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, 4 insertions, 29 deletions

diff --git a/gcc/cfgrtl.c b/gcc/cfgrtl.c
index efd7a81..4f3b1e8 100644
--- a/gcc/cfgrtl.c
+++ b/gcc/cfgrtl.c
@@ -887,18 +887,6 @@ rtl_merge_blocks (basic_block a, basic_block b)
 
       del_first = a_end;
 
-      /* If this was a conditional jump, we need to also delete
-	 the insn that set cc0.  */
-      if (HAVE_cc0 && only_sets_cc0_p (prev))
-	{
-	  rtx_insn *tmp = prev;
-
-	  prev = prev_nonnote_insn (prev);
-	  if (!prev)
-	    prev = BB_HEAD (a);
-	  del_first = tmp;
-	}
-
       a_end = PREV_INSN (del_first);
     }
   else if (BARRIER_P (NEXT_INSN (a_end)))
@@ -1041,7 +1029,7 @@ edge
 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
 {
   basic_block src = e->src;
-  rtx_insn *insn = BB_END (src), *kill_from;
+  rtx_insn *insn = BB_END (src);
   rtx set;
   int fallthru = 0;
 
@@ -1078,13 +1066,6 @@ try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
   if (!set || side_effects_p (set))
     return NULL;
 
-  /* In case we zap a conditional jump, we'll need to kill
-     the cc0 setter too.  */
-  kill_from = insn;
-  if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, PATTERN (insn))
-      && only_sets_cc0_p (PREV_INSN (insn)))
-    kill_from = PREV_INSN (insn);
-
   /* See if we can create the fallthru edge.  */
   if (in_cfglayout || can_fallthru (src, target))
     {
@@ -1095,12 +1076,11 @@ try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
       /* Selectively unlink whole insn chain.  */
       if (in_cfglayout)
 	{
-	  delete_insn_chain (kill_from, BB_END (src), false);
+	  delete_insn_chain (insn, BB_END (src), false);
 	  remove_barriers_from_footer (src);
 	}
       else
-	delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
-			   false);
+	delete_insn_chain (insn, PREV_INSN (BB_HEAD (target)), false);
     }
 
   /* If this already is simplejump, redirect it.  */
@@ -1139,7 +1119,7 @@ try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
 		 INSN_UID (insn), INSN_UID (BB_END (src)));
 
 
-      delete_insn_chain (kill_from, insn, false);
+      delete_insn_chain (insn, insn, false);
 
       /* Recognize a tablejump that we are converting to a
 	 simple jump and remove its associated CODE_LABEL
@@ -1806,11 +1786,6 @@ rtl_tidy_fallthru_edge (edge e)
 	  delete_insn (table);
 	}
 
-      /* If this was a conditional jump, we need to also delete
-	 the insn that set cc0.  */
-      if (HAVE_cc0 && any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
-	q = PREV_INSN (q);
-
       q = PREV_INSN (q);
     }
   /* Unconditional jumps with side-effects (i.e. which we can't just delete