cmd/compile: make math.Ceil/Floor/Round/Trunc intrinsics on arm64

name       old time/op  new time/op  delta
Ceil        550ns ± 0%   486ns ± 7%  -11.64%  (p=0.000 n=13+18)
Floor       495ns ±19%   512ns ±12%     ~     (p=0.164 n=20+20)
Round       550ns ± 0%   487ns ± 8%  -11.49%  (p=0.000 n=12+19)
Trunc       563ns ± 7%   488ns ±13%  -13.44%  (p=0.000 n=15+2)

Change-Id: I53f234b160b3c026a277506e2cf977d150379464
Reviewed-on: https://go-review.googlesource.com/88295
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/compile/internal/gc/asm_test.go

@@ -248,7 +248,7 @@ var allAsmTests = []*asmTests{
 	{
 		arch:    "arm64",
 		os:      "linux",
-		imports: []string{"encoding/binary", "math/bits"},
+		imports: []string{"encoding/binary", "math", "math/bits"},
 		tests:   linuxARM64Tests,
 	},
 	{
@@ -2849,6 +2849,47 @@ var linuxARM64Tests = []*asmTest{
 		pos: []string{"\tMOVHU\t\\(R[0-9]+\\)"},
 		neg: []string{"ORR\tR[0-9]+<<8\t"},
 	},
+	// Intrinsic tests for math.
+	{
+		fn: `
+		func sqrt(x float64) float64 {
+			return math.Sqrt(x)
+		}
+		`,
+		pos: []string{"FSQRTD"},
+	},
+	{
+		fn: `
+		func ceil(x float64) float64 {
+			return math.Ceil(x)
+		}
+		`,
+		pos: []string{"FRINTPD"},
+	},
+	{
+		fn: `
+		func floor(x float64) float64 {
+			return math.Floor(x)
+		}
+		`,
+		pos: []string{"FRINTMD"},
+	},
+	{
+		fn: `
+		func round(x float64) float64 {
+			return math.Round(x)
+		}
+		`,
+		pos: []string{"FRINTAD"},
+	},
+	{
+		fn: `
+		func trunc(x float64) float64 {
+			return math.Trunc(x)
+		}
+		`,
+		pos: []string{"FRINTZD"},
+	},
 }
 
 var linuxMIPSTests = []*asmTest{