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-rw-r--r--lib/CodeGen/IfConversion.cpp112
1 files changed, 65 insertions, 47 deletions
diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index a22ce0dab9c2..f12d00071b24 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -252,7 +252,7 @@ namespace {
BBInfo &TrueBBI, BBInfo &FalseBBI) const;
void AnalyzeBlock(MachineBasicBlock &MBB,
std::vector<std::unique_ptr<IfcvtToken>> &Tokens);
- bool FeasibilityAnalysis(BBInfo &BBI, SmallVectorImpl<MachineOperand> &Cond,
+ bool FeasibilityAnalysis(BBInfo &BBI, SmallVectorImpl<MachineOperand> &Pred,
bool isTriangle = false, bool RevBranch = false,
bool hasCommonTail = false);
void AnalyzeBlocks(MachineFunction &MF,
@@ -347,7 +347,7 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
BranchFolder::MBFIWrapper MBFI(getAnalysis<MachineBlockFrequencyInfo>());
MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
MRI = &MF.getRegInfo();
- SchedModel.init(ST.getSchedModel(), &ST, TII);
+ SchedModel.init(&ST);
if (!TII) return false;
@@ -361,14 +361,14 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
getAnalysisIfAvailable<MachineModuleInfo>());
}
- DEBUG(dbgs() << "\nIfcvt: function (" << ++FnNum << ") \'"
- << MF.getName() << "\'");
+ LLVM_DEBUG(dbgs() << "\nIfcvt: function (" << ++FnNum << ") \'"
+ << MF.getName() << "\'");
if (FnNum < IfCvtFnStart || (IfCvtFnStop != -1 && FnNum > IfCvtFnStop)) {
- DEBUG(dbgs() << " skipped\n");
+ LLVM_DEBUG(dbgs() << " skipped\n");
return false;
}
- DEBUG(dbgs() << "\n");
+ LLVM_DEBUG(dbgs() << "\n");
MF.RenumberBlocks();
BBAnalysis.resize(MF.getNumBlockIDs());
@@ -406,14 +406,14 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
case ICSimpleFalse: {
bool isFalse = Kind == ICSimpleFalse;
if ((isFalse && DisableSimpleF) || (!isFalse && DisableSimple)) break;
- DEBUG(dbgs() << "Ifcvt (Simple"
- << (Kind == ICSimpleFalse ? " false" : "")
- << "): " << printMBBReference(*BBI.BB) << " ("
- << ((Kind == ICSimpleFalse) ? BBI.FalseBB->getNumber()
- : BBI.TrueBB->getNumber())
- << ") ");
+ LLVM_DEBUG(dbgs() << "Ifcvt (Simple"
+ << (Kind == ICSimpleFalse ? " false" : "")
+ << "): " << printMBBReference(*BBI.BB) << " ("
+ << ((Kind == ICSimpleFalse) ? BBI.FalseBB->getNumber()
+ : BBI.TrueBB->getNumber())
+ << ") ");
RetVal = IfConvertSimple(BBI, Kind);
- DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
+ LLVM_DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
if (RetVal) {
if (isFalse) ++NumSimpleFalse;
else ++NumSimple;
@@ -430,16 +430,16 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
if (DisableTriangleR && !isFalse && isRev) break;
if (DisableTriangleF && isFalse && !isRev) break;
if (DisableTriangleFR && isFalse && isRev) break;
- DEBUG(dbgs() << "Ifcvt (Triangle");
+ LLVM_DEBUG(dbgs() << "Ifcvt (Triangle");
if (isFalse)
- DEBUG(dbgs() << " false");
+ LLVM_DEBUG(dbgs() << " false");
if (isRev)
- DEBUG(dbgs() << " rev");
- DEBUG(dbgs() << "): " << printMBBReference(*BBI.BB)
- << " (T:" << BBI.TrueBB->getNumber()
- << ",F:" << BBI.FalseBB->getNumber() << ") ");
+ LLVM_DEBUG(dbgs() << " rev");
+ LLVM_DEBUG(dbgs() << "): " << printMBBReference(*BBI.BB)
+ << " (T:" << BBI.TrueBB->getNumber()
+ << ",F:" << BBI.FalseBB->getNumber() << ") ");
RetVal = IfConvertTriangle(BBI, Kind);
- DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
+ LLVM_DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
if (RetVal) {
if (isFalse) {
if (isRev) ++NumTriangleFRev;
@@ -453,24 +453,25 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
}
case ICDiamond:
if (DisableDiamond) break;
- DEBUG(dbgs() << "Ifcvt (Diamond): " << printMBBReference(*BBI.BB)
- << " (T:" << BBI.TrueBB->getNumber()
- << ",F:" << BBI.FalseBB->getNumber() << ") ");
+ LLVM_DEBUG(dbgs() << "Ifcvt (Diamond): " << printMBBReference(*BBI.BB)
+ << " (T:" << BBI.TrueBB->getNumber()
+ << ",F:" << BBI.FalseBB->getNumber() << ") ");
RetVal = IfConvertDiamond(BBI, Kind, NumDups, NumDups2,
Token->TClobbersPred,
Token->FClobbersPred);
- DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
+ LLVM_DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
if (RetVal) ++NumDiamonds;
break;
case ICForkedDiamond:
if (DisableForkedDiamond) break;
- DEBUG(dbgs() << "Ifcvt (Forked Diamond): " << printMBBReference(*BBI.BB)
- << " (T:" << BBI.TrueBB->getNumber()
- << ",F:" << BBI.FalseBB->getNumber() << ") ");
+ LLVM_DEBUG(dbgs() << "Ifcvt (Forked Diamond): "
+ << printMBBReference(*BBI.BB)
+ << " (T:" << BBI.TrueBB->getNumber()
+ << ",F:" << BBI.FalseBB->getNumber() << ") ");
RetVal = IfConvertForkedDiamond(BBI, Kind, NumDups, NumDups2,
Token->TClobbersPred,
Token->FClobbersPred);
- DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
+ LLVM_DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
if (RetVal) ++NumForkedDiamonds;
break;
}
@@ -948,7 +949,7 @@ void IfConverter::ScanInstructions(BBInfo &BBI,
BBI.ExtraCost2 = 0;
BBI.ClobbersPred = false;
for (MachineInstr &MI : make_range(Begin, End)) {
- if (MI.isDebugValue())
+ if (MI.isDebugInstr())
continue;
// It's unsafe to duplicate convergent instructions in this context, so set
@@ -1714,21 +1715,26 @@ bool IfConverter::IfConvertDiamondCommon(
}
// Remove the duplicated instructions at the beginnings of both paths.
- // Skip dbg_value instructions
+ // Skip dbg_value instructions.
MachineBasicBlock::iterator DI1 = MBB1.getFirstNonDebugInstr();
MachineBasicBlock::iterator DI2 = MBB2.getFirstNonDebugInstr();
BBI1->NonPredSize -= NumDups1;
BBI2->NonPredSize -= NumDups1;
// Skip past the dups on each side separately since there may be
- // differing dbg_value entries.
+ // differing dbg_value entries. NumDups1 can include a "return"
+ // instruction, if it's not marked as "branch".
for (unsigned i = 0; i < NumDups1; ++DI1) {
- if (!DI1->isDebugValue())
+ if (DI1 == MBB1.end())
+ break;
+ if (!DI1->isDebugInstr())
++i;
}
while (NumDups1 != 0) {
++DI2;
- if (!DI2->isDebugValue())
+ if (DI2 == MBB2.end())
+ break;
+ if (!DI2->isDebugInstr())
--NumDups1;
}
@@ -1738,11 +1744,16 @@ bool IfConverter::IfConvertDiamondCommon(
Redefs.stepForward(MI, Dummy);
}
}
+
BBI.BB->splice(BBI.BB->end(), &MBB1, MBB1.begin(), DI1);
MBB2.erase(MBB2.begin(), DI2);
- // The branches have been checked to match, so it is safe to remove the branch
- // in BB1 and rely on the copy in BB2
+ // The branches have been checked to match, so it is safe to remove the
+ // branch in BB1 and rely on the copy in BB2. The complication is that
+ // the blocks may end with a return instruction, which may or may not
+ // be marked as "branch". If it's not, then it could be included in
+ // "dups1", leaving the blocks potentially empty after moving the common
+ // duplicates.
#ifndef NDEBUG
// Unanalyzable branches must match exactly. Check that now.
if (!BBI1->IsBrAnalyzable)
@@ -1757,7 +1768,7 @@ bool IfConverter::IfConvertDiamondCommon(
assert(DI1 != MBB1.begin());
--DI1;
// skip dbg_value instructions
- if (!DI1->isDebugValue())
+ if (!DI1->isDebugInstr())
++i;
}
MBB1.erase(DI1, MBB1.end());
@@ -1768,11 +1779,14 @@ bool IfConverter::IfConvertDiamondCommon(
if (RemoveBranch)
BBI2->NonPredSize -= TII->removeBranch(*BBI2->BB);
else {
- do {
- assert(DI2 != MBB2.begin());
- DI2--;
- } while (DI2->isBranch() || DI2->isDebugValue());
- DI2++;
+ // Make DI2 point to the end of the range where the common "tail"
+ // instructions could be found.
+ while (DI2 != MBB2.begin()) {
+ MachineBasicBlock::iterator Prev = std::prev(DI2);
+ if (!Prev->isBranch() && !Prev->isDebugInstr())
+ break;
+ DI2 = Prev;
+ }
}
while (NumDups2 != 0) {
// NumDups2 only counted non-dbg_value instructions, so this won't
@@ -1780,7 +1794,7 @@ bool IfConverter::IfConvertDiamondCommon(
assert(DI2 != MBB2.begin());
--DI2;
// skip dbg_value instructions
- if (!DI2->isDebugValue())
+ if (!DI2->isDebugInstr())
--NumDups2;
}
@@ -1796,7 +1810,7 @@ bool IfConverter::IfConvertDiamondCommon(
SmallSet<unsigned, 4> ExtUses;
if (TII->isProfitableToUnpredicate(MBB1, MBB2)) {
for (const MachineInstr &FI : make_range(MBB2.begin(), DI2)) {
- if (FI.isDebugValue())
+ if (FI.isDebugInstr())
continue;
SmallVector<unsigned, 4> Defs;
for (const MachineOperand &MO : FI.operands()) {
@@ -1833,11 +1847,15 @@ bool IfConverter::IfConvertDiamondCommon(
// a non-predicated in BBI2, then we don't want to predicate the one from
// BBI2. The reason is that if we merged these blocks, we would end up with
// two predicated terminators in the same block.
+ // Also, if the branches in MBB1 and MBB2 were non-analyzable, then don't
+ // predicate them either. They were checked to be identical, and so the
+ // same branch would happen regardless of which path was taken.
if (!MBB2.empty() && (DI2 == MBB2.end())) {
MachineBasicBlock::iterator BBI1T = MBB1.getFirstTerminator();
MachineBasicBlock::iterator BBI2T = MBB2.getFirstTerminator();
- if (BBI1T != MBB1.end() && TII->isPredicated(*BBI1T) &&
- BBI2T != MBB2.end() && !TII->isPredicated(*BBI2T))
+ bool BB1Predicated = BBI1T != MBB1.end() && TII->isPredicated(*BBI1T);
+ bool BB2NonPredicated = BBI2T != MBB2.end() && !TII->isPredicated(*BBI2T);
+ if (BB2NonPredicated && (BB1Predicated || !BBI2->IsBrAnalyzable))
--DI2;
}
@@ -1985,7 +2003,7 @@ void IfConverter::PredicateBlock(BBInfo &BBI,
bool AnyUnpred = false;
bool MaySpec = LaterRedefs != nullptr;
for (MachineInstr &I : make_range(BBI.BB->begin(), E)) {
- if (I.isDebugValue() || TII->isPredicated(I))
+ if (I.isDebugInstr() || TII->isPredicated(I))
continue;
// It may be possible not to predicate an instruction if it's the 'true'
// side of a diamond and the 'false' side may re-define the instruction's
@@ -2041,7 +2059,7 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
ToBBI.ExtraCost += NumCycles-1;
ToBBI.ExtraCost2 += ExtraPredCost;
- if (!TII->isPredicated(I) && !MI->isDebugValue()) {
+ if (!TII->isPredicated(I) && !MI->isDebugInstr()) {
if (!TII->PredicateInstruction(*MI, Cond)) {
#ifndef NDEBUG
dbgs() << "Unable to predicate " << I << "!\n";
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-05 18:22:35 +0000