cmd/compile: use unsigned power-of-two detector for unsigned mod

Same as CL 689815, but for modulus instead of division.

Updates #74485

Change-Id: I73000231c886a987a1093669ff207fd9117a8160
Reviewed-on: https://go-review.googlesource.com/c/go/+/689895
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/test/codegen/issue74485.go b/test/codegen/issue74485.go
index 570707509b..b5aba9568c 100644
--- a/test/codegen/issue74485.go
+++ b/test/codegen/issue74485.go
@@ -25,3 +25,23 @@ func divUint8(b uint8) uint8 {
 	// amd64:"SHRB	[$]7, AL"
 	return b / 128
 }
+
+func modUint64(b uint64) uint64 {
+	// amd64:"BTRQ	[$]63, AX"
+	return b % 9223372036854775808
+}
+
+func modUint32(b uint32) uint32 {
+	// amd64:"ANDL	[$]2147483647, AX"
+	return b % 2147483648
+}
+
+func modUint16(b uint16) uint16 {
+	// amd64:"ANDL	[$]32767, AX"
+	return b % 32768
+}
+
+func modUint8(b uint8) uint8 {
+	// amd64:"ANDL	[$]127, AX"
+	return b % 128
+}