With calls we now often get contraints like
callarg = *callarg + UNKNOWN
or similar cases. The important thing to note is that this
complex constraint changes the node solution itself, so when
solving the node is marked as changed immediately again. When
that happens it's profitable to iterat
This patch, long on my TODO list, speeds up PTA by removing the
costly hashtable lookup when looking for related fields of
a sub-variable. Instead we now keep a pointer to the first
field. For space-savings I changed head/next to be the variable
info ID instead. This speeds up a fortran testcas
