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Diffstat (limited to 'gcc/tm.texi')
| -rw-r--r-- | gcc/tm.texi | 48 |
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diff --git a/gcc/tm.texi b/gcc/tm.texi index 9f20053..e3dd530 100644 --- a/gcc/tm.texi +++ b/gcc/tm.texi @@ -2505,6 +2505,54 @@ You only need to define this macro if the default is incorrect, and you want to support call frame debugging information like that provided by DWARF 2. +@findex EH_RETURN_DATA_REGNO +@item EH_RETURN_DATA_REGNO (@var{N}) +A C expression whose value is the @var{N}th register number used for +data by exception handlers, or @code{INVALID_REGNUM} if fewer than +@var{N} registers are usable. + +The exception handling library routines communicate with the exception +handlers via a set of agreed upon registers. Ideally these registers +should be call-clobbered; it is possible to use call-saved registers, +but may negatively impact code size. The target must support at least +2 data registers, but should define 4 if there are enough free registers. + +You must define this macro if you want to support call frame exception +handling like that provided by DWARF 2. + +@findex EH_RETURN_STACKADJ_RTX +@item EH_RETURN_STACKADJ_RTX +A C expression whose value is RTL representing a location in which +to store a stack adjustment to be applied before function return. +This is used to unwind the stack to an exception handler's call frame. +It will be assigned zero on code paths that return normally. + +Typically this is a call-clobbered hard register that is otherwise +untouched by the epilogue, but could also be a stack slot. + +You must define this macro if you want to support call frame exception +handling like that provided by DWARF 2. + +@findex EH_RETURN_HANDLER_RTX +@item EH_RETURN_HANDLER_RTX +A C expression whose value is RTL representing a location in which +to store the address of an exception handler to which we should +return. It will not be assigned on code paths that return normally. + +Typically this is the location in the call frame at which the normal +return address is stored. For targets that return by popping an +address off the stack, this might be a memory address just below +the @emph{target} call frame rather than inside the current call +frame. @code{EH_RETURN_STACKADJ_RTX} will have already been assigned, +so it may be used to calculate the location of the target call frame. + +Some targets have more complex requirements than storing to an +address calculable during initial code generation. In that case +the @code{eh_return} instruction pattern should be used instead. + +If you want to support call frame exception handling, you must +define either this macro or the @code{eh_return} instruction pattern. + @findex SMALL_STACK @item SMALL_STACK Define this macro if the stack size for the target is very small. This |