runtime: remove sizeToClass

CL 32219 added precomputed sizeclass tables.

Remove the unused sizeToClass method which was previously only
called from initSizes.

Change-Id: I907bf9ed78430ecfaabbec7fca77ef2375010081
Reviewed-on: https://go-review.googlesource.com/38113
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/msize.go

@@ -9,28 +9,6 @@
 
 package runtime
 
-// sizeToClass(0 <= n <= MaxSmallSize) returns the size class,
-//	1 <= sizeclass < NumSizeClasses, for n.
-//	Size class 0 is reserved to mean "not small".
-//
-// The sizeToClass lookup is implemented using two arrays,
-// one mapping sizes <= 1024 to their class and one mapping
-// sizes >= 1024 and <= MaxSmallSize to their class.
-// All objects are 8-aligned, so the first array is indexed by
-// the size divided by 8 (rounded up).  Objects >= 1024 bytes
-// are 128-aligned, so the second array is indexed by the
-// size divided by 128 (rounded up).  The arrays are constants
-// in sizeclass.go generated by mksizeclass.go.
-func sizeToClass(size uint32) uint32 {
-	if size > _MaxSmallSize {
-		throw("invalid size")
-	}
-	if size > smallSizeMax-8 {
-		return uint32(size_to_class128[(size-smallSizeMax+largeSizeDiv-1)/largeSizeDiv])
-	}
-	return uint32(size_to_class8[(size+smallSizeDiv-1)/smallSizeDiv])
-}
-
 // Returns size of the memory block that mallocgc will allocate if you ask for the size.
 func roundupsize(size uintptr) uintptr {
 	if size < _MaxSmallSize {