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author | Evan Cheng <evan.cheng@apple.com> | 2007-06-09 01:03:43 +0000 |
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committer | Evan Cheng <evan.cheng@apple.com> | 2007-06-09 01:03:43 +0000 |
commit | 1c9f91d7b2653dc730a80f49ac3b6e2b9d6ca236 (patch) | |
tree | 397d7596ee7315516f3ec197adc89ce4f5c9861d /lib/CodeGen/IfConversion.cpp | |
parent | b8b873cb7d7511ac6f58a40e324857a0d879bcf5 (diff) | |
download | external_llvm-1c9f91d7b2653dc730a80f49ac3b6e2b9d6ca236.zip external_llvm-1c9f91d7b2653dc730a80f49ac3b6e2b9d6ca236.tar.gz external_llvm-1c9f91d7b2653dc730a80f49ac3b6e2b9d6ca236.tar.bz2 |
Don't change CFG during analysis stage. Do so during ifcvt and invalidate predecessors accordingly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37531 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/IfConversion.cpp')
-rw-r--r-- | lib/CodeGen/IfConversion.cpp | 162 |
1 files changed, 106 insertions, 56 deletions
diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp index 1302ec2..4adf859 100644 --- a/lib/CodeGen/IfConversion.cpp +++ b/lib/CodeGen/IfConversion.cpp @@ -32,19 +32,25 @@ namespace { cl::opt<int> IfCvtLimit("ifcvt-limit", cl::init(-1), cl::Hidden); cl::opt<bool> DisableSimple("disable-ifcvt-simple", cl::init(false), cl::Hidden); - cl::opt<bool> DisableSimpleFalse("disable-ifcvt-simple-false", - cl::init(false), cl::Hidden); + cl::opt<bool> DisableSimpleF("disable-ifcvt-simple-false", + cl::init(false), cl::Hidden); cl::opt<bool> DisableTriangle("disable-ifcvt-triangle", cl::init(false), cl::Hidden); + cl::opt<bool> DisableTriangleF("disable-ifcvt-triangle-false", + cl::init(false), cl::Hidden); + cl::opt<bool> DisableTriangleFR("disable-ifcvt-triangle-false-rev", + cl::init(false), cl::Hidden); cl::opt<bool> DisableDiamond("disable-ifcvt-diamond", cl::init(false), cl::Hidden); } -STATISTIC(NumSimple, "Number of simple if-conversions performed"); -STATISTIC(NumSimpleRev, "Number of simple (reversed) if-conversions performed"); -STATISTIC(NumTriangle, "Number of triangle if-conversions performed"); -STATISTIC(NumDiamonds, "Number of diamond if-conversions performed"); -STATISTIC(NumIfConvBBs, "Number of if-converted blocks"); +STATISTIC(NumSimple, "Number of simple if-conversions performed"); +STATISTIC(NumSimpleFalse, "Number of simple (F) if-conversions performed"); +STATISTIC(NumTriangle, "Number of triangle if-conversions performed"); +STATISTIC(NumTriangleFalse,"Number of triangle (F) if-conversions performed"); +STATISTIC(NumTriangleFRev, "Number of triangle (F/R) if-conversions performed"); +STATISTIC(NumDiamonds, "Number of diamond if-conversions performed"); +STATISTIC(NumIfConvBBs, "Number of if-converted blocks"); namespace { class IfConverter : public MachineFunctionPass { @@ -55,6 +61,8 @@ namespace { ICSimple, // BB is entry of an one split, no rejoin sub-CFG. ICSimpleFalse, // Same as ICSimple, but on the false path. ICTriangle, // BB is entry of a triangle sub-CFG. + ICTriangleFalse, // Same as ICTriangle, but on the false path. + ICTriangleFRev, // Same as ICTriangleFalse, but false path rev condition. ICDiamond, // BB is entry of a diamond sub-CFG. ICChild, // BB is part of the sub-CFG that'll be predicated. ICDead // BB cannot be if-converted again. @@ -80,7 +88,7 @@ namespace { BBICKind Kind; unsigned NonPredSize; bool IsAnalyzable; - bool hasFallThrough; + bool HasFallThrough; bool ModifyPredicate; MachineBasicBlock *BB; MachineBasicBlock *TrueBB; @@ -89,7 +97,7 @@ namespace { std::vector<MachineOperand> BrCond; std::vector<MachineOperand> Predicate; BBInfo() : Kind(ICNotAnalyzed), NonPredSize(0), - IsAnalyzable(false), hasFallThrough(false), + IsAnalyzable(false), HasFallThrough(false), ModifyPredicate(false), BB(0), TrueBB(0), FalseBB(0), TailBB(0) {} }; @@ -195,8 +203,8 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) { break; case ICSimple: case ICSimpleFalse: { - bool isRev = BBI.Kind == ICSimpleFalse; - if ((isRev && DisableSimpleFalse) || (!isRev && DisableSimple)) break; + bool isFalse = BBI.Kind == ICSimpleFalse; + if ((isFalse && DisableSimpleF) || (!isFalse && DisableSimple)) break; DOUT << "Ifcvt (Simple" << (BBI.Kind == ICSimpleFalse ? " false" : "") << "): BB#" << BBI.BB->getNumber() << " (" << ((BBI.Kind == ICSimpleFalse) @@ -204,18 +212,33 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) { RetVal = IfConvertSimple(BBI); DOUT << (RetVal ? "succeeded!" : "failed!") << "\n"; if (RetVal) - if (isRev) NumSimpleRev++; - else NumSimple++; + if (isFalse) NumSimpleFalse++; + else NumSimple++; break; } case ICTriangle: - if (DisableTriangle) break; - DOUT << "Ifcvt (Triangle): BB#" << BBI.BB->getNumber() << " (T:" + case ICTriangleFalse: + case ICTriangleFRev: + bool isFalse = BBI.Kind == ICTriangleFalse; + bool isFalseRev = BBI.Kind == ICTriangleFRev; + if (DisableTriangle && !isFalse && !isFalseRev) break; + if (DisableTriangleF && isFalse) break; + if (DisableTriangleFR && isFalseRev) break; + DOUT << "Ifcvt (Triangle"; + if (isFalse) + DOUT << " false"; + if (isFalseRev) + DOUT << " false/rev"; + DOUT << "): BB#" << BBI.BB->getNumber() << " (T:" << BBI.TrueBB->getNumber() << ",F:" << BBI.FalseBB->getNumber() << ") "; RetVal = IfConvertTriangle(BBI); DOUT << (RetVal ? "succeeded!" : "failed!") << "\n"; - if (RetVal) NumTriangle++; + if (RetVal) { + if (isFalseRev) NumTriangleFRev++; + else if (isFalse) NumTriangleFalse++; + else NumTriangle++; + } break; case ICDiamond: if (DisableDiamond) break; @@ -231,7 +254,7 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) { } Change |= RetVal; - if (IfCvtLimit != -1 && (int)NumIfConvBBs > IfCvtLimit) + if (IfCvtLimit != -1 && (int)NumIfConvBBs >= IfCvtLimit) break; } @@ -267,6 +290,16 @@ bool IfConverter::ReverseBranchCondition(BBInfo &BBI) { return false; } +/// getNextBlock - Returns the next block in the function blocks ordering. If +/// it is the end, returns NULL. +static inline MachineBasicBlock *getNextBlock(MachineBasicBlock *BB) { + MachineFunction::iterator I = BB; + MachineFunction::iterator E = BB->getParent()->end(); + if (++I == E) + return NULL; + return I; +} + /// ValidSimple - Returns true if the 'true' block (along with its /// predecessor) forms a valid simple shape for ifcvt. bool IfConverter::ValidSimple(BBInfo &TrueBBI) const { @@ -294,9 +327,19 @@ bool IfConverter::ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI, /// ValidDiamond - Returns true if the 'true' and 'false' blocks (along /// with their common predecessor) forms a valid diamond shape for ifcvt. bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI) const { - // FIXME: Also look for fallthrough - return (TrueBBI.TrueBB == FalseBBI.TrueBB && - TrueBBI.BB->pred_size() == 1 && + MachineBasicBlock *TT = TrueBBI.TrueBB; + MachineBasicBlock *FT = FalseBBI.TrueBB; + + if (!TT && blockAlwaysFallThrough(TrueBBI)) + TT = getNextBlock(TrueBBI.BB); + if (!FT && blockAlwaysFallThrough(FalseBBI)) + FT = getNextBlock(FalseBBI.BB); + if (TT != FT) + return false; + if (TT == NULL && (TrueBBI.IsAnalyzable || FalseBBI.IsAnalyzable)) + return false; + // FIXME: Allow false block to have an early exit? + return (TrueBBI.BB->pred_size() == 1 && FalseBBI.BB->pred_size() == 1 && !TrueBBI.FalseBB && !FalseBBI.FalseBB); } @@ -321,7 +364,7 @@ void IfConverter::AnalyzeBlock(MachineBasicBlock *BB) { BBI.Kind = ICNotClassfied; BBI.IsAnalyzable = !TII->AnalyzeBranch(*BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond); - BBI.hasFallThrough = BBI.IsAnalyzable && BBI.FalseBB == NULL; + BBI.HasFallThrough = BBI.IsAnalyzable && BBI.FalseBB == NULL; // Unanalyable or ends with fallthrough or unconditional branch. if (!BBI.IsAnalyzable || BBI.BrCond.size() == 0) return; @@ -395,15 +438,11 @@ void IfConverter::AnalyzeBlock(MachineBasicBlock *BB) { // Try the other path... if (ValidTriangle(FalseBBI, TrueBBI) && FeasibilityAnalysis(FalseBBI, RevCond, true)) { - // Reverse 'true' and 'false' paths. - ReverseBranchCondition(BBI); - BBI.Kind = ICTriangle; + BBI.Kind = ICTriangleFalse; FalseBBI.Kind = ICChild; } else if (ValidTriangle(FalseBBI, TrueBBI, true) && FeasibilityAnalysis(FalseBBI, RevCond, true, true)) { - ReverseBranchCondition(FalseBBI); - ReverseBranchCondition(BBI); - BBI.Kind = ICTriangle; + BBI.Kind = ICTriangleFRev; FalseBBI.Kind = ICChild; } else if (ValidSimple(FalseBBI) && FeasibilityAnalysis(FalseBBI, RevCond)) { @@ -556,16 +595,6 @@ static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) { return true; } -/// getNextBlock - Returns the next block in the function blocks ordering. If -/// it is the end, returns NULL. -static inline MachineBasicBlock *getNextBlock(MachineBasicBlock *BB) { - MachineFunction::iterator I = BB; - MachineFunction::iterator E = BB->getParent()->end(); - if (++I == E) - return NULL; - return I; -} - /// ReTryPreds - Invalidate predecessor BB info so it would be re-analyzed /// to determine if it can be if-converted. void IfConverter::ReTryPreds(MachineBasicBlock *BB) { @@ -625,7 +654,7 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI) { bool IterIfcvt = true; if (!canFallThroughTo(BBI.BB, NextBBI->BB)) { InsertUncondBranch(BBI.BB, NextBBI->BB, TII); - BBI.hasFallThrough = false; + BBI.HasFallThrough = false; // Now ifcvt'd block will look like this: // BB: // ... @@ -657,40 +686,61 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI) { /// bool IfConverter::IfConvertTriangle(BBInfo &BBI) { BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()]; + BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()]; + BBInfo *CvtBBI = &TrueBBI; + BBInfo *NextBBI = &FalseBBI; + + std::vector<MachineOperand> Cond(BBI.BrCond); + if (BBI.Kind == ICTriangleFalse || BBI.Kind == ICTriangleFRev) { + if (BBI.Kind == ICTriangleFRev) { + ReverseBranchCondition(*NextBBI); + // False BB has been changed, modify its predecessors (except for this + // one) so they don't get ifcvt'ed based on bad intel. + for (MachineBasicBlock::pred_iterator PI = NextBBI->BB->pred_begin(), + E = NextBBI->BB->pred_end(); PI != E; ++PI) { + MachineBasicBlock *PBB = *PI; + if (PBB == BBI.BB) + continue; + BBInfo &PBBI = BBAnalysis[PBB->getNumber()]; + PBBI.Kind = ICReAnalyze; + } + } + std::swap(CvtBBI, NextBBI); + TII->ReverseBranchCondition(Cond); + } // Predicate the 'true' block after removing its branch. - TrueBBI.NonPredSize -= TII->RemoveBranch(*BBI.TrueBB); - PredicateBlock(TrueBBI, BBI.BrCond); + TrueBBI.NonPredSize -= TII->RemoveBranch(*CvtBBI->BB); + PredicateBlock(*CvtBBI, Cond); // If 'true' block has a 'false' successor, add an exit branch to it. - bool HasEarlyExit = TrueBBI.FalseBB != NULL; + bool HasEarlyExit = CvtBBI->FalseBB != NULL; if (HasEarlyExit) { - std::vector<MachineOperand> RevCond(TrueBBI.BrCond); + std::vector<MachineOperand> RevCond(CvtBBI->BrCond); if (TII->ReverseBranchCondition(RevCond)) assert(false && "Unable to reverse branch condition!"); - TII->InsertBranch(*BBI.TrueBB, TrueBBI.FalseBB, NULL, RevCond); + TII->InsertBranch(*CvtBBI->BB, CvtBBI->FalseBB, NULL, RevCond); } // Now merge the entry of the triangle with the true block. BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); - MergeBlocks(BBI, TrueBBI); + MergeBlocks(BBI, *CvtBBI); // Merge in the 'false' block if the 'false' block has no other // predecessors. Otherwise, add a unconditional branch from to 'false'. - BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()]; bool FalseBBDead = false; bool IterIfcvt = true; - bool isFallThrough = canFallThroughTo(BBI.BB, FalseBBI.BB); + bool isFallThrough = canFallThroughTo(BBI.BB, NextBBI->BB); if (!isFallThrough) { // Only merge them if the true block does not fallthrough to the false // block. By not merging them, we make it possible to iteratively // ifcvt the blocks. - if (!HasEarlyExit && FalseBBI.BB->pred_size() == 1) { - MergeBlocks(BBI, FalseBBI); + if (!HasEarlyExit && NextBBI->BB->pred_size() == 1) { + MergeBlocks(BBI, *NextBBI); FalseBBDead = true; } else { - InsertUncondBranch(BBI.BB, FalseBBI.BB, TII); - TrueBBI.hasFallThrough = false; + InsertUncondBranch(BBI.BB, NextBBI->BB, TII); + BBI.HasFallThrough = false; } // Mixed predicated and unpredicated code. This cannot be iteratively // predicated. @@ -705,9 +755,9 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI) { else BBI.Kind = ICDead; ReTryPreds(BBI.BB); - TrueBBI.Kind = ICDead; + CvtBBI->Kind = ICDead; if (FalseBBDead) - FalseBBI.Kind = ICDead; + NextBBI->Kind = ICDead; // FIXME: Must maintain LiveIns. return true; @@ -797,7 +847,7 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI) { // or branch is fine. if (!canFallThroughTo(BBI.BB, *BBI2->BB->succ_begin())) { InsertUncondBranch(BBI2->BB, *BBI2->BB->succ_begin(), TII); - BBI2->hasFallThrough = false; + BBI2->HasFallThrough = false; } } @@ -815,7 +865,7 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI) { // branch to the 'false' block. if (NeedBr1 && !canFallThroughTo(BBI.BB, BBI2->BB)) { InsertUncondBranch(BBI.BB, BBI2->BB, TII); - BBI1->hasFallThrough = false; + BBI1->HasFallThrough = false; } // If the if-converted block fallthrough or unconditionally branch into the @@ -883,7 +933,7 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) { std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(), FromBBI.BB->succ_end()); MachineBasicBlock *NBB = getNextBlock(FromBBI.BB); - MachineBasicBlock *FallThrough = FromBBI.hasFallThrough ? NBB : NULL; + MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL; for (unsigned i = 0, e = Succs.size(); i != e; ++i) { MachineBasicBlock *Succ = Succs[i]; @@ -903,7 +953,7 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) { FromBBI.NonPredSize = 0; ToBBI.ModifyPredicate |= FromBBI.ModifyPredicate; - ToBBI.hasFallThrough = FromBBI.hasFallThrough; + ToBBI.HasFallThrough = FromBBI.HasFallThrough; std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(), std::back_inserter(ToBBI.Predicate)); |