Return assignment optimization to chosen places

Author: aafemt

src/common/cvt.cpp

@@ -1648,7 +1648,7 @@ double CVT_get_double(const dsc* desc, DecimalStatus decSt, ErrorFunction err, b
 }
 
 
-void CVT_move_common(const dsc* from, dsc* to, DecimalStatus decSt, Callbacks* cb)
+void CVT_move_common(const dsc* from, dsc* to, DecimalStatus decSt, Callbacks* cb, bool trustedSource)
 {
 /**************************************
  *
@@ -1673,7 +1673,9 @@ void CVT_move_common(const dsc* from, dsc* to, DecimalStatus decSt, Callbacks* c
 	// (real source length must be validated against target maximum length
 	// and this is the first common place where both are present).
 
-	if (DSC_EQUIV(from, to, false) && !DTYPE_IS_TEXT(from->dsc_dtype))
+	// ...unless these strings are coming from a trusted source (for example a cached record buffer)
+
+	if (DSC_EQUIV(from, to, false) && (trustedSource || !DTYPE_IS_TEXT(from->dsc_dtype)))
 	{
 		if (length) {
 			memcpy(p, q, length);
@@ -1987,6 +1989,9 @@ void CVT_move_common(const dsc* from, dsc* to, DecimalStatus decSt, Callbacks* c
 				if (cb->transliterate(from, to, charset2))
 					return;
 
+				// At this point both `from` and `to` are guaranteed to have the same charset and this is stored in charset2
+				// Because of this we can freely use `toCharset` against `from`.
+
 				{ // scope
 					USHORT strtype_unused;
 					UCHAR *ptr;
@@ -1997,8 +2002,23 @@ void CVT_move_common(const dsc* from, dsc* to, DecimalStatus decSt, Callbacks* c
 				const USHORT to_size = TEXT_LEN(to);
 				CharSet* toCharset = cb->getToCharset(charset2);
 
-				cb->validateData(toCharset, length, q);
-				ULONG toLength = cb->validateLength(toCharset, charset2, length, q, to_size);
+				ULONG toLength = length;
+
+				if (!trustedSource)
+				{
+					// Most likely data already has been validated once or twice, but another validation won't hurt much.
+					cb->validateData(toCharset, length, q);
+					toLength = cb->validateLength(toCharset, charset2, length, q, to_size);
+				}
+				else
+				{
+					// Silently truncate. In the wild this should never happen
+					if (length > to_size)
+					{
+						fb_assert(from->dsc_dtype == dtype_text);
+						toLength = to_size;
+					}
+				}
 
 				switch (to->dsc_dtype)
 				{
@@ -3776,7 +3796,7 @@ USHORT CVT_get_string_ptr(const dsc* desc, USHORT* ttype, UCHAR** address,
 }
 
 
-void CVT_move(const dsc* from, dsc* to, DecimalStatus decSt, ErrorFunction err)
+void CVT_move(const dsc* from, dsc* to, DecimalStatus decSt, ErrorFunction err, bool trustedSource)
 {
 /**************************************
  *
@@ -3789,5 +3809,5 @@ void CVT_move(const dsc* from, dsc* to, DecimalStatus decSt, ErrorFunction err)
  *
  **************************************/
 	CommonCallbacks callbacks(err);
-	CVT_move_common(from, to, decSt, &callbacks);
+	CVT_move_common(from, to, decSt, &callbacks, trustedSource);
 }

src/common/cvt.h

@@ -95,8 +95,8 @@ Firebird::Decimal128 CVT_get_dec128(const dsc*, Firebird::DecimalStatus, ErrorFu
 Firebird::Int128 CVT_get_int128(const dsc*, SSHORT, Firebird::DecimalStatus, ErrorFunction);
 Firebird::Int128 CVT_hex_to_int128(const char* str, USHORT len);
 USHORT CVT_make_string(const dsc*, USHORT, const char**, vary*, USHORT, Firebird::DecimalStatus, ErrorFunction);
-void CVT_move_common(const dsc*, dsc*, Firebird::DecimalStatus, Firebird::Callbacks*);
-void CVT_move(const dsc*, dsc*, Firebird::DecimalStatus, ErrorFunction);
+void CVT_move_common(const dsc*, dsc*, Firebird::DecimalStatus, Firebird::Callbacks*, bool trustedSource = false);
+void CVT_move(const dsc*, dsc*, Firebird::DecimalStatus, ErrorFunction, bool trustedSource = false);
 SSHORT CVT_decompose(const char*, USHORT, Firebird::Int128*, ErrorFunction);
 USHORT CVT_get_string_ptr(const dsc*, USHORT*, UCHAR**, vary*, USHORT, Firebird::DecimalStatus, ErrorFunction);
 USHORT CVT_get_string_ptr_common(const dsc*, USHORT*, UCHAR**, vary*, USHORT, Firebird::DecimalStatus, Firebird::Callbacks*);

src/jrd/mov.cpp

@@ -438,7 +438,7 @@ Firebird::string MOV_make_string2(Jrd::thread_db* tdbb, const dsc* desc, USHORT
 }
 
 
-void MOV_move(Jrd::thread_db* tdbb, /*const*/ dsc* from, dsc* to)
+void MOV_move(Jrd::thread_db* tdbb, /*const*/ dsc* from, dsc* to, bool trustedSource)
 {
 /**************************************
  *
@@ -454,7 +454,7 @@ void MOV_move(Jrd::thread_db* tdbb, /*const*/ dsc* from, dsc* to)
 	if (DTYPE_IS_BLOB_OR_QUAD(from->dsc_dtype) || DTYPE_IS_BLOB_OR_QUAD(to->dsc_dtype))
 		Jrd::blb::move(tdbb, from, to);
 	else
-		CVT_move(from, to, tdbb->getAttachment()->att_dec_status);
+		CVT_move_common(from, to, tdbb->getAttachment()->att_dec_status, &Jrd::EngineCallbacks::instance, trustedSource);
 }
 
 

src/jrd/mov_proto.h

@@ -52,7 +52,7 @@ USHORT	MOV_make_string(Jrd::thread_db*, const dsc*, USHORT, const char**, vary*,
 ULONG	MOV_make_string2(Jrd::thread_db*, const dsc*, USHORT, UCHAR**, Jrd::MoveBuffer&, bool = true);
 Firebird::string MOV_make_string2(Jrd::thread_db* tdbb, const dsc* desc, USHORT ttype,
 	bool limit = true);
-void	MOV_move(Jrd::thread_db*, /*const*/ dsc*, dsc*);
+void	MOV_move(Jrd::thread_db*, /*const*/ dsc*, dsc*, bool trustedSource = false);
 Firebird::Decimal64 MOV_get_dec64(Jrd::thread_db*, const dsc*);
 Firebird::Decimal128 MOV_get_dec128(Jrd::thread_db*, const dsc*);
 Firebird::Int128 MOV_get_int128(Jrd::thread_db*, const dsc*, SSHORT);

src/jrd/recsrc/BufferedStream.cpp

@@ -199,7 +199,7 @@ bool BufferedStream::internalGetRecord(thread_db* tdbb) const
 			switch (map.map_type)
 			{
 			case FieldMap::REGULAR_FIELD:
-				MOV_move(tdbb, &from, &to);
+				MOV_move(tdbb, &from, &to, true);
 				break;
 
 			case FieldMap::TRANSACTION_ID:
@@ -271,7 +271,7 @@ bool BufferedStream::internalGetRecord(thread_db* tdbb) const
 				else
 				{
 					EVL_field(relation, record, map.map_id, &to);
-					MOV_move(tdbb, &from, &to);
+					MOV_move(tdbb, &from, &to, true);
 					record->clearNull(map.map_id);
 				}
 

src/jrd/recsrc/HashJoin.cpp

@@ -687,7 +687,7 @@ ULONG HashJoin::computeHash(thread_db* tdbb,
 				else
 				{
 					// This call ensures that the padding bytes are appended
-					MOV_move(tdbb, desc, &to);
+					MOV_move(tdbb, desc, &to, true);
 				}
 			}
 			else

src/jrd/recsrc/SortedStream.cpp

@@ -278,7 +278,7 @@ Sort* SortedStream::init(thread_db* tdbb) const
 				}
 				else
 				{
-					MOV_move(tdbb, from, &to);
+					MOV_move(tdbb, from, &to, true);
 				}
 			}
 		}
@@ -438,7 +438,7 @@ void SortedStream::mapData(thread_db* tdbb, Request* request, UCHAR* data) const
 		else
 		{
 			EVL_field(relation, record, id, &to);
-			MOV_move(tdbb, &from, &to);
+			MOV_move(tdbb, &from, &to, true);
 			record->clearNull(id);
 		}
 	}

src/jrd/recsrc/WindowedStream.cpp

@@ -889,7 +889,7 @@ bool WindowedStream::WindowStream::internalGetRecord(thread_db* tdbb) const
 				record->setNull(id);
 			else
 			{
-				MOV_move(tdbb, desc, EVL_assign_to(tdbb, *target));
+				MOV_move(tdbb, desc, EVL_assign_to(tdbb, *target), true);
 				record->clearNull(id);
 			}