combine.c (expand_compound_operation): Add comment that we fall through after case.

	* combine.c (expand_compound_operation)  <ZERO_EXTRACT>: Add
	comment that we fall through after case.
	(mark_used_regs_combine): Don't expect a SIGN_EXTRACT in a SET_DEST.
	(distribute_links): Likewise.
	* cse.c (cse_insn): Likewise.
	* cselib.c (cselib_invalidate_mem): Likewise.
	* df.c: Update comments at the top of the file.
	(read_modify_subreg_p): Update comments here too.
	(df_def_record_1): Don't expect a SIGN_EXTRACT in a SET_DEST.
	* flow.c (mark_set_1): Likewise.
	(mark_used_regs): Likewise.
	* gcse.c (mems_conflict_for_gcse_p): Likewise.
	(canon_list_insert): Likewise.
	(mark_set): Likewise.
	(try_replace_reg): Likewise.
	(store_killed_in_insn): Likewise.
	* loop.c (count_one_set): Likewise.
	(basic_induction_var): Likewise.
	* postreload-gcse.c (find_mem_conflicts): Likewise.
	* postreload.c (reload_combine_note_store): Likewise.
	(move2add_note_store): Likewise.
	* reload.c (find_equiv_reg): Likewise.
	(mark_referenced_resources): Likewise.
	* rtlanal.c (set_noop_p): Likewise.
	(note_stores): Likewise.
	(note_uses): Likewise.
	* sched-deps.c (sched_analyze_1): Likewise.
	* sched-rgn.c (check_live_1): Likewise.
	(update_live_1): Likewise.
	* config/i860/i860.c: Likewise.

	* rtl.dec (SIGN_EXTRACT): Document that this cannot appear as
	an lvalue.
	(ZERO_EXTRACT): Mention that this one can be an lvalue.

	* doc/rtl.texi: Update documentation for bit-fields and SET.

From-SVN: r92974

1 files changed, 7 insertions, 11 deletions

diff --git a/gcc/cse.c b/gcc/cse.c
index 766c725..eee2742 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -4865,7 +4865,7 @@ cse_insn (rtx insn, rtx libcall_insn)
       else
 	SET_SRC (sets[i].rtl) = new;
 
-      if (GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SIGN_EXTRACT)
+      if (GET_CODE (dest) == ZERO_EXTRACT)
 	{
 	  validate_change (insn, &XEXP (dest, 1),
 			   canon_reg (XEXP (dest, 1), insn), 1);
@@ -4873,9 +4873,9 @@ cse_insn (rtx insn, rtx libcall_insn)
 			   canon_reg (XEXP (dest, 2), insn), 1);
 	}
 
-      while (GET_CODE (dest) == SUBREG || GET_CODE (dest) == STRICT_LOW_PART
+      while (GET_CODE (dest) == SUBREG
 	     || GET_CODE (dest) == ZERO_EXTRACT
-	     || GET_CODE (dest) == SIGN_EXTRACT)
+	     || GET_CODE (dest) == STRICT_LOW_PART)
 	dest = XEXP (dest, 0);
 
       if (MEM_P (dest))
@@ -4972,8 +4972,7 @@ cse_insn (rtx insn, rtx libcall_insn)
 	 causes later instructions to be mis-optimized.  */
       /* If storing a constant in a bitfield, pre-truncate the constant
 	 so we will be able to record it later.  */
-      if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT
-	  || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT)
+      if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT)
 	{
 	  rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
 
@@ -5629,11 +5628,9 @@ cse_insn (rtx insn, rtx libcall_insn)
       /* Now deal with the destination.  */
       do_not_record = 0;
 
-      /* Look within any SIGN_EXTRACT or ZERO_EXTRACT
-	 to the MEM or REG within it.  */
-      while (GET_CODE (dest) == SIGN_EXTRACT
+      /* Look within any ZERO_EXTRACT to the MEM or REG within it.  */
+      while (GET_CODE (dest) == SUBREG
 	     || GET_CODE (dest) == ZERO_EXTRACT
-	     || GET_CODE (dest) == SUBREG
 	     || GET_CODE (dest) == STRICT_LOW_PART)
 	dest = XEXP (dest, 0);
 
@@ -5661,8 +5658,7 @@ cse_insn (rtx insn, rtx libcall_insn)
 	 because the value in it after the store
 	 may not equal what was stored, due to truncation.  */
 
-      if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT
-	  || GET_CODE (SET_DEST (sets[i].rtl)) == SIGN_EXTRACT)
+      if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT)
 	{
 	  rtx width = XEXP (SET_DEST (sets[i].rtl), 1);