Re: [PATCH] remove more dead regmove code

[Richard Guenther <richard dot guenther at gmail dot com>]

On Wed, Feb 25, 2009 at 1:37 PM, Paolo Bonzini <bonzini@gnu.org> wrote:
> Most of regmove code is not needed anymore after IRA. ?Vladimir removed
> most of the code a few weeks ago, but a little ugly part remained. ?I
> bootstrapped/regtested the attached patch on i686-pc-linux-gnu; ok for
> trunk (since Vlad's patch went there) or for 4.5?

Ok for trunk.

Richard.

> Paolo
>
> 2009-01-25 ?Paolo Bonzini ?<bonzini@gnu.org>
>
> ? ? ? ?* regmove.c (discover_flags_reg, flags_set_1, mark_flags_life_zones,
> ? ? ? ?flags_set_1_rtx, flags_set_1_set): Delete.
> ? ? ? ?(regmove_optimize): Do not call mark_flags_life_zones.
>
> Index: regmove.c
> ===================================================================
> --- regmove.c ? (revision 144226)
> +++ regmove.c ? (working copy)
> @@ -58,10 +58,6 @@ struct match {
> ? int early_clobber[MAX_RECOG_OPERANDS];
> ?};
>
> -static rtx discover_flags_reg (void);
> -static void mark_flags_life_zones (rtx);
> -static void flags_set_1 (rtx, const_rtx, void *);
> -
> ?static int find_matches (rtx, struct match *);
> ?static int regclass_compatible_p (int, int);
> ?static int fixup_match_2 (rtx, rtx, rtx, rtx);
> @@ -79,171 +75,6 @@ regclass_compatible_p (int class0, int c
> ?}
>
>
> -/* Determine if the pattern generated by add_optab has a clobber,
> - ? such as might be issued for a flags hard register. ?To make the
> - ? code elsewhere simpler, we handle cc0 in this same framework.
> -
> - ? Return the register if one was discovered. ?Return NULL_RTX if
> - ? if no flags were found. ?Return pc_rtx if we got confused. ?*/
> -
> -static rtx
> -discover_flags_reg (void)
> -{
> - ?rtx tmp;
> - ?tmp = gen_rtx_REG (word_mode, 10000);
> - ?tmp = gen_add3_insn (tmp, tmp, const2_rtx);
> -
> - ?/* If we get something that isn't a simple set, or a
> - ? ? [(set ..) (clobber ..)], this whole function will go wrong. ?*/
> - ?if (GET_CODE (tmp) == SET)
> - ? ?return NULL_RTX;
> - ?else if (GET_CODE (tmp) == PARALLEL)
> - ? ?{
> - ? ? ?int found;
> -
> - ? ? ?if (XVECLEN (tmp, 0) != 2)
> - ? ? ? return pc_rtx;
> - ? ? ?tmp = XVECEXP (tmp, 0, 1);
> - ? ? ?if (GET_CODE (tmp) != CLOBBER)
> - ? ? ? return pc_rtx;
> - ? ? ?tmp = XEXP (tmp, 0);
> -
> - ? ? ?/* Don't do anything foolish if the md wanted to clobber a
> - ? ? ? ?scratch or something. ?We only care about hard regs.
> - ? ? ? ?Moreover we don't like the notion of subregs of hard regs. ?*/
> - ? ? ?if (GET_CODE (tmp) == SUBREG
> - ? ? ? ? && REG_P (SUBREG_REG (tmp))
> - ? ? ? ? && REGNO (SUBREG_REG (tmp)) < FIRST_PSEUDO_REGISTER)
> - ? ? ? return pc_rtx;
> - ? ? ?found = (REG_P (tmp) && REGNO (tmp) < FIRST_PSEUDO_REGISTER);
> -
> - ? ? ?return (found ? tmp : NULL_RTX);
> - ? ?}
> -
> - ?return pc_rtx;
> -}
> -
> -/* It is a tedious task identifying when the flags register is live and
> - ? when it is safe to optimize. ?Since we process the instruction stream
> - ? multiple times, locate and record these live zones by marking the
> - ? mode of the instructions --
> -
> - ? QImode is used on the instruction at which the flags becomes live.
> -
> - ? HImode is used within the range (exclusive) that the flags are
> - ? live. ?Thus the user of the flags is not marked.
> -
> - ? All other instructions are cleared to VOIDmode. ?*/
> -
> -/* Used to communicate with flags_set_1. ?*/
> -static rtx flags_set_1_rtx;
> -static int flags_set_1_set;
> -
> -static void
> -mark_flags_life_zones (rtx flags)
> -{
> - ?int flags_regno;
> - ?int flags_nregs;
> - ?basic_block block;
> -
> -#ifdef HAVE_cc0
> - ?/* If we found a flags register on a cc0 host, bail. ?*/
> - ?if (flags == NULL_RTX)
> - ? ?flags = cc0_rtx;
> - ?else if (flags != cc0_rtx)
> - ? ?flags = pc_rtx;
> -#endif
> -
> - ?/* Simple cases first: if no flags, clear all modes. ?If confusing,
> - ? ? mark the entire function as being in a flags shadow. ?*/
> - ?if (flags == NULL_RTX || flags == pc_rtx)
> - ? ?{
> - ? ? ?enum machine_mode mode = (flags ? HImode : VOIDmode);
> - ? ? ?rtx insn;
> - ? ? ?for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
> - ? ? ? PUT_MODE (insn, mode);
> - ? ? ?return;
> - ? ?}
> -
> -#ifdef HAVE_cc0
> - ?flags_regno = -1;
> - ?flags_nregs = 1;
> -#else
> - ?flags_regno = REGNO (flags);
> - ?flags_nregs = hard_regno_nregs[flags_regno][GET_MODE (flags)];
> -#endif
> - ?flags_set_1_rtx = flags;
> -
> - ?/* Process each basic block. ?*/
> - ?FOR_EACH_BB_REVERSE (block)
> - ? ?{
> - ? ? ?rtx insn, end;
> - ? ? ?int live;
> -
> - ? ? ?insn = BB_HEAD (block);
> - ? ? ?end = BB_END (block);
> -
> - ? ? ?/* Look out for the (unlikely) case of flags being live across
> - ? ? ? ?basic block boundaries. ?*/
> - ? ? ?live = 0;
> -#ifndef HAVE_cc0
> - ? ? ?{
> - ? ? ? int i;
> - ? ? ? for (i = 0; i < flags_nregs; ++i)
> - ? ? ? ? live |= REGNO_REG_SET_P (df_get_live_in (block), flags_regno + i);
> - ? ? ?}
> -#endif
> -
> - ? ? ?while (1)
> - ? ? ? {
> - ? ? ? ? /* Process liveness in reverse order of importance --
> - ? ? ? ? ? ?alive, death, birth. ?This lets more important info
> - ? ? ? ? ? ?overwrite the mode of lesser info. ?*/
> -
> - ? ? ? ? if (INSN_P (insn))
> - ? ? ? ? ? {
> -#ifdef HAVE_cc0
> - ? ? ? ? ? ? /* In the cc0 case, death is not marked in reg notes,
> - ? ? ? ? ? ? ? ?but is instead the mere use of cc0 when it is alive. ?*/
> - ? ? ? ? ? ? if (live && reg_mentioned_p (cc0_rtx, PATTERN (insn)))
> - ? ? ? ? ? ? ? live = 0;
> -#else
> - ? ? ? ? ? ? /* In the hard reg case, we watch death notes. ?*/
> - ? ? ? ? ? ? if (live && find_regno_note (insn, REG_DEAD, flags_regno))
> - ? ? ? ? ? ? ? live = 0;
> -#endif
> - ? ? ? ? ? ? PUT_MODE (insn, (live ? HImode : VOIDmode));
> -
> - ? ? ? ? ? ? /* In either case, birth is denoted simply by its presence
> - ? ? ? ? ? ? ? ?as the destination of a set. ?*/
> - ? ? ? ? ? ? flags_set_1_set = 0;
> - ? ? ? ? ? ? note_stores (PATTERN (insn), flags_set_1, NULL);
> - ? ? ? ? ? ? if (flags_set_1_set)
> - ? ? ? ? ? ? ? {
> - ? ? ? ? ? ? ? ? live = 1;
> - ? ? ? ? ? ? ? ? PUT_MODE (insn, QImode);
> - ? ? ? ? ? ? ? }
> - ? ? ? ? ? }
> - ? ? ? ? else
> - ? ? ? ? ? PUT_MODE (insn, (live ? HImode : VOIDmode));
> -
> - ? ? ? ? if (insn == end)
> - ? ? ? ? ? break;
> - ? ? ? ? insn = NEXT_INSN (insn);
> - ? ? ? }
> - ? ?}
> -}
> -
> -/* A subroutine of mark_flags_life_zones, called through note_stores. ?*/
> -
> -static void
> -flags_set_1 (rtx x, const_rtx pat, void *data ATTRIBUTE_UNUSED)
> -{
> - ?if (GET_CODE (pat) == SET
> - ? ? ?&& reg_overlap_mentioned_p (x, flags_set_1_rtx))
> - ? ?flags_set_1_set = 1;
> -}
> -
> ?#ifdef AUTO_INC_DEC
>
> ?/* Find the place in the rtx X where REG is used as a memory address.
> @@ -1077,10 +908,6 @@ regmove_optimize (rtx f, int nregs)
> ? regstat_init_n_sets_and_refs ();
> ? regstat_compute_ri ();
>
> - ?/* Find out where a potential flags register is live, and so that we
> - ? ? can suppress some optimizations in those zones. ?*/
> - ?mark_flags_life_zones (discover_flags_reg ());
> -
> ? regno_src_regno = XNEWVEC (int, nregs);
> ? for (i = nregs; --i >= 0; )
> ? ? regno_src_regno[i] = -1;
>
>