* reload.c (subst_reloads): Take INSN argument. When

replacing a LABEL_REF in a JUMP_INSN, add a REG_LABEL note.
* reload.h (subst_reloads): Adjust prototype.
* reload1.c (reload_as_needed): Pass INSN to subst_reloads.
* jump.c (mark_all_labels): Canonicalize any REG_LABEL notes
present in JUMP_INSNs and copy them to JUMP_LABEL.
* flow.c (find_label_refs, find_basic_blocks_1): Skip
JUMP_INSNs and insns with REG_LABELs that are followed by
JUMP_INSNs with the same REG_LABEL.
* sched-rgn.c (is_cfg_nonregular): Likewise.
* rtlanal.c (computed_jump_p): Make it false if a REG_LABEL
note is available.
* unroll.c (unroll_loop): Look for REG_LABEL notes in
JUMP_INSNs too.
* rtl.texi (REG_LABEL): Document usage in JUMP_INSNs.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@38755 138bc75d-0d04-0410-961f-82ee72b054a4

10 files changed, 90 insertions, 24 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2ae2ced5039..e912ed00b91 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,21 @@
+2001-01-07  Alexandre Oliva  <aoliva@redhat.com>
+
+	* reload.c (subst_reloads): Take INSN argument.  When
+	replacing a LABEL_REF in a JUMP_INSN, add a REG_LABEL note.
+	* reload.h (subst_reloads): Adjust prototype.
+	* reload1.c (reload_as_needed): Pass INSN to subst_reloads.
+	* jump.c (mark_all_labels): Canonicalize any REG_LABEL notes
+	present in JUMP_INSNs and copy them to JUMP_LABEL.
+	* flow.c (find_label_refs, find_basic_blocks_1): Skip
+	JUMP_INSNs and insns with REG_LABELs that are followed by
+	JUMP_INSNs with the same REG_LABEL.
+	* sched-rgn.c (is_cfg_nonregular): Likewise.
+	* rtlanal.c (computed_jump_p): Make it false if a REG_LABEL
+	note is available.
+	* unroll.c (unroll_loop): Look for REG_LABEL notes in
+	JUMP_INSNs too.
+	* rtl.texi (REG_LABEL): Document usage in JUMP_INSNs.
+
 2001-01-06  Richard Henderson  <rth@redhat.com>
 
 	* loop.c (scan_loop): Use xcalloc for the regs array.
diff --git a/gcc/flow.c b/gcc/flow.c
index 5eaf116238f..a53043dc534 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -640,7 +640,7 @@ find_label_refs (f, lvl)
   rtx insn;
 
   for (insn = f; insn; insn = NEXT_INSN (insn))
-    if (INSN_P (insn))
+    if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
       {
 	rtx note;
 
@@ -651,7 +651,10 @@ find_label_refs (f, lvl)
 	   as this would be a part of the tablejump setup code.
 
 	   Make a special exception for the eh_return_stub_label, which
-	   we know isn't part of any otherwise visible control flow.  */
+	   we know isn't part of any otherwise visible control flow.
+
+	   Make a special exception to registers loaded with label
+	   values just before jump insns that use them.  */
 
 	for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
 	  if (REG_NOTE_KIND (note) == REG_LABEL)
@@ -667,6 +670,9 @@ find_label_refs (f, lvl)
 		;
 	      else if (GET_CODE (lab) == NOTE)
 		;
+	      else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
+		       && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
+		;
 	      else
 		lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
 	    }
@@ -862,18 +868,21 @@ find_basic_blocks_1 (f)
 	  break;
 	}
 
-      if (GET_RTX_CLASS (code) == 'i')
+      if (GET_RTX_CLASS (code) == 'i'
+	  && GET_CODE (insn) != JUMP_INSN)
 	{
 	  rtx note;
 
-	  /* Make a list of all labels referred to other than by jumps
-	     (which just don't have the REG_LABEL notes).
+	  /* Make a list of all labels referred to other than by jumps.
 
 	     Make a special exception for labels followed by an ADDR*VEC,
 	     as this would be a part of the tablejump setup code.
 
 	     Make a special exception for the eh_return_stub_label, which
-	     we know isn't part of any otherwise visible control flow.  */
+	     we know isn't part of any otherwise visible control flow.
+
+	     Make a special exception to registers loaded with label
+	     values just before jump insns that use them.  */
 
 	  for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
 	    if (REG_NOTE_KIND (note) == REG_LABEL)
@@ -889,6 +898,9 @@ find_basic_blocks_1 (f)
 		  ;
 		else if (GET_CODE (lab) == NOTE)
 		  ;
+		else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
+			 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
+		  ;
 		else
 		  lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
 	      }
diff --git a/gcc/jump.c b/gcc/jump.c
index 1c6c3a633d6..032172d3907 100644
--- a/gcc/jump.c
+++ b/gcc/jump.c
@@ -863,6 +863,24 @@ mark_all_labels (f, cross_jump)
 	mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
 	if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
 	  {
+	    /* When we know the LABEL_REF contained in a REG used in
+	       an indirect jump, we'll have a REG_LABEL note so that
+	       flow can tell where it's going.  */
+	    if (JUMP_LABEL (insn) == 0)
+	      {
+		rtx label_note = find_reg_note (insn, REG_LABEL, NULL_RTX);
+		if (label_note)
+		  {
+		    /* But a LABEL_REF around the REG_LABEL note, so
+		       that we can canonicalize it.  */
+		    rtx label_ref = gen_rtx_LABEL_REF (VOIDmode,
+						       XEXP (label_note, 0));
+
+		    mark_jump_label (label_ref, insn, cross_jump, 0);
+		    XEXP (label_note, 0) = XEXP (label_ref, 0);
+		    JUMP_LABEL (insn) = XEXP (label_note, 0);
+		  }
+	      }
 	    if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
 	      {
 		jump_chain[INSN_UID (insn)]
diff --git a/gcc/reload.c b/gcc/reload.c
index 7b9b669e09e..11e33f05fc8 100644
--- a/gcc/reload.c
+++ b/gcc/reload.c
@@ -5679,7 +5679,8 @@ find_reloads_subreg_address (x, force_replace, opnum, type,
    Return the rtx that X translates into; usually X, but modified.  */
 
 void
-subst_reloads ()
+subst_reloads (insn)
+     rtx insn;
 {
   register int i;
 
@@ -5689,6 +5690,15 @@ subst_reloads ()
       register rtx reloadreg = rld[r->what].reg_rtx;
       if (reloadreg)
 	{
+	  /* If we're replacing a LABEL_REF with a register, add a
+	     REG_LABEL note to indicate to flow which label this
+	     register refers to.  */
+	  if (GET_CODE (*r->where) == LABEL_REF
+	      && GET_CODE (insn) == JUMP_INSN)
+	    REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL,
+						  XEXP (*r->where, 0),
+						  REG_NOTES (insn));
+
 	  /* Encapsulate RELOADREG so its machine mode matches what
 	     used to be there.  Note that gen_lowpart_common will
 	     do the wrong thing if RELOADREG is multi-word.  RELOADREG
diff --git a/gcc/reload.h b/gcc/reload.h
index 7841c7ad7d1..b604184a529 100644
--- a/gcc/reload.h
+++ b/gcc/reload.h
@@ -1,6 +1,6 @@
 /* Communication between reload.c and reload1.c.
    Copyright (C) 1987, 1991, 1992, 1993, 1994, 1995, 1997, 1998,
-   1999, 2000 Free Software Foundation, Inc.
+   1999, 2000, 2001 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -302,7 +302,7 @@ extern rtx form_sum PARAMS ((rtx, rtx));
 
 /* Substitute into the current INSN the registers into which we have reloaded
    the things that need reloading.  */
-extern void subst_reloads PARAMS ((void));
+extern void subst_reloads PARAMS ((rtx));
 
 /* Make a copy of any replacements being done into X and move those copies
    to locations in Y, a copy of X.  We only look at the highest level of
diff --git a/gcc/reload1.c b/gcc/reload1.c
index 3a3dab0e7d4..783c8dc9beb 100644
--- a/gcc/reload1.c
+++ b/gcc/reload1.c
@@ -3830,7 +3830,7 @@ reload_as_needed (live_known)
 		 into the insn's body (or perhaps into the bodies of other
 		 load and store insn that we just made for reloading
 		 and that we moved the structure into).  */
-	      subst_reloads ();
+	      subst_reloads (insn);
 
 	      /* If this was an ASM, make sure that all the reload insns
 		 we have generated are valid.  If not, give an error
diff --git a/gcc/rtl.texi b/gcc/rtl.texi
index 15911cd7ce8..0e9d8c48652 100644
--- a/gcc/rtl.texi
+++ b/gcc/rtl.texi
@@ -1,4 +1,5 @@
-@c Copyright (C) 1988, 89, 92, 94, 97, 1998, 1999, 2000 Free Software Foundation, Inc.
+@c Copyright (C) 1988, 1989, 1992, 1994, 1997, 1998, 1999, 2000, 2001
+@c Free Software Foundation, Inc.
 @c This is part of the GCC manual.
 @c For copying conditions, see the file gcc.texi.
 
@@ -2752,8 +2753,10 @@ last insns, respectively.
 @findex REG_LABEL
 @item REG_LABEL
 This insn uses @var{op}, a @code{code_label}, but is not a
-@code{jump_insn}.  The presence of this note allows jump optimization to
-be aware that @var{op} is, in fact, being used.
+@code{jump_insn}, or it is a @code{jump_insn} that required the label to
+be held in a register.  The presence of this note allows jump
+optimization to be aware that @var{op} is, in fact, being used, and flow
+optimization to build an accurate flow graph.
 @end table
 
 The following notes describe attributes of outputs of an insn:
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 67c5319dfbf..b0fbcf31063 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -1,6 +1,6 @@
 /* Analyze RTL for C-Compiler
    Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000 Free Software Foundation, Inc.
+   1999, 2000, 2001 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -2285,7 +2285,9 @@ computed_jump_p (insn)
     {
       rtx pat = PATTERN (insn);
 
-      if (GET_CODE (pat) == PARALLEL)
+      if (find_reg_note (insn, REG_LABEL, NULL_RTX))
+	return 0;
+      else if (GET_CODE (pat) == PARALLEL)
 	{
 	  int len = XVECLEN (pat, 0);
 	  int has_use_labelref = 0;
diff --git a/gcc/sched-rgn.c b/gcc/sched-rgn.c
index db4cc877b36..c1c215a1ea9 100644
--- a/gcc/sched-rgn.c
+++ b/gcc/sched-rgn.c
@@ -1,6 +1,6 @@
 /* Instruction scheduling pass.
    Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000 Free Software Foundation, Inc.
+   1999, 2000, 2001 Free Software Foundation, Inc.
    Contributed by Michael Tiemann (tiemann@cygnus.com) Enhanced by,
    and currently maintained by, Jim Wilson (wilson@cygnus.com)
 
@@ -349,13 +349,16 @@ is_cfg_nonregular ()
     for (insn = BLOCK_HEAD (b);; insn = NEXT_INSN (insn))
       {
 	code = GET_CODE (insn);
-	if (GET_RTX_CLASS (code) == 'i')
+	if (GET_RTX_CLASS (code) == 'i' && code != JUMP_INSN)
 	  {
-	    rtx note;
-
-	    for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
-	      if (REG_NOTE_KIND (note) == REG_LABEL)
-		return 1;
+	    rtx note = find_reg_note (REG_NOTES (insn), REG_LABEL, NULL_RTX);
+
+	    if (note
+		&& ! (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
+		      && find_reg_note (REG_NOTES (NEXT_INSN (insn)),
+					REG_LABEL,
+					XEXP (note, 0))))
+	      return 1;
 	  }
 
 	if (insn == BLOCK_END (b))
diff --git a/gcc/unroll.c b/gcc/unroll.c
index 0b4a89bfd28..bdd6cb4e781 100644
--- a/gcc/unroll.c
+++ b/gcc/unroll.c
@@ -1,5 +1,5 @@
 /* Try to unroll loops, and split induction variables.
-   Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000
+   Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001
    Free Software Foundation, Inc.
    Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
 
@@ -768,7 +768,7 @@ unroll_loop (loop, insn_count, end_insert_before, strength_reduce_p)
 		}
 	    }
 	}
-      else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
+      if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
 	set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
 			  XEXP (note, 0));
     }