Move HandlePHINodesInSuccessorBlocks functions out of SelectionDAGISel
and into SelectionDAGBuilder and FastISel.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102123 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index ad7b411..132c42e 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -744,7 +744,8 @@
FastISel::FastISel(MachineFunction &mf,
DenseMap<const Value *, unsigned> &vm,
DenseMap<const BasicBlock *, MachineBasicBlock *> &bm,
- DenseMap<const AllocaInst *, int> &am
+ DenseMap<const AllocaInst *, int> &am,
+ std::vector<std::pair<MachineInstr*, unsigned> > &pn
#ifndef NDEBUG
, SmallSet<const Instruction *, 8> &cil
#endif
@@ -753,6 +754,7 @@
ValueMap(vm),
MBBMap(bm),
StaticAllocaMap(am),
+ PHINodesToUpdate(pn),
#ifndef NDEBUG
CatchInfoLost(cil),
#endif
@@ -1020,3 +1022,67 @@
unsigned FastISel::FastEmitZExtFromI1(MVT VT, unsigned Op) {
return FastEmit_ri(VT, VT, ISD::AND, Op, 1);
}
+
+/// HandlePHINodesInSuccessorBlocks - Handle PHI nodes in successor blocks.
+/// Emit code to ensure constants are copied into registers when needed.
+/// Remember the virtual registers that need to be added to the Machine PHI
+/// nodes as input. We cannot just directly add them, because expansion
+/// might result in multiple MBB's for one BB. As such, the start of the
+/// BB might correspond to a different MBB than the end.
+bool FastISel::HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB) {
+ const TerminatorInst *TI = LLVMBB->getTerminator();
+
+ SmallPtrSet<MachineBasicBlock *, 4> SuccsHandled;
+ unsigned OrigNumPHINodesToUpdate = PHINodesToUpdate.size();
+
+ // Check successor nodes' PHI nodes that expect a constant to be available
+ // from this block.
+ for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
+ const BasicBlock *SuccBB = TI->getSuccessor(succ);
+ if (!isa<PHINode>(SuccBB->begin())) continue;
+ MachineBasicBlock *SuccMBB = MBBMap[SuccBB];
+
+ // If this terminator has multiple identical successors (common for
+ // switches), only handle each succ once.
+ if (!SuccsHandled.insert(SuccMBB)) continue;
+
+ MachineBasicBlock::iterator MBBI = SuccMBB->begin();
+
+ // At this point we know that there is a 1-1 correspondence between LLVM PHI
+ // nodes and Machine PHI nodes, but the incoming operands have not been
+ // emitted yet.
+ for (BasicBlock::const_iterator I = SuccBB->begin();
+ const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
+ // Ignore dead phi's.
+ if (PN->use_empty()) continue;
+
+ // Only handle legal types. Two interesting things to note here. First,
+ // by bailing out early, we may leave behind some dead instructions,
+ // since SelectionDAG's HandlePHINodesInSuccessorBlocks will insert its
+ // own moves. Second, this check is necessary becuase FastISel doesn't
+ // use CreateRegForValue to create registers, so it always creates
+ // exactly one register for each non-void instruction.
+ EVT VT = TLI.getValueType(PN->getType(), /*AllowUnknown=*/true);
+ if (VT == MVT::Other || !TLI.isTypeLegal(VT)) {
+ // Promote MVT::i1.
+ if (VT == MVT::i1)
+ VT = TLI.getTypeToTransformTo(LLVMBB->getContext(), VT);
+ else {
+ PHINodesToUpdate.resize(OrigNumPHINodesToUpdate);
+ return false;
+ }
+ }
+
+ const Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
+
+ unsigned Reg = getRegForValue(PHIOp);
+ if (Reg == 0) {
+ PHINodesToUpdate.resize(OrigNumPHINodesToUpdate);
+ return false;
+ }
+ PHINodesToUpdate.push_back(std::make_pair(MBBI++, Reg));
+ }
+ }
+
+ return true;
+}