writing code, if I can think of enough things to say here.
\subsection{Working together}
-This section says something about working with colleagues in various ways.
+Since the compiler plays a fairly central role in the development process at
+Recore, I have been cooperating with a number of different people, in different
+areas. On one end, the compiler is directly used by the DSP engineers, so a lot
+of the requirements and wishes for the compiler come from them. Also, they are
+often providing bug reports and other feedback, which ensures regular contact.
+
+On the other end, I have been in contact with the developer of the backend very
+intensively, since most changes made to either component needed changes in the
+other one as well. So compiler changes also require hardware support, so working
+with the hardware developers was not uncommon either. In practice, most of this
+communication went through the backend developer, except for the design
+discussion concerning the new Montium hardware design (also see section
+\ref{Pipelining} below).
+
+In addition, discussions regarding design issues at various levels often happen
+out in the open, which easily invites people with an opinion about something to
+chime in, without having to gather people around for every discussion that
+happens. This allows for very quick feedback on ideas from people in all areas
+in an efficient way.
\subsection{Staying generic}
\label{StayingGeneric}
-This section says something about the challenge of writing generic code:
-(changes to) transformations that are useful for both LLVM (ie on regular
-architectures) as well as for Recore (on the Montium).
+The toughest challenge by far was to fit the features and changes required by
+Recore into code that is maintained by the LLVM project. The main problem here
+is clash of goals: The LLVM project aims for code that performs well on their
+supported architectures, while Recore aims for code that performs well (or more
+often, can compile at all) on the Montium architecture.
+
+In general, these problems mainly occur because MontiumC and in particular
+MontiumIR poses a number of constraints that are not present in other
+architectures. This means that some transformations present in LLVM will violate
+these constraints (which would result in better code on most other
+architectures) resulting in miscompiled or uncompilable code.
+
+In some cases, these extra constraints can be formulated in a generic way, such
+that the LLVM code can handle architectures with or without the constraint.
+In a lot of cases, however, the constraint is so Montium specific that changing
+LLVM to support it is not feasible. In a few cases, this meant that the backend
+was changed to support more features of the LLVM IR. In other cases, a
+Recore-specific pass was added to solve these problems. In a few more cases, the
+problems are still unresolved, effectively resulting in additional constraints
+on the MontiumC language.
\subsection{Pipelined scheduling}
+\label{Pipelining}
I've also been involved for a bit with the instruction scheduling algorithm
required for the new (pipelined) hardware design. Even though this is completely
outside of the area of my assignment, the initial prototype of that scheduler
projects / matthijs / projects / internship.git / blobdiff