On Sun, Nov 15, 2015 at 11:29:29PM -0700, htio2 wrote: > Hi, > > I was trying to split the sub instructuction into 2 16bit process and came > across this error: > error: could not split insn > > using gdb i was able to trace the error to the below in try_split (rtx pat, > rtx trial, int last) function: > /* We're not good at redistributing frame information. */ > if (RTX_FRAME_RELATED_P (trial)) > return trial; > > my question is is there any reason that frame insn cannot be split ? and how > do I fix it ? This was added by <https://gcc.gnu.org/ml/gcc-patches/2009-05/msg00277.html>. RTX_FRAME_RELATED_P says there are frame (unwind) notes for the debugger on this insn. You need to have those REG_CFA_* notes. You either need to split this insn earlier, or not split it at all, or your prologue or epilogue are just wrong. Need more details to give better advice. Segher
