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Diffstat (limited to 'clang/docs/LanguageExtensions.rst')
| -rw-r--r-- | clang/docs/LanguageExtensions.rst | 42 |
1 files changed, 0 insertions, 42 deletions
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst index 15bad2da3c1..457b0a386b3 100644 --- a/clang/docs/LanguageExtensions.rst +++ b/clang/docs/LanguageExtensions.rst @@ -1629,48 +1629,6 @@ Which compiles to (on X86-32): movl %gs:(%eax), %eax ret -ARM Language Extensions ------------------------ - -Interrupt attribute -^^^^^^^^^^^^^^^^^^^ - -Clang supports the GNU style ``__attribute__((interrupt("TYPE")))`` attribute on -ARM targets. This attribute may be attached to a function definition and -instructs the backend to generate appropriate function entry/exit code so that -it can be used directly as an interrupt service routine. - -The parameter passed to the interrupt attribute is optional, but if -provided it must be a string literal with one of the following values: "IRQ", -"FIQ", "SWI", "ABORT", "UNDEF". - -The semantics are as follows: - -- If the function is AAPCS, Clang instructs the backend to realign the stack to - 8 bytes on entry. This is a general requirement of the AAPCS at public - interfaces, but may not hold when an exception is taken. Doing this allows - other AAPCS functions to be called. -- If the CPU is M-class this is all that needs to be done since the architecture - itself is designed in such a way that functions obeying the normal AAPCS ABI - constraints are valid exception handlers. -- If the CPU is not M-class, the prologue and epilogue are modified to save all - non-banked registers that are used, so that upon return the user-mode state - will not be corrupted. Note that to avoid unnecessary overhead, only - general-purpose (integer) registers are saved in this way. If VFP operations - are needed, that state must be saved manually. - - Specifically, interrupt kinds other than "FIQ" will save all core registers - except "lr" and "sp". "FIQ" interrupts will save r0-r7. -- If the CPU is not M-class, the return instruction is changed to one of the - canonical sequences permitted by the architecture for exception return. Where - possible the function itself will make the necessary "lr" adjustments so that - the "preferred return address" is selected. - - Unfortunately the compiler is unable to make this guarantee for an "UNDEF" - handler, where the offset from "lr" to the preferred return address depends on - the execution state of the code which generated the exception. In this case - a sequence equivalent to "movs pc, lr" will be used. - Extensions for Static Analysis ============================== |
