runtime: simplify syntax for pointer arithmetic in mapaccess functions

This harmonizes the syntax between mapaccess1 and mapaccess2, and
simplifies the code.

Change-Id: I6db25ffdc871018d399f9030259894b3994c5793
Reviewed-on: https://go-review.googlesource.com/c/go/+/308951
Reviewed-by: Keith Randall <[email protected]>
Run-TryBot: Keith Randall <[email protected]>
Trust: Emmanuel Odeke <[email protected]>
TryBot-Result: Go Bot <[email protected]>

Author: kortschak

src/runtime/map.go

@@ -470,13 +470,13 @@ func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool)
 	}
 	hash := t.hasher(key, uintptr(h.hash0))
 	m := bucketMask(h.B)
-	b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + (hash&m)*uintptr(t.bucketsize)))
+	b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
 	if c := h.oldbuckets; c != nil {
 		if !h.sameSizeGrow() {
 			// There used to be half as many buckets; mask down one more power of two.
 			m >>= 1
 		}
-		oldb := (*bmap)(unsafe.Pointer(uintptr(c) + (hash&m)*uintptr(t.bucketsize)))
+		oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize)))
 		if !evacuated(oldb) {
 			b = oldb
 		}
@@ -514,13 +514,13 @@ func mapaccessK(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, unsafe
 	}
 	hash := t.hasher(key, uintptr(h.hash0))
 	m := bucketMask(h.B)
-	b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + (hash&m)*uintptr(t.bucketsize)))
+	b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
 	if c := h.oldbuckets; c != nil {
 		if !h.sameSizeGrow() {
 			// There used to be half as many buckets; mask down one more power of two.
 			m >>= 1
 		}
-		oldb := (*bmap)(unsafe.Pointer(uintptr(c) + (hash&m)*uintptr(t.bucketsize)))
+		oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize)))
 		if !evacuated(oldb) {
 			b = oldb
 		}