runtime: clean up power-of-two rounding code with align functions

This change renames the "round" function to the more appropriately named
"alignUp" which rounds an integer up to the next multiple of a power of
two.

This change also adds the alignDown function, which is almost like
alignUp but rounds down to the previous multiple of a power of two.

With these two functions, we also go and replace manual rounding code
with it where we can.

Change-Id: Ie1487366280484dcb2662972b01b4f7135f72fec
Reviewed-on: https://go-review.googlesource.com/c/go/+/190618
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/runtime/msize.go b/src/runtime/msize.go
index 0accb83eb8..11d06ce025 100644
--- a/src/runtime/msize.go
+++ b/src/runtime/msize.go
@@ -21,5 +21,5 @@ func roundupsize(size uintptr) uintptr {
 	if size+_PageSize < size {
 		return size
 	}
-	return round(size, _PageSize)
+	return alignUp(size, _PageSize)
 }