[PATCH] D122171: [SelectionDAG] Move extension type for ConstantSDNode from getCopyToRegs to HandlePHINodesInSuccessorBlocks.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, efriedma, arsenm, spatel.
Herald added subscribers: StephenFan, ecnelises, hiraditya.
Herald added a project: All.
craig.topper requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

D122053 <https://reviews.llvm.org/D122053> set the ExtendType for ConstantSDNodes in getCopyToRegs to
ZERO_EXTEND to match assumptions in ComputePHILiveOutRegInfo. PHIs
are probably not the only way ConstantSDNodeNodes can get to
getCopyToRegs.

This patch adds an ExtendType parameter to CopyValueToVirtualRegister and
has HandlePHINodesInSuccessorBlocks pass ISD::ZERO_EXTEND for ConstantInts.
This way we only affect ConstantSDNodes for PHIs.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D122171

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -284,7 +284,8 @@
     return CurInst ? CurInst->getDebugLoc() : DebugLoc();
   }
 
-  void CopyValueToVirtualRegister(const Value *V, unsigned Reg);
+  void CopyValueToVirtualRegister(const Value *V, unsigned Reg,
+                                  ISD::NodeType ExtendType = ISD::ANY_EXTEND);
 
   void visit(const Instruction &I);
 
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -918,10 +918,7 @@
                                           CallConv.getValue(), RegVTs[Value])
                                     : RegVTs[Value];
 
-    // We need to zero extend constants that are liveout to match assumptions
-    // in FunctionLoweringInfo::ComputePHILiveOutRegInfo.
-    if (ExtendKind == ISD::ANY_EXTEND &&
-        (TLI.isZExtFree(Val, RegisterVT) || isa<ConstantSDNode>(Val)))
+    if (ExtendKind == ISD::ANY_EXTEND && TLI.isZExtFree(Val, RegisterVT))
       ExtendKind = ISD::ZERO_EXTEND;
 
     getCopyToParts(DAG, dl, Val.getValue(Val.getResNo() + Value), &Parts[Part],
@@ -10011,8 +10008,9 @@
   llvm_unreachable("LowerOperation not implemented for this target!");
 }
 
-void
-SelectionDAGBuilder::CopyValueToVirtualRegister(const Value *V, unsigned Reg) {
+void SelectionDAGBuilder::CopyValueToVirtualRegister(const Value *V,
+                                                     unsigned Reg,
+                                                     ISD::NodeType ExtendType) {
   SDValue Op = getNonRegisterValue(V);
   assert((Op.getOpcode() != ISD::CopyFromReg ||
           cast<RegisterSDNode>(Op.getOperand(1))->getReg() != Reg) &&
@@ -10027,10 +10025,11 @@
                    None); // This is not an ABI copy.
   SDValue Chain = DAG.getEntryNode();
 
-  ISD::NodeType ExtendType = ISD::ANY_EXTEND;
-  auto PreferredExtendIt = FuncInfo.PreferredExtendType.find(V);
-  if (PreferredExtendIt != FuncInfo.PreferredExtendType.end())
-    ExtendType = PreferredExtendIt->second;
+  if (ExtendType == ISD::ANY_EXTEND) {
+    auto PreferredExtendIt = FuncInfo.PreferredExtendType.find(V);
+    if (PreferredExtendIt != FuncInfo.PreferredExtendType.end())
+      ExtendType = PreferredExtendIt->second;
+  }
   RFV.getCopyToRegs(Op, DAG, getCurSDLoc(), Chain, nullptr, V, ExtendType);
   PendingExports.push_back(Chain);
 }
@@ -10640,7 +10639,11 @@
         unsigned &RegOut = ConstantsOut[C];
         if (RegOut == 0) {
           RegOut = FuncInfo.CreateRegs(C);
-          CopyValueToVirtualRegister(C, RegOut);
+          // We need to zero extend ConstantInt phi operands to match
+          // assumptions in FunctionLoweringInfo::ComputePHILiveOutRegInfo.
+          ISD::NodeType ExtendType =
+              isa<ConstantInt>(PHIOp) ? ISD::ZERO_EXTEND : ISD::ANY_EXTEND;
+          CopyValueToVirtualRegister(C, RegOut, ExtendType);
         }
         Reg = RegOut;
       } else {


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