compress: reordering fields to reduce struct sizes

Overall, there are 32 bytes reduced.

Change-Id: I455bf0874b33fa47719f42618e4800c7ff2a9e88
GitHub-Last-Rev: 7670344c4a
GitHub-Pull-Request: golang/go#67010
Reviewed-on: https://go-review.googlesource.com/c/go/+/581355
Reviewed-by: Joedian Reid <joedian@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>

src/compress/bzip2/bzip2.go

@@ -27,8 +27,8 @@ type reader struct {
 	blockCRC     uint32
 	wantBlockCRC uint32
 	setupDone    bool // true if we have parsed the bzip2 header.
-	blockSize    int  // blockSize in bytes, i.e. 900 * 1000.
 	eof          bool
+	blockSize    int       // blockSize in bytes, i.e. 900 * 1000.
 	c            [256]uint // the ``C'' array for the inverse BWT.
 	tt           []uint32  // mirrors the ``tt'' array in the bzip2 source and contains the P array in the upper 24 bits.
 	tPos         uint32    // Index of the next output byte in tt.

src/compress/flate/deflate.go

@@ -87,7 +87,6 @@ type compressor struct {
 	// compression algorithm
 	fill      func(*compressor, []byte) int // copy data to window
 	step      func(*compressor)             // process window
-	sync      bool                          // requesting flush
 	bestSpeed *deflateFast                  // Encoder for BestSpeed
 
 	// Input hash chains
@@ -107,6 +106,8 @@ type compressor struct {
 	blockStart    int  // window index where current tokens start
 	byteAvailable bool // if true, still need to process window[index-1].
 
+	sync bool // requesting flush
+
 	// queued output tokens
 	tokens []token
 

src/compress/gzip/gzip.go

@@ -30,11 +30,11 @@ type Writer struct {
 	w           io.Writer
 	level       int
 	wroteHeader bool
+	closed      bool
+	buf         [10]byte
 	compressor  *flate.Writer
 	digest      uint32 // CRC-32, IEEE polynomial (section 8)
 	size        uint32 // Uncompressed size (section 2.3.1)
-	closed      bool
-	buf         [10]byte
 	err         error
 }
 

src/compress/lzw/writer.go

@@ -36,15 +36,15 @@ const (
 type Writer struct {
 	// w is the writer that compressed bytes are written to.
 	w writer
+	// litWidth is the width in bits of literal codes.
+	litWidth uint
 	// order, write, bits, nBits and width are the state for
 	// converting a code stream into a byte stream.
 	order Order
 	write func(*Writer, uint32) error
-	bits  uint32
 	nBits uint
 	width uint
-	// litWidth is the width in bits of literal codes.
+	bits  uint32
-	litWidth uint
 	// hi is the code implied by the next code emission.
 	// overflow is the code at which hi overflows the code width.
 	hi, overflow uint32