[AArch64] Compute the Newton series for reciprocals natively

Implement the Newton series for square root, its reciprocal and reciprocal
natively using the specialized instructions in AArch64 to perform each
series iteration.

Differential revision: https://reviews.llvm.org/D26518

llvm-svn: 286907

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 803481e..403021e 100644 (file)
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -959,8 +959,10 @@ const char *AArch64TargetLowering::getTargetNodeName(unsigned Opcode) const {
   case AArch64ISD::ST4LANEpost:       return "AArch64ISD::ST4LANEpost";
   case AArch64ISD::SMULL:             return "AArch64ISD::SMULL";
   case AArch64ISD::UMULL:             return "AArch64ISD::UMULL";
-  case AArch64ISD::FRSQRTE:           return "AArch64ISD::FRSQRTE";
   case AArch64ISD::FRECPE:            return "AArch64ISD::FRECPE";
+  case AArch64ISD::FRECPS:            return "AArch64ISD::FRECPS";
+  case AArch64ISD::FRSQRTE:           return "AArch64ISD::FRSQRTE";
+  case AArch64ISD::FRSQRTS:           return "AArch64ISD::FRSQRTS";
   }
   return nullptr;
 }
@@ -4653,7 +4655,34 @@ SDValue AArch64TargetLowering::getSqrtEstimate(SDValue Operand,
       (Enabled == ReciprocalEstimate::Unspecified && Subtarget->useRSqrt()))
     if (SDValue Estimate = getEstimate(Subtarget, AArch64ISD::FRSQRTE, Operand,
                                        DAG, ExtraSteps)) {
-      UseOneConst = true;
+      SDLoc DL(Operand);
+      EVT VT = Operand.getValueType();
+
+      SDNodeFlags Flags;
+      Flags.setUnsafeAlgebra(true);
+
+      // Newton reciprocal square root iteration: E * 0.5 * (3 - X * E^2)
+      // AArch64 reciprocal square root iteration instruction: 0.5 * (3 - M * N)
+      for (int i = ExtraSteps; i > 0; --i) {
+        SDValue Step = DAG.getNode(ISD::FMUL, DL, VT, Estimate, Estimate,
+                                   &Flags);
+        Step = DAG.getNode(AArch64ISD::FRSQRTS, DL, VT, Operand, Step, &Flags);
+        Estimate = DAG.getNode(ISD::FMUL, DL, VT, Estimate, Step, &Flags);
+      }
+
+      if (!Reciprocal) {
+        EVT CCVT = getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(),
+                                      VT);
+        SDValue FPZero = DAG.getConstantFP(0.0, DL, VT);
+        SDValue Eq = DAG.getSetCC(DL, CCVT, Operand, FPZero, ISD::SETEQ);
+
+        Estimate = DAG.getNode(ISD::FMUL, DL, VT, Operand, Estimate, &Flags);
+        // Correct the result if the operand is 0.0.
+        Estimate = DAG.getNode(VT.isVector() ? ISD::VSELECT : ISD::SELECT, DL,
+                               VT, Eq, Operand, Estimate);
+      }
+
+      ExtraSteps = 0;
       return Estimate;
     }
 
@@ -4665,8 +4694,24 @@ SDValue AArch64TargetLowering::getRecipEstimate(SDValue Operand,
                                                 int &ExtraSteps) const {
   if (Enabled == ReciprocalEstimate::Enabled)
     if (SDValue Estimate = getEstimate(Subtarget, AArch64ISD::FRECPE, Operand,
-                                       DAG, ExtraSteps))
+                                       DAG, ExtraSteps)) {
+      SDLoc DL(Operand);
+      EVT VT = Operand.getValueType();
+
+      SDNodeFlags Flags;
+      Flags.setUnsafeAlgebra(true);
+
+      // Newton reciprocal iteration: E * (2 - X * E)
+      // AArch64 reciprocal iteration instruction: (2 - M * N)
+      for (int i = ExtraSteps; i > 0; --i) {
+        SDValue Step = DAG.getNode(AArch64ISD::FRECPS, DL, VT, Operand,
+                                   Estimate, &Flags);
+        Estimate = DAG.getNode(ISD::FMUL, DL, VT, Estimate, Step, &Flags);
+      }
+
+      ExtraSteps = 0;
       return Estimate;
+    }
 
   return SDValue();
 }

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.h b/llvm/lib/Target/AArch64/AArch64ISelLowering.h
index 7b317d6..7867d7c 100644 (file)
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.h
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.h
@@ -187,9 +187,9 @@ enum NodeType : unsigned {
   SMULL,
   UMULL,
 
-  // Reciprocal estimates.
-  FRECPE,
-  FRSQRTE,
+  // Reciprocal estimates and steps.
+  FRECPE, FRECPS,
+  FRSQRTE, FRSQRTS,
 
   // NEON Load/Store with post-increment base updates
   LD2post = ISD::FIRST_TARGET_MEMORY_OPCODE,

diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.td b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
index e8386a6..3bed500 100644 (file)
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.td
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
@@ -287,7 +287,9 @@ def AArch64smull    : SDNode<"AArch64ISD::SMULL", SDT_AArch64mull>;
 def AArch64umull    : SDNode<"AArch64ISD::UMULL", SDT_AArch64mull>;
 
 def AArch64frecpe   : SDNode<"AArch64ISD::FRECPE", SDTFPUnaryOp>;
+def AArch64frecps   : SDNode<"AArch64ISD::FRECPS", SDTFPBinOp>;
 def AArch64frsqrte  : SDNode<"AArch64ISD::FRSQRTE", SDTFPUnaryOp>;
+def AArch64frsqrts  : SDNode<"AArch64ISD::FRSQRTS", SDTFPBinOp>;
 
 def AArch64saddv    : SDNode<"AArch64ISD::SADDV", SDT_AArch64UnaryVec>;
 def AArch64uaddv    : SDNode<"AArch64ISD::UADDV", SDT_AArch64UnaryVec>;
@@ -3422,6 +3424,17 @@ def : Pat<(v1f64 (AArch64frecpe (v1f64 FPR64:$Rn))),
 def : Pat<(v2f64 (AArch64frecpe (v2f64 FPR128:$Rn))),
           (FRECPEv2f64 FPR128:$Rn)>;
 
+def : Pat<(f32 (AArch64frecps (f32 FPR32:$Rn), (f32 FPR32:$Rm))),
+          (FRECPS32 FPR32:$Rn, FPR32:$Rm)>;
+def : Pat<(v2f32 (AArch64frecps (v2f32 V64:$Rn), (v2f32 V64:$Rm))),
+          (FRECPSv2f32 V64:$Rn, V64:$Rm)>;
+def : Pat<(v4f32 (AArch64frecps (v4f32 FPR128:$Rn), (v4f32 FPR128:$Rm))),
+          (FRECPSv4f32 FPR128:$Rn, FPR128:$Rm)>;
+def : Pat<(f64 (AArch64frecps (f64 FPR64:$Rn), (f64 FPR64:$Rm))),
+          (FRECPS64 FPR64:$Rn, FPR64:$Rm)>;
+def : Pat<(v2f64 (AArch64frecps (v2f64 FPR128:$Rn), (v2f64 FPR128:$Rm))),
+          (FRECPSv2f64 FPR128:$Rn, FPR128:$Rm)>;
+
 def : Pat<(f32 (int_aarch64_neon_frecpx (f32 FPR32:$Rn))),
           (FRECPXv1i32 FPR32:$Rn)>;
 def : Pat<(f64 (int_aarch64_neon_frecpx (f64 FPR64:$Rn))),
@@ -3447,6 +3460,17 @@ def : Pat<(v1f64 (AArch64frsqrte (v1f64 FPR64:$Rn))),
 def : Pat<(v2f64 (AArch64frsqrte (v2f64 FPR128:$Rn))),
           (FRSQRTEv2f64 FPR128:$Rn)>;
 
+def : Pat<(f32 (AArch64frsqrts (f32 FPR32:$Rn), (f32 FPR32:$Rm))),
+          (FRSQRTS32 FPR32:$Rn, FPR32:$Rm)>;
+def : Pat<(v2f32 (AArch64frsqrts (v2f32 V64:$Rn), (v2f32 V64:$Rm))),
+          (FRSQRTSv2f32 V64:$Rn, V64:$Rm)>;
+def : Pat<(v4f32 (AArch64frsqrts (v4f32 FPR128:$Rn), (v4f32 FPR128:$Rm))),
+          (FRSQRTSv4f32 FPR128:$Rn, FPR128:$Rm)>;
+def : Pat<(f64 (AArch64frsqrts (f64 FPR64:$Rn), (f64 FPR64:$Rm))),
+          (FRSQRTS64 FPR64:$Rn, FPR64:$Rm)>;
+def : Pat<(v2f64 (AArch64frsqrts (v2f64 FPR128:$Rn), (v2f64 FPR128:$Rm))),
+          (FRSQRTSv2f64 FPR128:$Rn, FPR128:$Rm)>;
+
 // If an integer is about to be converted to a floating point value,
 // just load it on the floating point unit.
 // Here are the patterns for 8 and 16-bits to float.

diff --git a/llvm/test/CodeGen/AArch64/recp-fastmath.ll b/llvm/test/CodeGen/AArch64/recp-fastmath.ll
index 280ef75..38e0fb3 100644 (file)
--- a/llvm/test/CodeGen/AArch64/recp-fastmath.ll
+++ b/llvm/test/CodeGen/AArch64/recp-fastmath.ll
@@ -16,8 +16,8 @@ define float @frecp1(float %x) #1 {
 
 ; CHECK-LABEL: frecp1:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: frecpe
-; CHECK-NEXT: fmov
+; CHECK-NEXT: frecpe [[R:s[0-7]]]
+; CHECK-NEXT: frecps {{s[0-7](, s[0-7])?}}, [[R]]
 }
 
 define <2 x float> @f2recp0(<2 x float> %x) #0 {
@@ -36,8 +36,8 @@ define <2 x float> @f2recp1(<2 x float> %x) #1 {
 
 ; CHECK-LABEL: f2recp1:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frecpe
+; CHECK-NEXT: frecpe [[R:v[0-7]\.2s]]
+; CHECK-NEXT: frecps {{v[0-7]\.2s(, v[0-7].2s)?}}, [[R]]
 }
 
 define <4 x float> @f4recp0(<4 x float> %x) #0 {
@@ -56,8 +56,8 @@ define <4 x float> @f4recp1(<4 x float> %x) #1 {
 
 ; CHECK-LABEL: f4recp1:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frecpe
+; CHECK-NEXT: frecpe [[R:v[0-7]\.4s]]
+; CHECK-NEXT: frecps {{v[0-7]\.4s(, v[0-7].4s)?}}, [[R]]
 }
 
 define <8 x float> @f8recp0(<8 x float> %x) #0 {
@@ -77,9 +77,10 @@ define <8 x float> @f8recp1(<8 x float> %x) #1 {
 
 ; CHECK-LABEL: f8recp1:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frecpe
-; CHECK: frecpe
+; CHECK-NEXT: frecpe [[RA:v[0-7]\.4s]]
+; CHECK-NEXT: frecpe [[RB:v[0-7]\.4s]]
+; CHECK-NEXT: frecps {{v[0-7]\.4s(, v[0-7].4s)?}}, [[RA]]
+; CHECK: frecps {{v[0-7]\.4s(, v[0-7].4s)?}}, [[RB]]
 }
 
 define double @drecp0(double %x) #0 {
@@ -98,8 +99,8 @@ define double @drecp1(double %x) #1 {
 
 ; CHECK-LABEL: drecp1:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: frecpe
-; CHECK-NEXT: fmov
+; CHECK-NEXT: frecpe [[R:d[0-7]]]
+; CHECK-NEXT: frecps {{d[0-7](, d[0-7])?}}, [[R]]
 }
 
 define <2 x double> @d2recp0(<2 x double> %x) #0 {
@@ -118,8 +119,8 @@ define <2 x double> @d2recp1(<2 x double> %x) #1 {
 
 ; CHECK-LABEL: d2recp1:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frecpe
+; CHECK-NEXT: frecpe [[R:v[0-7]\.2d]]
+; CHECK-NEXT: frecps {{v[0-7]\.2d(, v[0-7].2d)?}}, [[R]]
 }
 
 define <4 x double> @d4recp0(<4 x double> %x) #0 {
@@ -139,9 +140,10 @@ define <4 x double> @d4recp1(<4 x double> %x) #1 {
 
 ; CHECK-LABEL: d4recp1:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frecpe
-; CHECK: frecpe
+; CHECK-NEXT: frecpe [[RA:v[0-7]\.2d]]
+; CHECK-NEXT: frecpe [[RB:v[0-7]\.2d]]
+; CHECK-NEXT: frecps {{v[0-7]\.2d(, v[0-7].2d)?}}, [[RA]]
+; CHECK: frecps {{v[0-7]\.2d(, v[0-7].2d)?}}, [[RB]]
 }
 
 attributes #0 = { nounwind "unsafe-fp-math"="true" }

diff --git a/llvm/test/CodeGen/AArch64/sqrt-fastmath.ll b/llvm/test/CodeGen/AArch64/sqrt-fastmath.ll
index cd8200b..079562c 100644 (file)
--- a/llvm/test/CodeGen/AArch64/sqrt-fastmath.ll
+++ b/llvm/test/CodeGen/AArch64/sqrt-fastmath.ll
@@ -19,8 +19,10 @@ define float @fsqrt(float %a) #0 {
 
 ; CHECK-LABEL: fsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:s[0-7]]]
+; CHECK-NEXT: fmul [[RB:s[0-7]]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{s[0-7](, s[0-7])?}}, [[RB]]
+; CHECK: fcmp s0, #0
 }
 
 define <2 x float> @f2sqrt(<2 x float> %a) #0 {
@@ -33,9 +35,10 @@ define <2 x float> @f2sqrt(<2 x float> %a) #0 {
 
 ; CHECK-LABEL: f2sqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: mov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.2s]]
+; CHECK-NEXT: fmul [[RB:v[0-7]\.2s]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{v[0-7]\.2s(, v[0-7]\.2s)?}}, [[RB]]
+; CHECK: fcmeq {{v[0-7]\.2s, v0\.2s}}, #0
 }
 
 define <4 x float> @f4sqrt(<4 x float> %a) #0 {
@@ -48,9 +51,10 @@ define <4 x float> @f4sqrt(<4 x float> %a) #0 {
 
 ; CHECK-LABEL: f4sqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: mov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.4s]]
+; CHECK-NEXT: fmul [[RB:v[0-7]\.4s]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{v[0-7]\.4s(, v[0-7]\.4s)?}}, [[RB]]
+; CHECK: fcmeq {{v[0-7]\.4s, v0\.4s}}, #0
 }
 
 define <8 x float> @f8sqrt(<8 x float> %a) #0 {
@@ -64,10 +68,10 @@ define <8 x float> @f8sqrt(<8 x float> %a) #0 {
 
 ; CHECK-LABEL: f8sqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: mov
-; CHECK-NEXT: frsqrte
-; CHECK: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.4s]]
+; CHECK: fmul [[RB:v[0-7]\.4s]], [[RA]], [[RA]]
+; CHECK: frsqrts {{v[0-7]\.4s(, v[0-7]\.4s)?}}, [[RB]]
+; CHECK: fcmeq {{v[0-7]\.4s, v[0-1]\.4s}}, #0
 }
 
 define double @dsqrt(double %a) #0 {
@@ -80,8 +84,10 @@ define double @dsqrt(double %a) #0 {
 
 ; CHECK-LABEL: dsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:d[0-7]]]
+; CHECK-NEXT: fmul [[RB:d[0-7]]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{d[0-7](, d[0-7])?}}, [[RB]]
+; CHECK: fcmp d0, #0
 }
 
 define <2 x double> @d2sqrt(<2 x double> %a) #0 {
@@ -94,9 +100,10 @@ define <2 x double> @d2sqrt(<2 x double> %a) #0 {
 
 ; CHECK-LABEL: d2sqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: mov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.2d]]
+; CHECK-NEXT: fmul [[RB:v[0-7]\.2d]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{v[0-7]\.2d(, v[0-7]\.2d)?}}, [[RB]]
+; CHECK: fcmeq {{v[0-7]\.2d, v0\.2d}}, #0
 }
 
 define <4 x double> @d4sqrt(<4 x double> %a) #0 {
@@ -110,10 +117,10 @@ define <4 x double> @d4sqrt(<4 x double> %a) #0 {
 
 ; CHECK-LABEL: d4sqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: mov
-; CHECK-NEXT: frsqrte
-; CHECK: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.2d]]
+; CHECK: fmul [[RB:v[0-7]\.2d]], [[RA]], [[RA]]
+; CHECK: frsqrts {{v[0-7]\.2d(, v[0-7]\.2d)?}}, [[RB]]
+; CHECK: fcmeq {{v[0-7]\.2d, v[0-1]\.2d}}, #0
 }
 
 define float @frsqrt(float %a) #0 {
@@ -127,8 +134,10 @@ define float @frsqrt(float %a) #0 {
 
 ; CHECK-LABEL: frsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:s[0-7]]]
+; CHECK-NEXT: fmul [[RB:s[0-7]]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{s[0-7](, s[0-7])?}}, [[RB]]
+; CHECK-NOT: fcmp {{s[0-7]}}, #0
 }
 
 define <2 x float> @f2rsqrt(<2 x float> %a) #0 {
@@ -142,8 +151,10 @@ define <2 x float> @f2rsqrt(<2 x float> %a) #0 {
 
 ; CHECK-LABEL: f2rsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.2s]]
+; CHECK-NEXT: fmul [[RB:v[0-7]\.2s]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{v[0-7]\.2s(, v[0-7]\.2s)?}}, [[RB]]
+; CHECK-NOT: fcmeq {{v[0-7]\.2s, v0\.2s}}, #0
 }
 
 define <4 x float> @f4rsqrt(<4 x float> %a) #0 {
@@ -157,8 +168,10 @@ define <4 x float> @f4rsqrt(<4 x float> %a) #0 {
 
 ; CHECK-LABEL: f4rsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.4s]]
+; CHECK-NEXT: fmul [[RB:v[0-7]\.4s]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{v[0-7]\.4s(, v[0-7]\.4s)?}}, [[RB]]
+; CHECK-NOT: fcmeq {{v[0-7]\.4s, v0\.4s}}, #0
 }
 
 define <8 x float> @f8rsqrt(<8 x float> %a) #0 {
@@ -173,9 +186,10 @@ define <8 x float> @f8rsqrt(<8 x float> %a) #0 {
 
 ; CHECK-LABEL: f8rsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
-; CHECK: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.4s]]
+; CHECK: fmul [[RB:v[0-7]\.4s]], [[RA]], [[RA]]
+; CHECK: frsqrts {{v[0-7]\.4s(, v[0-7]\.4s)?}}, [[RB]]
+; CHECK-NOT: fcmeq {{v[0-7]\.4s, v0\.4s}}, #0
 }
 
 define double @drsqrt(double %a) #0 {
@@ -189,8 +203,10 @@ define double @drsqrt(double %a) #0 {
 
 ; CHECK-LABEL: drsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:d[0-7]]]
+; CHECK-NEXT: fmul [[RB:d[0-7]]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{d[0-7](, d[0-7])?}}, [[RB]]
+; CHECK-NOT: fcmp d0, #0
 }
 
 define <2 x double> @d2rsqrt(<2 x double> %a) #0 {
@@ -204,8 +220,10 @@ define <2 x double> @d2rsqrt(<2 x double> %a) #0 {
 
 ; CHECK-LABEL: d2rsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.2d]]
+; CHECK-NEXT: fmul [[RB:v[0-7]\.2d]], [[RA]], [[RA]]
+; CHECK-NEXT: frsqrts {{v[0-7]\.2d(, v[0-7]\.2d)?}}, [[RB]]
+; CHECK-NOT: fcmeq {{v[0-7]\.2d, v0\.2d}}, #0
 }
 
 define <4 x double> @d4rsqrt(<4 x double> %a) #0 {
@@ -220,9 +238,10 @@ define <4 x double> @d4rsqrt(<4 x double> %a) #0 {
 
 ; CHECK-LABEL: d4rsqrt:
 ; CHECK-NEXT: BB#0
-; CHECK-NEXT: fmov
-; CHECK-NEXT: frsqrte
-; CHECK: frsqrte
+; CHECK-NEXT: frsqrte [[RA:v[0-7]\.2d]]
+; CHECK: fmul [[RB:v[0-7]\.2d]], [[RA]], [[RA]]
+; CHECK: frsqrts {{v[0-7]\.2d(, v[0-7]\.2d)?}}, [[RB]]
+; CHECK-NOT: fcmeq {{v[0-7]\.2d, v0\.2d}}, #0
 }
 
 attributes #0 = { nounwind "unsafe-fp-math"="true" }