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These function attributes are supported by the RISC-V back end:
naked
This attribute allows the compiler to construct the
requisite function declaration, while allowing the body of the
function to be assembly code. The specified function will not have
prologue/epilogue sequences generated by the compiler. Only basic
asm
statements can safely be included in naked functions
(see Basic Asm). While using extended asm
or a mixture of
basic asm
and C code may appear to work, they cannot be
depended upon to work reliably and are not supported.
interrupt
Use this attribute to indicate that the specified function is an interrupt handler. The compiler generates function entry and exit sequences suitable for use in an interrupt handler when this attribute is present.
You can specify the kind of interrupt to be handled by adding an optional parameter to the interrupt attribute like this:
void f (void) __attribute__ ((interrupt ("user")));
Permissible values for this parameter are user
, supervisor
,
and machine
. If there is no parameter, then it defaults to
machine
.
You can specify an SiFive CLIC preemptible interrupt handler by adding an optional parameter to the interrupt attribute like this:
void f (void) __attribute__ ((interrupt ("SiFive-CLIC-preemptible")));
In this type of interrupt handler, in the prologue, the mepc and
mcause registers are saved, and interrupts are enabled. In the epilogue,
interrupts are disabled, and the mepc and mcause registers are restored.
This type of interrupt handler must be machine
mode, and must
not use the frame pointer.
You can specify an SiFive CLIC stack swapping interrupt handler by adding an optional parameter to the interrupt attribute like this:
void f (void) __attribute__ ((interrupt ("SiFive-CLIC-stack-swap")));
In this type of interrupt handler, the stack pointer will be swapped with
the mscratch
register in the prologue before the first use of the stack
pointer, and in the epilogue after the last use of the stack pointer. This
type of interrupt handler must be machine
mode.
Next: RL78 Function Attributes, Previous: PowerPC Function Attributes, Up: Function Attributes [Contents][Index]