From dfed7971fb42cbd5196ee92e27e8292f46fa72e9 Mon Sep 17 00:00:00 2001 From: Segher Boessenkool Date: Tue, 29 Nov 2016 06:29:47 +0100 Subject: [PATCH] rs6000: Make deallocation of a large frame work (PR77687) If we use ABI_V4 and we have a big stack frame, we end the epilogue with a "mr 1,11" (or similar) instruction. This instruction however has no dependencies on the earlier restores from stack (done via r11), so sched2 can end up reordering the insns, which is bad because we have no red zone so that you then restore from stack that is already deallocated. This fixes it by making that restore depend on the memory accesses. PR target/77687 * config/rs6000/rs6000.c (rs6000_emit_stack_reset): Emit the stack_restore_tie insn instead of stack_tie, for the SVR4 and SPE ABIs. * config/rs6000/rs6000.md (stack_restore_tie): New define_insn. From-SVN: r242949 --- gcc/ChangeLog | 8 ++++++++ gcc/config/rs6000/rs6000.c | 13 ++++++++----- gcc/config/rs6000/rs6000.md | 16 ++++++++++++++++ 3 files changed, 32 insertions(+), 5 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index da6c6409700..27f4137134a 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2016-11-29 Segher Boessenkool + + PR target/77687 + * config/rs6000/rs6000.c (rs6000_emit_stack_reset): Emit the + stack_restore_tie insn instead of stack_tie, for the SVR4 and + SPE ABIs. + * config/rs6000/rs6000.md (stack_restore_tie): New define_insn. + 2016-11-28 Segher Boessenkool * shrink-wrap.c (init_separate_shrink_wrap): Do not clear diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c index dfb5dc86b11..0a6a784a940 100644 --- a/gcc/config/rs6000/rs6000.c +++ b/gcc/config/rs6000/rs6000.c @@ -27534,7 +27534,11 @@ rs6000_emit_stack_reset (rs6000_stack_t *info, rtx frame_reg_rtx, HOST_WIDE_INT frame_off, unsigned updt_regno) { - rtx updt_reg_rtx; + /* If there is nothing to do, don't do anything. */ + if (frame_off == 0 && REGNO (frame_reg_rtx) == updt_regno) + return NULL_RTX; + + rtx updt_reg_rtx = gen_rtx_REG (Pmode, updt_regno); /* This blockage is needed so that sched doesn't decide to move the sp change before the register restores. */ @@ -27542,18 +27546,17 @@ rs6000_emit_stack_reset (rs6000_stack_t *info, || (TARGET_SPE_ABI && info->spe_64bit_regs_used != 0 && info->first_gp_reg_save != 32)) - rs6000_emit_stack_tie (frame_reg_rtx, frame_pointer_needed); + return emit_insn (gen_stack_restore_tie (updt_reg_rtx, frame_reg_rtx, + GEN_INT (frame_off))); /* If we are restoring registers out-of-line, we will be using the "exit" variants of the restore routines, which will reset the stack for us. But we do need to point updt_reg into the right place for those routines. */ - updt_reg_rtx = gen_rtx_REG (Pmode, updt_regno); - if (frame_off != 0) return emit_insn (gen_add3_insn (updt_reg_rtx, frame_reg_rtx, GEN_INT (frame_off))); - else if (REGNO (frame_reg_rtx) != updt_regno) + else return emit_move_insn (updt_reg_rtx, frame_reg_rtx); return NULL_RTX; diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md index f3d1d7156e3..cb982d383ca 100644 --- a/gcc/config/rs6000/rs6000.md +++ b/gcc/config/rs6000/rs6000.md @@ -12813,6 +12813,22 @@ "" [(set_attr "length" "0")]) +; Some 32-bit ABIs do not have a red zone, so the stack deallocation has to +; stay behind all restores from the stack, it cannot be reordered to before +; one. See PR77687. This insn is an add or mr, and a stack_tie on the +; operands of that. +(define_insn "stack_restore_tie" + [(set (match_operand:SI 0 "gpc_reg_operand" "=r,r") + (plus:SI (match_operand:SI 1 "gpc_reg_operand" "r,r") + (match_operand:SI 2 "reg_or_cint_operand" "O,rI"))) + (set (mem:BLK (match_dup 0)) (const_int 0)) + (set (mem:BLK (match_dup 1)) (const_int 0))] + "TARGET_32BIT" + "@ + mr %0,%1 + add%I2 %0,%1,%2" + [(set_attr "type" "*,add")]) + (define_expand "epilogue" [(use (const_int 0))] "" -- 2.30.2