Remove CC0

This removes CC0 and all directly related infrastructure.

CC_STATUS, CC_STATUS_MDEP, CC_STATUS_MDEP_INIT, and NOTICE_UPDATE_CC
are deleted and poisoned.  CC0 is only deleted (some targets use that
name for something else).  HAVE_cc0 is automatically generated, and we
no longer will do that after this patch.

CC_STATUS_INIT is suggested in final.c to also be useful for ports that
are not CC0, and at least arm seems to use it for something.  So I am
leaving that alone, but most targets that have it could remove it.

2021-05-04  Segher Boessenkool  <segher@kernel.crashing.org>

	* caller-save.c: Remove CC0.
	* cfgcleanup.c: Remove CC0.
	* cfgrtl.c: Remove CC0.
	* combine.c: Remove CC0.
	* compare-elim.c: Remove CC0.
	* conditions.h: Remove CC0.
	* config/h8300/h8300.h: Remove CC0.
	* config/h8300/h8300-protos.h: Remove CC0.
	* config/h8300/peepholes.md: Remove CC0.
	* config/i386/x86-tune-sched.c: Remove CC0.
	* config/m68k/m68k.c: Remove CC0.
	* config/rl78/rl78.c: Remove CC0.
	* config/sparc/sparc.c: Remove CC0.
	* config/xtensa/xtensa.c: Remove CC0.
	(gen_conditional_move):  Use pc_rtx instead of cc0_rtx in a piece of
	RTL where that is used as a placeholder only.
	* cprop.c: Remove CC0.
	* cse.c: Remove CC0.
	* cselib.c: Remove CC0.
	* df-problems.c: Remove CC0.
	* df-scan.c: Remove CC0.
	* doc/md.texi: Remove CC0.  Adjust an example.
	* doc/rtl.texi: Remove CC0.  Adjust an example.
	* doc/tm.texi: Regenerate.
	* doc/tm.texi.in: Remove CC0.
	* emit-rtl.c: Remove CC0.
	* final.c: Remove CC0.
	* fwprop.c: Remove CC0.
	* gcse-common.c: Remove CC0.
	* gcse.c: Remove CC0.
	* genattrtab.c: Remove CC0.
	* genconfig.c: Remove CC0.
	* genemit.c: Remove CC0.
	* genextract.c: Remove CC0.
	* gengenrtl.c: Remove CC0.
	* genrecog.c: Remove CC0.
	* haifa-sched.c: Remove CC0.
	* ifcvt.c: Remove CC0.
	* ira-costs.c: Remove CC0.
	* ira.c: Remove CC0.
	* jump.c: Remove CC0.
	* loop-invariant.c: Remove CC0.
	* lra-constraints.c: Remove CC0.
	* lra-eliminations.c: Remove CC0.
	* optabs.c: Remove CC0.
	* postreload-gcse.c: Remove CC0.
	* postreload.c: Remove CC0.
	* print-rtl.c: Remove CC0.
	* read-rtl-function.c: Remove CC0.
	* reg-notes.def: Remove CC0.
	* reg-stack.c: Remove CC0.
	* reginfo.c: Remove CC0.
	* regrename.c: Remove CC0.
	* reload.c: Remove CC0.
	* reload1.c: Remove CC0.
	* reorg.c: Remove CC0.
	* resource.c: Remove CC0.
	* rtl.c: Remove CC0.
	* rtl.def: Remove CC0.
	* rtl.h: Remove CC0.
	* rtlanal.c: Remove CC0.
	* sched-deps.c: Remove CC0.
	* sched-rgn.c: Remove CC0.
	* shrink-wrap.c: Remove CC0.
	* simplify-rtx.c: Remove CC0.
	* system.h: Remove CC0.  Poison NOTICE_UPDATE_CC, CC_STATUS_MDEP_INIT,
	CC_STATUS_MDEP, and CC_STATUS.
	* target.def: Remove CC0.
	* valtrack.c: Remove CC0.
	* var-tracking.c: Remove CC0.

1 files changed, 3 insertions, 53 deletions

diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 07e9086..ff3b444 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -123,7 +123,6 @@ rtx const_int_rtx[MAX_SAVED_CONST_INT * 2 + 1];
 rtx pc_rtx;
 rtx ret_rtx;
 rtx simple_return_rtx;
-rtx cc0_rtx;
 
 /* Marker used for denoting an INSN, which should never be accessed (i.e.,
    this pointer should normally never be dereferenced), but is required to be
@@ -2847,14 +2846,13 @@ verify_rtx_sharing (rtx orig, rtx insn)
     case LABEL_REF:
     case CODE_LABEL:
     case PC:
-    case CC0:
     case RETURN:
     case SIMPLE_RETURN:
     case SCRATCH:
       /* SCRATCH must be shared because they represent distinct values.  */
       return;
     case CLOBBER:
-      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+      /* Share clobbers of hard registers, but do not share pseudo reg
          clobbers or clobbers of hard registers that originated as pseudos.
          This is needed to allow safe register renaming.  */
       if (REG_P (XEXP (x, 0))
@@ -3100,14 +3098,13 @@ repeat:
     case LABEL_REF:
     case CODE_LABEL:
     case PC:
-    case CC0:
     case RETURN:
     case SIMPLE_RETURN:
     case SCRATCH:
       /* SCRATCH must be shared because they represent distinct values.  */
       return;
     case CLOBBER:
-      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+      /* Share clobbers of hard registers, but do not share pseudo reg
          clobbers or clobbers of hard registers that originated as pseudos.
          This is needed to allow safe register renaming.  */
       if (REG_P (XEXP (x, 0))
@@ -3223,7 +3220,6 @@ repeat:
     case SYMBOL_REF:
     case CODE_LABEL:
     case PC:
-    case CC0:
     case RETURN:
     case SIMPLE_RETURN:
       return;
@@ -3717,50 +3713,6 @@ prev_active_insn (rtx_insn *insn)
   return insn;
 }
 
-/* Return the next insn that uses CC0 after INSN, which is assumed to
-   set it.  This is the inverse of prev_cc0_setter (i.e., prev_cc0_setter
-   applied to the result of this function should yield INSN).
-
-   Normally, this is simply the next insn.  However, if a REG_CC_USER note
-   is present, it contains the insn that uses CC0.
-
-   Return 0 if we can't find the insn.  */
-
-rtx_insn *
-next_cc0_user (rtx_insn *insn)
-{
-  rtx note = find_reg_note (insn, REG_CC_USER, NULL_RTX);
-
-  if (note)
-    return safe_as_a <rtx_insn *> (XEXP (note, 0));
-
-  insn = next_nonnote_insn (insn);
-  if (insn && NONJUMP_INSN_P (insn) && GET_CODE (PATTERN (insn)) == SEQUENCE)
-    insn = as_a <rtx_sequence *> (PATTERN (insn))->insn (0);
-
-  if (insn && INSN_P (insn) && reg_mentioned_p (cc0_rtx, PATTERN (insn)))
-    return insn;
-
-  return 0;
-}
-
-/* Find the insn that set CC0 for INSN.  Unless INSN has a REG_CC_SETTER
-   note, it is the previous insn.  */
-
-rtx_insn *
-prev_cc0_setter (rtx_insn *insn)
-{
-  rtx note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
-
-  if (note)
-    return safe_as_a <rtx_insn *> (XEXP (note, 0));
-
-  insn = prev_nonnote_insn (insn);
-  gcc_assert (sets_cc0_p (PATTERN (insn)));
-
-  return insn;
-}
-
 /* Find a RTX_AUTOINC class rtx which matches DATA.  */
 
 static int
@@ -5687,12 +5639,11 @@ copy_insn_1 (rtx orig)
     case SYMBOL_REF:
     case CODE_LABEL:
     case PC:
-    case CC0:
     case RETURN:
     case SIMPLE_RETURN:
       return orig;
     case CLOBBER:
-      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
+      /* Share clobbers of hard registers, but do not share pseudo reg
          clobbers or clobbers of hard registers that originated as pseudos.
          This is needed to allow safe register renaming.  */
       if (REG_P (XEXP (orig, 0))
@@ -6413,7 +6364,6 @@ init_emit_once (void)
   pc_rtx = gen_rtx_fmt_ (PC, VOIDmode);
   ret_rtx = gen_rtx_fmt_ (RETURN, VOIDmode);
   simple_return_rtx = gen_rtx_fmt_ (SIMPLE_RETURN, VOIDmode);
-  cc0_rtx = gen_rtx_fmt_ (CC0, VOIDmode);
   invalid_insn_rtx = gen_rtx_INSN (VOIDmode,
 				   /*prev_insn=*/NULL,
 				   /*next_insn=*/NULL,