1mpicc(1) LAM TOOLS mpicc(1)
2
6 mpicc, mpiCC / mpic++ - Compile LAM/MPI C/C++ programs.
7
9 mpicc [-showme|-showme:compile|-showme:link] ...
10 mpiCC [-showme|-showme:compile|-showme:link] ...
12 mpic++ [-showme|-showme:compile|-showme:link] ...
14
16 -showme
17 Does not invoke the underlying C/C++ compiler. Instead, it
18 shows the command line that would be executed to compile the
19 C/C++ program.
20 -showme:compile
22 Does not invoke the underlying C/C++ compiler. Instead, it
23 shows the compiler flags that would be supplied to the C/C++
24 compiler.
25 -showme:link
27 Does not invoke the underlying C/C++ compiler. Instead, it
28 shows the linker flags that would be supplied to the C/C++ com‐
29 piler.
30 See cc(1) and CC(1) (or whatever your underlying C/C++ compilers are)
32 for all other options.
33
35 mpicc and mpiCC (mpic++ is a synonym for mpiCC provided for filenames
36 that do not support case-sensitive filenames) are convenience wrappers
37 for the local native C and C++ compilers. Translation of a LAM program
38 requires the linkage of the LAM specific libraries which may not reside
39 in one of the standard search directories of ld(1). It also often
40 requires the inclusion of header files what may also not be found in a
41 standard location. mpicc passes its arguments to the local native C
42 compiler along with the -I, -L and -l options required by LAM programs.
43 This includes all necessary options for ROMIO and/or C++ bindings sup‐
44 port (if ROMIO/C++ support was included when LAM was compiled).
45 mpiCC (and therefore mpic++) is similar, but invokes the native C++
47 compiler instead.
48 The LAM Team strongly encourages using mpicc and mpiCC instead of
50 attempting to link to the LAM libraries manually. This allows the spe‐
51 cific implementation of LAM to change without forcing changes to linker
52 directives in users' Makefiles (the specific set of underlying LAM
53 libraries has already changed multiple times, and will likely change
54 again in future versions).
55 Indeed, since mpicc/mpiCC are very thin wrappers on top of an underly‐
57 ing compiler, there are very, very few compelling reasons not to use
58 mpicc/mpiCC. When it is not possible to use mpicc/mpiCC, the
59 -showme:compile and -showme:link arguments should be used instead. For
60 example:
61 shell$ cc -c file1.c `mpicc -showme:compile`
63 shell$ cc -c file2.c `mpicc -showme:compile`
65 shell$ cc file1.o file2.o `mpicc -showme:link` -o my_mpi_program
67
69 By default, mpicc uses the C compiler that was selected when LAM was
70 configured (with the --with-cc flag to ./configure, or by setting the
71 environment variable CC before ./configure was invoked) as the local
72 native C compiler, but this can be overridden by the LAMMPICC environ‐
73 ment variable (an older name for this environment variable is LAMHCC --
74 this also still works, but its use is deprecated).
75 Likewise, mpiCC uses the C++ compiler that was selected when LAM was
77 configured (with the --with-cpp flag to ./configure, or by setting the
78 environment variable CXX before invoking ./configure) by default, but
79 this can be overridden by the LAMMPICXX environment variable (an older
80 name for this environment variable is LAMHCP -- this also still works,
81 but its use is deprecated).
82 If the environment variable LAMHOME is set, mpicc and mpiCC will use
84 its value as the location of the LAM installation directory instead of
85 the value that was compiled into mpicc/mpiCC. This means that
86 mpicc/mpiCC will use the value of LAMHOME as the base to create the -I
87 and -L arguments that are passed to the lower-level compiler, not the
88 installation directory that was supplied when mpicc/mpiCC were created.
89 This is almost always a Bad Idea.
90 The use of LAMHOME is discouraged except for some rare configuration
92 cases in oddly networked sites (in which case your system administrator
93 should probably set this up), and for advanced users with multiple
94 LAM/MPI installations who really know what they are doing; if the
95 LAMHOME environment variable is unintentionally left set, it can lead
96 to tremendous user confusion. For example, if LAMHOME points to LAM
97 installation A, but the user's PATH points to LAM installation B, then
98 even though B's mpicc will be used, the user program will be compiled
99 and linked against LAM installation A.
100 The LAMHOME environment variable is mainly only left in place for back‐
102 wards compatibility; it is not required for normal functioning of
103 LAM/MPI. The LAM Team discourages the use of the LAMHOME environment
104 variable, and instead advocates simply setting the PATH properly to
105 switch between multiple LAM/MPI implementations.
106
108 Previous versions of LAM encouraged the use of hcc and hcp to compile
109 LAM and/or MPI C and C++ applications, respectively. In very old ver‐
110 sions of LAM, hcc and hcp did not automatically add -lmpi to the com‐
111 mand line. hcc and hcp were eventually deprecated and replaced with
112 mpicc and mpiCC (or mpic++ on case-insensitive filesystems). The exe‐
113 cutables hcc and hcp are now simply symbolic links to mpicc and mpic++,
114 respectively, just in case there's anyone out there that still uses
115 those names. It should be harmless to pass in the additional -lmpi;
116 mpicc and mpic++ should silently do the Right Thing (only link in the
117 MPI library once).
118
120 cc(1), CC(1), ld(1), lam-helpfile(5), mpif77(1)
121LAM 7.1.2 March, 2006 mpicc(1)