eth/tracers: prestateTracer - exclude unchanged storage slots in diffMode (#25944)

Fixes #25943

eth/tracers/internal/tracetest/testdata/prestate_tracer_with_diff_mode/simple.json

@@ -73,9 +73,6 @@
         "nonce": 1,
         "code": "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",
         "storage": {
-          "0x0000000000000000000000000000000000000000000000000000000000000000": "0x000000000000000000000001b436ba50d378d4bbc8660d312a13df6af6e89dfb",
-          "0x0000000000000000000000000000000000000000000000000000000000000001": "0x00000000000000000000000000000000000000000000000006f05b59d3b20000",
-          "0x0000000000000000000000000000000000000000000000000000000000000002": "0x000000000000000000000000000000000000000000000000000000000000003c",
           "0x0000000000000000000000000000000000000000000000000000000000000003": "0x000000000000000000000000000000000000000000000000000000005a37b834"
         }
       },

eth/tracers/native/prestate.go

@@ -69,12 +69,10 @@ type prestateTracer struct {
 }
 
 type prestateTracerConfig struct {
-	DiffMode bool `json:"diffMode"` // If true, this tracer will return all diff states
+	DiffMode bool `json:"diffMode"` // If true, this tracer will return state modifications
 }
 
 func newPrestateTracer(ctx *tracers.Context, cfg json.RawMessage) (tracers.Tracer, error) {
-	// First callframe contains tx context info
-	// and is populated on start and end.
 	var config prestateTracerConfig
 	if cfg != nil {
 		if err := json.Unmarshal(cfg, &config); err != nil {
@@ -192,7 +190,7 @@ func (t *prestateTracer) CaptureTxEnd(restGas uint64) {
 	}
 
 	for addr, state := range t.pre {
-		// the deleted account's state is pruned
+		// The deleted account's state is pruned from `post` but kept in `pre`
 		if _, ok := t.deleted[addr]; ok {
 			continue
 		}
@@ -222,7 +220,10 @@ func (t *prestateTracer) CaptureTxEnd(restGas uint64) {
 			}
 
 			newVal := t.env.StateDB.GetState(addr, key)
-			if val != newVal {
+			if val == newVal {
+				// Omit unchanged slots
+				delete(t.pre[addr].Storage, key)
+			} else {
 				modified = true
 				if newVal != (common.Hash{}) {
 					postAccount.Storage[key] = newVal