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If true / false blocks fallthrough before ifcvt, add unconditional branches to ifcvt'd block.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37200 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-05-18 01:55:58 +00:00
parent dcc50a4aee
commit 47d2502072
1 changed files with 19 additions and 4 deletions
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23
lib/CodeGen/IfConversion.cpp
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@ -87,8 +87,6 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
TII = MF.getTarget().getInstrInfo();
if (!TII) return false;
MadeChange = false;
MF.RenumberBlocks();
unsigned NumBBs = MF.getNumBlockIDs();
BBAnalysis.resize(NumBBs);
@ -98,6 +96,7 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
// candidates to perform if-convesion.
InitialFunctionAnalysis(MF, Candidates);
MadeChange = false;
for (unsigned i = 0, e = Candidates.size(); i != e; ++i) {
BBInfo &BBI = BBAnalysis[Candidates[i]];
switch (BBI.Kind) {
@ -111,6 +110,9 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
break;
}
}
BBAnalysis.clear();
return MadeChange;
}
@ -150,6 +152,10 @@ void IfConverter::AnalyzeBlock(MachineBasicBlock *BB) {
if (TrueBBI.Kind != ICNotClassfied)
return;
// TODO: Only handle very simple cases for now.
if (TrueBBI.FalseBB || TrueBBI.Cond.size())
return;
// No false branch. This BB must end with a conditional branch and a
// fallthrough.
if (!BBI.FalseBB)
@ -168,8 +174,7 @@ void IfConverter::AnalyzeBlock(MachineBasicBlock *BB) {
return;
// TODO: Only handle very simple cases for now.
if (TrueBBI.FalseBB || FalseBBI.FalseBB ||
TrueBBI.Cond.size() || FalseBBI.Cond.size())
if (FalseBBI.FalseBB || FalseBBI.Cond.size())
return;
if (TrueBBI.TrueBB && TrueBBI.TrueBB == BBI.FalseBB) {
@ -309,11 +314,21 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
TrueBBI.Size -= TII->RemoveBranch(*BBI.TrueBB);
PredicateBlock(BBI.TrueBB, BBI.Cond);
// Either the 'true' block fallthrough to another block or it ends with a
// return. If it's the former, add a conditional branch to its successor.
if (!TrueBBI.TrueBB)
TII->InsertBranch(*BBI.TrueBB, *BBI.TrueBB->succ_begin(), NULL, BBI.Cond);
// Predicate the 'false' block.
std::vector<MachineOperand> NewCond(BBI.Cond);
TII->ReverseBranchCondition(NewCond);
PredicateBlock(BBI.FalseBB, NewCond, true);
// Either the 'false' block fallthrough to another block or it ends with a
// return. If it's the former, add a conditional branch to its successor.
if (!FalseBBI.TrueBB)
TII->InsertBranch(*BBI.FalseBB, *BBI.FalseBB->succ_begin(), NULL,NewCond);
// Merge the 'true' and 'false' blocks by copying the instructions
// from the 'false' block to the 'true' block.
MergeBlocks(TrueBBI, FalseBBI);