From c0a9f820d851baf66577a87c69ef383df41bbe32 Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Thu, 29 Mar 2012 21:56:11 +0000
Subject: [PATCH] Try using vmov.i32 to materialize FP32 constants that can't
 be materialized by vmov.f32.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153696 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMISelLowering.cpp | 77 +++++++++++++++++++++---------
 1 file changed, 54 insertions(+), 23 deletions(-)

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 433b444384d..8abbf76ff6f 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -507,7 +507,7 @@ ARMTargetLowering::ARMTargetLowering(TargetMachine &TM)
     setOperationAction(ISD::FRINT, MVT::v2f64, Expand);
     setOperationAction(ISD::FNEARBYINT, MVT::v2f64, Expand);
     setOperationAction(ISD::FFLOOR, MVT::v2f64, Expand);
-    
+
     setOperationAction(ISD::FSQRT, MVT::v4f32, Expand);
     setOperationAction(ISD::FSIN, MVT::v4f32, Expand);
     setOperationAction(ISD::FCOS, MVT::v4f32, Expand);
@@ -3672,27 +3672,6 @@ static SDValue LowerVSETCC(SDValue Op, SelectionDAG &DAG) {
   return Result;
 }
 
-SDValue ARMTargetLowering::LowerConstantFP(SDValue Op, SelectionDAG &DAG,
-                                           const ARMSubtarget *ST) const {
-  if (!ST->useNEONForSinglePrecisionFP() || !ST->hasVFP3() || ST->hasD16())
-    return SDValue();
-
-  ConstantFPSDNode *CFP = cast<ConstantFPSDNode>(Op);
-  assert(Op.getValueType() == MVT::f32 &&
-         "ConstantFP custom lowering should only occur for f32.");
-
-  APFloat FPVal = CFP->getValueAPF();
-  int ImmVal = ARM_AM::getFP32Imm(FPVal);
-  if (ImmVal == -1)
-    return SDValue();
-
-  DebugLoc DL = Op.getDebugLoc();
-  SDValue NewVal = DAG.getTargetConstant(ImmVal, MVT::i32);
-  SDValue VecConstant = DAG.getNode(ARMISD::VMOVFPIMM, DL, MVT::v2f32, NewVal);
-  return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::f32, VecConstant,
-                     DAG.getConstant(0, MVT::i32));
-}
-
 /// isNEONModifiedImm - Check if the specified splat value corresponds to a
 /// valid vector constant for a NEON instruction with a "modified immediate"
 /// operand (e.g., VMOV).  If so, return the encoded value.
@@ -3829,6 +3808,58 @@ static SDValue isNEONModifiedImm(uint64_t SplatBits, uint64_t SplatUndef,
   return DAG.getTargetConstant(EncodedVal, MVT::i32);
 }
 
+SDValue ARMTargetLowering::LowerConstantFP(SDValue Op, SelectionDAG &DAG,
+                                           const ARMSubtarget *ST) const {
+  if (!ST->useNEONForSinglePrecisionFP() || !ST->hasVFP3() || ST->hasD16())
+    return SDValue();
+
+  ConstantFPSDNode *CFP = cast<ConstantFPSDNode>(Op);
+  assert(Op.getValueType() == MVT::f32 &&
+         "ConstantFP custom lowering should only occur for f32.");
+
+  // Try splatting with a VMOV.f32...
+  APFloat FPVal = CFP->getValueAPF();
+  int ImmVal = ARM_AM::getFP32Imm(FPVal);
+  if (ImmVal != -1) {
+    DebugLoc DL = Op.getDebugLoc();
+    SDValue NewVal = DAG.getTargetConstant(ImmVal, MVT::i32);
+    SDValue VecConstant = DAG.getNode(ARMISD::VMOVFPIMM, DL, MVT::v2f32,
+                                      NewVal);
+    return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::f32, VecConstant,
+                       DAG.getConstant(0, MVT::i32));
+  }
+
+  // If that fails, try a VMOV.i32
+  EVT VMovVT;
+  unsigned iVal = FPVal.bitcastToAPInt().getZExtValue();
+  SDValue NewVal = isNEONModifiedImm(iVal, 0, 32, DAG, VMovVT, false,
+                                     VMOVModImm);
+  if (NewVal != SDValue()) {
+    DebugLoc DL = Op.getDebugLoc();
+    SDValue VecConstant = DAG.getNode(ARMISD::VMOVIMM, DL, VMovVT,
+                                      NewVal);
+    SDValue VecFConstant = DAG.getNode(ISD::BITCAST, DL, MVT::v2f32,
+                                       VecConstant);
+    return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::f32, VecFConstant,
+                       DAG.getConstant(0, MVT::i32));
+  }
+
+  // Finally, try a VMVN.i32
+  NewVal = isNEONModifiedImm(~iVal & 0xffffffff, 0, 32, DAG, VMovVT, false,
+                             VMVNModImm);
+  if (NewVal != SDValue()) {
+    DebugLoc DL = Op.getDebugLoc();
+    SDValue VecConstant = DAG.getNode(ARMISD::VMVNIMM, DL, VMovVT, NewVal);
+    SDValue VecFConstant = DAG.getNode(ISD::BITCAST, DL, MVT::v2f32,
+                                       VecConstant);
+    return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::f32, VecFConstant,
+                       DAG.getConstant(0, MVT::i32));
+  }
+
+  return SDValue();
+}
+
+
 static bool isVEXTMask(ArrayRef<int> M, EVT VT,
                        bool &ReverseVEXT, unsigned &Imm) {
   unsigned NumElts = VT.getVectorNumElements();
@@ -5869,7 +5900,7 @@ EmitSjLjDispatchBlock(MachineInstr *MI, MachineBasicBlock *MBB) const {
     BuildMI(DispatchBB, dl, TII->get(ARM::tInt_eh_sjlj_dispatchsetup));
   else if (!Subtarget->hasVFP2())
     BuildMI(DispatchBB, dl, TII->get(ARM::Int_eh_sjlj_dispatchsetup_nofp));
-  else 
+  else
     BuildMI(DispatchBB, dl, TII->get(ARM::Int_eh_sjlj_dispatchsetup));
 
   unsigned NumLPads = LPadList.size();