| Message ID | 20160504131107.GZ18915@bubble.grove.modra.org |
|---|---|
| State | New |
| Headers | show |
On Wed, May 04, 2016 at 10:41:07PM +0930, Alan Modra wrote: > Bootstrap and regression tested powerpc64le-linux. Fixes 771 Go > testsuite regressions. OK to apply everywhere? > > The alternative of adding all parameter regs used by cfun to the > __morestack CALL_INSN_FUNCTION_USAGE and uses for cfun return value > regs seems overkill when all we need to do is protect a very small > sequence of insns. > > PR target/70947 > * config/rs6000/rs6000.c (rs6000_expand_split_stack_prologue): Stop > regrename modifying insns saving lr before __morestack call. > * config/rs6000/rs6000.md (split_stack_return): Similarly for > insns restoring lr after __morestack call. Okay for trunk. Okay for the other branches after some suitable burn-in period. Thanks, Segher
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c index ceb3705..0660427 100644 --- a/gcc/config/rs6000/rs6000.c +++ b/gcc/config/rs6000/rs6000.c @@ -27970,6 +27970,11 @@ rs6000_expand_split_stack_prologue (void) const0_rtx, const0_rtx)); call_fusage = NULL_RTX; use_reg (&call_fusage, r12); + /* Say the call uses r0, even though it doesn't, to stop regrename + from twiddling with the insns saving lr, trashing args for cfun. + The insns restoring lr are similarly protected by making + split_stack_return use r0. */ + use_reg (&call_fusage, r0); add_function_usage_to (insn, call_fusage); emit_insn (gen_frame_load (r0, r1, info->lr_save_offset)); insn = emit_move_insn (lr, r0); diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md index a6f219c..87e7879 100644 --- a/gcc/config/rs6000/rs6000.md +++ b/gcc/config/rs6000/rs6000.md @@ -12587,8 +12587,10 @@ (set_attr "indexed" "no")]) ;; A return instruction which the middle-end doesn't see. +;; Use r0 to stop regrename twiddling with lr restore insns emitted +;; after the call to __morestack. (define_insn "split_stack_return" - [(unspec_volatile [(const_int 0)] UNSPECV_SPLIT_STACK_RETURN)] + [(unspec_volatile [(use (reg:SI 0))] UNSPECV_SPLIT_STACK_RETURN)] "" "blr" [(set_attr "type" "jmpreg")])