misc/benchcmp: show byte allocation statistics

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6971048

misc/benchcmp

@@ -35,18 +35,28 @@ $1 ~ /Benchmark/ && $4 == "ns/op" {
 
 		# allocs/op might be at $8 or $10 depending on if
 		# SetBytes was used or not.
-		if($8 == "allocs/op")
+		# B/op might be at $6 or $8, it should be immediately
+		# followed by allocs/op
+		if($8 == "allocs/op") {
+			newbytes[$1] = $5
 			newalloc[$1] = $7
-		if($10 == "allocs/op")
+		}
+		if($10 == "allocs/op") {
+			newbytes[$1] = $7
 			newalloc[$1] = $9
+		}
 	} else {
 		old[$1] = $3
 		if($6 == "MB/s")
 			oldmb[$1] = $5
-		if($8 == "allocs/op")
+		if($8 == "allocs/op") {
+			oldbytes[$1] = $5
 			oldalloc[$1] = $7
-		if($10 == "allocs/op")
+		}
+		if($10 == "allocs/op") {
+			oldbytes[$1] = $7
 			oldalloc[$1] = $9
+		}
 	}
 }
 
@@ -94,5 +104,21 @@ END {
 		printf("%-*s %12d %12d  %6s%%\n", len, what,
 			oldalloc[what], newalloc[what], delta)
 	}
+
+	# print alloc bytes
+	anybytes = 0
+	for(i=0; i<n; i++) {
+		what = name[i]
+		if(!(what in newbytes))
+			continue
+		if(anybytes++ == 0)
+			printf("\n%-*s %12s %12s  %7s\n", len, "benchmark", "old bytes", "new bytes", "delta")
+		if(oldbytes[what] == 0)
+			delta="n/a"
+		else
+			delta=sprintf("%.2f", 100*newbytes[what]/oldbytes[what]-100)
+		printf("%-*s %12d %12d  %6s%%\n", len, what,
+			oldbytes[what], newbytes[what], delta)
+	}
 }
 ' "$@"