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visitSwitchCase knows how to insert conditional branches well. Change

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visitBr to just call visitSwitchCase, eliminating duplicate logic.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31167 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2006-10-24 18:07:37 +00:00
parent 57ab65972e
commit 2452595927
1 changed files with 8 additions and 37 deletions
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43
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@@ -788,43 +788,14 @@ void SelectionDAGLowering::visitBr(BranchInst &I) {
// If this condition is one of the special cases we handle, do special stuff // If this condition is one of the special cases we handle, do special stuff
// now. // now.
Value *CondVal = I.getCondition(); Value *CondVal = I.getCondition();
// Update machine-CFG edges.
CurMBB->addSuccessor(Succ0MBB);
MachineBasicBlock *Succ1MBB = FuncInfo.MBBMap[I.getSuccessor(1)]; MachineBasicBlock *Succ1MBB = FuncInfo.MBBMap[I.getSuccessor(1)];
CurMBB->addSuccessor(Succ1MBB);
SDOperand Cond = getValue(CondVal); // Create a CaseBlock record representing this branch.
if (Succ1MBB == NextBlock) { SelectionDAGISel::CaseBlock CB(ISD::SETEQ, CondVal, 0,
// If the condition is false, fall through. This means we should branch Succ0MBB, Succ1MBB, CurMBB);
// if the condition is true to Succ #0. // Use visitSwitchCase to actually insert the fast branch sequence for this
DAG.setRoot(DAG.getNode(ISD::BRCOND, MVT::Other, getRoot(), // cond branch.
Cond, DAG.getBasicBlock(Succ0MBB))); visitSwitchCase(CB);
} else if (Succ0MBB == NextBlock) {
// If the condition is true, fall through. This means we should branch if
// the condition is false to Succ #1. Invert the condition first.
SDOperand True = DAG.getConstant(1, Cond.getValueType());
Cond = DAG.getNode(ISD::XOR, Cond.getValueType(), Cond, True);
DAG.setRoot(DAG.getNode(ISD::BRCOND, MVT::Other, getRoot(),
Cond, DAG.getBasicBlock(Succ1MBB)));
} else {
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
// If the false case is the current basic block, then this is a self
// loop. We do not want to emit "Loop: ... brcond Out; br Loop", as it
// adds an extra instruction in the loop. Instead, invert the
// condition and emit "Loop: ... br!cond Loop; br Out.
if (CurMBB == Succ1MBB) {
std::swap(Succ0MBB, Succ1MBB);
SDOperand True = DAG.getConstant(1, Cond.getValueType());
Cond = DAG.getNode(ISD::XOR, Cond.getValueType(), Cond, True);
}
SDOperand True = DAG.getNode(ISD::BRCOND, MVT::Other, getRoot(), Cond,
DAG.getBasicBlock(Succ0MBB));
DAG.setRoot(DAG.getNode(ISD::BR, MVT::Other, True,
DAG.getBasicBlock(Succ1MBB)));
}
} }
/// visitSwitchCase - Emits the necessary code to represent a single node in /// visitSwitchCase - Emits the necessary code to represent a single node in
@@ -3769,7 +3740,7 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
SwitchCases[i].FalseBB = 0; SwitchCases[i].FalseBB = 0;
// If we haven't handled the RHS, do so now. Otherwise, we're done. // If we haven't handled the RHS, do so now. Otherwise, we're done.
SwitchCases[i].TrueBB = SwitchCases[i].TrueBB; SwitchCases[i].TrueBB = SwitchCases[i].FalseBB;
SwitchCases[i].FalseBB = 0; SwitchCases[i].FalseBB = 0;
} }
assert(SwitchCases[i].TrueBB == 0 && SwitchCases[i].FalseBB == 0); assert(SwitchCases[i].TrueBB == 0 && SwitchCases[i].FalseBB == 0);