Merge bitcoin#9572: Skip witness sighash cache for non-segwit transactions

laanwj · laanwj · commit 17f2acedbe07 · 2017-10-05T19:49:42.000+02:00
0da49b5 Skip precompute sighash for transactions without witness (Johnson Lau) Pull request description: This saves unnecessary hash caching for non-segwit transactions, but I am not sure if the difference is noticeable. Tree-SHA512: 5cd733a729a52a45781510b3572b26e76837a94155caa14311c6d23a27a12e9613ff278dfc2592e21f640202782f22c5ad00fca85c4de5efacaa617c48ccb08d
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
@@ -1168,9 +1168,13 @@ uint256 GetOutputsHash(const CTransaction& txTo) {
 
 PrecomputedTransactionData::PrecomputedTransactionData(const CTransaction& txTo)
 {
-    hashPrevouts = GetPrevoutHash(txTo);
-    hashSequence = GetSequenceHash(txTo);
-    hashOutputs = GetOutputsHash(txTo);
+    // Cache is calculated only for transactions with witness
+    if (txTo.HasWitness()) {
+        hashPrevouts = GetPrevoutHash(txTo);
+        hashSequence = GetSequenceHash(txTo);
+        hashOutputs = GetOutputsHash(txTo);
+        ready = true;
+    }
 }
 
 uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache)
@@ -1181,18 +1185,19 @@ uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsig
         uint256 hashPrevouts;
         uint256 hashSequence;
         uint256 hashOutputs;
+        const bool cacheready = cache && cache->ready;
 
         if (!(nHashType & SIGHASH_ANYONECANPAY)) {
-            hashPrevouts = cache ? cache->hashPrevouts : GetPrevoutHash(txTo);
+            hashPrevouts = cacheready ? cache->hashPrevouts : GetPrevoutHash(txTo);
         }
 
         if (!(nHashType & SIGHASH_ANYONECANPAY) && (nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
-            hashSequence = cache ? cache->hashSequence : GetSequenceHash(txTo);
+            hashSequence = cacheready ? cache->hashSequence : GetSequenceHash(txTo);
         }
 
 
         if ((nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
-            hashOutputs = cache ? cache->hashOutputs : GetOutputsHash(txTo);
+            hashOutputs = cacheready ? cache->hashOutputs : GetOutputsHash(txTo);
         } else if ((nHashType & 0x1f) == SIGHASH_SINGLE && nIn < txTo.vout.size()) {
             CHashWriter ss(SER_GETHASH, 0);
             ss << txTo.vout[nIn];
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
@@ -113,6 +113,7 @@ bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned i
 struct PrecomputedTransactionData
 {
     uint256 hashPrevouts, hashSequence, hashOutputs;
+    bool ready = false;
 
     explicit PrecomputedTransactionData(const CTransaction& tx);
 };

Original file line number	Diff line number	Diff line change
`@@ -113,6 +113,7 @@ bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned i`
`113`	`113`	`struct PrecomputedTransactionData`
`114`	`114`	`{`
`115`	`115`	`uint256 hashPrevouts, hashSequence, hashOutputs;`
	`116`	`+ bool ready = false;`
`116`	`117`
`117`	`118`	`explicit PrecomputedTransactionData(const CTransaction& tx);`
`118`	`119`	`};`