From 892979effc920252246c8e6909b552e936748a76 Mon Sep 17 00:00:00 2001
From: Aditya Nandakumar <aditya_nandakumar@apple.com>
Date: Fri, 25 Aug 2017 04:57:27 +0000
Subject: [GISel]: Implement widenScalar for Legalizing G_PHI

https://reviews.llvm.org/D37018

llvm-svn: 311763
---
 llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp  | 31 ++++++++++++++++++++++++
 llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp | 30 ++++++++++++-----------
 2 files changed, 47 insertions(+), 14 deletions(-)

(limited to 'llvm/lib/CodeGen')

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index c54b12b52ee..5e75f4da9bd 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -659,6 +659,37 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
     MI.getOperand(2).setReg(OffsetExt);
     return Legalized;
   }
+  case TargetOpcode::G_PHI: {
+    assert(TypeIdx == 0 && "Expecting only Idx 0");
+    MachineFunction *MF = MI.getParent()->getParent();
+    auto getExtendedReg = [this, MF, WideTy](unsigned Reg,
+                                             MachineBasicBlock &MBB) {
+      auto FirstTermIt = MBB.getFirstTerminator();
+      MIRBuilder.setInsertPt(MBB, FirstTermIt);
+      MachineInstr *DefMI = MRI.getVRegDef(Reg);
+      MachineInstrBuilder MIB;
+      if (DefMI->getOpcode() == TargetOpcode::G_TRUNC)
+        MIB = MIRBuilder.buildAnyExtOrTrunc(WideTy,
+                                            DefMI->getOperand(1).getReg());
+      else
+        MIB = MIRBuilder.buildAnyExt(WideTy, Reg);
+      return MIB->getOperand(0).getReg();
+    };
+    auto MIB = MIRBuilder.buildInstr(TargetOpcode::G_PHI, WideTy);
+    for (auto OpIt = MI.operands_begin() + 1, OpE = MI.operands_end();
+         OpIt != OpE;) {
+      unsigned Reg = OpIt++->getReg();
+      MachineBasicBlock *OpMBB = OpIt++->getMBB();
+      MIB.addReg(getExtendedReg(Reg, *OpMBB));
+      MIB.addMBB(OpMBB);
+    }
+    auto *MBB = MI.getParent();
+    MIRBuilder.setInsertPt(*MBB, MBB->getFirstNonPHI());
+    MIRBuilder.buildTrunc(MI.getOperand(0).getReg(),
+                          MIB->getOperand(0).getReg());
+    MI.eraseFromParent();
+    return Legalized;
+  }
   }
 }
 
diff --git a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
index 8ca07f36c9c..b4fe5f15fdd 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -346,14 +346,17 @@ MachineInstrBuilder MachineIRBuilder::buildZExt(unsigned Res, unsigned Op) {
   return buildInstr(TargetOpcode::G_ZEXT).addDef(Res).addUse(Op);
 }
 
-MachineInstrBuilder MachineIRBuilder::buildSExtOrTrunc(unsigned Res,
-                                                       unsigned Op) {
+MachineInstrBuilder
+MachineIRBuilder::buildExtOrTrunc(unsigned ExtOpc, unsigned Res, unsigned Op) {
+  assert((TargetOpcode::G_ANYEXT == ExtOpc || TargetOpcode::G_ZEXT == ExtOpc ||
+          TargetOpcode::G_SEXT == ExtOpc) &&
+         "Expecting Extending Opc");
   assert(MRI->getType(Res).isScalar() || MRI->getType(Res).isVector());
   assert(MRI->getType(Res).isScalar() == MRI->getType(Op).isScalar());
 
   unsigned Opcode = TargetOpcode::COPY;
   if (MRI->getType(Res).getSizeInBits() > MRI->getType(Op).getSizeInBits())
-    Opcode = TargetOpcode::G_SEXT;
+    Opcode = ExtOpc;
   else if (MRI->getType(Res).getSizeInBits() < MRI->getType(Op).getSizeInBits())
     Opcode = TargetOpcode::G_TRUNC;
   else
@@ -362,20 +365,19 @@ MachineInstrBuilder MachineIRBuilder::buildSExtOrTrunc(unsigned Res,
   return buildInstr(Opcode).addDef(Res).addUse(Op);
 }
 
-MachineInstrBuilder MachineIRBuilder::buildZExtOrTrunc(unsigned Res,
+MachineInstrBuilder MachineIRBuilder::buildSExtOrTrunc(unsigned Res,
                                                        unsigned Op) {
-  assert(MRI->getType(Res).isScalar() || MRI->getType(Res).isVector());
-  assert(MRI->getType(Res).isScalar() == MRI->getType(Op).isScalar());
+  return buildExtOrTrunc(TargetOpcode::G_SEXT, Res, Op);
+}
 
-  unsigned Opcode = TargetOpcode::COPY;
-  if (MRI->getType(Res).getSizeInBits() > MRI->getType(Op).getSizeInBits())
-    Opcode = TargetOpcode::G_ZEXT;
-  else if (MRI->getType(Res).getSizeInBits() < MRI->getType(Op).getSizeInBits())
-    Opcode = TargetOpcode::G_TRUNC;
-  else
-    assert(MRI->getType(Res) == MRI->getType(Op));
+MachineInstrBuilder MachineIRBuilder::buildZExtOrTrunc(unsigned Res,
+                                                       unsigned Op) {
+  return buildExtOrTrunc(TargetOpcode::G_ZEXT, Res, Op);
+}
 
-  return buildInstr(Opcode).addDef(Res).addUse(Op);
+MachineInstrBuilder MachineIRBuilder::buildAnyExtOrTrunc(unsigned Res,
+                                                         unsigned Op) {
+  return buildExtOrTrunc(TargetOpcode::G_ANYEXT, Res, Op);
 }
 
 MachineInstrBuilder MachineIRBuilder::buildCast(unsigned Dst, unsigned Src) {
-- 
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