Note, interrupt handlers for the m68k, H8/300, H8/300H, H8S, and SH processors can be specified via the interrupt_handler attribute. This has a similar effect as the -fno-toplevel-reorder option, but only applies to the marked symbols. If the format_arg attribute had not been specified, all the compiler could tell in such calls to format functions would be that the format string argument is not constant; this would If the format_arg attribute had not been specified, all the compiler could tell in such calls to format functions would be that the format string argument is not constant; this would navigate here
For functions declared inline, this attribute inlines the function even if no optimization level was specified. Similarly, the destructor attribute causes the function to be called automatically after main () has completed or exit () has been called. The function is optimized more aggressively and on many targets it is placed into a special subsection of the text section so all hot functions appear close together, improving locality. Functions that take a variable number of arguments will continue to be passed all of their arguments on the stack.
const Many functions do not examine any values except their arguments, and have no effects except the return value. This attribute expects an integer argument specifying the trap number to be used. The options supported are specific to each target. This happens when the class has a dllimported constructor or a non-inline, non-pure virtual function and, for either of those two conditions, the class also has an inline constructor or destructor
nothrowThe nothrow attribute is used to inform the compiler that a function cannot throw an exception. Interesting non-pure functions are functions with infinite loops or those depending on volatile memory or other system resource, that may change between two consecutive calls (such as feof in a multithreading kspisusp When used together with interrupt_handler , exception_handler or nmi_handler , code is generated to load the stack pointer from the USP register in the function prologue. For a function marked with this attribute, every call inside this function is inlined, if possible.
returns_twice The returns_twice attribute tells the compiler that a function may return more than one time. The use of the dllimport attribute on functions is not necessary, but provides a small performance benefit by eliminating a thunk in the dll. Why do train companies require two hours to deliver your ticket to the machine? l1_text This attribute specifies a function to be placed into L1 Instruction SRAM.
For example, the declaration: extern void foobar (void) __attribute__ ((section ("bar"))); puts the function foobar in the bar section. More importantly, it helps avoid spurious warnings of uninitialized variables. The section attribute specifies that a function lives in a particular section. It is available if either of the preprocessor macros __GNUC_GNU_INLINE__ or __GNUC_STDC_INLINE__ are defined.
The keyword __attribute__ allows you to specify special attributes when making a declaration. https://sourceforge.net/p/libjson/bugs/28/ These attributes override both the -mlongcall switch and, on the RS/6000 and PowerPC, the #pragma longcall setting. This will often improve optimization. For example, you may use __noreturn__ instead of noreturn .
It is an error to explicitly specify any other visibility. Except in strictly conforming C standard modes, the X/Open function strfmon is also checked as are printf_unlocked and fprintf_unlocked. May 12 '15 at 9:16 This question has been asked before and already has an answer. In C99 mode, the functions snprintf, vsnprintf, vscanf, vfscanf and vsscanf are also checked.
The first of the two arguments specifies the number of halfwords to be added before the function label. The default is to use the Microsoft ABI when targeting Windows. An alternative way to declare that a function has no side effects, which works in the current version and in some older versions, is as follows: typedef int intfn (); extern not_nested This interrupt service routine is not interruptible.
visibility ("visibility_type")The visibility attribute on ELF targets causes the declaration to be emitted with default, hidden, protected or internal visibility. micromips, MIPS nomicromips, MIPS On MIPS targets, you can use the micromips and nomicromips function attributes to locally select or turn off microMIPS code generation. Note the tiny data area is limited to slightly under 32kbytes of data.
Some file formats do not support arbitrary sections so the section attribute is not available on all platforms. Don't tell me to reduce the optimization level. The format attribute allows you to identify your own functions that take format strings as arguments, so that GCC can check the calls to these functions for errors. The compiler will generate corresponding sections for use in a reset handler.
asked 2 years ago viewed 1654 times active 2 years ago Related 376How to generate a stacktrace when my gcc C++ app crashes1gcc(v4.1.2 cross-compiler) integer promotion problem1644Why doesn't GCC optimize a*a*a*a*a*a Such a function can be subject to common subexpression elimination and loop optimization just as an arithmetic operator would be. Parameters are handled sequentially, so one handler can be assigned to multiple entries in multiple tables. This is useful for compile-time checking, especially together with __builtin_constant_p and inline functions where checking the inline function arguments is not possible through extern char [(condition) ? 1 : -1]; tricks.
Which g++ version are you using? –Andreas Fester Jan 15 '14 at 13:52 Using 4.6.3 for powerpc. –ShaneCook Jan 15 '14 at 14:18 add a comment| Your Answer On IA-64, use this attribute to set the addressability of an object. The compiler will generate function entry and exit sequences suitable for use in an interrupt handler when this attribute is present. In no case is the function compiled as a standalone function, not even if you take its address explicitly.
The warning also includes the location of the declaration of the deprecated function, to enable users to easily find further information about why the function is deprecated, or what they should The attribute has no effect on functions defined within the current compilation unit. warm Provide a user-defined function to handle warm reset exception. sseregparm On x86-32 targets with SSE support, the sseregparm attribute causes the compiler to pass up to 3 floating-point arguments For example, the declaration: extern void foobar (void) __attribute__ ((section ("bar"))); puts the function foobar in the bar section.
The pointer name is formed by combining __imp_ and the function name. sp_switchUse this attribute on the SH to indicate an interrupt_handler function should switch to an alternate stack. Numbers are assumed to be an optimization level. Mixed MIPS16 and non-MIPS16 code may interact badly with some GCC extensions such as __builtin_apply (see Constructing Calls ).
This can be used for instance to have functions compiled with a different ISA (instruction set architecture) than the default.
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