diff options
| -rw-r--r-- | gcc/fwprop.c | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/gcc/fwprop.c b/gcc/fwprop.c index eff8f7c..123cc22 100644 --- a/gcc/fwprop.c +++ b/gcc/fwprop.c @@ -176,7 +176,7 @@ namespace static const uint16_t CONSTANT = FIRST_SPARE_RESULT << 1; static const uint16_t PROFITABLE = FIRST_SPARE_RESULT << 2; - fwprop_propagation (rtx_insn *, rtx, rtx); + fwprop_propagation (insn_info *, insn_info *, rtx, rtx); bool changed_mem_p () const { return result_flags & CHANGED_MEM; } bool folded_to_constants_p () const; @@ -185,13 +185,20 @@ namespace bool check_mem (int, rtx) final override; void note_simplification (int, uint16_t, rtx, rtx) final override; uint16_t classify_result (rtx, rtx); + + private: + const bool single_use_p; + const bool single_ebb_p; }; } /* Prepare to replace FROM with TO in INSN. */ -fwprop_propagation::fwprop_propagation (rtx_insn *insn, rtx from, rtx to) - : insn_propagation (insn, from, to) +fwprop_propagation::fwprop_propagation (insn_info *use_insn, + insn_info *def_insn, rtx from, rtx to) + : insn_propagation (use_insn->rtl (), from, to), + single_use_p (def_insn->num_uses () == 1), + single_ebb_p (use_insn->ebb () == def_insn->ebb ()) { should_check_mems = true; should_note_simplifications = true; @@ -262,6 +269,22 @@ fwprop_propagation::classify_result (rtx old_rtx, rtx new_rtx) && GET_MODE (new_rtx) == GET_MODE_INNER (GET_MODE (from))) return PROFITABLE; + /* Allow (subreg (mem)) -> (mem) simplifications with the following + exceptions: + 1) Propagating (mem)s into multiple uses is not profitable. + 2) Propagating (mem)s across EBBs may not be profitable if the source EBB + runs less frequently. + 3) Propagating (mem)s into paradoxical (subreg)s is not profitable. + 4) Creating new (mem/v)s is not correct, since DCE will not remove the old + ones. */ + if (single_use_p + && single_ebb_p + && SUBREG_P (old_rtx) + && !paradoxical_subreg_p (old_rtx) + && MEM_P (new_rtx) + && !MEM_VOLATILE_P (new_rtx)) + return PROFITABLE; + return 0; } @@ -363,7 +386,7 @@ try_fwprop_subst_note (insn_info *use_insn, insn_info *def_insn, rtx_insn *use_rtl = use_insn->rtl (); insn_change_watermark watermark; - fwprop_propagation prop (use_rtl, dest, src); + fwprop_propagation prop (use_insn, def_insn, dest, src); if (!prop.apply_to_rvalue (&XEXP (note, 0))) { if (dump_file && (dump_flags & TDF_DETAILS)) @@ -426,7 +449,7 @@ try_fwprop_subst_pattern (obstack_watermark &attempt, insn_change &use_change, rtx_insn *use_rtl = use_insn->rtl (); insn_change_watermark watermark; - fwprop_propagation prop (use_rtl, dest, src); + fwprop_propagation prop (use_insn, def_insn, dest, src); if (!prop.apply_to_pattern (loc)) { if (dump_file && (dump_flags & TDF_DETAILS)) |