Sun Studio 12: C++ User's Guide

2.4 Compiling and Linking

This section describes some aspects of compiling and linking programs. In the following example, CC is used to compile three source files and to link the object files to produce an executable file named prgrm.


example% CC file1.cc file2.cc file3.cc -o prgrm

2.4.1 Compile-Link Sequence

In the previous example, the compiler automatically generates the loader object files (file1.o, file2.o and file3.o) and then invokes the system linker to create the executable program for the file prgrm.

After compilation, the object files (file1.o, file2.o,and file3.o) remain. This convention permits you to easily relink and recompile your files.


Note –

If only one source file is compiled and a program is linked in the same operation, the corresponding .o file is deleted automatically. To preserve all .o files, do not compile and link in the same operation unless more than one source file gets compiled.


If the compilation fails, you will receive a message for each error. No .o files are generated for those source files with errors, and no executable program is written.

2.4.2 Separate Compiling and Linking

You can compile and link in separate steps. The -c option compiles source files and generates .o object files, but does not create an executable. Without the -c option, the compiler invokes the linker. By splitting the compile and link steps, a complete recompilation is not needed just to fix one file. The following example shows how to compile one file and link with others in separate steps:


example% CC -c file1.cc         Make new object file
example% CC -o prgrm file1.o file2.o file3.o       Make executable file

Be sure that the link step lists all the object files needed to make the complete program. If any object files are missing from this step, the link will fail with “undefined external reference” errors (missing routines).

2.4.3 Consistent Compiling and Linking

If you do compile and link in separate steps, consistent compiling and linking is critical when using the following compiler options:

If you compile any subprogram using any of these options, be sure to link using the same option as well:

In the following example, the programs are compiled using the -xcg92 compiler option. This option is a macro for -xtarget=ss1000 and expands to: -xarch=v8 -xchip=super -xcache=16/64/4:1024/64/1.


 example% CC -c -xcg92 sbr.cc
 example% CC -c -xcg92 smain.cc
 example% CC -xcg92 sbr.o smain.o

If the program uses templates, it is possible that some templates will get instantiated at link time. In that case the command line options from the last line (the link line) will be used to compile the instantiated templates.

2.4.4 Compiling for SPARC V9

The compilation, linking, and execution of 64-bit objects is supported only in a V9 SPARC, Solaris 8 operating system with a 64-bit kernel running. Compilation for 64-bits is indicated by the –xarch=v9, –xarch=v9a, and -xarch=v9b options.

2.4.5 Diagnosing the Compiler

You can use the –verbose option to display helpful information while compiling a program, such as the names and version numbers of the programs that it invokes and the command line for each compilation phase.

Any arguments on the command line that the compiler does not recognize are interpreted as linker options, object program file names, or library names.

The basic distinctions are:

In the following example, note that -bit is not recognized by CC and the option is passed on to the linker (ld), which tries to interpret it. Because single letter ld options can be strung together, the linker sees -bit as -b -i -t, all of which are legitimate ld options. This might not be what you intend or expect:


example% CC -bit move.cc           < - -bit is not a recognized CC option

CC: Warning: Option -bit passed to ld, if ld is invoked, ignored otherwise

In the next example, the user intended to type the CC option -fast but omitted the leading dash. The compiler again passes the argument to the linker, which in turn interprets it as a file name:


example% CC fast move.cc           < -  The user meant to type -fast
move.CC:
ld: fatal: file fast: cannot open file; errno=2
ld: fatal: File processing errors. No output written to a.out

2.4.6 Understanding the Compiler Organization

The C++ compiler package consists of a front end, optimizer, code generator, assembler, template prelinker, and link editor. The CC command invokes each of these components automatically unless you use command-line options to specify otherwise.

Because any of these components may generate an error, and the components perform different tasks, it may be helpful to identify the component that generates an error. Use the -v and -dryrun options to help with this.

As shown in the following table, input files to the various compiler components have different file name suffixes. The suffix establishes the kind of compilation that is done. Refer to Table 2–1 for the meanings of the file suffixes.

Table 2–2 Components of the C++ Compilation System

Component 

Description  

Notes on Use  

ccfe

Front end (compiler preprocessor and compiler) 

 

iropt

SPARC: Code optimizer 

-xO[2-5], -fast

ir2hf

x86: Intermediate language translator 

-xO[2-5], -fast

inline

SPARC: Inline expansion of assembly language templates 

.il file specified

ube_ipa

x86: Interprocedural analyzer 

-xcrossfile=1 with -xO4, -xO5, or -fast

fbe

Assembler 

 

cg

SPARC: Code generator, inliner, assembler 

 

ube

x86: Code generator 

-xO[2-5], -fast

CClink

Template pre-linker 

 

ld

Nonincremental link editor