On Thu, Dec 20, 2018 at 12:43 PM Eric Botcazou <ebotca...@adacore.com> wrote: > > Hi, > > this is a regression introduced on the SPARC by the somewhat controversial > combiner change for hard registers: the compiler can no longer apply the leaf > registers optimization to a small function so a register window is now used. > > The combiner change might be an overall win, but my understanding is that it's > dependent on the target and SPARC seems to be in the wrong basket: almost all > changes to the gcc.c-torture/compile testsuite at -O2 are pessimizations in > the form of additional move instructions between registers on function entry. > > Clearly that's counter-productive for a LEAF_REGISTERS target like SPARC so > the proposed fix is to re-enable hard register combining for leaf registers. > > Tested on SPARC/Solaris 11, OK for the mainline?
This only affects xtensa besides sparc so unless Segher objects this is OK. Does this solve most of the pessimizations? Please add a testcase if it doesn't solve existing FAILs. Thanks, Richard. > > 2018-12-20 Eric Botcazou <ebotca...@adacore.com> > > PR rtl-optimization/87727 > * combine.c (cant_combine_insn_p): On a LEAF_REGISTERS target, combine > again moves from leaf hard registers. > > -- > Eric Botcazou
