[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/test/CodeGen/AArch64/recp-fastmath.ll b/llvm/test/CodeGen/AArch64/recp-fastmath.ll
index 280ef75..38e0fb3 100644
--- a/llvm/test/CodeGen/AArch64/recp-fastmath.ll
+++ b/llvm/test/CodeGen/AArch64/recp-fastmath.ll
@@ -16,8 +16,8 @@
 
 ; 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 @@
 
 ; 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 @@
 
 ; 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 @@
 
 ; 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 @@
 
 ; 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 @@
 
 ; 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 @@
 
 ; 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" }