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Revert "CodeGen: If Convert blocks that would form a diamond when tail-merged."

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This reverts commit r278287.

This commit broke the clang-cmake-thumbv7-a15-full-sh bot.
See https://llvm.org/bugs/show_bug.cgi?id=28949

llvm-svn: 278621
This commit is contained in:
Diana Picus 2016-08-14 02:10:18 +00:00
parent 2f3bd961bd
commit 0c45f41a02
3 changed files with 69 additions and 430 deletions
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416
lib/CodeGen/IfConversion.cpp
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@ -15,7 +15,6 @@
#include "llvm/CodeGen/Passes.h"
#include "BranchFolding.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/LivePhysRegs.h"
@ -59,8 +58,6 @@ static cl::opt<bool> DisableTriangleFR("disable-ifcvt-triangle-false-rev",
cl::init(false), cl::Hidden);
static cl::opt<bool> DisableDiamond("disable-ifcvt-diamond",
cl::init(false), cl::Hidden);
static cl::opt<bool> DisableForkedDiamond("disable-ifcvt-forked-diamond",
cl::init(false), cl::Hidden);
static cl::opt<bool> IfCvtBranchFold("ifcvt-branch-fold",
cl::init(true), cl::Hidden);
@ -71,7 +68,6 @@ STATISTIC(NumTriangleRev, "Number of triangle (R) 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(NumForkedDiamonds, "Number of forked-diamond if-conversions performed");
STATISTIC(NumIfConvBBs, "Number of if-converted blocks");
STATISTIC(NumDupBBs, "Number of duplicated blocks");
STATISTIC(NumUnpred, "Number of true blocks of diamonds unpredicated");
@ -86,9 +82,7 @@ namespace {
ICTriangleRev, // Same as ICTriangle, but true path rev condition.
ICTriangleFalse, // Same as ICTriangle, but on the false path.
ICTriangle, // BB is entry of a triangle sub-CFG.
ICDiamond, // BB is entry of a diamond sub-CFG.
ICForkedDiamond // BB is entry of an almost diamond sub-CFG, with a
// common tail that can be shared.
ICDiamond // BB is entry of a diamond sub-CFG.
};
/// BBInfo - One per MachineBasicBlock, this is used to cache the result
@ -120,7 +114,6 @@ namespace {
bool IsAnalyzed : 1;
bool IsEnqueued : 1;
bool IsBrAnalyzable : 1;
bool IsBrReversible : 1;
bool HasFallThrough : 1;
bool IsUnpredicable : 1;
bool CannotBeCopied : 1;
@ -135,10 +128,9 @@ namespace {
SmallVector<MachineOperand, 4> Predicate;
BBInfo() : IsDone(false), IsBeingAnalyzed(false),
IsAnalyzed(false), IsEnqueued(false), IsBrAnalyzable(false),
IsBrReversible(false), HasFallThrough(false),
IsUnpredicable(false), CannotBeCopied(false),
ClobbersPred(false), NonPredSize(0), ExtraCost(0),
ExtraCost2(0), BB(nullptr), TrueBB(nullptr),
HasFallThrough(false), IsUnpredicable(false),
CannotBeCopied(false), ClobbersPred(false), NonPredSize(0),
ExtraCost(0), ExtraCost2(0), BB(nullptr), TrueBB(nullptr),
FalseBB(nullptr) {}
};
@ -156,15 +148,11 @@ namespace {
struct IfcvtToken {
BBInfo &BBI;
IfcvtKind Kind;
bool NeedSubsumption;
unsigned NumDups;
unsigned NumDups2;
bool NeedSubsumption : 1;
bool TClobbersPred : 1;
bool FClobbersPred : 1;
IfcvtToken(BBInfo &b, IfcvtKind k, bool s, unsigned d, unsigned d2 = 0,
bool tc = false, bool fc = false)
: BBI(b), Kind(k), NumDups(d), NumDups2(d2), NeedSubsumption(s),
TClobbersPred(tc), FClobbersPred(fc) {}
IfcvtToken(BBInfo &b, IfcvtKind k, bool s, unsigned d, unsigned d2 = 0)
: BBI(b), Kind(k), NeedSubsumption(s), NumDups(d), NumDups2(d2) {}
};
/// BBAnalysis - Results of if-conversion feasibility analysis indexed by
@ -214,40 +202,23 @@ namespace {
bool FalseBranch, unsigned &Dups,
BranchProbability Prediction) const;
bool ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
unsigned &Dups1, unsigned &Dups2,
BBInfo &TrueBBICalc, BBInfo &FalseBBICalc) const;
bool ValidForkedDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
unsigned &Dups1, unsigned &Dups2,
BBInfo &TrueBBICalc, BBInfo &FalseBBICalc) const;
unsigned &Dups1, unsigned &Dups2) const;
void AnalyzeBranches(BBInfo &BBI);
void ScanInstructions(BBInfo &BBI,
MachineBasicBlock::iterator &Begin,
MachineBasicBlock::iterator &End) const;
bool RescanInstructions(
MachineBasicBlock::iterator &TIB, MachineBasicBlock::iterator &FIB,
MachineBasicBlock::iterator &TIE, MachineBasicBlock::iterator &FIE,
BBInfo &TrueBBI, BBInfo &FalseBBI) const;
void AnalyzeBlock(MachineBasicBlock *MBB,
std::vector<std::unique_ptr<IfcvtToken>> &Tokens);
bool FeasibilityAnalysis(BBInfo &BBI, SmallVectorImpl<MachineOperand> &Cond,
bool isTriangle = false, bool RevBranch = false,
bool hasCommonTail = false);
bool isTriangle = false, bool RevBranch = false);
void AnalyzeBlocks(MachineFunction &MF,
std::vector<std::unique_ptr<IfcvtToken>> &Tokens);
void InvalidatePreds(MachineBasicBlock *BB);
void RemoveExtraEdges(BBInfo &BBI);
bool IfConvertSimple(BBInfo &BBI, IfcvtKind Kind);
bool IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind);
bool IfConvertDiamondCommon(BBInfo &BBI, BBInfo &TrueBBI, BBInfo &FalseBBI,
unsigned NumDups1, unsigned NumDups2,
bool TClobbersPred, bool FClobbersPred,
bool RemoveTrueBranch, bool RemoveFalseBranch,
bool MergeAddEdges);
bool IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
unsigned NumDups1, unsigned NumDups2);
bool IfConvertForkedDiamond(BBInfo &BBI, IfcvtKind Kind,
unsigned NumDups1, unsigned NumDups2,
bool TClobbers, bool FClobbers);
void PredicateBlock(BBInfo &BBI,
MachineBasicBlock::iterator E,
SmallVectorImpl<MachineOperand> &Cond,
@ -439,19 +410,6 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
if (RetVal) ++NumDiamonds;
break;
}
case ICForkedDiamond: {
if (DisableForkedDiamond) break;
DEBUG(dbgs() << "Ifcvt (Forked Diamond): BB#"
<< BBI.BB->getNumber() << " (T:"
<< BBI.TrueBB->getNumber() << ",F:"
<< BBI.FalseBB->getNumber() << ") ");
RetVal = IfConvertForkedDiamond(BBI, Kind, NumDups, NumDups2,
Token->TClobbersPred,
Token->FClobbersPred);
DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
if (RetVal) ++NumForkedDiamonds;
break;
}
}
Change |= RetVal;
@ -653,13 +611,6 @@ static void countDuplicatedInstructions(
return;
--TIE;
--FIE;
// Upon exit TIE and FIE will both point at the last non-shared instruction,
// they need to be moved forward to point past the last non-shared
// instruction.
auto IncrementEndIteratorsOnExit = make_scope_exit([&]() {
++TIE; ++FIE;
});
if (!TBB.succ_empty() || !FBB.succ_empty()) {
if (SkipConditionalBranches) {
while (TIE != TIB && TIE->isBranch())
@ -697,125 +648,10 @@ static void countDuplicatedInstructions(
}
}
/// RescanInstructions - Run ScanInstructions on a pair of blocks.
/// @param TIB - True Iterator Begin, points to first non-shared instruction
/// @param FIB - False Iterator Begin, points to first non-shared instruction
/// @param TIE - True Iterator End, points past last non-shared instruction
/// @param FIE - False Iterator End, points past last non-shared instruction
/// @param TrueBBI - BBInfo to update for the true block.
/// @param FalseBBI - BBInfo to update for the false block.
/// @returns - false if either block cannot be predicated or if both blocks end
/// with a predicate-clobbering instruction.
bool IfConverter::RescanInstructions(
MachineBasicBlock::iterator &TIB, MachineBasicBlock::iterator &FIB,
MachineBasicBlock::iterator &TIE, MachineBasicBlock::iterator &FIE,
BBInfo &TrueBBI, BBInfo &FalseBBI) const {
ScanInstructions(TrueBBI, TIB, TIE);
if (TrueBBI.IsUnpredicable)
return false;
ScanInstructions(FalseBBI, FIB, FIE);
if (FalseBBI.IsUnpredicable)
return false;
if (TrueBBI.ClobbersPred && FalseBBI.ClobbersPred)
return false;
return true;
}
/// ValidForkedDiamond - Returns true if the 'true' and 'false' blocks (along
/// with their common predecessor) form a diamond if a common tail block is
/// extracted.
/// While not strictly a diamond, this pattern would form a diamond if
/// tail-merging had merged the shared tails.
/// EBB
/// _/ \_
/// | |
/// TBB FBB
/// / \ / \
/// FalseBB TrueBB FalseBB
/// Currently only handles analyzable branches.
/// Specifically excludes actual diamonds to avoid overlap.
bool IfConverter::ValidForkedDiamond(
BBInfo &TrueBBI, BBInfo &FalseBBI,
unsigned &Dups1, unsigned &Dups2,
BBInfo &TrueBBICalc, BBInfo &FalseBBICalc) const {
Dups1 = Dups2 = 0;
if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone ||
FalseBBI.IsBeingAnalyzed || FalseBBI.IsDone)
return false;
if (!TrueBBI.IsBrAnalyzable || !FalseBBI.IsBrAnalyzable)
return false;
// Don't IfConvert blocks that can't be folded into their predecessor.
if (TrueBBI.BB->pred_size() > 1 || FalseBBI.BB->pred_size() > 1)
return false;
// This function is specifically looking for conditional tails, as
// unconditional tails are already handled by the standard diamond case.
if (TrueBBI.BrCond.size() == 0 ||
FalseBBI.BrCond.size() == 0)
return false;
MachineBasicBlock *TT = TrueBBI.TrueBB;
MachineBasicBlock *TF = TrueBBI.FalseBB;
MachineBasicBlock *FT = FalseBBI.TrueBB;
MachineBasicBlock *FF = FalseBBI.FalseBB;
if (!TT)
TT = getNextBlock(TrueBBI.BB);
if (!TF)
TF = getNextBlock(TrueBBI.BB);
if (!FT)
FT = getNextBlock(FalseBBI.BB);
if (!FF)
FF = getNextBlock(FalseBBI.BB);
if (!TT || !TF)
return false;
// Check successors. If they don't match, bail.
if (!((TT == FT && TF == FF) || (TF == FT && TT == FF)))
return false;
bool FalseReversed = false;
if (TF == FT && TT == FF) {
// If the branches are opposing, but we can't reverse, don't do it.
if (!FalseBBI.IsBrReversible)
return false;
FalseReversed = true;
ReverseBranchCondition(FalseBBI);
}
auto UnReverseOnExit = make_scope_exit([&]() {
if (FalseReversed)
ReverseBranchCondition(FalseBBI);
});
// Count duplicate instructions at the beginning of the true and false blocks.
MachineBasicBlock::iterator TIB = TrueBBI.BB->begin();
MachineBasicBlock::iterator FIB = FalseBBI.BB->begin();
MachineBasicBlock::iterator TIE = TrueBBI.BB->end();
MachineBasicBlock::iterator FIE = FalseBBI.BB->end();
countDuplicatedInstructions(TIB, FIB, TIE, FIE, Dups1, Dups2,
*TrueBBI.BB, *FalseBBI.BB,
/* SkipConditionalBranches */ false);
TrueBBICalc.BB = TrueBBI.BB;
FalseBBICalc.BB = FalseBBI.BB;
if (!RescanInstructions(TIB, FIB, TIE, FIE, TrueBBICalc, FalseBBICalc))
return false;
// The size is used to decide whether to if-convert, and the shared portions
// are subtracted off. Because of the subtraction, we just use the size that
// was calculated by the original ScanInstructions, as it is correct.
TrueBBICalc.NonPredSize = TrueBBI.NonPredSize;
FalseBBICalc.NonPredSize = FalseBBI.NonPredSize;
return true;
}
/// 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,
unsigned &Dups1, unsigned &Dups2,
BBInfo &TrueBBICalc, BBInfo &FalseBBICalc) const {
bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
unsigned &Dups1, unsigned &Dups2) const {
Dups1 = Dups2 = 0;
if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone ||
FalseBBI.IsBeingAnalyzed || FalseBBI.IsDone)
@ -836,7 +672,8 @@ bool IfConverter::ValidDiamond(
return false;
// FIXME: Allow true block to have an early exit?
if (TrueBBI.FalseBB || FalseBBI.FalseBB)
if (TrueBBI.FalseBB || FalseBBI.FalseBB ||
(TrueBBI.ClobbersPred && FalseBBI.ClobbersPred))
return false;
// Count duplicate instructions at the beginning and end of the true and
@ -848,16 +685,6 @@ bool IfConverter::ValidDiamond(
countDuplicatedInstructions(TIB, FIB, TIE, FIE, Dups1, Dups2,
*TrueBBI.BB, *FalseBBI.BB,
/* SkipConditionalBranches */ true);
TrueBBICalc.BB = TrueBBI.BB;
FalseBBICalc.BB = FalseBBI.BB;
if (!RescanInstructions(TIB, FIB, TIE, FIE, TrueBBICalc, FalseBBICalc))
return false;
// The size is used to decide whether to if-convert, and the shared portions
// are subtracted off. Because of the subtraction, we just use the size that
// was calculated by the original ScanInstructions, as it is correct.
TrueBBICalc.NonPredSize = TrueBBI.NonPredSize;
FalseBBICalc.NonPredSize = FalseBBI.NonPredSize;
return true;
}
@ -871,9 +698,6 @@ void IfConverter::AnalyzeBranches(BBInfo &BBI) {
BBI.BrCond.clear();
BBI.IsBrAnalyzable =
!TII->analyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond);
SmallVector<MachineOperand, 4> RevCond(BBI.BrCond.begin(), BBI.BrCond.end());
BBI.IsBrReversible = (RevCond.size() == 0) ||
!TII->ReverseBranchCondition(RevCond);
BBI.HasFallThrough = BBI.IsBrAnalyzable && BBI.FalseBB == nullptr;
if (BBI.BrCond.size()) {
@ -989,22 +813,11 @@ void IfConverter::ScanInstructions(BBInfo &BBI,
/// FeasibilityAnalysis - Determine if the block is a suitable candidate to be
/// predicated by the specified predicate.
/// @param BBI BBInfo for the block to check
/// @param Pred Predicate array for the branch that leads to BBI
/// @param isTriangle true if the Analysis is for a triangle
/// @param RevBranch true if Reverse(Pred) leads to BBI (e.g. BBI is the false
/// case
/// @param hasCommonTail true if BBI shares a tail with a sibling block that
/// contains any instruction that would make the block unpredicable.
bool IfConverter::FeasibilityAnalysis(BBInfo &BBI,
SmallVectorImpl<MachineOperand> &Pred,
bool isTriangle, bool RevBranch,
bool hasCommonTail) {
bool isTriangle, bool RevBranch) {
// If the block is dead or unpredicable, then it cannot be predicated.
// Two blocks may share a common unpredicable tail, but this doesn't prevent
// them from being if-converted. The non-shared portion is assumed to have
// been checked
if (BBI.IsDone || (BBI.IsUnpredicable && !hasCommonTail))
if (BBI.IsDone || BBI.IsUnpredicable)
return false;
// If it is already predicated but we couldn't analyze its terminator, the
@ -1018,7 +831,7 @@ bool IfConverter::FeasibilityAnalysis(BBInfo &BBI,
if (BBI.Predicate.size() && !TII->SubsumesPredicate(Pred, BBI.Predicate))
return false;
if (!hasCommonTail && BBI.BrCond.size()) {
if (BBI.BrCond.size()) {
if (!isTriangle)
return false;
@ -1126,58 +939,25 @@ void IfConverter::AnalyzeBlock(
BranchProbability Prediction = MBPI->getEdgeProbability(BB, TrueBBI.BB);
if (CanRevCond) {
BBInfo TrueBBICalc, FalseBBICalc;
auto feasibleDiamond = [&]() {
return (
MeetIfcvtSizeLimit(
*TrueBBI.BB, (TrueBBICalc.NonPredSize - (Dups + Dups2) +
TrueBBICalc.ExtraCost), TrueBBICalc.ExtraCost2,
*FalseBBI.BB, (FalseBBICalc.NonPredSize - (Dups + Dups2) +
FalseBBICalc.ExtraCost), FalseBBICalc.ExtraCost2,
Prediction) &&
FeasibilityAnalysis(TrueBBI, BBI.BrCond,
/* IsTriangle */ false, /* RevCond */ false,
/* hasCommonTail */ true) &&
FeasibilityAnalysis(FalseBBI, RevCond,
/* IsTriangle */ false, /* RevCond */ false,
/* hasCommonTail */ true));
};
if (ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2,
TrueBBICalc, FalseBBICalc)) {
if (feasibleDiamond()) {
// Diamond:
// EBB
// / \_
// | |
// TBB FBB
// \ /
// TailBB
// Note TailBB can be empty.
Tokens.push_back(llvm::make_unique<IfcvtToken>(
BBI, ICDiamond, TNeedSub | FNeedSub, Dups, Dups2));
Enqueued = true;
}
} else if (ValidForkedDiamond(TrueBBI, FalseBBI, Dups, Dups2,
TrueBBICalc, FalseBBICalc)) {
if (feasibleDiamond()) {
// ForkedDiamond:
// if TBB and FBB have a common tail that includes their conditional
// branch instructions, then we can If Convert this pattern.
// EBB
// _/ \_
// | |
// TBB FBB
// / \ / \
// FalseBB TrueBB FalseBB
//
Tokens.push_back(llvm::make_unique<IfcvtToken>(
BBI, ICForkedDiamond, TNeedSub | FNeedSub, Dups, Dups2,
(bool) TrueBBICalc.ClobbersPred, (bool) FalseBBICalc.ClobbersPred));
Enqueued = true;
}
}
if (CanRevCond && ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2) &&
MeetIfcvtSizeLimit(*TrueBBI.BB, (TrueBBI.NonPredSize - (Dups + Dups2) +
TrueBBI.ExtraCost), TrueBBI.ExtraCost2,
*FalseBBI.BB, (FalseBBI.NonPredSize - (Dups + Dups2) +
FalseBBI.ExtraCost),FalseBBI.ExtraCost2,
Prediction) &&
FeasibilityAnalysis(TrueBBI, BBI.BrCond) &&
FeasibilityAnalysis(FalseBBI, RevCond)) {
// Diamond:
// EBB
// / \_
// | |
// TBB FBB
// \ /
// TailBB
// Note TailBB can be empty.
Tokens.push_back(llvm::make_unique<IfcvtToken>(
BBI, ICDiamond, TNeedSub | FNeedSub, Dups, Dups2));
Enqueued = true;
}
if (ValidTriangle(TrueBBI, FalseBBI, false, Dups, Prediction) &&
@ -1629,26 +1409,23 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
return true;
}
/// IfConvertDiamondCommon - Common code shared between diamond conversions.
/// BBI, TrueBBI, and FalseBBI form the diamond shape.
/// NumDups1 - number of shared instructions at the beginning of TrueBBI and
/// FalseBBI
/// NumDups2 - number of shared instructions at the end of TrueBBI and FalseBBI
/// RemoveTrueBranch - Remove the branch of the true block before predicating
/// Only false for unanalyzable fallthrough cases.
/// RemoveFalseBranch - Remove the branch of the false block before predicating
/// Only false for unanalyzable fallthrough cases.
/// MergeAddEdges - Add successor edges when merging blocks. Only false for
/// unanalyzable fallthrough
bool IfConverter::IfConvertDiamondCommon(
BBInfo &BBI, BBInfo &TrueBBI, BBInfo &FalseBBI,
unsigned NumDups1, unsigned NumDups2,
bool TClobbersPred, bool FClobbersPred,
bool RemoveTrueBranch, bool RemoveFalseBranch,
bool MergeAddEdges) {
/// IfConvertDiamond - If convert a diamond sub-CFG.
///
bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
unsigned NumDups1, unsigned NumDups2) {
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
MachineBasicBlock *TailBB = TrueBBI.TrueBB;
// True block must fall through or end with an unanalyzable terminator.
if (!TailBB) {
if (blockAlwaysFallThrough(TrueBBI))
TailBB = FalseBBI.TrueBB;
assert((TailBB || !TrueBBI.IsBrAnalyzable) && "Unexpected!");
}
if (TrueBBI.IsDone || FalseBBI.IsDone ||
TrueBBI.BB->pred_size() > 1 || FalseBBI.BB->pred_size() > 1) {
TrueBBI.BB->pred_size() > 1 ||
FalseBBI.BB->pred_size() > 1) {
// Something has changed. It's no longer safe to predicate these blocks.
BBI.IsAnalyzed = false;
TrueBBI.IsAnalyzed = false;
@ -1673,16 +1450,15 @@ bool IfConverter::IfConvertDiamondCommon(
// Figure out the more profitable ordering.
bool DoSwap = false;
if (TClobbersPred && !FClobbersPred)
if (TrueBBI.ClobbersPred && !FalseBBI.ClobbersPred)
DoSwap = true;
else if (TClobbersPred == FClobbersPred) {
else if (TrueBBI.ClobbersPred == FalseBBI.ClobbersPred) {
if (TrueBBI.NonPredSize > FalseBBI.NonPredSize)
DoSwap = true;
}
if (DoSwap) {
std::swap(BBI1, BBI2);
std::swap(Cond1, Cond2);
std::swap(RemoveTrueBranch, RemoveFalseBranch);
}
// Remove the conditional branch from entry to the blocks.
@ -1734,7 +1510,11 @@ bool IfConverter::IfConvertDiamondCommon(
BBI.BB->splice(BBI.BB->end(), BBI1->BB, BBI1->BB->begin(), DI1);
BBI2->BB->erase(BBI2->BB->begin(), DI2);
if (RemoveTrueBranch)
// Remove branch from the 'true' block, unless it was not analyzable.
// Non-analyzable branches need to be preserved, since in such cases,
// the CFG structure is not an actual diamond (the join block may not
// be present).
if (BBI1->IsBrAnalyzable)
BBI1->NonPredSize -= TII->RemoveBranch(*BBI1->BB);
// Remove duplicated instructions.
DI1 = BBI1->BB->end();
@ -1753,9 +1533,9 @@ bool IfConverter::IfConvertDiamondCommon(
// must be removed.
RemoveKills(BBI1->BB->begin(), BBI1->BB->end(), DontKill, *TRI);
// Remove 'false' block branch, and find the last instruction to predicate.
// Save the debug location.
if (RemoveFalseBranch)
// Remove 'false' block branch (unless it was not analyzable), and find
// the last instruction to predicate.
if (BBI2->IsBrAnalyzable)
BBI2->NonPredSize -= TII->RemoveBranch(*BBI2->BB);
DI2 = BBI2->BB->end();
while (NumDups2 != 0) {
@ -1831,74 +1611,8 @@ bool IfConverter::IfConvertDiamondCommon(
PredicateBlock(*BBI2, DI2, *Cond2);
// Merge the true block into the entry of the diamond.
MergeBlocks(BBI, *BBI1, MergeAddEdges);
MergeBlocks(BBI, *BBI2, MergeAddEdges);
return true;
}
/// IfConvertForkedDiamond - If convert an almost-diamond sub-CFG where the true
/// and false blocks share a common tail.
bool IfConverter::IfConvertForkedDiamond(
BBInfo &BBI, IfcvtKind Kind,
unsigned NumDups1, unsigned NumDups2,
bool TClobbersPred, bool FClobbersPred) {
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
// Save the debug location for later.
DebugLoc dl;
MachineBasicBlock::iterator TIE = TrueBBI.BB->getFirstTerminator();
if (TIE != TrueBBI.BB->end())
dl = TIE->getDebugLoc();
// Removing branches from both blocks is safe, because we have already
// determined that both blocks have the same branch instructions. The branch
// will be added back at the end, unpredicated.
if (!IfConvertDiamondCommon(
BBI, TrueBBI, FalseBBI,
NumDups1, NumDups2,
TClobbersPred, FClobbersPred,
/* RemoveTrueBranch */ true, /* RemoveFalseBranch */ true,
/* MergeAddEdges */ true))
return false;
// Add back the branch.
// Debug location saved above when removing the branch from BBI2
TII->InsertBranch(*BBI.BB, TrueBBI.TrueBB, TrueBBI.FalseBB,
TrueBBI.BrCond, dl);
RemoveExtraEdges(BBI);
// Update block info.
BBI.IsDone = TrueBBI.IsDone = FalseBBI.IsDone = true;
InvalidatePreds(BBI.BB);
// FIXME: Must maintain LiveIns.
return true;
}
/// IfConvertDiamond - If convert a diamond sub-CFG.
///
bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
unsigned NumDups1, unsigned NumDups2) {
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
MachineBasicBlock *TailBB = TrueBBI.TrueBB;
// True block must fall through or end with an unanalyzable terminator.
if (!TailBB) {
if (blockAlwaysFallThrough(TrueBBI))
TailBB = FalseBBI.TrueBB;
assert((TailBB || !TrueBBI.IsBrAnalyzable) && "Unexpected!");
}
if (!IfConvertDiamondCommon(
BBI, TrueBBI, FalseBBI,
NumDups1, NumDups2,
TrueBBI.ClobbersPred, FalseBBI.ClobbersPred,
/* RemoveTrueBranch */ TrueBBI.IsBrAnalyzable,
/* RemoveFalseBranch */ FalseBBI.IsBrAnalyzable,
/* MergeAddEdges */ TailBB == nullptr))
return false;
MergeBlocks(BBI, *BBI1, TailBB == nullptr);
MergeBlocks(BBI, *BBI2, TailBB == nullptr);
// If the if-converted block falls through or unconditionally branches into
// the tail block, and the tail block does not have other predecessors, then
@ -1921,7 +1635,7 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
CanMergeTail = false;
else if (NumPreds == 1 && CanMergeTail) {
MachineBasicBlock::pred_iterator PI = TailBB->pred_begin();
if (*PI != TrueBBI.BB && *PI != FalseBBI.BB)
if (*PI != BBI1->BB && *PI != BBI2->BB)
CanMergeTail = false;
}
if (CanMergeTail) {
@ -1937,8 +1651,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
// RemoveExtraEdges won't work if the block has an unanalyzable branch,
// which can happen here if TailBB is unanalyzable and is merged, so
// explicitly remove BBI1 and BBI2 as successors.
BBI.BB->removeSuccessor(TrueBBI.BB);
BBI.BB->removeSuccessor(FalseBBI.BB, /* NormalizeSuccessProbs */ true);
BBI.BB->removeSuccessor(BBI1->BB);
BBI.BB->removeSuccessor(BBI2->BB, true);
RemoveExtraEdges(BBI);
// Update block info.

36
test/CodeGen/PowerPC/ifcvt-forked-bug-2016-08-08.ll
View File

@ -1,36 +0,0 @@
; ModuleID = 'bugpoint-reduced-instructions.bc'
; RUN: llc -O2 -o - %s | FileCheck %s
source_filename = "bugpoint-output-9ad75f8.bc"
target datalayout = "e-m:e-i64:64-n32:64"
target triple = "powerpc64le-unknown-linux-gnu"
; Function Attrs: nounwind uwtable
define hidden void @_ZN11__sanitizer25MaybeStartBackgroudThreadEv() local_unnamed_addr #0 {
entry:
br i1 undef, label %land.lhs.true, label %if.end
; CHECK: # %land.lhs.true
; CHECK-NEXT: bclr
; CHECK-NEXT: # %if.end4
land.lhs.true: ; preds = %entry
br i1 undef, label %return, label %if.end4
if.end: ; preds = %entry
br i1 icmp ne (i32 (i8*, i8*, i8* (i8*)*, i8*)* @_ZN11__sanitizer19real_pthread_createEPvS0_PFS0_S0_ES0_, i32 (i8*, i8*, i8* (i8*)*, i8*)* null), label %if.end4, label %return
if.end4: ; preds = %if.end, %land.lhs.true
%call5 = tail call i8* @_ZN11__sanitizer21internal_start_threadEPFvPvES0_(void (i8*)* nonnull @_ZN11__sanitizer16BackgroundThreadEPv, i8* null) #7
unreachable
return: ; preds = %if.end, %land.lhs.true
ret void
}
declare extern_weak signext i32 @_ZN11__sanitizer19real_pthread_createEPvS0_PFS0_S0_ES0_(i8*, i8*, i8* (i8*)*, i8*) #2
declare i8* @_ZN11__sanitizer21internal_start_threadEPFvPvES0_(void (i8*)*, i8*) local_unnamed_addr #2
declare hidden void @_ZN11__sanitizer16BackgroundThreadEPv(i8* nocapture readnone) #5
attributes #0 = { nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="ppc64le" "target-features"="+altivec,+bpermd,+crypto,+direct-move,+extdiv,+power8-vector,+vsx,-qpx" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #7 = { nobuiltin nounwind }

47
test/CodeGen/Thumb2/thumb2-ifcvt1.ll
View File

@ -1,7 +1,6 @@
; RUN: llc < %s -mtriple=thumbv7-apple-darwin | FileCheck %s
; RUN: llc < %s -mtriple=thumbv7-apple-darwin -arm-default-it | FileCheck %s
; RUN: llc < %s -mtriple=thumbv8 -arm-no-restrict-it | FileCheck %s
; RUN: llc < %s -mtriple=thumbv8 -arm-no-restrict-it -enable-tail-merge=0 | FileCheck %s
; RUN: llc < %s -mtriple=thumbv8 -arm-no-restrict-it |FileCheck %s
define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
; CHECK-LABEL: t1:
; CHECK: ittt ne
@ -26,9 +25,9 @@ cond_next:
define i32 @t2(i32 %a, i32 %b) nounwind {
entry:
; CHECK-LABEL: t2:
; CHECK: ite {{gt|le}}
; CHECK-DAG: suble
; CHECK-DAG: subgt
; CHECK: ite gt
; CHECK: subgt
; CHECK: suble
%tmp1434 = icmp eq i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp1434, label %bb17, label %bb.outer
@ -61,44 +60,6 @@ bb17: ; preds = %cond_false, %cond_true, %entry
ret i32 %a_addr.026.1
}
define i32 @t2_nomerge(i32 %a, i32 %b) nounwind {
entry:
; CHECK-LABEL: t2_nomerge:
; CHECK-NOT: ite {{gt|le}}
; CHECK-NOT: suble
; CHECK-NOT: subgt
%tmp1434 = icmp eq i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp1434, label %bb17, label %bb.outer
bb.outer: ; preds = %cond_false, %entry
%b_addr.021.0.ph = phi i32 [ %b, %entry ], [ %tmp10, %cond_false ] ; <i32> [#uses=5]
%a_addr.026.0.ph = phi i32 [ %a, %entry ], [ %a_addr.026.0, %cond_false ] ; <i32> [#uses=1]
br label %bb
bb: ; preds = %cond_true, %bb.outer
%indvar = phi i32 [ 0, %bb.outer ], [ %indvar.next, %cond_true ] ; <i32> [#uses=2]
%tmp. = sub i32 0, %b_addr.021.0.ph ; <i32> [#uses=1]
%tmp.40 = mul i32 %indvar, %tmp. ; <i32> [#uses=1]
%a_addr.026.0 = add i32 %tmp.40, %a_addr.026.0.ph ; <i32> [#uses=6]
%tmp3 = icmp sgt i32 %a_addr.026.0, %b_addr.021.0.ph ; <i1> [#uses=1]
br i1 %tmp3, label %cond_true, label %cond_false
cond_true: ; preds = %bb
%tmp7 = sub i32 %a_addr.026.0, %b_addr.021.0.ph ; <i32> [#uses=2]
%tmp1437 = icmp eq i32 %tmp7, %b_addr.021.0.ph ; <i1> [#uses=1]
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
br i1 %tmp1437, label %bb17, label %bb
cond_false: ; preds = %bb
%tmp10 = sub i32 %b_addr.021.0.ph, %a_addr.026.0 ; <i32> [#uses=2]
%tmp14 = icmp eq i32 %b_addr.021.0.ph, %tmp10 ; <i1> [#uses=1]
br i1 %tmp14, label %bb17, label %bb.outer
bb17: ; preds = %cond_false, %cond_true, %entry
%a_addr.026.1 = phi i32 [ %a, %entry ], [ %tmp7, %cond_true ], [ %a_addr.026.0, %cond_false ] ; <i32> [#uses=1]
ret i32 %a_addr.026.1
}
@x = external global i32* ; <i32**> [#uses=1]
define void @foo(i32 %a) nounwind {