Predefined macros compiler software

Arm compiler toolchain compiler reference version 5. Where the value field is empty, the symbol is only defined. Dec 16, 2019 preprocessor symbols macros let you substitute values in a program before it is compiled. Mar 05, 2019 download predefined compiler macros for free. An integer that specifies the current compilers version. Mar 30, 2020 preprocessor symbols macros substitute values in a program before it is compiled. Figure 1 compiler defined macros the predefined macros from figure 1 that identify the compiler can be used as part of a preprocessor directive to conditionally compile code. You can alter the values of these variables in the makefile, with arguments to make, or in the environment to alter how the implicit rules work without redefining the rules themselves. The compiler supports these predefined macros specified by the iso c99. Predefined macros are also used extensively within makes implicit rules. Low 8 bits represent the minor version, high 8 bits represent major version. Systemspecific predefined macros the c preprocessor. Using predefined macros eliminates the need to edit makefiles when the underlying compilation environment changes. The unroll compiler option instructs the compiler to perform loop unrolling, which is an optimization that replicates a loop body multiple times, and adjusts the loop control code accordingly.

The recipes in builtin implicit rules make liberal use of certain predefined variables. Macros defined by the compiler are documented in the predefined macros chapter in the online reference. Each compiler that may be used can then be added to the conditional statement with the nonportable preprocessor directive that is needed for the task at hand. Overview of predefined compiler macros for standards, compilers, operating systems, and hardware architectures. Defined to the micro patch version of the compiler. The gnu make utility in linux comes to your rescue by reading and interpreting a makefile. We are slowly phasing out all predefined macros which are outside the reserved namespace. The cx51 compiler provides the following predefined constants you may use in preprocessor directives and c code to create portable programs. They act like predefined macros, but you cannot undefine them. Variables or macros in the gnu make utility dummies. If compiling to use the software floatingpoint calling standard and library. If you want to use other symbol names, you need to specify them on the command line. They are available with the same meanings regardless of the machine or operating system on which you are using gnu c. Macros also provide access to the cflags macro and other flags macros for supplying compiler options from the command line.

These macros are defined by all gnu compilers that use the c preprocessor. If not initialized explicitly, the value held by that variable in indeterministic. Show all predefined macros for your compiler magnumripper. Using predefined preprocessor symbols intel fortran. The substitution is performed in the preprocessing phase. Aug 09, 2008 i recently stumbled across an article referencing macros defined by gcc. These macros provide information about toolchain version numbers and compiler options. Please note that not all compilers defines these macros, e. You can use the d compiler option to define the symbol names to be used during preprocessing.

All names which begin with two underscores, or an underscore and a capital letter, are reserved for the compiler and library to. An integer that specifies the current compiler s version. C is there predefinedmacros define about byte order in armcc. Predefined macros in c with examples geeksforgeeks. Common predefined macros gcc, the gnu compiler collection. One of my friend homolka richard gave me a very nice tip. How to list predefined macros in the preprocessor cypress. In addition to the basic capability of building targets from dependents, gnu make includes many features that make it easy for you to express the dependencies and rules for building a target from its dependents.

This topic documents the predefined macros of the arm compiler. When the ansi option, or any std option that requests strict conformance, is given to the compiler, all the systemspecific predefined macros outside the reserved namespace are suppressed. For example, if we want to use a generic or opaque pointer type, we use void pointers. When defined, the macro indicates that the program is a console application.

All of these macros are predefined by a specific compiler option or suboption, or any invocation or pragma that implies that suboption. Predefined compiler macros wiki compilers sourceforge. Generic macros, of which at least one is defined on a unix compliant platform. Macros related to compiler option settings the following macros can be tested for various features, including source input characteristics, output file characteristics, and optimization. Tips and tricks writing portable code using compiler. The c standard requires that all systemspecific macros be part of the reserved namespace. In your code, int i is an automatic local variable. The parallel macros, inside the reserved namespace, remain defined. The preprocessor symbols shown in the table below are predefined by the compiler system and are available to compiler directives and to fpp. The compiler supports the predefined macros listed in the table below. Loop unrolling exposes instruction level parallelism for instruction scheduling and software pipelining and thus can improve a programs performance. These pages lists various predefined compiler macros that can be used to identify standards, compilers, operating systems, hardware architectures, and even basic runtime libraries at compiletime.

These macros are in addition to the ansi predefined macros. These pages lists various pre defined compiler macros that can be used to identify standards, compilers, operating. This gives you a way to find out what is predefined in your version of cpp. Notice that clang also defines the gnu c version macros, but you should use the clang.