sched-deps.c (fixup_sched_groups): Rename to...

gcc/
	* sched-deps.c (fixup_sched_groups): Rename to...
	(chain_to_prev_insn): ...this.
	(chain_to_prev_insn_p): New function.
	(deps_analyze_insn): Use it instead of SCHED_GROUP_P.

From-SVN: r186883

gcc/ChangeLog

 2012-04-26  Richard Sandiford  <richard.sandiford@linaro.org>
 
+	* sched-deps.c (fixup_sched_groups): Rename to...
+	(chain_to_prev_insn): ...this.
+	(chain_to_prev_insn_p): New function.
+	(deps_analyze_insn): Use it instead of SCHED_GROUP_P.
+
+2012-04-26  Richard Sandiford  <richard.sandiford@linaro.org>
+
 	* sched-int.h (_haifa_insn_data): Move priority_status.
 	Add model_index.
 	(INSN_MODEL_INDEX): New macro.

gcc/sched-deps.c

@@ -477,7 +477,7 @@ static void add_dependence_list (rtx, rtx, int, enum reg_note);
 static void add_dependence_list_and_free (struct deps_desc *, rtx,
 					  rtx *, int, enum reg_note);
 static void delete_all_dependences (rtx);
-static void fixup_sched_groups (rtx);
+static void chain_to_prev_insn (rtx);
 
 static void flush_pending_lists (struct deps_desc *, rtx, int, int);
 static void sched_analyze_1 (struct deps_desc *, rtx, rtx);
@@ -1652,7 +1652,7 @@ delete_all_dependences (rtx insn)
    the previous nonnote insn.  */
 
 static void
-fixup_sched_groups (rtx insn)
+chain_to_prev_insn (rtx insn)
 {
   sd_iterator_def sd_it;
   dep_t dep;
@@ -3295,7 +3295,7 @@ sched_analyze_insn (struct deps_desc *deps, rtx x, rtx insn)
 	       instructions that follow seem like they should be part
 	       of the call group.
 
-	       Also, if we did, fixup_sched_groups() would move the
+	       Also, if we did, chain_to_prev_insn would move the
 	       deps of the debug insn to the call insn, modifying
 	       non-debug post-dependency counts of the debug insn
 	       dependencies and otherwise messing with the scheduling
@@ -3441,6 +3441,37 @@ call_may_noreturn_p (rtx insn)
   return true;
 }
 
+/* Return true if INSN should be made dependent on the previous instruction
+   group, and if all INSN's dependencies should be moved to the first
+   instruction of that group.  */
+
+static bool
+chain_to_prev_insn_p (rtx insn)
+{
+  rtx prev, x;
+
+  /* INSN forms a group with the previous instruction.  */
+  if (SCHED_GROUP_P (insn))
+    return true;
+
+  /* If the previous instruction clobbers a register R and this one sets
+     part of R, the clobber was added specifically to help us track the
+     liveness of R.  There's no point scheduling the clobber and leaving
+     INSN behind, especially if we move the clobber to another block.  */
+  prev = prev_nonnote_nondebug_insn (insn);
+  if (prev
+      && INSN_P (prev)
+      && BLOCK_FOR_INSN (prev) == BLOCK_FOR_INSN (insn)
+      && GET_CODE (PATTERN (prev)) == CLOBBER)
+    {
+      x = XEXP (PATTERN (prev), 0);
+      if (set_of (x, insn))
+	return true;
+    }
+
+  return false;
+}
+
 /* Analyze INSN with DEPS as a context.  */
 void
 deps_analyze_insn (struct deps_desc *deps, rtx insn)
@@ -3608,8 +3639,9 @@ deps_analyze_insn (struct deps_desc *deps, rtx insn)
 
   /* Fixup the dependencies in the sched group.  */
   if ((NONJUMP_INSN_P (insn) || JUMP_P (insn))
-      && SCHED_GROUP_P (insn) && !sel_sched_p ())
-    fixup_sched_groups (insn);
+      && chain_to_prev_insn_p (insn)
+      && !sel_sched_p ())
+    chain_to_prev_insn (insn);
 }
 
 /* Initialize DEPS for the new block beginning with HEAD.  */