runtime: simplify readUnaligned

We already have a pure go code sequence that is compiled into single load.
Just use it everywhere, instead of pointer hackery.
Passes toolstash-check.

Change-Id: I0c42b5532fa9a5665da3385913609c6d42aaff27
Reviewed-on: https://go-review.googlesource.com/c/go/+/118568
Run-TryBot: Ilya Tocar <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Austin Clements <[email protected]>

Author: TocarIP

src/runtime/alg.go

@@ -316,3 +316,21 @@ func initAlgAES() {
 	// Initialize with random data so hash collisions will be hard to engineer.
 	getRandomData(aeskeysched[:])
 }
+
+// Note: These routines perform the read with an native endianness.
+func readUnaligned32(p unsafe.Pointer) uint32 {
+	q := (*[4]byte)(p)
+	if sys.BigEndian {
+		return uint32(q[3]) | uint32(q[2])<<8 | uint32(q[1])<<16 | uint32(q[0])<<24
+	}
+	return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24
+}
+
+func readUnaligned64(p unsafe.Pointer) uint64 {
+	q := (*[8]byte)(p)
+	if sys.BigEndian {
+		return uint64(q[7]) | uint64(q[6])<<8 | uint64(q[5])<<16 | uint64(q[4])<<24 |
+			uint64(q[3])<<32 | uint64(q[2])<<40 | uint64(q[1])<<48 | uint64(q[0])<<56
+	}
+	return uint64(q[0]) | uint64(q[1])<<8 | uint64(q[2])<<16 | uint64(q[3])<<24 | uint64(q[4])<<32 | uint64(q[5])<<40 | uint64(q[6])<<48 | uint64(q[7])<<56
+}