diff options
Diffstat (limited to 'gcc/md.texi')
| -rw-r--r-- | gcc/md.texi | 32 |
1 files changed, 15 insertions, 17 deletions
diff --git a/gcc/md.texi b/gcc/md.texi index 411f67fc754..047f25669a8 100644 --- a/gcc/md.texi +++ b/gcc/md.texi @@ -2848,26 +2848,24 @@ You will not normally need to define this pattern unless you also define @code{builtin_setjmp_setup}. The single argument is a pointer to the @code{jmp_buf}. -@cindex @code{eh_epilogue} instruction pattern -@item @samp{eh_epilogue} +@cindex @code{eh_return} instruction pattern +@item @samp{eh_return} This pattern, if defined, affects the way @code{__builtin_eh_return}, -and thence @code{__throw} are built. It is intended to allow communication -between the exception handling machinery and the normal epilogue code -for the target. - -The pattern takes three arguments. The first is the exception context -pointer. This will have already been copied to the function return -register appropriate for a pointer; normally this can be ignored. The -second argument is an offset to be added to the stack pointer. It will -have been copied to some arbitrary call-clobbered hard reg so that it -will survive until after reload to when the normal epilogue is generated. -The final argument is the address of the exception handler to which +and thence the call frame exception handling library routines, are +built. It is intended to handle non-trivial actions needed along +the abnormal return path. + +The pattern takes two arguments. The first is an offset to be applied +to the stack pointer. It will have been copied to some appropriate +location (typically @code{EH_RETURN_STACKADJ_RTX}) which will survive +until after reload to when the normal epilogue is generated. +The second argument is the address of the exception handler to which the function should return. This will normally need to copied by the -pattern to some special register. +pattern to some special register or memory location. -This pattern must be defined if @code{RETURN_ADDR_RTX} does not yield -something that can be reliably and permanently modified, i.e. a fixed -hard register or a stack memory reference. +This pattern only needs to be defined if call frame exception handling +is to be used, and simple moves to @code{EH_RETURN_STACKADJ_RTX} and +@code{EH_RETURN_HANDLER_RTX} are not sufficient. @cindex @code{prologue} instruction pattern @item @samp{prologue} |