From a03b5b44fcb08d492c73aa81d35330ff9f7a8142 Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.cardoso@gmail.com>
Date: Fri, 13 Nov 2009 18:49:59 +0000
Subject: [PATCH] Support fp64 immediate zero, this fixes only part of PR5445
 because the testcase is triggering one more bug.

llvm-svn: 88674
---
 llvm/lib/Target/Mips/MipsISelDAGToDAG.cpp | 10 ++++++++++
 llvm/lib/Target/Mips/MipsInstrInfo.cpp    | 15 ++++++++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/Mips/MipsISelDAGToDAG.cpp b/llvm/lib/Target/Mips/MipsISelDAGToDAG.cpp
index a7216582fb3f..42e70bb720d1 100644
--- a/llvm/lib/Target/Mips/MipsISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Mips/MipsISelDAGToDAG.cpp
@@ -314,6 +314,16 @@ SDNode* MipsDAGToDAGISel::Select(SDValue N) {
     case ISD::GLOBAL_OFFSET_TABLE:
       return getGlobalBaseReg();
 
+    case ISD::ConstantFP: {
+      ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(N);
+      if (N.getValueType() == MVT::f64 && CN->isExactlyValue(+0.0)) { 
+        SDValue Zero = CurDAG->getRegister(Mips::ZERO, MVT::i32);
+        ReplaceUses(N, Zero);
+        return Zero.getNode();
+      }
+      break;
+    }
+
     /// Handle direct and indirect calls when using PIC. On PIC, when 
     /// GOT is smaller than about 64k (small code) the GA target is 
     /// loaded with only one instruction. Otherwise GA's target must 
diff --git a/llvm/lib/Target/Mips/MipsInstrInfo.cpp b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
index 91599043cb2c..af64c9f74112 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
@@ -134,6 +134,9 @@ copyRegToReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
              const TargetRegisterClass *DestRC,
              const TargetRegisterClass *SrcRC) const {
   DebugLoc DL = DebugLoc::getUnknownLoc();
+  const MachineFunction *MF = MBB.getParent();
+  const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
+  
   if (I != MBB.end()) DL = I->getDebugLoc();
 
   if (DestRC != SrcRC) {
@@ -153,6 +156,13 @@ copyRegToReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
     else if ((DestRC == Mips::FGR32RegisterClass) &&
              (SrcRC == Mips::CPURegsRegisterClass))
       BuildMI(MBB, I, DL, get(Mips::MTC1), DestReg).addReg(SrcReg);
+    else if ((DestRC == Mips::AFGR64RegisterClass) &&
+             (SrcRC == Mips::CPURegsRegisterClass) &&
+             (SrcReg == Mips::ZERO)) {
+      const unsigned *AliasSet = TRI->getAliasSet(DestReg);
+      BuildMI(MBB, I, DL, get(Mips::MTC1), AliasSet[0]).addReg(SrcReg);
+      BuildMI(MBB, I, DL, get(Mips::MTC1), AliasSet[1]).addReg(SrcReg);
+    }         
 
     // Move from/to Hi/Lo registers
     else if ((DestRC == Mips::HILORegisterClass) &&
@@ -163,9 +173,8 @@ copyRegToReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
                (DestRC == Mips::CPURegsRegisterClass)) {
       unsigned Opc = (SrcReg == Mips::HI) ? Mips::MFHI : Mips::MFLO;
       BuildMI(MBB, I, DL, get(Opc), DestReg);
-
-    // Can't copy this register
-    } else
+    } else 
+      // Can't copy this register
       return false; 
 
     return true;