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

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The following function currently relies on tail-merging for if
conversion to succeed. The common tail of cond_true and cond_false is
extracted, and this then forms a diamond pattern that can be
successfully if converted.

If this block does not get extracted, either because tail-merging is
disabled or the threshold is higher, we should still recognize this
pattern and if-convert it.

Fixed a regression in the original commit. Need to un-reverse branches after
reversing them, or other conversions go awry.

define i32 @t2(i32 %a, i32 %b) nounwind {
entry:
        %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 ]
        %a_addr.026.0.ph = phi i32 [ %a, %entry ], [ %a_addr.026.0, %cond_false ]
        br label %bb

bb:             ; preds = %cond_true, %bb.outer
        %indvar = phi i32 [ 0, %bb.outer ], [ %indvar.next, %cond_true ]
        %tmp. = sub i32 0, %b_addr.021.0.ph
        %tmp.40 = mul i32 %indvar, %tmp.
        %a_addr.026.0 = add i32 %tmp.40, %a_addr.026.0.ph
        %tmp3 = icmp sgt i32 %a_addr.026.0, %b_addr.021.0.ph
        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
        %tmp1437 = icmp eq i32 %tmp7, %b_addr.021.0.ph
        %indvar.next = add i32 %indvar, 1
        br i1 %tmp1437, label %bb17, label %bb

cond_false:             ; preds = %bb
        %tmp10 = sub i32 %b_addr.021.0.ph, %a_addr.026.0
        %tmp14 = icmp eq i32 %a_addr.026.0, %tmp10
        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 ]
        ret i32 %a_addr.026.1
}

Without tail-merging or diamond-tail if conversion:
LBB1_1:                                 @ %bb
                                        @ =>This Inner Loop Header: Depth=1
        cmp     r0, r1
        ble     LBB1_3
@ BB#2:                                 @ %cond_true
                                        @   in Loop: Header=BB1_1 Depth=1
        subs    r0, r0, r1
        cmp     r1, r0
        it      ne
        cmpne   r0, r1
        bgt     LBB1_4
LBB1_3:                                 @ %cond_false
                                        @   in Loop: Header=BB1_1 Depth=1
        subs    r1, r1, r0
        cmp     r1, r0
        bne     LBB1_1
LBB1_4:                                 @ %bb17
        bx      lr

With diamond-tail if conversion, but without tail-merging:
@ BB#0:                                 @ %entry
        cmp     r0, r1
        it      eq
        bxeq    lr
LBB1_1:                                 @ %bb
                                        @ =>This Inner Loop Header: Depth=1
        cmp     r0, r1
        ite     le
        suble   r1, r1, r0
        subgt   r0, r0, r1
        cmp     r1, r0
        bne     LBB1_1
@ BB#2:                                 @ %bb17
        bx      lr

llvm-svn: 279671
This commit is contained in:
Kyle Butt 2016-08-24 21:34:27 +00:00
parent 2a20a3f170
commit 3fc7c8cb26
3 changed files with 356 additions and 78 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

327
lib/CodeGen/IfConversion.cpp
View File

@ -59,6 +59,8 @@ 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);
@ -69,6 +71,7 @@ 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");
@ -83,7 +86,9 @@ 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.
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.
};
/// One per MachineBasicBlock, this is used to cache the result
@ -115,6 +120,7 @@ namespace {
bool IsAnalyzed : 1;
bool IsEnqueued : 1;
bool IsBrAnalyzable : 1;
bool IsBrReversible : 1;
bool HasFallThrough : 1;
bool IsUnpredicable : 1;
bool CannotBeCopied : 1;
@ -129,9 +135,10 @@ namespace {
SmallVector<MachineOperand, 4> Predicate;
BBInfo() : IsDone(false), IsBeingAnalyzed(false),
IsAnalyzed(false), IsEnqueued(false), IsBrAnalyzable(false),
HasFallThrough(false), IsUnpredicable(false),
CannotBeCopied(false), ClobbersPred(false), NonPredSize(0),
ExtraCost(0), ExtraCost2(0), BB(nullptr), TrueBB(nullptr),
IsBrReversible(false), HasFallThrough(false),
IsUnpredicable(false), CannotBeCopied(false),
ClobbersPred(false), NonPredSize(0), ExtraCost(0),
ExtraCost2(0), BB(nullptr), TrueBB(nullptr),
FalseBB(nullptr) {}
};
@ -215,6 +222,9 @@ namespace {
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;
void AnalyzeBranches(BBInfo &BBI);
void ScanInstructions(BBInfo &BBI,
MachineBasicBlock::iterator &Begin,
@ -235,9 +245,17 @@ namespace {
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 TClobbers, bool FClobbers);
bool IfConvertForkedDiamond(BBInfo &BBI, IfcvtKind Kind,
unsigned NumDups1, unsigned NumDups2,
bool TClobbers, bool FClobbers);
void PredicateBlock(BBInfo &BBI,
MachineBasicBlock::iterator E,
SmallVectorImpl<MachineOperand> &Cond,
@ -431,6 +449,19 @@ 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;
@ -646,9 +677,6 @@ bool IfConverter::CountDuplicatedInstructions(
++FIB;
}
// If both blocks are returning don't skip the branches, since they will
// likely be both identical return instructions. In such cases the return
// can be left unpredicated.
// Check for already containing all of the block.
if (TIB == TIE || FIB == FIE)
return true;
@ -732,6 +760,97 @@ bool IfConverter::RescanInstructions(
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();
if(!CountDuplicatedInstructions(TIB, FIB, TIE, FIE, Dups1, Dups2,
*TrueBBI.BB, *FalseBBI.BB,
/* SkipUnconditionalBranches */ true))
return 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(
@ -798,6 +917,9 @@ 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()) {
@ -1056,21 +1178,25 @@ void IfConverter::AnalyzeBlock(
if (CanRevCond) {
BBInfo TrueBBICalc, FalseBBICalc;
auto feasibleDiamond = [&]() {
bool MeetsSize = MeetIfcvtSizeLimit(
*TrueBBI.BB, (TrueBBICalc.NonPredSize - (Dups + Dups2) +
TrueBBICalc.ExtraCost), TrueBBICalc.ExtraCost2,
*FalseBBI.BB, (FalseBBICalc.NonPredSize - (Dups + Dups2) +
FalseBBICalc.ExtraCost), FalseBBICalc.ExtraCost2,
Prediction);
bool TrueFeasible = FeasibilityAnalysis(TrueBBI, BBI.BrCond,
/* IsTriangle */ false, /* RevCond */ false,
/* hasCommonTail */ true);
bool FalseFeasible = FeasibilityAnalysis(FalseBBI, RevCond,
/* IsTriangle */ false, /* RevCond */ false,
/* hasCommonTail */ true);
return MeetsSize && TrueFeasible && FalseFeasible;
};
if (ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2,
TrueBBICalc, FalseBBICalc) &&
MeetIfcvtSizeLimit(*TrueBBI.BB, (TrueBBI.NonPredSize - (Dups + Dups2) +
TrueBBICalc.ExtraCost),
TrueBBICalc.ExtraCost2,
*FalseBBI.BB, (FalseBBI.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)) {
TrueBBICalc, FalseBBICalc)) {
if (feasibleDiamond()) {
// Diamond:
// EBB
// / \_
@ -1081,10 +1207,28 @@ void IfConverter::AnalyzeBlock(
// Note TailBB can be empty.
Tokens.push_back(llvm::make_unique<IfcvtToken>(
BBI, ICDiamond, TNeedSub | FNeedSub, Dups, Dups2,
(bool) TrueBBICalc.ClobbersPred,
(bool) FalseBBICalc.ClobbersPred));
(bool) TrueBBICalc.ClobbersPred, (bool) FalseBBICalc.ClobbersPred));
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 (ValidTriangle(TrueBBI, FalseBBI, false, Dups, Prediction) &&
@ -1528,32 +1672,28 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
return true;
}
/// If convert a diamond sub-CFG.
/// \p BBI is the head of the diamond
/// \p NumDups1 - number of shared instructions at the beginning of TrueBBI and
/// FalseBBI
/// \p NumDups2 - number of shared instructions at the end of TrueBBI and
/// FalseBBI
/// \p TClobbersPred - True if the true block clobbers the predicate in the
/// non-shared portion.
/// \p TClobbersPred - True if the false block clobbers the predicate in the
/// non-shared portion.
bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
/// Common code shared between diamond conversions.
/// \p BBI, \p TrueBBI, and \p FalseBBI form the diamond shape.
/// \p NumDups1 - number of shared instructions at the beginning of \p TrueBBI
/// and FalseBBI
/// \p NumDups2 - number of shared instructions at the end of \p TrueBBI
/// and \p FalseBBI
/// \p RemoveTrueBranch - Remove the branch of the true block before predicating
/// Only false for unanalyzable fallthrough cases.
/// \p RemoveFalseBranch - Remove the branch of the false block before
/// predicating Only false for unanalyzable fallthrough
/// cases.
/// \p 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) {
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!");
}
bool TClobbersPred, bool FClobbersPred,
bool RemoveTrueBranch, bool RemoveFalseBranch,
bool MergeAddEdges) {
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;
@ -1587,6 +1727,7 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
if (DoSwap) {
std::swap(BBI1, BBI2);
std::swap(Cond1, Cond2);
std::swap(RemoveTrueBranch, RemoveFalseBranch);
}
// Remove the conditional branch from entry to the blocks.
@ -1639,12 +1780,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
BBI.BB->splice(BBI.BB->end(), &MBB1, MBB1.begin(), DI1);
MBB2.erase(MBB2.begin(), DI2);
// 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(MBB1);
if (RemoveTrueBranch)
BBI1->NonPredSize -= TII->RemoveBranch(*BBI1->BB);
// Remove duplicated instructions.
DI1 = MBB1.end();
for (unsigned i = 0; i != NumDups2; ) {
@ -1662,11 +1799,11 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
// must be removed.
RemoveKills(MBB1.begin(), MBB1.end(), DontKill, *TRI);
// Remove 'false' block branch (unless it was not analyzable), and find
// the last instruction to predicate.
if (BBI2->IsBrAnalyzable)
BBI2->NonPredSize -= TII->RemoveBranch(MBB2);
DI2 = MBB2.end();
// Remove 'false' block branch, and find the last instruction to predicate.
// Save the debug location.
if (RemoveFalseBranch)
BBI2->NonPredSize -= TII->RemoveBranch(*BBI2->BB);
DI2 = BBI2->BB->end();
while (NumDups2 != 0) {
// NumDups2 only counted non-dbg_value instructions, so this won't
// run off the head of the list.
@ -1738,8 +1875,74 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
PredicateBlock(*BBI2, DI2, *Cond2);
// Merge the true block into the entry of the diamond.
MergeBlocks(BBI, *BBI1, TailBB == nullptr);
MergeBlocks(BBI, *BBI2, TailBB == nullptr);
MergeBlocks(BBI, *BBI1, MergeAddEdges);
MergeBlocks(BBI, *BBI2, MergeAddEdges);
return true;
}
/// 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;
}
/// If convert a diamond sub-CFG.
bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
unsigned NumDups1, unsigned NumDups2,
bool TClobbersPred, bool FClobbersPred) {
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;
// If the if-converted block falls through or unconditionally branches into
// the tail block, and the tail block does not have other predecessors, then
@ -1762,7 +1965,7 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
CanMergeTail = false;
else if (NumPreds == 1 && CanMergeTail) {
MachineBasicBlock::pred_iterator PI = TailBB->pred_begin();
if (*PI != &MBB1 && *PI != &MBB2)
if (*PI != TrueBBI.BB && *PI != FalseBBI.BB)
CanMergeTail = false;
}
if (CanMergeTail) {
@ -1778,8 +1981,8 @@ 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(&MBB1);
BBI.BB->removeSuccessor(&MBB2, true);
BBI.BB->removeSuccessor(TrueBBI.BB);
BBI.BB->removeSuccessor(FalseBBI.BB, /* NormalizeSuccessProbs */ true);
RemoveExtraEdges(BBI);
// Update block info.

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

@ -0,0 +1,36 @@
; 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 }

45
test/CodeGen/Thumb2/thumb2-ifcvt1.ll
View File

@ -1,6 +1,7 @@
; 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
define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
; CHECK-LABEL: t1:
; CHECK: ittt ne
@ -25,9 +26,9 @@ cond_next:
define i32 @t2(i32 %a, i32 %b) nounwind {
entry:
; CHECK-LABEL: t2:
; CHECK: ite gt
; CHECK: subgt
; CHECK: suble
; CHECK: ite {{gt|le}}
; CHECK-DAG: suble
; CHECK-DAG: subgt
%tmp1434 = icmp eq i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp1434, label %bb17, label %bb.outer
@ -60,6 +61,44 @@ 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 {