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1 The SUIF Frequently Asked Questions List
2 ========================================
4 1. Q: ``The Makefile is broken. What does, `Must be a separator on
5 rules line 5. Stop.' mean?''
6 A: It means you're not using GNU make. Try ``gmake'' instead.
7 If gmake isn't in your path, find out where it's installed on
8 your system and put it in your path. If gmake isn't
9 installed, you'll need to install it. See the SUIF README
10 file.
12 2. Q: ``I compile the SPEC benchmark tomcatv (or some other large
13 FORTRAN program) with SUIF and the compilation seems to work,
14 but when I run the resulting binary it seg faults immediately.
15 What's wrong?''
16 A: You need to remove the limit on the stack size of processes.
17 Under csh, try ``unlimit stack''. This program uses an
18 enormous (in the MB range) local array. SUIF puts locals on
19 the stack, so if you have low stack-size limits, which are
20 often the default, the program will crash.
22 3. Q: ``When I compile a program (on a non-MIPS machine, or on a
23 MIPS machine with -s2c), why do I get errors like:
25 "/tmp/scc00684_5.out.c", line 227: syntax error at or near variable name "F"
27 or other similar errors in a weird .out.c file?''
28 A: The s2c backend, which is run by default on non-MIPS machines,
29 or if you specify the -s2c option to scc, converts SUIF into C
30 and then runs your native C compiler to generate an executable.
31 The output of s2c is ANSI-C compliant, but many C compilers are
32 unable to handle ANSI-C code. You should use an ANSI-C compliant
33 compiler, such as gcc, instead. You can specify the name of
34 another compiler with the "-cc name" option to scc, such as
35 "-cc gcc".
37 4. Q: ``If I want to run the output program on a different machine
38 than the one on which I run SUIF, can I do that?''
39 A: Yes, this is called cross-compiling, and SUIF is generally
40 capable of cross compiling for any target machine that has an
41 ANSI C compiler. There are a couple of issues you should be
42 aware of, though. They have to do with ensuring that SUIF
43 uses information about the true target machine instead of
44 information about that machine on which SUIF is running.
45 Since the most common case is to target the machine on which
46 SUIF is running (or a machine with the same processor and OS),
47 by default SUIF uses the information about the machine on
48 which it is running as the target information. Since SUIF is
49 designed to facilitate cross-compilation, the assumptions
50 about the target machine are made at only two points in the
51 compilation:
53 * The C pre-processor stage (note that this stage is used in
54 Fortran compilation, not just C compilation). At the
55 pre-processor stage, system include files are incorporated
56 into the program by directives such as
57 ``#include <stdio.h>''. These include files are highly
58 system-dependent. Typically they are provided by the OS,
59 mostly in /usr/include. To cross-compile, you must first
60 run the passes that come before the C pre-processor (cpp),
61 which is nothing for C programs, but is the ``sf2c'' pass
62 for Fortran programs (run ``scc -.c file.f'') on the
63 machine that runs SUIF. Then, you must transfer all the
64 files to the target machine, run the pre-processor to
65 generate .i files (cpp on some systems, ``cc -E'' on other
66 systems, and other things on other systems). Then you
67 must transfer all the .i files back to the machine running
68 SUIF and then you can continue the compilation from the .i
69 files. That always works. As an alternative, you can try
70 duplicating the entire /usr/include directory tree for
71 target machine <machine> under
72 $SUIFHOME/<machine>/include. You also have to generate
73 the proper $SUIFHOME/<machine>/predefined.txt file showing
74 what pre-defined macros <machine> defines by default in
75 its pre-processor (see
76 $SUIFHOME/src/basesuif/config/README.config for details).
77 If you can do that correctly, then all you have to do is
78 specify ``-Target <machine>'' to scc and it will be able
79 to run cpp on the SUIF machine and yet get everything
80 correctly set up for <machine> as target.
82 * The snoot pass. This pass initializes a table used by
83 snoot and all later passes that gives informatin about the
84 target machine, mostly sizes and alignments of data types.
85 This information is passed along in the SUIF file, so it
86 only needs to be set once, in snoot, and all later passes
87 will have the correct information. By default, snoot
88 assumes the parameters of the machine running SUIF (snoot
89 auto-detects this information). But for cross-compiling,
90 snoot must be given the information about the target
91 machine. This information is kept in a table in
92 $SUIFHOME/src/basesuif/snoot/config.h. This table may
93 have any number of entries -- a table with a few sample
94 entries for popular machines is distributed. A table for
95 a new machine can be automatically constructed using the
96 ``find_params.c'' file from snoot's source directory. See
97 comments in that file for details. Once you have the
98 table for the new machine, you can add it to config.h,
99 then you must recompile snoot. After snoot is recompiled,
100 it will understand the name you have given for your new
101 machine as a valid target. You can use
102 ``scc -Target <machine>'' to pass the machine name to
103 snoot, or, if you are running snoot directly, you can use
104 ``snoot -T<machine>''.
106 Note that if you want to do the work to set it all up, you can
107 get SUIF to compile straight from source to output C file (or
108 other back-end output) on the machine running SUIF for several
109 different targets, and choose between them by changing nothing
110 more than the argument to the ``-Target'' option for scc.