Do not lose branch weights when lowering SwitchInst.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136529 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 329fb51..60d4391 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1282,10 +1282,12 @@
return BPI->getEdgeWeight(SrcBB, DstBB);
}
-void SelectionDAGBuilder::addSuccessorWithWeight(MachineBasicBlock *Src,
- MachineBasicBlock *Dst) {
- uint32_t weight = getEdgeWeight(Src, Dst);
- Src->addSuccessor(Dst, weight);
+void SelectionDAGBuilder::
+addSuccessorWithWeight(MachineBasicBlock *Src, MachineBasicBlock *Dst,
+ uint32_t Weight /* = 0 */) {
+ if (!Weight)
+ Weight = getEdgeWeight(Src, Dst);
+ Src->addSuccessor(Dst, Weight);
}
@@ -1558,8 +1560,8 @@
}
// Update successor info
- addSuccessorWithWeight(SwitchBB, CB.TrueBB);
- addSuccessorWithWeight(SwitchBB, CB.FalseBB);
+ addSuccessorWithWeight(SwitchBB, CB.TrueBB, CB.TrueWeight);
+ 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.
@@ -1910,8 +1912,8 @@
ISD::SETEQ);
// Update successor info.
- SwitchBB->addSuccessor(Small.BB);
- SwitchBB->addSuccessor(Default);
+ addSuccessorWithWeight(SwitchBB, Small.BB);
+ addSuccessorWithWeight(SwitchBB, Default);
// Insert the true branch.
SDValue BrCond = DAG.getNode(ISD::BRCOND, DL, MVT::Other,
@@ -1967,7 +1969,11 @@
CC = ISD::SETLE;
LHS = I->Low; MHS = SV; RHS = I->High;
}
- CaseBlock CB(CC, LHS, RHS, MHS, I->BB, FallThrough, CurBlock);
+
+ uint32_t ExtraWeight = I->ExtraWeight;
+ CaseBlock CB(CC, LHS, RHS, MHS, /* truebb */ I->BB, /* falsebb */ FallThrough,
+ /* me */ CurBlock,
+ /* trueweight */ ExtraWeight / 2, /* falseweight */ ExtraWeight / 2);
// If emitting the first comparison, just call visitSwitchCase to emit the
// code into the current block. Otherwise, push the CaseBlock onto the
@@ -2362,12 +2368,17 @@
const SwitchInst& SI) {
size_t numCmps = 0;
+ BranchProbabilityInfo *BPI = FuncInfo.BPI;
// Start with "simple" cases
for (size_t i = 1; i < SI.getNumSuccessors(); ++i) {
- MachineBasicBlock *SMBB = FuncInfo.MBBMap[SI.getSuccessor(i)];
+ BasicBlock *SuccBB = SI.getSuccessor(i);
+ MachineBasicBlock *SMBB = FuncInfo.MBBMap[SuccBB];
+
+ uint32_t ExtraWeight = BPI ? BPI->getEdgeWeight(SI.getParent(), SuccBB) : 0;
+
Cases.push_back(Case(SI.getSuccessorValue(i),
SI.getSuccessorValue(i),
- SMBB));
+ SMBB, ExtraWeight));
}
std::sort(Cases.begin(), Cases.end(), CaseCmp());
@@ -2387,6 +2398,16 @@
if ((nextValue - currentValue == 1) && (currentBB == nextBB)) {
I->High = J->High;
J = Cases.erase(J);
+
+ if (BranchProbabilityInfo *BPI = FuncInfo.BPI) {
+ uint32_t CurWeight = currentBB->getBasicBlock() ?
+ BPI->getEdgeWeight(SI.getParent(), currentBB->getBasicBlock()) : 16;
+ uint32_t NextWeight = nextBB->getBasicBlock() ?
+ BPI->getEdgeWeight(SI.getParent(), nextBB->getBasicBlock()) : 16;
+
+ BPI->setEdgeWeight(SI.getParent(), currentBB->getBasicBlock(),
+ CurWeight + NextWeight);
+ }
} else {
I = J++;
}