EECS 583 – Homework 1
Winter 2002
Assigned: Wednesday, January 23, 2002
Due: Wednesday, February 6, 2002
Warmup
Setup and install the Trimaran compiler system under Linux. You can do this either on
your CAEN account or own system. Source code available on course webpage, this has
some fixes for gcc 2.96, plus some code to get you started. If you have already installed
trimaran from http://www.trimaran.org , then you should get the code from the course
webpage and extract the following files, overwrite your files with these.
trimaran/elcor/src/GNUmakefile, trimaran/elcor/src/Main/eecs583.cpp,
trimaran/elcor/src/Main/process_function.cpp, trimaran/elcor/src/Main/el_driver_init.h
and .cpp, trimaran/elcor/parms/DRIVER_DEFAULTS, trimaran/envrc
After untarring, modify first line of envrc appropriately, then add to your .cshrc, source
…/trimaran/envrc. This sets all the enviroment variables that trimaran requires. Then, cd
trimaran, run ./install (fix errors that come up ☺)
Problem #1
Implement an if-converter to convert branching code into sequential, predicated code
using the algorithms discussed in class. Your if-converter will operate on a complete,
acyclic procedure, converting it to straight-line, predicated code. You may assume the
procedure has no loops or cycles of any sort. As a result, there is no need to do any
backedge coalescing. The if-converter should convert the body of the procedure into a
single basic block without any branches (except of course any subroutine calls (BRL) and
the return from subroutine operation at the end of the procedure (RTS)). You may skip
all the CMPP compaction stuff. So, essentially, you are to implement steps 2 and 3 of the
if-conversion algorithm that was discussed in class.
Assumptions you can make:
- Procedure only contains basic blocks which in turn contain operations
- Generate only ON style CMPPs
- All branches are removed except BRLs and RTSs
You are given (see code provided in trimaran/elcor/src/Main/eecs583.cpp):
- Post dominator, and immediate post dominator for each basic block
- Function to create an ON style CMPP
- Function to create a predicate clear (remember to initialize each ON predicate!)
Steps:
1. Compute control dependences for each basic block, CD(x)
2. Create predicates for each unique control dependence
3. Construct and insert CMPPs
4. Guard all operations (initially everything is guarded by True)
5. (bonus, if you have the guts!) Remove control flow
