Don't copy the operand of a SwitchInst into virtual registers as
eagerly. This helps avoid CopyToReg nodes in some cases where they
aren't needed, and also helps subsequent optimizer heuristics
in cases where the extra nodes would cause the node to appear
to have multiple results. This doesn't have a significant impact
currently; it'll help an upcoming change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68667 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
index ba59906..fd15603 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
@@ -243,9 +243,7 @@
if (isa<PHINode>(I)) return true;
BasicBlock *BB = I->getParent();
for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; ++UI)
- if (cast<Instruction>(*UI)->getParent() != BB || isa<PHINode>(*UI) ||
- // FIXME: Remove switchinst special case.
- isa<SwitchInst>(*UI))
+ if (cast<Instruction>(*UI)->getParent() != BB || isa<PHINode>(*UI))
return true;
return false;
}
@@ -1640,6 +1638,9 @@
if (I != E-1) {
FallThrough = CurMF->CreateMachineBasicBlock(CurBlock->getBasicBlock());
CurMF->insert(BBI, FallThrough);
+
+ // Put SV in a virtual register to make it available from the new blocks.
+ ExportFromCurrentBlock(SV);
} else {
// If the last case doesn't match, go to the default block.
FallThrough = Default;
@@ -1874,6 +1875,9 @@
TrueBB = CurMF->CreateMachineBasicBlock(LLVMBB);
CurMF->insert(BBI, TrueBB);
WorkList.push_back(CaseRec(TrueBB, C, CR.GE, LHSR));
+
+ // Put SV in a virtual register to make it available from the new blocks.
+ ExportFromCurrentBlock(SV);
}
// Similar to the optimization above, if the Value being switched on is
@@ -1888,6 +1892,9 @@
FalseBB = CurMF->CreateMachineBasicBlock(LLVMBB);
CurMF->insert(BBI, FalseBB);
WorkList.push_back(CaseRec(FalseBB,CR.LT,C,RHSR));
+
+ // Put SV in a virtual register to make it available from the new blocks.
+ ExportFromCurrentBlock(SV);
}
// Create a CaseBlock record representing a conditional branch to
@@ -2013,6 +2020,9 @@
BTC.push_back(BitTestCase(CasesBits[i].Mask,
CaseBB,
CasesBits[i].BB));
+
+ // Put SV in a virtual register to make it available from the new blocks.
+ ExportFromCurrentBlock(SV);
}
BitTestBlock BTB(lowBound, cmpRange, SV,