Backlog of Qt and QtWebKit problems

Qt problems

• ARM optimized qdrawhelper is only enabled for RCVT (symbian) . The needs to be transferred to gcc inline assembly. This will optimize memfill, Source, SourceOver and some blend functions.

• ARMv6 should be auto detected. Currently arm/armv6 can be passed as -embedded options. The benefit of ARMv6 in src/corelib is the use of atomic load and exchange, instead of the old "swap" extension. __ARCH_ARM_6__ should be used to detect it.

• Enabled pld (preload) in qdrawhelper for ARMv5te and upwards

• QImageReader deserves some optimatations. E.g. decode to the QImage provided to the decoder, do not parse every gif when trying to determine the size.

• Changes to QHttpNetworkReply to reduce memory reallocations. Reserve some bytes instead of doing QByteArray::append all them time.

• Cut down on the usage of QUrl::toEncoded as it shows up in the profile of starting jobs.

QtWebKit problems

• Image decoder changes to greatly reduce memory and load speed. See this ​bug for planned changes. The possible impact is quite big.

• Loading of ​http://en.wikipedia.org/wiki/Maxwell_equations is triggering bad "scheduling". The loading_standalone test has been extracted but is not able to highlight the problem. This is a Qt and QtWebKit issue, it must be understood first.

• TCmalloc needs to be tested. Does it make anything faster/slower? How to test memory fragmentation.

• The fuzz testing will make QtWebKit go in infinite loops and stop working. This situation needs to be analyzed as this can be a serve reliabality problem.