WorkList.empty()) {
- Info = WorkList.pop_back_val();
- Preds.clear();
- FindPredecessorBlocks(Info, &Preds, Allocator);
-
- // Treat an unreachable predecessor as a definition with 'undef'.
- if (Info->NumPreds == 0) {
- // Insert an implicit_def to represent an undef value.
- MachineInstr *NewDef = InsertNewDef(TargetOpcode::IMPLICIT_DEF,
- Info->BB,
- Info->BB->getFirstTerminator(),
- VRC, MRI, TII);
- Info->AvailableVal = NewDef->getOperand(0).getReg();
- Info->DefBB = Info;
- RootList.push_back(Info);
- continue;
- }
-
- for (unsigned p = 0; p != Info->NumPreds; ++p) {
- MachineBasicBlock *Pred = Preds[p];
- // Check if BBMap already has a BBInfo for the predecessor block.
- BBMapTy::value_type &BBMapBucket = BBMap->FindAndConstruct(Pred);
- if (BBMapBucket.second) {
- Info->Preds[p] = BBMapBucket.second;
- continue;
- }
-
- // Create a new BBInfo for the predecessor.
- unsigned PredVal = AvailableVals.lookup(Pred);
- BBInfo *PredInfo = new (*Allocator) BBInfo(Pred, PredVal);
- BBMapBucket.second = PredInfo;
- Info->Preds[p] = PredInfo;
-
- if (PredInfo->AvailableVal) {
- RootList.push_back(PredInfo);
- continue;
- }
- WorkList.push_back(PredInfo);
- }
+ Updater->VRC, Updater->MRI,
+ Updater->TII);
+ return NewDef->getOperand(0).getReg();
}
- // Now that we know what blocks are backwards-reachable from the starting
- // block, do a forward depth-first traversal to assign postorder numbers
- // to those blocks.
- BBInfo *PseudoEntry = new (*Allocator) BBInfo(0, 0);
- unsigned BlkNum = 1;
-
- // Initialize the worklist with the roots from the backward traversal.
- while (!RootList.empty()) {
- Info = RootList.pop_back_val();
- Info->IDom = PseudoEntry;
- Info->BlkNum = -1;
- WorkList.push_back(Info);
- }
-
- while (!WorkList.empty()) {
- Info = WorkList.back();
-
- if (Info->BlkNum == -2) {
- // All the successors have been handled; assign the postorder number.
- Info->BlkNum = BlkNum++;
- // If not a root, put it on the BlockList.
- if (!Info->AvailableVal)
- BlockList->push_back(Info);
- WorkList.pop_back();
- continue;
- }
-
- // Leave this entry on the worklist, but set its BlkNum to mark that its
- // successors have been put on the worklist. When it returns to the top
- // the list, after handling its successors, it will be assigned a number.
- Info->BlkNum = -2;
-
- // Add unvisited successors to the work list.
- for (MachineBasicBlock::succ_iterator SI = Info->BB->succ_begin(),
- E = Info->BB->succ_end(); SI != E; ++SI) {
- BBInfo *SuccInfo = (*BBMap)[*SI];
- if (!SuccInfo || SuccInfo->BlkNum)
- continue;
- SuccInfo->BlkNum = -1;
- WorkList.push_back(SuccInfo);
- }
+ /// CreateEmptyPHI - Create a PHI instruction that defines a new register.
+ /// Add it into the specified block and return the register.
+ static unsigned CreateEmptyPHI(MachineBasicBlock *BB, unsigned NumPreds,
+ MachineSSAUpdater *Updater) {
+ MachineBasicBlock::iterator Loc = BB->empty() ? BB->end() : BB->front();
+ MachineInstr *PHI = InsertNewDef(TargetOpcode::PHI, BB, Loc,
+ Updater->VRC, Updater->MRI,
+ Updater->TII);
+ return PHI->getOperand(0).getReg();
+ }
+
+ /// AddPHIOperand - Add the specified value as an operand of the PHI for
+ /// the specified predecessor block.
+ static void AddPHIOperand(MachineInstr *PHI, unsigned Val,
+ MachineBasicBlock *Pred) {
+ PHI->addOperand(MachineOperand::CreateReg(Val, false));
+ PHI->addOperand(MachineOperand::CreateMBB(Pred));
+ }
+
+ /// InstrIsPHI - Check if an instruction is a PHI.
+ ///
+ static MachineInstr *InstrIsPHI(MachineInstr *I) {
+ if (I->isPHI())
+ return I;
+ return 0;
}
- PseudoEntry->BlkNum = BlkNum;
-}
-/// IntersectDominators - This is the dataflow lattice "meet" operation for
-/// finding dominators. Given two basic blocks, it walks up the dominator
-/// tree until it finds a common dominator of both. It uses the postorder
-/// number of the blocks to determine how to do that.
-static MachineSSAUpdater::BBInfo *
-IntersectDominators(MachineSSAUpdater::BBInfo *Blk1,
- MachineSSAUpdater::BBInfo *Blk2) {
- while (Blk1 != Blk2) {
- while (Blk1->BlkNum < Blk2->BlkNum) {
- Blk1 = Blk1->IDom;
- if (!Blk1)
- return Blk2;
- }
- while (Blk2->BlkNum < Blk1->BlkNum) {
- Blk2 = Blk2->IDom;
- if (!Blk2)
- return Blk1;
- }
+ /// ValueIsPHI - Check if the instruction that defines the specified register
+ /// is a PHI instruction.
+ static MachineInstr *ValueIsPHI(unsigned Val, MachineSSAUpdater *Updater) {
+ return InstrIsPHI(Updater->MRI->getVRegDef(Val));
}
- return Blk1;
-}
-
-/// FindDominators - Calculate the dominator tree for the subset of the CFG
-/// corresponding to the basic blocks on the BlockList. This uses the
-/// algorithm from: "A Simple, Fast Dominance Algorithm" by Cooper, Harvey and
-/// Kennedy, published in Software--Practice and Experience, 2001, 4:1-10.
-/// Because the CFG subset does not include any edges leading into blocks that
-/// define the value, the results are not the usual dominator tree. The CFG
-/// subset has a single pseudo-entry node with edges to a set of root nodes
-/// for blocks that define the value. The dominators for this subset CFG are
-/// not the standard dominators but they are adequate for placing PHIs within
-/// the subset CFG.
-void MachineSSAUpdater::FindDominators(BlockListTy *BlockList) {
- bool Changed;
- do {
- Changed = false;
- // Iterate over the list in reverse order, i.e., forward on CFG edges.
- for (BlockListTy::reverse_iterator I = BlockList->rbegin(),
- E = BlockList->rend(); I != E; ++I) {
- BBInfo *Info = *I;
-
- // Start with the first predecessor.
- assert(Info->NumPreds > 0 && "unreachable block");
- BBInfo *NewIDom = Info->Preds[0];
-
- // Iterate through the block's other predecessors.
- for (unsigned p = 1; p != Info->NumPreds; ++p) {
- BBInfo *Pred = Info->Preds[p];
- NewIDom = IntersectDominators(NewIDom, Pred);
- }
- // Check if the IDom value has changed.
- if (NewIDom != Info->IDom) {
- Info->IDom = NewIDom;
- Changed = true;
- }
- }
- } while (Changed);
-}
-
-/// IsDefInDomFrontier - Search up the dominator tree from Pred to IDom for
-/// any blocks containing definitions of the value. If one is found, then the
-/// successor of Pred is in the dominance frontier for the definition, and
-/// this function returns true.
-static bool IsDefInDomFrontier(const MachineSSAUpdater::BBInfo *Pred,
- const MachineSSAUpdater::BBInfo *IDom) {
- for (; Pred != IDom; Pred = Pred->IDom) {
- if (Pred->DefBB == Pred)
- return true;
- }
- return false;
-}
-
-/// FindPHIPlacement - PHIs are needed in the iterated dominance frontiers of
-/// the known definitions. Iteratively add PHIs in the dom frontiers until
-/// nothing changes. Along the way, keep track of the nearest dominating
-/// definitions for non-PHI blocks.
-void MachineSSAUpdater::FindPHIPlacement(BlockListTy *BlockList) {
- bool Changed;
- do {
- Changed = false;
- // Iterate over the list in reverse order, i.e., forward on CFG edges.
- for (BlockListTy::reverse_iterator I = BlockList->rbegin(),
- E = BlockList->rend(); I != E; ++I) {
- BBInfo *Info = *I;
-
- // If this block already needs a PHI, there is nothing to do here.
- if (Info->DefBB == Info)
- continue;
-
- // Default to use the same def as the immediate dominator.
- BBInfo *NewDefBB = Info->IDom->DefBB;
- for (unsigned p = 0; p != Info->NumPreds; ++p) {
- if (IsDefInDomFrontier(Info->Preds[p], Info->IDom)) {
- // Need a PHI here.
- NewDefBB = Info;
- break;
- }
- }
-
- // Check if anything changed.
- if (NewDefBB != Info->DefBB) {
- Info->DefBB = NewDefBB;
- Changed = true;
- }
- }
- } while (Changed);
-}
-
-/// FindAvailableVal - If this block requires a PHI, first check if an existing
-/// PHI matches the PHI placement and reaching definitions computed earlier,
-/// and if not, create a new PHI. Visit all the block's predecessors to
-/// calculate the available value for each one and fill in the incoming values
-/// for a new PHI.
-void MachineSSAUpdater::FindAvailableVals(BlockListTy *BlockList) {
- AvailableValsTy &AvailableVals = getAvailableVals(AV);
-
- // Go through the worklist in forward order (i.e., backward through the CFG)
- // and check if existing PHIs can be used. If not, create empty PHIs where
- // they are needed.
- for (BlockListTy::iterator I = BlockList->begin(), E = BlockList->end();
- I != E; ++I) {
- BBInfo *Info = *I;
- // Check if there needs to be a PHI in BB.
- if (Info->DefBB != Info)
- continue;
-
- // Look for an existing PHI.
- FindExistingPHI(Info->BB, BlockList);
- if (Info->AvailableVal)
- continue;
-
- MachineBasicBlock::iterator Loc =
- Info->BB->empty() ? Info->BB->end() : Info->BB->front();
- MachineInstr *InsertedPHI = InsertNewDef(TargetOpcode::PHI, Info->BB, Loc,
- VRC, MRI, TII);
- unsigned PHI = InsertedPHI->getOperand(0).getReg();
- Info->AvailableVal = PHI;
- AvailableVals[Info->BB] = PHI;
- }
-
- // Now go back through the worklist in reverse order to fill in the arguments
- // for any new PHIs added in the forward traversal.
- for (BlockListTy::reverse_iterator I = BlockList->rbegin(),
- E = BlockList->rend(); I != E; ++I) {
- BBInfo *Info = *I;
-
- if (Info->DefBB != Info) {
- // Record the available value at join nodes to speed up subsequent
- // uses of this SSAUpdater for the same value.
- if (Info->NumPreds > 1)
- AvailableVals[Info->BB] = Info->DefBB->AvailableVal;
- continue;
- }
-
- // Check if this block contains a newly added PHI.
- unsigned PHI = Info->AvailableVal;
- MachineInstr *InsertedPHI = MRI->getVRegDef(PHI);
- if (!InsertedPHI->isPHI() || InsertedPHI->getNumOperands() > 1)
- continue;
-
- // Iterate through the block's predecessors.
- MachineInstrBuilder MIB(InsertedPHI);
- for (unsigned p = 0; p != Info->NumPreds; ++p) {
- BBInfo *PredInfo = Info->Preds[p];
- MachineBasicBlock *Pred = PredInfo->BB;
- // Skip to the nearest preceding definition.
- if (PredInfo->DefBB != PredInfo)
- PredInfo = PredInfo->DefBB;
- MIB.addReg(PredInfo->AvailableVal).addMBB(Pred);
- }
-
- DEBUG(dbgs() << " Inserted PHI: " << *InsertedPHI << "\n");
-
- // If the client wants to know about all new instructions, tell it.
- if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI);
+ /// ValueIsNewPHI - Like ValueIsPHI but also check if the PHI has no source
+ /// operands, i.e., it was just added.
+ static MachineInstr *ValueIsNewPHI(unsigned Val, MachineSSAUpdater *Updater) {
+ MachineInstr *PHI = ValueIsPHI(Val, Updater);
+ if (PHI && PHI->getNumOperands() <= 1)
+ return PHI;
+ return 0;
}
-}
-/// FindExistingPHI - Look through the PHI nodes in a block to see if any of
-/// them match what is needed.
-void MachineSSAUpdater::FindExistingPHI(MachineBasicBlock *BB,
- BlockListTy *BlockList) {
- for (MachineBasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
- BBI != BBE && BBI->isPHI(); ++BBI) {
- if (CheckIfPHIMatches(BBI)) {
- RecordMatchingPHI(BBI);
- break;
- }
- // Match failed: clear all the PHITag values.
- for (BlockListTy::iterator I = BlockList->begin(), E = BlockList->end();
- I != E; ++I)
- (*I)->PHITag = 0;
+ /// GetPHIValue - For the specified PHI instruction, return the register
+ /// that it defines.
+ static unsigned GetPHIValue(MachineInstr *PHI) {
+ return PHI->getOperand(0).getReg();
}
-}
-
-/// CheckIfPHIMatches - Check if a PHI node matches the placement and values
-/// in the BBMap.
-bool MachineSSAUpdater::CheckIfPHIMatches(MachineInstr *PHI) {
- BBMapTy *BBMap = getBBMap(BM);
- SmallVector<MachineInstr*, 20> WorkList;
- WorkList.push_back(PHI);
-
- // Mark that the block containing this PHI has been visited.
- (*BBMap)[PHI->getParent()]->PHITag = PHI;
-
- while (!WorkList.empty()) {
- PHI = WorkList.pop_back_val();
-
- // Iterate through the PHI's incoming values.
- for (unsigned i = 1, e = PHI->getNumOperands(); i != e; i += 2) {
- unsigned IncomingVal = PHI->getOperand(i).getReg();
- BBInfo *PredInfo = (*BBMap)[PHI->getOperand(i+1).getMBB()];
- // Skip to the nearest preceding definition.
- if (PredInfo->DefBB != PredInfo)
- PredInfo = PredInfo->DefBB;
-
- // Check if it matches the expected value.
- if (PredInfo->AvailableVal) {
- if (IncomingVal == PredInfo->AvailableVal)
- continue;
- return false;
- }
-
- // Check if the value is a PHI in the correct block.
- MachineInstr *IncomingPHIVal = MRI->getVRegDef(IncomingVal);
- if (!IncomingPHIVal->isPHI() ||
- IncomingPHIVal->getParent() != PredInfo->BB)
- return false;
-
- // If this block has already been visited, check if this PHI matches.
- if (PredInfo->PHITag) {
- if (IncomingPHIVal == PredInfo->PHITag)
- continue;
- return false;
- }
- PredInfo->PHITag = IncomingPHIVal;
+};
- WorkList.push_back(IncomingPHIVal);
- }
- }
- return true;
-}
+} // End llvm namespace
-/// RecordMatchingPHI - For a PHI node that matches, record it and its input
-/// PHIs in both the BBMap and the AvailableVals mapping.
-void MachineSSAUpdater::RecordMatchingPHI(MachineInstr *PHI) {
- BBMapTy *BBMap = getBBMap(BM);
+/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry
+/// for the specified BB and if so, return it. If not, construct SSA form by
+/// first calculating the required placement of PHIs and then inserting new
+/// PHIs where needed.
+unsigned MachineSSAUpdater::GetValueAtEndOfBlockInternal(MachineBasicBlock *BB){
AvailableValsTy &AvailableVals = getAvailableVals(AV);
- SmallVector<MachineInstr*, 20> WorkList;
- WorkList.push_back(PHI);
+ if (unsigned V = AvailableVals[BB])
+ return V;
- // Record this PHI.
- MachineBasicBlock *BB = PHI->getParent();
- AvailableVals[BB] = PHI->getOperand(0).getReg();
- (*BBMap)[BB]->AvailableVal = PHI->getOperand(0).getReg();
-
- while (!WorkList.empty()) {
- PHI = WorkList.pop_back_val();
-
- // Iterate through the PHI's incoming values.
- for (unsigned i = 1, e = PHI->getNumOperands(); i != e; i += 2) {
- unsigned IncomingVal = PHI->getOperand(i).getReg();
- MachineInstr *IncomingPHIVal = MRI->getVRegDef(IncomingVal);
- if (!IncomingPHIVal->isPHI()) continue;
- BB = IncomingPHIVal->getParent();
- BBInfo *Info = (*BBMap)[BB];
- if (!Info || Info->AvailableVal)
- continue;
-
- // Record the PHI and add it to the worklist.
- AvailableVals[BB] = IncomingVal;
- Info->AvailableVal = IncomingVal;
- WorkList.push_back(IncomingPHIVal);
- }
- }
+ SSAUpdaterImpl<MachineSSAUpdater> Impl(this, &AvailableVals, InsertedPHIs);
+ return Impl.GetValue(BB);
}
Modified: llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp?rev=103060&r1=103059&r2=103060&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp Tue May 4 18:18:19 2010
@@ -12,7 +12,6 @@
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "ssaupdater"
-#include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/Instructions.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/AlignOf.h"
@@ -20,40 +19,17 @@
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
+#include "llvm/Transforms/Utils/SSAUpdaterImpl.h"
using namespace llvm;
-/// BBInfo - Per-basic block information used internally by SSAUpdater.
-/// The predecessors of each block are cached here since pred_iterator is
-/// slow and we need to iterate over the blocks at least a few times.
-class SSAUpdater::BBInfo {
-public:
- BasicBlock *BB; // Back-pointer to the corresponding block.
- Value *AvailableVal; // Value to use in this block.
- BBInfo *DefBB; // Block that defines the available value.
- int BlkNum; // Postorder number.
- BBInfo *IDom; // Immediate dominator.
- unsigned NumPreds; // Number of predecessor blocks.
- BBInfo **Preds; // Array[NumPreds] of predecessor blocks.
- PHINode *PHITag; // Marker for existing PHIs that match.
-
- BBInfo(BasicBlock *ThisBB, Value *V)
- : BB(ThisBB), AvailableVal(V), DefBB(V ? this : 0), BlkNum(0), IDom(0),
- NumPreds(0), Preds(0), PHITag(0) { }
-};
-
-typedef DenseMap<BasicBlock*, SSAUpdater::BBInfo*> BBMapTy;
-
typedef DenseMap<BasicBlock*, Value*> AvailableValsTy;
static AvailableValsTy &getAvailableVals(void *AV) {
return *static_cast<AvailableValsTy*>(AV);
}
-static BBMapTy *getBBMap(void *BM) {
- return static_cast<BBMapTy*>(BM);
-}
-
SSAUpdater::SSAUpdater(SmallVectorImpl<PHINode*> *NewPHI)
- : AV(0), PrototypeValue(0), BM(0), InsertedPHIs(NewPHI) {}
+ : AV(0), PrototypeValue(0), InsertedPHIs(NewPHI) {}
SSAUpdater::~SSAUpdater() {
delete &getAvailableVals(AV);
@@ -105,9 +81,7 @@
/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is
/// live at the end of the specified block.
Value *SSAUpdater::GetValueAtEndOfBlock(BasicBlock *BB) {
- assert(BM == 0 && "Unexpected Internal State");
Value *Res = GetValueAtEndOfBlockInternal(BB);
- assert(BM == 0 && "Unexpected Internal State");
return Res;
}
@@ -231,6 +205,117 @@
U.set(V);
}
+/// PHIiter - Iterator for PHI operands. This is used for the PHI_iterator
+/// in the SSAUpdaterImpl template.
+namespace {
+ class PHIiter {
+ private:
+ PHINode *PHI;
+ unsigned idx;
+
+ public:
+ explicit PHIiter(PHINode *P) // begin iterator
+ : PHI(P), idx(0) {}
+ PHIiter(PHINode *P, bool) // end iterator
+ : PHI(P), idx(PHI->getNumIncomingValues()) {}
+
+ PHIiter &operator++() { ++idx; return *this; }
+ bool operator==(const PHIiter& x) const { return idx == x.idx; }
+ bool operator!=(const PHIiter& x) const { return !operator==(x); }
+ Value *getIncomingValue() { return PHI->getIncomingValue(idx); }
+ BasicBlock *getIncomingBlock() { return PHI->getIncomingBlock(idx); }
+ };
+}
+
+/// SSAUpdaterTraits<SSAUpdater> - Traits for the SSAUpdaterImpl template,
+/// specialized for SSAUpdater.
+namespace llvm {
+template<>
+class SSAUpdaterTraits<SSAUpdater> {
+public:
+ typedef BasicBlock BlkT;
+ typedef Value *ValT;
+ typedef PHINode PhiT;
+
+ typedef succ_iterator BlkSucc_iterator;
+ static BlkSucc_iterator BlkSucc_begin(BlkT *BB) { return succ_begin(BB); }
+ static BlkSucc_iterator BlkSucc_end(BlkT *BB) { return succ_end(BB); }
+
+ typedef PHIiter PHI_iterator;
+ static inline PHI_iterator PHI_begin(PhiT *PHI) { return PHI_iterator(PHI); }
+ static inline PHI_iterator PHI_end(PhiT *PHI) {
+ return PHI_iterator(PHI, true);
+ }
+
+ /// FindPredecessorBlocks - Put the predecessors of Info->BB into the Preds
+ /// vector, set Info->NumPreds, and allocate space in Info->Preds.
+ static void FindPredecessorBlocks(BasicBlock *BB,
+ SmallVectorImpl<BasicBlock*> *Preds) {
+ // We can get our predecessor info by walking the pred_iterator list,
+ // but it is relatively slow. If we already have PHI nodes in this
+ // block, walk one of them to get the predecessor list instead.
+ if (PHINode *SomePhi = dyn_cast<PHINode>(BB->begin())) {
+ for (unsigned PI = 0, E = SomePhi->getNumIncomingValues(); PI != E; ++PI)
+ Preds->push_back(SomePhi->getIncomingBlock(PI));
+ } else {
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ Preds->push_back(*PI);
+ }
+ }
+
+ /// GetUndefVal - Get an undefined value of the same type as the value
+ /// being handled.
+ static Value *GetUndefVal(BasicBlock *BB, SSAUpdater *Updater) {
+ return UndefValue::get(Updater->PrototypeValue->getType());
+ }
+
+ /// CreateEmptyPHI - Create a new PHI instruction in the specified block.
+ /// Reserve space for the operands but do not fill them in yet.
+ static Value *CreateEmptyPHI(BasicBlock *BB, unsigned NumPreds,
+ SSAUpdater *Updater) {
+ PHINode *PHI = PHINode::Create(Updater->PrototypeValue->getType(),
+ Updater->PrototypeValue->getName(),
+ &BB->front());
+ PHI->reserveOperandSpace(NumPreds);
+ return PHI;
+ }
+
+ /// AddPHIOperand - Add the specified value as an operand of the PHI for
+ /// the specified predecessor block.
+ static void AddPHIOperand(PHINode *PHI, Value *Val, BasicBlock *Pred) {
+ PHI->addIncoming(Val, Pred);
+ }
+
+ /// InstrIsPHI - Check if an instruction is a PHI.
+ ///
+ static PHINode *InstrIsPHI(Instruction *I) {
+ return dyn_cast<PHINode>(I);
+ }
+
+ /// ValueIsPHI - Check if a value is a PHI.
+ ///
+ static PHINode *ValueIsPHI(Value *Val, SSAUpdater *Updater) {
+ return dyn_cast<PHINode>(Val);
+ }
+
+ /// ValueIsNewPHI - Like ValueIsPHI but also check if the PHI has no source
+ /// operands, i.e., it was just added.
+ static PHINode *ValueIsNewPHI(Value *Val, SSAUpdater *Updater) {
+ PHINode *PHI = ValueIsPHI(Val, Updater);
+ if (PHI && PHI->getNumIncomingValues() == 0)
+ return PHI;
+ return 0;
+ }
+
+ /// GetPHIValue - For the specified PHI instruction, return the value
+ /// that it defines.
+ static Value *GetPHIValue(PHINode *PHI) {
+ return PHI;
+ }
+};
+
+} // End llvm namespace
+
/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry
/// for the specified BB and if so, return it. If not, construct SSA form by
/// first calculating the required placement of PHIs and then inserting new
@@ -240,418 +325,6 @@
if (Value *V = AvailableVals[BB])
return V;
- // Pool allocation used internally by GetValueAtEndOfBlock.
- BumpPtrAllocator Allocator;
- BBMapTy BBMapObj;
- BM = &BBMapObj;
-
- SmallVector<BBInfo*, 100> BlockList;
- BuildBlockList(BB, &BlockList, &Allocator);
-
- // Special case: bail out if BB is unreachable.
- if (BlockList.size() == 0) {
- BM = 0;
- return UndefValue::get(PrototypeValue->getType());
- }
-
- FindDominators(&BlockList);
- FindPHIPlacement(&BlockList);
- FindAvailableVals(&BlockList);
-
- BM = 0;
- return BBMapObj[BB]->DefBB->AvailableVal;
-}
-
-/// FindPredecessorBlocks - Put the predecessors of Info->BB into the Preds
-/// vector, set Info->NumPreds, and allocate space in Info->Preds.
-static void FindPredecessorBlocks(SSAUpdater::BBInfo *Info,
- SmallVectorImpl<BasicBlock*> *Preds,
- BumpPtrAllocator *Allocator) {
- // We can get our predecessor info by walking the pred_iterator list,
- // but it is relatively slow. If we already have PHI nodes in this
- // block, walk one of them to get the predecessor list instead.
- BasicBlock *BB = Info->BB;
- if (PHINode *SomePhi = dyn_cast<PHINode>(BB->begin())) {
- for (unsigned PI = 0, E = SomePhi->getNumIncomingValues(); PI != E; ++PI)
- Preds->push_back(SomePhi->getIncomingBlock(PI));
- } else {
- for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
- Preds->push_back(*PI);
- }
-
- Info->NumPreds = Preds->size();
- Info->Preds = static_cast<SSAUpdater::BBInfo**>
- (Allocator->Allocate(Info->NumPreds * sizeof(SSAUpdater::BBInfo*),
- AlignOf<SSAUpdater::BBInfo*>::Alignment));
-}
-
-/// BuildBlockList - Starting from the specified basic block, traverse back
-/// through its predecessors until reaching blocks with known values. Create
-/// BBInfo structures for the blocks and append them to the block list.
-void SSAUpdater::BuildBlockList(BasicBlock *BB, BlockListTy *BlockList,
- BumpPtrAllocator *Allocator) {
- AvailableValsTy &AvailableVals = getAvailableVals(AV);
- BBMapTy *BBMap = getBBMap(BM);
- SmallVector<BBInfo*, 10> RootList;
- SmallVector<BBInfo*, 64> WorkList;
-
- BBInfo *Info = new (*Allocator) BBInfo(BB, 0);
- (*BBMap)[BB] = Info;
- WorkList.push_back(Info);
-
- // Search backward from BB, creating BBInfos along the way and stopping when
- // reaching blocks that define the value. Record those defining blocks on
- // the RootList.
- SmallVector<BasicBlock*, 10> Preds;
- while (!WorkList.empty()) {
- Info = WorkList.pop_back_val();
- Preds.clear();
- FindPredecessorBlocks(Info, &Preds, Allocator);
-
- // Treat an unreachable predecessor as a definition with 'undef'.
- if (Info->NumPreds == 0) {
- Info->AvailableVal = UndefValue::get(PrototypeValue->getType());
- Info->DefBB = Info;
- RootList.push_back(Info);
- continue;
- }
-
- for (unsigned p = 0; p != Info->NumPreds; ++p) {
- BasicBlock *Pred = Preds[p];
- // Check if BBMap already has a BBInfo for the predecessor block.
- BBMapTy::value_type &BBMapBucket = BBMap->FindAndConstruct(Pred);
- if (BBMapBucket.second) {
- Info->Preds[p] = BBMapBucket.second;
- continue;
- }
-
- // Create a new BBInfo for the predecessor.
- Value *PredVal = AvailableVals.lookup(Pred);
- BBInfo *PredInfo = new (*Allocator) BBInfo(Pred, PredVal);
- BBMapBucket.second = PredInfo;
- Info->Preds[p] = PredInfo;
-
- if (PredInfo->AvailableVal) {
- RootList.push_back(PredInfo);
- continue;
- }
- WorkList.push_back(PredInfo);
- }
- }
-
- // Now that we know what blocks are backwards-reachable from the starting
- // block, do a forward depth-first traversal to assign postorder numbers
- // to those blocks.
- BBInfo *PseudoEntry = new (*Allocator) BBInfo(0, 0);
- unsigned BlkNum = 1;
-
- // Initialize the worklist with the roots from the backward traversal.
- while (!RootList.empty()) {
- Info = RootList.pop_back_val();
- Info->IDom = PseudoEntry;
- Info->BlkNum = -1;
- WorkList.push_back(Info);
- }
-
- while (!WorkList.empty()) {
- Info = WorkList.back();
-
- if (Info->BlkNum == -2) {
- // All the successors have been handled; assign the postorder number.
- Info->BlkNum = BlkNum++;
- // If not a root, put it on the BlockList.
- if (!Info->AvailableVal)
- BlockList->push_back(Info);
- WorkList.pop_back();
- continue;
- }
-
- // Leave this entry on the worklist, but set its BlkNum to mark that its
- // successors have been put on the worklist. When it returns to the top
- // the list, after handling its successors, it will be assigned a number.
- Info->BlkNum = -2;
-
- // Add unvisited successors to the work list.
- for (succ_iterator SI = succ_begin(Info->BB), E = succ_end(Info->BB);
- SI != E; ++SI) {
- BBInfo *SuccInfo = (*BBMap)[*SI];
- if (!SuccInfo || SuccInfo->BlkNum)
- continue;
- SuccInfo->BlkNum = -1;
- WorkList.push_back(SuccInfo);
- }
- }
- PseudoEntry->BlkNum = BlkNum;
-}
-
-/// IntersectDominators - This is the dataflow lattice "meet" operation for
-/// finding dominators. Given two basic blocks, it walks up the dominator
-/// tree until it finds a common dominator of both. It uses the postorder
-/// number of the blocks to determine how to do that.
-static SSAUpdater::BBInfo *IntersectDominators(SSAUpdater::BBInfo *Blk1,
- SSAUpdater::BBInfo *Blk2) {
- while (Blk1 != Blk2) {
- while (Blk1->BlkNum < Blk2->BlkNum) {
- Blk1 = Blk1->IDom;
- if (!Blk1)
- return Blk2;
- }
- while (Blk2->BlkNum < Blk1->BlkNum) {
- Blk2 = Blk2->IDom;
- if (!Blk2)
- return Blk1;
- }
- }
- return Blk1;
-}
-
-/// FindDominators - Calculate the dominator tree for the subset of the CFG
-/// corresponding to the basic blocks on the BlockList. This uses the
-/// algorithm from: "A Simple, Fast Dominance Algorithm" by Cooper, Harvey and
-/// Kennedy, published in Software--Practice and Experience, 2001, 4:1-10.
-/// Because the CFG subset does not include any edges leading into blocks that
-/// define the value, the results are not the usual dominator tree. The CFG
-/// subset has a single pseudo-entry node with edges to a set of root nodes
-/// for blocks that define the value. The dominators for this subset CFG are
-/// not the standard dominators but they are adequate for placing PHIs within
-/// the subset CFG.
-void SSAUpdater::FindDominators(BlockListTy *BlockList) {
- bool Changed;
- do {
- Changed = false;
- // Iterate over the list in reverse order, i.e., forward on CFG edges.
- for (BlockListTy::reverse_iterator I = BlockList->rbegin(),
- E = BlockList->rend(); I != E; ++I) {
- BBInfo *Info = *I;
-
- // Start with the first predecessor.
- assert(Info->NumPreds > 0 && "unreachable block");
- BBInfo *NewIDom = Info->Preds[0];
-
- // Iterate through the block's other predecessors.
- for (unsigned p = 1; p != Info->NumPreds; ++p) {
- BBInfo *Pred = Info->Preds[p];
- NewIDom = IntersectDominators(NewIDom, Pred);
- }
-
- // Check if the IDom value has changed.
- if (NewIDom != Info->IDom) {
- Info->IDom = NewIDom;
- Changed = true;
- }
- }
- } while (Changed);
-}
-
-/// IsDefInDomFrontier - Search up the dominator tree from Pred to IDom for
-/// any blocks containing definitions of the value. If one is found, then the
-/// successor of Pred is in the dominance frontier for the definition, and
-/// this function returns true.
-static bool IsDefInDomFrontier(const SSAUpdater::BBInfo *Pred,
- const SSAUpdater::BBInfo *IDom) {
- for (; Pred != IDom; Pred = Pred->IDom) {
- if (Pred->DefBB == Pred)
- return true;
- }
- return false;
-}
-
-/// FindPHIPlacement - PHIs are needed in the iterated dominance frontiers of
-/// the known definitions. Iteratively add PHIs in the dom frontiers until
-/// nothing changes. Along the way, keep track of the nearest dominating
-/// definitions for non-PHI blocks.
-void SSAUpdater::FindPHIPlacement(BlockListTy *BlockList) {
- bool Changed;
- do {
- Changed = false;
- // Iterate over the list in reverse order, i.e., forward on CFG edges.
- for (BlockListTy::reverse_iterator I = BlockList->rbegin(),
- E = BlockList->rend(); I != E; ++I) {
- BBInfo *Info = *I;
-
- // If this block already needs a PHI, there is nothing to do here.
- if (Info->DefBB == Info)
- continue;
-
- // Default to use the same def as the immediate dominator.
- BBInfo *NewDefBB = Info->IDom->DefBB;
- for (unsigned p = 0; p != Info->NumPreds; ++p) {
- if (IsDefInDomFrontier(Info->Preds[p], Info->IDom)) {
- // Need a PHI here.
- NewDefBB = Info;
- break;
- }
- }
-
- // Check if anything changed.
- if (NewDefBB != Info->DefBB) {
- Info->DefBB = NewDefBB;
- Changed = true;
- }
- }
- } while (Changed);
-}
-
-/// FindAvailableVal - If this block requires a PHI, first check if an existing
-/// PHI matches the PHI placement and reaching definitions computed earlier,
-/// and if not, create a new PHI. Visit all the block's predecessors to
-/// calculate the available value for each one and fill in the incoming values
-/// for a new PHI.
-void SSAUpdater::FindAvailableVals(BlockListTy *BlockList) {
- AvailableValsTy &AvailableVals = getAvailableVals(AV);
-
- // Go through the worklist in forward order (i.e., backward through the CFG)
- // and check if existing PHIs can be used. If not, create empty PHIs where
- // they are needed.
- for (BlockListTy::iterator I = BlockList->begin(), E = BlockList->end();
- I != E; ++I) {
- BBInfo *Info = *I;
- // Check if there needs to be a PHI in BB.
- if (Info->DefBB != Info)
- continue;
-
- // Look for an existing PHI.
- FindExistingPHI(Info->BB, BlockList);
- if (Info->AvailableVal)
- continue;
-
- PHINode *PHI = PHINode::Create(PrototypeValue->getType(),
- PrototypeValue->getName(),
- &Info->BB->front());
- PHI->reserveOperandSpace(Info->NumPreds);
- Info->AvailableVal = PHI;
- AvailableVals[Info->BB] = PHI;
- }
-
- // Now go back through the worklist in reverse order to fill in the arguments
- // for any new PHIs added in the forward traversal.
- for (BlockListTy::reverse_iterator I = BlockList->rbegin(),
- E = BlockList->rend(); I != E; ++I) {
- BBInfo *Info = *I;
-
- if (Info->DefBB != Info) {
- // Record the available value at join nodes to speed up subsequent
- // uses of this SSAUpdater for the same value.
- if (Info->NumPreds > 1)
- AvailableVals[Info->BB] = Info->DefBB->AvailableVal;
- continue;
- }
-
- // Check if this block contains a newly added PHI.
- PHINode *PHI = dyn_cast<PHINode>(Info->AvailableVal);
- if (!PHI || PHI->getNumIncomingValues() == Info->NumPreds)
- continue;
-
- // Iterate through the block's predecessors.
- for (unsigned p = 0; p != Info->NumPreds; ++p) {
- BBInfo *PredInfo = Info->Preds[p];
- BasicBlock *Pred = PredInfo->BB;
- // Skip to the nearest preceding definition.
- if (PredInfo->DefBB != PredInfo)
- PredInfo = PredInfo->DefBB;
- PHI->addIncoming(PredInfo->AvailableVal, Pred);
- }
-
- DEBUG(dbgs() << " Inserted PHI: " << *PHI << "\n");
-
- // If the client wants to know about all new instructions, tell it.
- if (InsertedPHIs) InsertedPHIs->push_back(PHI);
- }
-}
-
-/// FindExistingPHI - Look through the PHI nodes in a block to see if any of
-/// them match what is needed.
-void SSAUpdater::FindExistingPHI(BasicBlock *BB, BlockListTy *BlockList) {
- PHINode *SomePHI;
- for (BasicBlock::iterator It = BB->begin();
- (SomePHI = dyn_cast<PHINode>(It)); ++It) {
- if (CheckIfPHIMatches(SomePHI)) {
- RecordMatchingPHI(SomePHI);
- break;
- }
- // Match failed: clear all the PHITag values.
- for (BlockListTy::iterator I = BlockList->begin(), E = BlockList->end();
- I != E; ++I)
- (*I)->PHITag = 0;
- }
-}
-
-/// CheckIfPHIMatches - Check if a PHI node matches the placement and values
-/// in the BBMap.
-bool SSAUpdater::CheckIfPHIMatches(PHINode *PHI) {
- BBMapTy *BBMap = getBBMap(BM);
- SmallVector<PHINode*, 20> WorkList;
- WorkList.push_back(PHI);
-
- // Mark that the block containing this PHI has been visited.
- (*BBMap)[PHI->getParent()]->PHITag = PHI;
-
- while (!WorkList.empty()) {
- PHI = WorkList.pop_back_val();
-
- // Iterate through the PHI's incoming values.
- for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) {
- Value *IncomingVal = PHI->getIncomingValue(i);
- BBInfo *PredInfo = (*BBMap)[PHI->getIncomingBlock(i)];
- // Skip to the nearest preceding definition.
- if (PredInfo->DefBB != PredInfo)
- PredInfo = PredInfo->DefBB;
-
- // Check if it matches the expected value.
- if (PredInfo->AvailableVal) {
- if (IncomingVal == PredInfo->AvailableVal)
- continue;
- return false;
- }
-
- // Check if the value is a PHI in the correct block.
- PHINode *IncomingPHIVal = dyn_cast<PHINode>(IncomingVal);
- if (!IncomingPHIVal || IncomingPHIVal->getParent() != PredInfo->BB)
- return false;
-
- // If this block has already been visited, check if this PHI matches.
- if (PredInfo->PHITag) {
- if (IncomingPHIVal == PredInfo->PHITag)
- continue;
- return false;
- }
- PredInfo->PHITag = IncomingPHIVal;
-
- WorkList.push_back(IncomingPHIVal);
- }
- }
- return true;
-}
-
-/// RecordMatchingPHI - For a PHI node that matches, record it and its input
-/// PHIs in both the BBMap and the AvailableVals mapping.
-void SSAUpdater::RecordMatchingPHI(PHINode *PHI) {
- BBMapTy *BBMap = getBBMap(BM);
- AvailableValsTy &AvailableVals = getAvailableVals(AV);
- SmallVector<PHINode*, 20> WorkList;
- WorkList.push_back(PHI);
-
- // Record this PHI.
- BasicBlock *BB = PHI->getParent();
- AvailableVals[BB] = PHI;
- (*BBMap)[BB]->AvailableVal = PHI;
-
- while (!WorkList.empty()) {
- PHI = WorkList.pop_back_val();
-
- // Iterate through the PHI's incoming values.
- for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) {
- PHINode *IncomingPHIVal = dyn_cast<PHINode>(PHI->getIncomingValue(i));
- if (!IncomingPHIVal) continue;
- BB = IncomingPHIVal->getParent();
- BBInfo *Info = (*BBMap)[BB];
- if (!Info || Info->AvailableVal)
- continue;
-
- // Record the PHI and add it to the worklist.
- AvailableVals[BB] = IncomingPHIVal;
- Info->AvailableVal = IncomingPHIVal;
- WorkList.push_back(IncomingPHIVal);
- }
- }
+ SSAUpdaterImpl<SSAUpdater> Impl(this, &AvailableVals, InsertedPHIs);
+ return Impl.GetValue(BB);
}
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