prog: profile what consumes space in exec encoding

Allow to profile how many bytes are consumed for what in the exec encoding.
The profile shows there are not many opportunities left.
53% are consumed by data blobs.
13% for const args.
18% for non-arg things (syscall number, copyout index, props, etc).

1 files changed, 42 insertions, 27 deletions

diff --git a/prog/decodeexec.go b/prog/decodeexec.go
index 2113d24c7..2356e051b 100644
--- a/prog/decodeexec.go
+++ b/prog/decodeexec.go
@@ -7,6 +7,7 @@ import (
 	"encoding/binary"
 	"fmt"
 	"reflect"
+	"strings"
 )
 
 type ExecProg struct {
@@ -71,8 +72,8 @@ type ExecCsumChunk struct {
 	Size  uint64
 }
 
-func (target *Target) DeserializeExec(exec []byte) (ExecProg, error) {
-	dec := &execDecoder{target: target, data: exec}
+func (target *Target) DeserializeExec(exec []byte, stats map[string]int) (ExecProg, error) {
+	dec := &execDecoder{target: target, data: exec, stats: stats}
 	dec.parse()
 	if dec.err != nil {
 		return ExecProg{}, dec.err
@@ -96,22 +97,23 @@ type execDecoder struct {
 	vars    []uint64
 	call    ExecCall
 	calls   []ExecCall
+	stats   map[string]int
 }
 
 func (dec *execDecoder) parse() {
 	for dec.err == nil {
-		switch instr := dec.read(); instr {
+		switch instr := dec.read("instr/opcode"); instr {
 		case execInstrCopyin:
 			dec.commitCall()
 			dec.call.Copyin = append(dec.call.Copyin, ExecCopyin{
-				Addr: dec.read() + dec.target.DataOffset,
+				Addr: dec.read("instr/copyin") + dec.target.DataOffset,
 				Arg:  dec.readArg(),
 			})
 		case execInstrCopyout:
 			dec.call.Copyout = append(dec.call.Copyout, ExecCopyout{
-				Index: dec.read(),
-				Addr:  dec.read() + dec.target.DataOffset,
-				Size:  dec.read(),
+				Index: dec.read("instr/copyout/index"),
+				Addr:  dec.read("instr/copyout/addr") + dec.target.DataOffset,
+				Size:  dec.read("instr/copyout/size"),
 			})
 		case execInstrEOF:
 			dec.commitCall()
@@ -126,8 +128,8 @@ func (dec *execDecoder) parse() {
 				return
 			}
 			dec.call.Meta = dec.target.Syscalls[instr]
-			dec.call.Index = dec.read()
-			for i := dec.read(); i > 0; i-- {
+			dec.call.Index = dec.read("instr/index")
+			for i := dec.read("instr/nargs"); i > 0; i-- {
 				switch arg := dec.readArg(); arg.(type) {
 				case ExecArgConst, ExecArgResult:
 					dec.call.Args = append(dec.call.Args, arg)
@@ -142,7 +144,7 @@ func (dec *execDecoder) parse() {
 
 func (dec *execDecoder) readCallProps(props *CallProps) {
 	props.ForeachProp(func(_, _ string, value reflect.Value) {
-		arg := dec.read()
+		arg := dec.read("call prop")
 		switch kind := value.Kind(); kind {
 		case reflect.Int:
 			value.SetInt(int64(arg))
@@ -157,11 +159,11 @@ func (dec *execDecoder) readCallProps(props *CallProps) {
 }
 
 func (dec *execDecoder) readArg() ExecArg {
-	switch typ := dec.read(); typ {
+	switch typ := dec.read("arg/type"); typ {
 	case execArgConst:
-		meta := dec.read()
+		meta := dec.read("arg/const/meta")
 		return ExecArgConst{
-			Value:          dec.read(),
+			Value:          dec.read("arg/const/value"),
 			Size:           meta & 0xff,
 			Format:         BinaryFormat((meta >> 8) & 0xff),
 			BitfieldOffset: (meta >> 16) & 0xff,
@@ -176,18 +178,18 @@ func (dec *execDecoder) readArg() ExecArg {
 			size = 8
 		}
 		return ExecArgConst{
-			Value: dec.read() + dec.target.DataOffset,
+			Value: dec.read("arg/addr") + dec.target.DataOffset,
 			Size:  uint64(size),
 		}
 	case execArgResult:
-		meta := dec.read()
+		meta := dec.read("arg/result/meta")
 		arg := ExecArgResult{
 			Size:    meta & 0xff,
 			Format:  BinaryFormat((meta >> 8) & 0xff),
-			Index:   dec.read(),
-			DivOp:   dec.read(),
-			AddOp:   dec.read(),
-			Default: dec.read(),
+			Index:   dec.read("arg/result/index"),
+			DivOp:   dec.read("arg/result/divop"),
+			AddOp:   dec.read("arg/result/addop"),
+			Default: dec.read("arg/result/default"),
 		}
 		for uint64(len(dec.vars)) <= arg.Index {
 			dec.vars = append(dec.vars, 0)
@@ -195,22 +197,23 @@ func (dec *execDecoder) readArg() ExecArg {
 		dec.vars[arg.Index] = arg.Default
 		return arg
 	case execArgData:
-		flags := dec.read()
+		flags := dec.read("arg/data/size")
 		size := flags & ^execArgDataReadable
+		dec.addStat("arg/data/blob", int(size))
 		readable := flags&execArgDataReadable != 0
 		return ExecArgData{
 			Data:     dec.readBlob(size),
 			Readable: readable,
 		}
 	case execArgCsum:
-		size := dec.read()
-		switch kind := dec.read(); kind {
+		size := dec.read("arg/csum/size")
+		switch kind := dec.read("arg/csum/kind"); kind {
 		case ExecArgCsumInet:
-			chunks := make([]ExecCsumChunk, dec.read())
+			chunks := make([]ExecCsumChunk, dec.read("arg/csum/chunks"))
 			for i := range chunks {
-				kind := dec.read()
-				addr := dec.read()
-				size := dec.read()
+				kind := dec.read("arg/csum/chunk/kind")
+				addr := dec.read("arg/csum/chunk/addr")
+				size := dec.read("arg/csum/chunk/size")
 				if kind == ExecArgCsumChunkData {
 					addr += dec.target.DataOffset
 				}
@@ -235,7 +238,7 @@ func (dec *execDecoder) readArg() ExecArg {
 	}
 }
 
-func (dec *execDecoder) read() uint64 {
+func (dec *execDecoder) read(stat string) uint64 {
 	if dec.err != nil {
 		return 0
 	}
@@ -244,6 +247,7 @@ func (dec *execDecoder) read() uint64 {
 		dec.setErr(fmt.Errorf("exec program overflow"))
 		return 0
 	}
+	dec.addStat(stat, n)
 	dec.data = dec.data[n:]
 	return uint64(v)
 }
@@ -281,3 +285,14 @@ func (dec *execDecoder) commitCall() {
 	dec.calls = append(dec.calls, dec.call)
 	dec.call = ExecCall{}
 }
+
+func (dec *execDecoder) addStat(stat string, n int) {
+	if dec.stats == nil {
+		return
+	}
+	prefix := ""
+	for _, part := range strings.Split(stat, "/") {
+		dec.stats[prefix+part] += n
+		prefix += part + "/"
+	}
+}