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Diffstat (limited to 'lib/CodeGen/MachineSink.cpp')
-rw-r--r--lib/CodeGen/MachineSink.cpp125
1 files changed, 78 insertions, 47 deletions
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index aed0e500d441..1b9be50068a9 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -73,6 +73,9 @@ namespace {
SparseBitVector<> RegsToClearKillFlags;
+ typedef std::map<MachineBasicBlock *, SmallVector<MachineBasicBlock *, 4>>
+ AllSuccsCache;
+
public:
static char ID; // Pass identification
MachineSinking() : MachineFunctionPass(ID) {
@@ -120,18 +123,24 @@ namespace {
MachineBasicBlock *From,
MachineBasicBlock *To,
bool BreakPHIEdge);
- bool SinkInstruction(MachineInstr *MI, bool &SawStore);
+ bool SinkInstruction(MachineInstr *MI, bool &SawStore,
+ AllSuccsCache &AllSuccessors);
bool AllUsesDominatedByBlock(unsigned Reg, MachineBasicBlock *MBB,
MachineBasicBlock *DefMBB,
bool &BreakPHIEdge, bool &LocalUse) const;
MachineBasicBlock *FindSuccToSinkTo(MachineInstr *MI, MachineBasicBlock *MBB,
- bool &BreakPHIEdge);
+ bool &BreakPHIEdge, AllSuccsCache &AllSuccessors);
bool isProfitableToSinkTo(unsigned Reg, MachineInstr *MI,
MachineBasicBlock *MBB,
- MachineBasicBlock *SuccToSinkTo);
+ MachineBasicBlock *SuccToSinkTo,
+ AllSuccsCache &AllSuccessors);
bool PerformTrivialForwardCoalescing(MachineInstr *MI,
MachineBasicBlock *MBB);
+
+ SmallVector<MachineBasicBlock *, 4> &
+ GetAllSortedSuccessors(MachineInstr *MI, MachineBasicBlock *MBB,
+ AllSuccsCache &AllSuccessors) const;
};
} // end anonymous namespace
@@ -269,9 +278,8 @@ bool MachineSinking::runOnMachineFunction(MachineFunction &MF) {
// Process all basic blocks.
CEBCandidates.clear();
ToSplit.clear();
- for (MachineFunction::iterator I = MF.begin(), E = MF.end();
- I != E; ++I)
- MadeChange |= ProcessBlock(*I);
+ for (auto &MBB: MF)
+ MadeChange |= ProcessBlock(MBB);
// If we have anything we marked as toSplit, split it now.
for (auto &Pair : ToSplit) {
@@ -310,6 +318,9 @@ bool MachineSinking::ProcessBlock(MachineBasicBlock &MBB) {
bool MadeChange = false;
+ // Cache all successors, sorted by frequency info and loop depth.
+ AllSuccsCache AllSuccessors;
+
// Walk the basic block bottom-up. Remember if we saw a store.
MachineBasicBlock::iterator I = MBB.end();
--I;
@@ -332,7 +343,7 @@ bool MachineSinking::ProcessBlock(MachineBasicBlock &MBB) {
continue;
}
- if (SinkInstruction(MI, SawStore))
+ if (SinkInstruction(MI, SawStore, AllSuccessors))
++NumSunk, MadeChange = true;
// If we just processed the first instruction in the block, we're done.
@@ -484,7 +495,8 @@ static void collectDebugValues(MachineInstr *MI,
/// isProfitableToSinkTo - Return true if it is profitable to sink MI.
bool MachineSinking::isProfitableToSinkTo(unsigned Reg, MachineInstr *MI,
MachineBasicBlock *MBB,
- MachineBasicBlock *SuccToSinkTo) {
+ MachineBasicBlock *SuccToSinkTo,
+ AllSuccsCache &AllSuccessors) {
assert (MI && "Invalid MachineInstr!");
assert (SuccToSinkTo && "Invalid SinkTo Candidate BB");
@@ -514,18 +526,66 @@ bool MachineSinking::isProfitableToSinkTo(unsigned Reg, MachineInstr *MI,
// can further profitably sinked into another block in next round.
bool BreakPHIEdge = false;
// FIXME - If finding successor is compile time expensive then cache results.
- if (MachineBasicBlock *MBB2 = FindSuccToSinkTo(MI, SuccToSinkTo, BreakPHIEdge))
- return isProfitableToSinkTo(Reg, MI, SuccToSinkTo, MBB2);
+ if (MachineBasicBlock *MBB2 =
+ FindSuccToSinkTo(MI, SuccToSinkTo, BreakPHIEdge, AllSuccessors))
+ return isProfitableToSinkTo(Reg, MI, SuccToSinkTo, MBB2, AllSuccessors);
// If SuccToSinkTo is final destination and it is a post dominator of current
// block then it is not profitable to sink MI into SuccToSinkTo block.
return false;
}
+/// Get the sorted sequence of successors for this MachineBasicBlock, possibly
+/// computing it if it was not already cached.
+SmallVector<MachineBasicBlock *, 4> &
+MachineSinking::GetAllSortedSuccessors(MachineInstr *MI, MachineBasicBlock *MBB,
+ AllSuccsCache &AllSuccessors) const {
+
+ // Do we have the sorted successors in cache ?
+ auto Succs = AllSuccessors.find(MBB);
+ if (Succs != AllSuccessors.end())
+ return Succs->second;
+
+ SmallVector<MachineBasicBlock *, 4> AllSuccs(MBB->succ_begin(),
+ MBB->succ_end());
+
+ // Handle cases where sinking can happen but where the sink point isn't a
+ // successor. For example:
+ //
+ // x = computation
+ // if () {} else {}
+ // use x
+ //
+ const std::vector<MachineDomTreeNode *> &Children =
+ DT->getNode(MBB)->getChildren();
+ for (const auto &DTChild : Children)
+ // DomTree children of MBB that have MBB as immediate dominator are added.
+ if (DTChild->getIDom()->getBlock() == MI->getParent() &&
+ // Skip MBBs already added to the AllSuccs vector above.
+ !MBB->isSuccessor(DTChild->getBlock()))
+ AllSuccs.push_back(DTChild->getBlock());
+
+ // Sort Successors according to their loop depth or block frequency info.
+ std::stable_sort(
+ AllSuccs.begin(), AllSuccs.end(),
+ [this](const MachineBasicBlock *L, const MachineBasicBlock *R) {
+ uint64_t LHSFreq = MBFI ? MBFI->getBlockFreq(L).getFrequency() : 0;
+ uint64_t RHSFreq = MBFI ? MBFI->getBlockFreq(R).getFrequency() : 0;
+ bool HasBlockFreq = LHSFreq != 0 && RHSFreq != 0;
+ return HasBlockFreq ? LHSFreq < RHSFreq
+ : LI->getLoopDepth(L) < LI->getLoopDepth(R);
+ });
+
+ auto it = AllSuccessors.insert(std::make_pair(MBB, AllSuccs));
+
+ return it.first->second;
+}
+
/// FindSuccToSinkTo - Find a successor to sink this instruction to.
MachineBasicBlock *MachineSinking::FindSuccToSinkTo(MachineInstr *MI,
MachineBasicBlock *MBB,
- bool &BreakPHIEdge) {
+ bool &BreakPHIEdge,
+ AllSuccsCache &AllSuccessors) {
assert (MI && "Invalid MachineInstr!");
assert (MBB && "Invalid MachineBasicBlock!");
@@ -579,38 +639,8 @@ MachineBasicBlock *MachineSinking::FindSuccToSinkTo(MachineInstr *MI,
// we should sink to. If we have reliable block frequency information
// (frequency != 0) available, give successors with smaller frequencies
// higher priority, otherwise prioritize smaller loop depths.
- SmallVector<MachineBasicBlock*, 4> Succs(MBB->succ_begin(),
- MBB->succ_end());
-
- // Handle cases where sinking can happen but where the sink point isn't a
- // successor. For example:
- //
- // x = computation
- // if () {} else {}
- // use x
- //
- const std::vector<MachineDomTreeNode *> &Children =
- DT->getNode(MBB)->getChildren();
- for (const auto &DTChild : Children)
- // DomTree children of MBB that have MBB as immediate dominator are added.
- if (DTChild->getIDom()->getBlock() == MI->getParent() &&
- // Skip MBBs already added to the Succs vector above.
- !MBB->isSuccessor(DTChild->getBlock()))
- Succs.push_back(DTChild->getBlock());
-
- // Sort Successors according to their loop depth or block frequency info.
- std::stable_sort(
- Succs.begin(), Succs.end(),
- [this](const MachineBasicBlock *L, const MachineBasicBlock *R) {
- uint64_t LHSFreq = MBFI ? MBFI->getBlockFreq(L).getFrequency() : 0;
- uint64_t RHSFreq = MBFI ? MBFI->getBlockFreq(R).getFrequency() : 0;
- bool HasBlockFreq = LHSFreq != 0 && RHSFreq != 0;
- return HasBlockFreq ? LHSFreq < RHSFreq
- : LI->getLoopDepth(L) < LI->getLoopDepth(R);
- });
- for (SmallVectorImpl<MachineBasicBlock *>::iterator SI = Succs.begin(),
- E = Succs.end(); SI != E; ++SI) {
- MachineBasicBlock *SuccBlock = *SI;
+ for (MachineBasicBlock *SuccBlock :
+ GetAllSortedSuccessors(MI, MBB, AllSuccessors)) {
bool LocalUse = false;
if (AllUsesDominatedByBlock(Reg, SuccBlock, MBB,
BreakPHIEdge, LocalUse)) {
@@ -625,7 +655,7 @@ MachineBasicBlock *MachineSinking::FindSuccToSinkTo(MachineInstr *MI,
// If we couldn't find a block to sink to, ignore this instruction.
if (!SuccToSinkTo)
return nullptr;
- if (!isProfitableToSinkTo(Reg, MI, MBB, SuccToSinkTo))
+ if (!isProfitableToSinkTo(Reg, MI, MBB, SuccToSinkTo, AllSuccessors))
return nullptr;
}
}
@@ -645,7 +675,8 @@ MachineBasicBlock *MachineSinking::FindSuccToSinkTo(MachineInstr *MI,
/// SinkInstruction - Determine whether it is safe to sink the specified machine
/// instruction out of its current block into a successor.
-bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
+bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore,
+ AllSuccsCache &AllSuccessors) {
// Don't sink insert_subreg, subreg_to_reg, reg_sequence. These are meant to
// be close to the source to make it easier to coalesce.
if (AvoidsSinking(MI, MRI))
@@ -669,8 +700,8 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
bool BreakPHIEdge = false;
MachineBasicBlock *ParentBlock = MI->getParent();
- MachineBasicBlock *SuccToSinkTo = FindSuccToSinkTo(MI, ParentBlock,
- BreakPHIEdge);
+ MachineBasicBlock *SuccToSinkTo =
+ FindSuccToSinkTo(MI, ParentBlock, BreakPHIEdge, AllSuccessors);
// If there are no outputs, it must have side-effects.
if (!SuccToSinkTo)
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-15 22:32:47 +0000