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, 2 insertions, 34 deletions

diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
index 260a896..f05cb61 100644
--- a/gcc/cfgcleanup.c
+++ b/gcc/cfgcleanup.c
@@ -1449,12 +1449,6 @@ flow_find_cross_jump (basic_block bb1, basic_block bb2, rtx_insn **f1,
       i2 = PREV_INSN (i2);
     }
 
-  /* Don't allow the insn after a compare to be shared by
-     cross-jumping unless the compare is also shared.  */
-  if (HAVE_cc0 && ninsns && reg_mentioned_p (cc0_rtx, last1)
-      && ! sets_cc0_p (last1))
-    last1 = afterlast1, last2 = afterlast2, last_dir = afterlast_dir, ninsns--;
-
   /* Include preceding notes and labels in the cross-jump.  One,
      this may bring us to the head of the blocks as requested above.
      Two, it keeps line number notes as matched as may be.  */
@@ -1571,12 +1565,6 @@ flow_find_head_matching_sequence (basic_block bb1, basic_block bb2, rtx_insn **f
       i2 = NEXT_INSN (i2);
     }
 
-  /* Don't allow a compare to be shared by cross-jumping unless the insn
-     after the compare is also shared.  */
-  if (HAVE_cc0 && ninsns && reg_mentioned_p (cc0_rtx, last1)
-      && sets_cc0_p (last1))
-    last1 = beforelast1, last2 = beforelast2, ninsns--;
-
   if (ninsns)
     {
       *f1 = last1;
@@ -2340,12 +2328,7 @@ try_head_merge_bb (basic_block bb)
 
   cond = get_condition (jump, &move_before, true, false);
   if (cond == NULL_RTX)
-    {
-      if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, jump))
-	move_before = prev_nonnote_nondebug_insn (jump);
-      else
-	move_before = jump;
-    }
+    move_before = jump;
 
   for (ix = 0; ix < nedges; ix++)
     if (EDGE_SUCC (bb, ix)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
@@ -2505,12 +2488,7 @@ try_head_merge_bb (basic_block bb)
       jump = BB_END (final_dest_bb);
       cond = get_condition (jump, &move_before, true, false);
       if (cond == NULL_RTX)
-	{
-	  if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, jump))
-	    move_before = prev_nonnote_nondebug_insn (jump);
-	  else
-	    move_before = jump;
-	}
+	move_before = jump;
     }
 
   do
@@ -2527,11 +2505,6 @@ try_head_merge_bb (basic_block bb)
 	  /* Try again, using a different insertion point.  */
 	  move_before = jump;
 
-	  /* Don't try moving before a cc0 user, as that may invalidate
-	     the cc0.  */
-	  if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, jump))
-	    break;
-
 	  continue;
 	}
 
@@ -2585,11 +2558,6 @@ try_head_merge_bb (basic_block bb)
 	  /* For the unmerged insns, try a different insertion point.  */
 	  move_before = jump;
 
-	  /* Don't try moving before a cc0 user, as that may invalidate
-	     the cc0.  */
-	  if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, jump))
-	    break;
-
 	  for (ix = 0; ix < nedges; ix++)
 	    currptr[ix] = headptr[ix] = nextptr[ix];
 	}