[llvm] r232759 - Switch lowering: extract NextBlock function. NFC.
Hans Wennborg
hans at hanshq.net
Thu Mar 19 13:41:48 PDT 2015
Author: hans
Date: Thu Mar 19 15:41:48 2015
New Revision: 232759
URL: http://llvm.org/viewvc/llvm-project?rev=232759&view=rev
Log:
Switch lowering: extract NextBlock function. NFC.
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=232759&r1=232758&r2=232759&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Thu Mar 19 15:41:48 2015
@@ -1585,19 +1585,13 @@ void SelectionDAGBuilder::visitBr(const
// Update machine-CFG edges.
MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[I.getSuccessor(0)];
- // Figure out which block is immediately after the current one.
- MachineBasicBlock *NextBlock = nullptr;
- MachineFunction::iterator BBI = BrMBB;
- if (++BBI != FuncInfo.MF->end())
- NextBlock = BBI;
-
if (I.isUnconditional()) {
// Update machine-CFG edges.
BrMBB->addSuccessor(Succ0MBB);
// If this is not a fall-through branch or optimizations are switched off,
// emit the branch.
- if (Succ0MBB != NextBlock || TM.getOptLevel() == CodeGenOpt::None)
+ if (Succ0MBB != NextBlock(BrMBB) || TM.getOptLevel() == CodeGenOpt::None)
DAG.setRoot(DAG.getNode(ISD::BR, getCurSDLoc(),
MVT::Other, getControlRoot(),
DAG.getBasicBlock(Succ0MBB)));
@@ -1717,16 +1711,9 @@ void SelectionDAGBuilder::visitSwitchCas
if (CB.TrueBB != CB.FalseBB)
addSuccessorWithWeight(SwitchBB, CB.FalseBB, CB.FalseWeight);
- // Set NextBlock to be the MBB immediately after the current one, if any.
- // This is used to avoid emitting unnecessary branches to the next block.
- MachineBasicBlock *NextBlock = nullptr;
- MachineFunction::iterator BBI = SwitchBB;
- if (++BBI != FuncInfo.MF->end())
- NextBlock = BBI;
-
// If the lhs block is the next block, invert the condition so that we can
// fall through to the lhs instead of the rhs block.
- if (CB.TrueBB == NextBlock) {
+ if (CB.TrueBB == NextBlock(SwitchBB)) {
std::swap(CB.TrueBB, CB.FalseBB);
SDValue True = DAG.getConstant(1, Cond.getValueType());
Cond = DAG.getNode(ISD::XOR, dl, Cond.getValueType(), Cond, True);
@@ -1793,19 +1780,12 @@ void SelectionDAGBuilder::visitJumpTable
Sub.getValueType()),
Sub, DAG.getConstant(JTH.Last - JTH.First, VT), ISD::SETUGT);
- // Set NextBlock to be the MBB immediately after the current one, if any.
- // This is used to avoid emitting unnecessary branches to the next block.
- MachineBasicBlock *NextBlock = nullptr;
- MachineFunction::iterator BBI = SwitchBB;
-
- if (++BBI != FuncInfo.MF->end())
- NextBlock = BBI;
-
SDValue BrCond = DAG.getNode(ISD::BRCOND, getCurSDLoc(),
MVT::Other, CopyTo, CMP,
DAG.getBasicBlock(JT.Default));
- if (JT.MBB != NextBlock)
+ // Avoid emitting unnecessary branches to the next block.
+ if (JT.MBB != NextBlock(SwitchBB))
BrCond = DAG.getNode(ISD::BR, getCurSDLoc(), MVT::Other, BrCond,
DAG.getBasicBlock(JT.MBB));
@@ -1934,13 +1914,6 @@ void SelectionDAGBuilder::visitBitTestHe
SDValue CopyTo = DAG.getCopyToReg(getControlRoot(), getCurSDLoc(),
B.Reg, Sub);
- // Set NextBlock to be the MBB immediately after the current one, if any.
- // This is used to avoid emitting unnecessary branches to the next block.
- MachineBasicBlock *NextBlock = nullptr;
- MachineFunction::iterator BBI = SwitchBB;
- if (++BBI != FuncInfo.MF->end())
- NextBlock = BBI;
-
MachineBasicBlock* MBB = B.Cases[0].ThisBB;
addSuccessorWithWeight(SwitchBB, B.Default);
@@ -1950,7 +1923,8 @@ void SelectionDAGBuilder::visitBitTestHe
MVT::Other, CopyTo, RangeCmp,
DAG.getBasicBlock(B.Default));
- if (MBB != NextBlock)
+ // Avoid emitting unnecessary branches to the next block.
+ if (MBB != NextBlock(SwitchBB))
BrRange = DAG.getNode(ISD::BR, getCurSDLoc(), MVT::Other, CopyTo,
DAG.getBasicBlock(MBB));
@@ -2003,14 +1977,8 @@ void SelectionDAGBuilder::visitBitTestCa
MVT::Other, getControlRoot(),
Cmp, DAG.getBasicBlock(B.TargetBB));
- // Set NextBlock to be the MBB immediately after the current one, if any.
- // This is used to avoid emitting unnecessary branches to the next block.
- MachineBasicBlock *NextBlock = nullptr;
- MachineFunction::iterator BBI = SwitchBB;
- if (++BBI != FuncInfo.MF->end())
- NextBlock = BBI;
-
- if (NextMBB != NextBlock)
+ // Avoid emitting unnecessary branches to the next block.
+ if (NextMBB != NextBlock(SwitchBB))
BrAnd = DAG.getNode(ISD::BR, getCurSDLoc(), MVT::Other, BrAnd,
DAG.getBasicBlock(NextMBB));
@@ -2147,11 +2115,10 @@ bool SelectionDAGBuilder::handleSmallSwi
MachineFunction *CurMF = FuncInfo.MF;
// Figure out which block is immediately after the current one.
- MachineBasicBlock *NextBlock = nullptr;
+ MachineBasicBlock *NextMBB = nullptr;
MachineFunction::iterator BBI = CR.CaseBB;
-
if (++BBI != FuncInfo.MF->end())
- NextBlock = BBI;
+ NextMBB = BBI;
BranchProbabilityInfo *BPI = FuncInfo.BPI;
// If any two of the cases has the same destination, and if one value
@@ -2224,13 +2191,12 @@ bool SelectionDAGBuilder::handleSmallSwi
}
// Rearrange the case blocks so that the last one falls through if possible.
Case &BackCase = *(CR.Range.second-1);
- if (Size > 1 &&
- NextBlock && Default != NextBlock && BackCase.BB != NextBlock) {
- // The last case block won't fall through into 'NextBlock' if we emit the
+ if (Size > 1 && NextMBB && Default != NextMBB && BackCase.BB != NextMBB) {
+ // The last case block won't fall through into 'NextMBB' if we emit the
// branches in this order. See if rearranging a case value would help.
// We start at the bottom as it's the case with the least weight.
for (Case *I = &*(CR.Range.second-2), *E = &*CR.Range.first-1; I != E; --I)
- if (I->BB == NextBlock) {
+ if (I->BB == NextMBB) {
std::swap(*I, BackCase);
break;
}
@@ -2746,12 +2712,6 @@ void SelectionDAGBuilder::UpdateSplitBlo
void SelectionDAGBuilder::visitSwitch(const SwitchInst &SI) {
MachineBasicBlock *SwitchMBB = FuncInfo.MBB;
- // Figure out which block is immediately after the current one.
- MachineBasicBlock *NextBlock = nullptr;
- if (SwitchMBB + 1 != FuncInfo.MF->end())
- NextBlock = SwitchMBB + 1;
-
-
// Create a vector of Cases, sorted so that we can efficiently create a binary
// search tree from them.
CaseVector Cases;
@@ -2792,7 +2752,7 @@ void SelectionDAGBuilder::visitSwitch(co
SwitchMBB->addSuccessor(Default);
// If this is not a fall-through branch, emit the branch.
- if (Default != NextBlock) {
+ if (Default != NextBlock(SwitchMBB)) {
DAG.setRoot(DAG.getNode(ISD::BR, getCurSDLoc(), MVT::Other,
getControlRoot(), DAG.getBasicBlock(Default)));
}
@@ -7823,3 +7783,10 @@ AddSuccessorMBB(const BasicBlock *BB,
SuccMBB, BranchProbabilityInfo::getBranchWeightStackProtector(IsLikely));
return SuccMBB;
}
+
+MachineBasicBlock *SelectionDAGBuilder::NextBlock(MachineBasicBlock *MBB) {
+ MachineFunction::iterator I = MBB;
+ if (++I == FuncInfo.MF->end())
+ return nullptr;
+ return I;
+}
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h?rev=232759&r1=232758&r2=232759&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h Thu Mar 19 15:41:48 2015
@@ -832,6 +832,9 @@ private:
bool EmitFuncArgumentDbgValue(const Value *V, MDNode *Variable, MDNode *Expr,
int64_t Offset, bool IsIndirect,
const SDValue &N);
+
+ /// Return the next block after MBB, or nullptr if there is none.
+ MachineBasicBlock *NextBlock(MachineBasicBlock *MBB);
};
} // end namespace llvm
More information about the llvm-commits
mailing list