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https://github.com/RPCS3/llvm-mirror.git
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Make use of target specific block size limits; bug fixes.
llvm-svn: 37195
This commit is contained in:
Evan Cheng
parent
2fc338fac1
commit
c6aa69557a
@ -16,6 +16,7 @@
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetLowering.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/ADT/Statistic.h"
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@ -37,22 +38,24 @@ namespace {
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/// BBInfo - One per MachineBasicBlock, this is used to cache the result
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/// if-conversion feasibility analysis. This includes results from
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/// TargetInstrInfo::AnalyzeBranch() (i.e. TBB, FBB, and Cond), and its
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/// classification, and common merge block of its successors (if it's a
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/// classification, and common tail block of its successors (if it's a
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/// diamond shape).
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struct BBInfo {
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BBICKind Kind;
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MachineBasicBlock *EBB;
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MachineBasicBlock *TBB;
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MachineBasicBlock *FBB;
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MachineBasicBlock *CMBB;
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MachineBasicBlock *BB;
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MachineBasicBlock *TrueBB;
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MachineBasicBlock *FalseBB;
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MachineBasicBlock *TailBB;
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std::vector<MachineOperand> Cond;
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BBInfo() : Kind(ICInvalid), EBB(0), TBB(0), FBB(0), CMBB(0) {}
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unsigned Size;
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BBInfo() : Kind(ICInvalid), BB(0), TrueBB(0), FalseBB(0), TailBB(0), Size(0) {}
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};
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/// BBAnalysis - Results of if-conversion feasibility analysis indexed by
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/// basic block number.
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std::vector<BBInfo> BBAnalysis;
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const TargetLowering *TLI;
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const TargetInstrInfo *TII;
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bool MadeChange;
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public:
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@ -72,7 +75,7 @@ namespace {
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void PredicateBlock(MachineBasicBlock *BB,
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std::vector<MachineOperand> &Cond,
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bool IgnoreTerm = false);
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void MergeBlocks(MachineBasicBlock *TBB, MachineBasicBlock *FBB);
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void MergeBlocks(BBInfo &TrueBBI, BBInfo &FalseBBI);
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};
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char IfConverter::ID = 0;
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}
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@ -80,6 +83,7 @@ namespace {
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FunctionPass *llvm::createIfConverterPass() { return new IfConverter(); }
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bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
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TLI = MF.getTarget().getTargetLowering();
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TII = MF.getTarget().getInstrInfo();
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if (!TII) return false;
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@ -95,7 +99,7 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
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InitialFunctionAnalysis(MF, Candidates);
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for (unsigned i = 0, e = Candidates.size(); i != e; ++i) {
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BBInfo &BBI = BBAnalysis[i];
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BBInfo &BBI = BBAnalysis[Candidates[i]];
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switch (BBI.Kind) {
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default: assert(false && "Unexpected!");
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break;
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@ -111,11 +115,11 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
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}
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static MachineBasicBlock *findFalseBlock(MachineBasicBlock *BB,
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MachineBasicBlock *TBB) {
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MachineBasicBlock *TrueBB) {
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for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
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E = BB->succ_end(); SI != E; ++SI) {
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MachineBasicBlock *SuccBB = *SI;
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if (SuccBB != TBB)
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if (SuccBB != TrueBB)
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return SuccBB;
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}
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return NULL;
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@ -126,36 +130,49 @@ void IfConverter::AnalyzeBlock(MachineBasicBlock *BB) {
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if (BBI.Kind != ICInvalid)
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return; // Always analyzed.
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BBI.EBB = BB;
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BBI.BB = BB;
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BBI.Size = std::distance(BB->begin(), BB->end());
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// Look for 'root' of a simple (non-nested) triangle or diamond.
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BBI.Kind = ICNotClassfied;
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if (TII->AnalyzeBranch(*BB, BBI.TBB, BBI.FBB, BBI.Cond)
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|| !BBI.TBB || BBI.Cond.size() == 0)
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if (TII->AnalyzeBranch(*BB, BBI.TrueBB, BBI.FalseBB, BBI.Cond)
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|| !BBI.TrueBB || BBI.Cond.size() == 0)
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return;
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// Can't do it if 'true' block is already marked as to be if-converted.
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AnalyzeBlock(BBI.TBB);
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BBInfo &TBBI = BBAnalysis[BBI.TBB->getNumber()];
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if (TBBI.Kind != ICNotClassfied)
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// Not a candidate if 'true' block has another predecessor.
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// FIXME: Use or'd predicate or predicated cmp.
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if (BBI.TrueBB->pred_size() > 1)
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return;
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// Not a candidate if 'true' block is going to be if-converted.
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AnalyzeBlock(BBI.TrueBB);
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BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
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if (TrueBBI.Kind != ICNotClassfied)
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return;
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// No false branch. This BB must end with a conditional branch and a
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// fallthrough.
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if (!BBI.FBB)
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BBI.FBB = findFalseBlock(BB, BBI.TBB);
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assert(BBI.FBB && "Expected to find the fallthrough block!");
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if (!BBI.FalseBB)
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BBI.FalseBB = findFalseBlock(BB, BBI.TrueBB);
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assert(BBI.FalseBB && "Expected to find the fallthrough block!");
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// Can't do it if 'false' block is already marked as to be if-converted.
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AnalyzeBlock(BBI.FBB);
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BBInfo &FBBI = BBAnalysis[BBI.FBB->getNumber()];
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if (FBBI.Kind != ICNotClassfied)
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// Not a candidate if 'false' block has another predecessor.
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// FIXME: Invert condition and swap 'true' / 'false' blocks?
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if (BBI.FalseBB->pred_size() > 1)
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return;
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// Not a candidate if 'false' block is going to be if-converted.
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AnalyzeBlock(BBI.FalseBB);
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BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
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if (FalseBBI.Kind != ICNotClassfied)
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return;
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// TODO: Only handle very simple cases for now.
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if (TBBI.FBB || FBBI.FBB || TBBI.Cond.size() > 1 || FBBI.Cond.size() > 1)
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if (TrueBBI.FalseBB || FalseBBI.FalseBB ||
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TrueBBI.Cond.size() || FalseBBI.Cond.size())
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return;
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if (TBBI.TBB && TBBI.TBB == BBI.FBB) {
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if (TrueBBI.TrueBB && TrueBBI.TrueBB == BBI.FalseBB) {
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// Triangle:
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// EBB
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// | \_
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@ -164,19 +181,19 @@ void IfConverter::AnalyzeBlock(MachineBasicBlock *BB) {
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// | /
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// FBB
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BBI.Kind = ICTriangleEntry;
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TBBI.Kind = FBBI.Kind = ICTriangle;
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} else if (TBBI.TBB == FBBI.TBB) {
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TrueBBI.Kind = FalseBBI.Kind = ICTriangle;
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} else if (TrueBBI.TrueBB == FalseBBI.TrueBB) {
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// Diamond:
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// EBB
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// / \_
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// | |
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// TBB FBB
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// \ /
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// MBB
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// TailBB
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// Note MBB can be empty in case both TBB and FBB are return blocks.
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BBI.Kind = ICDiamondEntry;
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TBBI.Kind = FBBI.Kind = ICDiamond;
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BBI.CMBB = TBBI.TBB;
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TrueBBI.Kind = FalseBBI.Kind = ICDiamond;
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BBI.TailBB = TrueBBI.TrueBB;
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}
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return;
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}
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@ -194,24 +211,55 @@ void IfConverter::InitialFunctionAnalysis(MachineFunction &MF,
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}
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}
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/// TransferPreds - Transfer all the predecessors of FromBB to ToBB.
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///
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static void TransferPreds(MachineBasicBlock *ToBB, MachineBasicBlock *FromBB) {
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std::vector<MachineBasicBlock*> Preds(FromBB->pred_begin(),
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FromBB->pred_end());
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for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
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MachineBasicBlock *Pred = Preds[i];
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Pred->removeSuccessor(FromBB);
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if (!Pred->isSuccessor(ToBB))
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Pred->addSuccessor(ToBB);
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}
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}
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/// TransferSuccs - Transfer all the successors of FromBB to ToBB.
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///
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static void TransferSuccs(MachineBasicBlock *ToBB, MachineBasicBlock *FromBB) {
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std::vector<MachineBasicBlock*> Succs(FromBB->succ_begin(),
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FromBB->succ_end());
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for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
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MachineBasicBlock *Succ = Succs[i];
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FromBB->removeSuccessor(Succ);
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if (!ToBB->isSuccessor(Succ))
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ToBB->addSuccessor(Succ);
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}
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}
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/// IfConvertTriangle - If convert a triangle sub-CFG.
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///
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bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
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if (isBlockPredicable(BBI.TBB)) {
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if (isBlockPredicable(BBI.TrueBB)) {
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BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
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BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
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// Predicate the 'true' block after removing its branch.
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TII->RemoveBranch(*BBI.TBB);
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PredicateBlock(BBI.TBB, BBI.Cond);
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TrueBBI.Size -= TII->RemoveBranch(*BBI.TrueBB);
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PredicateBlock(BBI.TrueBB, BBI.Cond);
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// Join the 'true' and 'false' blocks by copying the instructions
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// from the 'false' block to the 'true' block.
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MergeBlocks(BBI.TBB, BBI.FBB);
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BBI.TrueBB->removeSuccessor(BBI.FalseBB);
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MergeBlocks(TrueBBI, FalseBBI);
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// Adjust entry block, it should have but a single unconditional
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// branch.
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BBI.EBB->removeSuccessor(BBI.FBB);
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TII->RemoveBranch(*BBI.EBB);
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std::vector<MachineOperand> NoCond;
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TII->InsertBranch(*BBI.EBB, BBI.TBB, NULL, NoCond);
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// Now merge the entry of the triangle with the true block.
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BBI.Size -= TII->RemoveBranch(*BBI.BB);
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MergeBlocks(BBI, TrueBBI);
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// Update block info.
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TrueBBI.Kind = ICInvalid;
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FalseBBI.Kind = ICInvalid;
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// FIXME: Must maintain LiveIns.
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NumIfConvBBs++;
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@ -223,14 +271,14 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
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/// IfConvertDiamond - If convert a diamond sub-CFG.
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///
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bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
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if (isBlockPredicable(BBI.TBB) && isBlockPredicable(BBI.FBB)) {
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if (isBlockPredicable(BBI.TrueBB) && isBlockPredicable(BBI.FalseBB)) {
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std::vector<MachineInstr*> Dups;
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if (!BBI.CMBB) {
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if (!BBI.TailBB) {
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// No common merge block. Check if the terminators (e.g. return) are
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// the same or predicable.
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MachineBasicBlock::iterator TT = BBI.TBB->getFirstTerminator();
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MachineBasicBlock::iterator FT = BBI.FBB->getFirstTerminator();
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while (TT != BBI.TBB->end() && FT != BBI.FBB->end()) {
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MachineBasicBlock::iterator TT = BBI.TrueBB->getFirstTerminator();
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MachineBasicBlock::iterator FT = BBI.FalseBB->getFirstTerminator();
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while (TT != BBI.TrueBB->end() && FT != BBI.FalseBB->end()) {
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if (TT->isIdenticalTo(FT))
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Dups.push_back(TT); // Will erase these later.
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else if (!TT->isPredicable() && !FT->isPredicable())
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@ -240,37 +288,65 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
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}
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// One of the two pathes have more terminators, make sure they are all
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// predicable.
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while (TT != BBI.TBB->end())
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while (TT != BBI.TrueBB->end())
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if (!TT->isPredicable())
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return false; // Can't if-convert. Abort!
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while (FT != BBI.FBB->end())
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while (FT != BBI.FalseBB->end())
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if (!FT->isPredicable())
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return false; // Can't if-convert. Abort!
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}
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BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
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BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
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// Remove the duplicated instructions from the 'true' block.
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for (unsigned i = 0, e = Dups.size(); i != e; ++i)
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for (unsigned i = 0, e = Dups.size(); i != e; ++i) {
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Dups[i]->eraseFromParent();
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--TrueBBI.Size;
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}
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// Predicate the 'true' block after removing its branch.
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TII->RemoveBranch(*BBI.TBB);
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PredicateBlock(BBI.TBB, BBI.Cond);
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TrueBBI.Size -= TII->RemoveBranch(*BBI.TrueBB);
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PredicateBlock(BBI.TrueBB, BBI.Cond);
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// Predicate the 'false' block.
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std::vector<MachineOperand> NewCond(BBI.Cond);
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TII->ReverseBranchCondition(NewCond);
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PredicateBlock(BBI.FBB, NewCond, true);
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PredicateBlock(BBI.FalseBB, NewCond, true);
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// Join the 'true' and 'false' blocks by copying the instructions
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// Merge the 'true' and 'false' blocks by copying the instructions
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// from the 'false' block to the 'true' block.
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MergeBlocks(BBI.TBB, BBI.FBB);
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MergeBlocks(TrueBBI, FalseBBI);
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// Adjust entry block, it should have but a single unconditional
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// branch .
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BBI.EBB->removeSuccessor(BBI.FBB);
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TII->RemoveBranch(*BBI.EBB);
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std::vector<MachineOperand> NoCond;
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TII->InsertBranch(*BBI.EBB, BBI.TBB, NULL, NoCond);
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// Remove the conditional branch from entry to the blocks.
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BBI.Size -= TII->RemoveBranch(*BBI.BB);
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// Merge the combined block into the entry of the diamond if the entry
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// block is the only predecessor. Otherwise, insert an unconditional
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// branch.
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BBInfo *CvtBBI = &TrueBBI;
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if (BBI.TrueBB->pred_size() == 1) {
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BBI.BB->removeSuccessor(BBI.TrueBB);
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MergeBlocks(BBI, TrueBBI);
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CvtBBI = &BBI;
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} else {
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std::vector<MachineOperand> NoCond;
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TII->InsertBranch(*BBI.BB, BBI.TrueBB, NULL, NoCond);
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}
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// If the if-converted block fallthrough into the tail block, then
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// fold the tail block in as well.
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if (BBI.TailBB && CvtBBI->BB->succ_size() == 1) {
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CvtBBI->Size -= TII->RemoveBranch(*CvtBBI->BB);
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CvtBBI->BB->removeSuccessor(BBI.TailBB);
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BBInfo TailBBI = BBAnalysis[BBI.TailBB->getNumber()];
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MergeBlocks(*CvtBBI, TailBBI);
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TailBBI.Kind = ICInvalid;
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}
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// Update block info.
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TrueBBI.Kind = ICInvalid;
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FalseBBI.Kind = ICInvalid;
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// FIXME: Must maintain LiveIns.
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NumIfConvBBs += 2;
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@ -283,6 +359,10 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
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/// cases, that means all the instructions in the block has M_PREDICABLE flag.
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/// It assume all the terminator instructions can be converted or deleted.
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bool IfConverter::isBlockPredicable(MachineBasicBlock *BB) const {
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const BBInfo &BBI = BBAnalysis[BB->getNumber()];
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if (BBI.Size == 0 || BBI.Size > TLI->getIfCvtBlockSizeLimit())
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return false;
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for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
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I != E; ++I) {
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if (TII->isTerminatorInstr(I->getOpcode()))
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@ -309,8 +389,13 @@ void IfConverter::PredicateBlock(MachineBasicBlock *BB,
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}
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}
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/// MergeBlocks - Move all instructions from FBB to the end of TBB.
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/// MergeBlocks - Move all instructions from FromBB to the end of ToBB.
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///
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void IfConverter::MergeBlocks(MachineBasicBlock *TBB, MachineBasicBlock *FBB) {
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TBB->splice(TBB->end(), FBB, FBB->begin(), FBB->end());
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void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) {
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ToBBI.BB->splice(ToBBI.BB->end(),
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FromBBI.BB, FromBBI.BB->begin(), FromBBI.BB->end());
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TransferPreds(ToBBI.BB, FromBBI.BB);
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TransferSuccs(ToBBI.BB, FromBBI.BB);
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ToBBI.Size += FromBBI.Size;
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FromBBI.Size = 0;
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}
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