RPCSX/llvm
1
0
Fork 0
mirror of https://github.com/RPCSX/llvm.git synced 2025-02-07 21:20:18 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Fix some fragile code wrt CFG edge updating.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37634 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-06-18 22:44:57 +00:00
parent 2bdb7d0cc8
commit c4047a8e96
1 changed files with 39 additions and 74 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

113
lib/CodeGen/IfConversion.cpp
View File

@ -486,11 +486,12 @@ bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
return false;
if (TT == NULL && (TrueBBI.IsBrAnalyzable || FalseBBI.IsBrAnalyzable))
return false;
// FIXME: Allow false block to have an early exit?
if (TrueBBI.BB->pred_size() > 1 ||
FalseBBI.BB->pred_size() > 1 ||
TrueBBI.FalseBB || FalseBBI.FalseBB ||
(TrueBBI.ClobbersPred && FalseBBI.ClobbersPred))
if (TrueBBI.BB->pred_size() > 1 || FalseBBI.BB->pred_size() > 1)
return false;
// FIXME: Allow true block to have an early exit?
if (TrueBBI.FalseBB || FalseBBI.FalseBB ||
(TrueBBI.ClobbersPred && FalseBBI.ClobbersPred))
return false;
MachineBasicBlock::iterator TI = TrueBBI.BB->begin();
@ -806,16 +807,8 @@ static void InsertUncondBranch(MachineBasicBlock *BB, MachineBasicBlock *ToBB,
void IfConverter::RemoveExtraEdges(BBInfo &BBI) {
MachineBasicBlock *TBB = NULL, *FBB = NULL;
std::vector<MachineOperand> Cond;
bool isAnalyzable = !TII->AnalyzeBranch(*BBI.BB, TBB, FBB, Cond);
bool CanFallthrough = isAnalyzable && (TBB == NULL || FBB == NULL);
if (BBI.TrueBB && BBI.BB->isSuccessor(BBI.TrueBB))
if (!(BBI.TrueBB == TBB || BBI.TrueBB == FBB ||
(CanFallthrough && getNextBlock(BBI.BB) == BBI.TrueBB)))
BBI.BB->removeSuccessor(BBI.TrueBB);
if (BBI.FalseBB && BBI.BB->isSuccessor(BBI.FalseBB))
if (!(BBI.FalseBB == TBB || BBI.FalseBB == FBB ||
(CanFallthrough && getNextBlock(BBI.BB) == BBI.FalseBB)))
BBI.BB->removeSuccessor(BBI.FalseBB);
if (!TII->AnalyzeBranch(*BBI.BB, TBB, FBB, Cond))
BBI.BB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty());
}
/// IfConvertSimple - If convert a simple (split, no rejoin) sub-CFG.
@ -936,23 +929,19 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond);
}
if (!DupBB) {
// Now merge the entry of the triangle with the true block.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
MergeBlocks(BBI, *CvtBBI);
}
// If 'true' block has a 'false' successor, add an exit branch to it.
if (HasEarlyExit) {
std::vector<MachineOperand> RevCond(CvtBBI->BrCond);
if (TII->ReverseBranchCondition(RevCond))
assert(false && "Unable to reverse branch condition!");
if (DupBB) {
TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond);
BBI.BB->addSuccessor(CvtBBI->FalseBB);
} else {
TII->InsertBranch(*CvtBBI->BB, CvtBBI->FalseBB, NULL, RevCond);
}
}
if (!DupBB) {
// Now merge the entry of the triangle with the true block.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
MergeBlocks(BBI, *CvtBBI);
TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond);
BBI.BB->addSuccessor(CvtBBI->FalseBB);
}
// Merge in the 'false' block if the 'false' block has no other
@ -1024,25 +1013,18 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
TII->ReverseBranchCondition(RevCond);
std::vector<MachineOperand> *Cond1 = &BBI.BrCond;
std::vector<MachineOperand> *Cond2 = &RevCond;
bool NeedBr1 = BBI1->FalseBB != NULL;
bool NeedBr2 = BBI2->FalseBB != NULL;
// Figure out the more profitable ordering.
bool DoSwap = false;
if (TrueBBI.ClobbersPred && !FalseBBI.ClobbersPred)
DoSwap = true;
else if (TrueBBI.ClobbersPred == FalseBBI.ClobbersPred) {
if (!NeedBr1 && NeedBr2)
if (TrueBBI.NonPredSize > FalseBBI.NonPredSize)
DoSwap = true;
else if (NeedBr1 == NeedBr2) {
if (TrueBBI.NonPredSize > FalseBBI.NonPredSize)
DoSwap = true;
}
}
if (DoSwap) {
std::swap(BBI1, BBI2);
std::swap(Cond1, Cond2);
std::swap(NeedBr1, NeedBr2);
}
// Remove the conditional branch from entry to the blocks.
@ -1069,10 +1051,6 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
BBI1->BB->erase(DI1, BBI1->BB->end());
PredicateBlock(*BBI1, BBI1->BB->end(), *Cond1);
// Add an early exit branch if needed.
if (NeedBr1)
TII->InsertBranch(*BBI1->BB, BBI1->FalseBB, NULL, *Cond1);
// Predicate the 'false' block.
BBI2->NonPredSize -= TII->RemoveBranch(*BBI2->BB);
DI2 = BBI2->BB->end();
@ -1082,30 +1060,9 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
}
PredicateBlock(*BBI2, DI2, *Cond2);
// Add an unconditional branch from 'false' to to 'false' successor if it
// will not be the fallthrough block.
if (NeedBr2 && !NeedBr1) {
// If BBI2 isn't going to be merged in, then the existing fallthrough
// or branch is fine.
if (!canFallThroughTo(BBI.BB, BBI2->FalseBB)) {
InsertUncondBranch(BBI2->BB, BBI2->FalseBB, TII);
BBI2->HasFallThrough = false;
}
}
// Keep them as two separate blocks if there is an early exit.
if (!NeedBr1)
MergeBlocks(*BBI1, *BBI2);
// Merge the combined block into the entry of the diamond.
// Merge the true block into the entry of the diamond.
MergeBlocks(BBI, *BBI1);
// 'True' and 'false' aren't combined, see if we need to add a unconditional
// branch to the 'false' block.
if (NeedBr1 && !canFallThroughTo(BBI.BB, BBI2->BB)) {
InsertUncondBranch(BBI.BB, BBI2->BB, TII);
BBI1->HasFallThrough = false;
}
MergeBlocks(BBI, *BBI2);
// If the if-converted block fallthrough or unconditionally branch into the
// tail block, and the tail block does not have other predecessors, then
@ -1113,19 +1070,13 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
// tail, add a unconditional branch to it.
if (TailBB) {
BBInfo TailBBI = BBAnalysis[TailBB->getNumber()];
BBInfo *LastBBI = NeedBr1 ? BBI2 : &BBI;
bool HasEarlyExit = NeedBr1 ? NeedBr2 : false;
if (!HasEarlyExit &&
TailBB->pred_size() == 1 && !TailBBI.HasFallThrough) {
LastBBI->NonPredSize -= TII->RemoveBranch(*LastBBI->BB);
MergeBlocks(*LastBBI, TailBBI);
if (TailBB->pred_size() == 1 && !TailBBI.HasFallThrough) {
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
MergeBlocks(BBI, TailBBI);
TailBBI.IsDone = true;
} else {
bool isFallThrough = canFallThroughTo(LastBBI->BB, TailBB);
if (!isFallThrough) {
InsertUncondBranch(LastBBI->BB, TailBB, TII);
LastBBI->HasFallThrough = false;
}
InsertUncondBranch(BBI.BB, TailBB, TII);
BBI.HasFallThrough = false;
}
}
@ -1185,6 +1136,20 @@ void IfConverter::CopyAndPredicateBlock(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;
for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
MachineBasicBlock *Succ = Succs[i];
// Fallthrough edge can't be transferred.
if (Succ == FallThrough)
continue;
if (!ToBBI.BB->isSuccessor(Succ))
ToBBI.BB->addSuccessor(Succ);
}
std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),
std::back_inserter(ToBBI.Predicate));
std::copy(Cond.begin(), Cond.end(), std::back_inserter(ToBBI.Predicate));
@ -1227,7 +1192,7 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) {
}
// Now FromBBI always fall through to the next block!
if (NBB)
if (NBB && !FromBBI.BB->isSuccessor(NBB))
FromBBI.BB->addSuccessor(NBB);
std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),