test/codegen: add tests of FMA for arm/arm64

This CL adds tests of fused multiplication-accumulation
on arm/arm64.

Change-Id: Ic85d5277c0d6acb7e1e723653372dfaf96824a39
Reviewed-on: https://go-review.googlesource.com/c/141652
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

test/codegen/floats.go

@@ -72,27 +72,43 @@ func indexStore(b0 []float64, b1 float64, idx int) {
 func FusedAdd32(x, y, z float32) float32 {
 	// s390x:"FMADDS\t"
 	// ppc64le:"FMADDS\t"
+	// arm/7:"MULAF"
+	// arm64:"FMADDS"
 	return x*y + z
 }
 
-func FusedSub32(x, y, z float32) float32 {
+func FusedSub32_a(x, y, z float32) float32 {
 	// s390x:"FMSUBS\t"
 	// ppc64le:"FMSUBS\t"
 	return x*y - z
 }
 
+func FusedSub32_b(x, y, z float32) float32 {
+	// arm/7:"MULSF"
+	// arm64:"FMSUBS"
+	return z - x*y
+}
+
 func FusedAdd64(x, y, z float64) float64 {
 	// s390x:"FMADD\t"
 	// ppc64le:"FMADD\t"
+	// arm/7:"MULAD"
+	// arm64:"FMADDD"
 	return x*y + z
 }
 
-func FusedSub64(x, y, z float64) float64 {
+func FusedSub64_a(x, y, z float64) float64 {
 	// s390x:"FMSUB\t"
 	// ppc64le:"FMSUB\t"
 	return x*y - z
 }
 
+func FusedSub64_b(x, y, z float64) float64 {
+	// arm/7:"MULSD"
+	// arm64:"FMSUBD"
+	return z - x*y
+}
+
 // ---------------- //
 //    Non-floats    //
 // ---------------- //