Use vmov.f32 to materialize f32 consts on ARM. This relaxes constraints on

register allocation by allowing all 32 D-registers to be used. Patch by Cameron
Zwarich.

llvm-svn: 152824

llvm/lib/Target/ARM/ARMISelLowering.cpp

@@ -456,6 +456,8 @@ ARMTargetLowering::ARMTargetLowering(TargetMachine &TM)
     setLoadExtAction(ISD::EXTLOAD, (MVT::SimpleValueType)VT, Expand);
   }
 
+  setOperationAction(ISD::ConstantFP, MVT::f32, Custom);
+
   if (Subtarget->hasNEON()) {
     addDRTypeForNEON(MVT::v2f32);
     addDRTypeForNEON(MVT::v8i8);
@@ -3673,6 +3675,27 @@ 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.
@@ -5109,6 +5132,7 @@ SDValue ARMTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   case ISD::SRA_PARTS:     return LowerShiftRightParts(Op, DAG);
   case ISD::CTTZ:          return LowerCTTZ(Op.getNode(), DAG, Subtarget);
   case ISD::SETCC:         return LowerVSETCC(Op, DAG);
+  case ISD::ConstantFP:    return LowerConstantFP(Op, DAG, Subtarget);
   case ISD::BUILD_VECTOR:  return LowerBUILD_VECTOR(Op, DAG, Subtarget);
   case ISD::VECTOR_SHUFFLE: return LowerVECTOR_SHUFFLE(Op, DAG);
   case ISD::INSERT_VECTOR_ELT: return LowerINSERT_VECTOR_ELT(Op, DAG);

llvm/lib/Target/ARM/ARMISelLowering.h

@@ -434,6 +434,8 @@ namespace llvm {
     SDValue LowerShiftRightParts(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerShiftLeftParts(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFLT_ROUNDS_(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerConstantFP(SDValue Op, SelectionDAG &DAG,
+                            const ARMSubtarget *ST) const;
     SDValue LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG,
                               const ARMSubtarget *ST) const;
 

llvm/test/CodeGen/ARM/2009-11-07-SubRegAsmPrinting.ll

@@ -1,4 +1,4 @@
-; RUN: llc -mcpu=cortex-a8 < %s | FileCheck %s
+; RUN: llc -mcpu=cortex-a8 -mattr=-neonfp < %s | FileCheck %s
 ; PR5423
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64"

llvm/test/CodeGen/ARM/2010-12-07-PEIBug.ll

@@ -4,36 +4,12 @@
 define hidden void @foo() nounwind ssp {
 entry:
 ; CHECK: foo:
-; CHECK: push {r7, lr}
-; CHECK-NEXT: mov r7, sp
+; CHECK: mov r7, sp
 ; CHECK-NEXT: vpush {d8}
 ; CHECK-NEXT: vpush {d10, d11}
-  %tmp40 = load <4 x i8>* undef
-  %tmp41 = extractelement <4 x i8> %tmp40, i32 2
-  %conv42 = zext i8 %tmp41 to i32
-  %conv43 = sitofp i32 %conv42 to float
-  %div44 = fdiv float %conv43, 2.560000e+02
-  %vecinit45 = insertelement <4 x float> undef, float %div44, i32 2
-  %vecinit46 = insertelement <4 x float> %vecinit45, float 1.000000e+00, i32 3
-  store <4 x float> %vecinit46, <4 x float>* undef
-  br i1 undef, label %if.then105, label %if.else109
-
-if.then105:                                       ; preds = %entry
-  br label %if.end114
-
-if.else109:                                       ; preds = %entry
-  br label %if.end114
-
-if.end114:                                        ; preds = %if.else109, %if.then105
-  %call185 = call float @bar()
-  %vecinit186 = insertelement <4 x float> undef, float %call185, i32 1
-  %call189 = call float @bar()
-  %vecinit190 = insertelement <4 x float> %vecinit186, float %call189, i32 2
-  %vecinit191 = insertelement <4 x float> %vecinit190, float 1.000000e+00, i32 3
-  store <4 x float> %vecinit191, <4 x float>* undef
+  tail call void asm sideeffect "","~{d8},~{d10},~{d11}"() nounwind
 ; CHECK: vpop {d10, d11}
 ; CHECK-NEXT: vpop {d8}
-; CHECK-NEXT: pop {r7, pc}
   ret void
 }