merge revision(s) 61587,61617,61618: [Backport #14273]

	compile.c: next label

	* compile.c (compile_next): label for jump to the end of block is
	  removable.

	compile.c: remove more unreachable chunk

	* compile.c (remove_unreachable_chunk): remove beyond labels to be
	  removed.

	compile.c: fix stack consistency error

	* compile.c (iseq_peephole_optimize): fix stack consistency error
	  from return in loop, by adding extra `pop` when replacing `jump`
	  with `leave`, which is never reached but needed to adjust sp
	  calculation.  [ruby-core:84589] [Bug #14273]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@62911 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 54 insertions, 14 deletions

diff --git a/compile.c b/compile.c
index 98d732d087..8f4a6dcc87 100644
--- a/compile.c
+++ b/compile.c
@@ -320,8 +320,8 @@ static void iseq_add_setlocal(rb_iseq_t *iseq, LINK_ANCHOR *const seq, int line,
 			   (VALUE)(ls) | 1, (VALUE)(le) | 1,			\
 			   (VALUE)(iseqv), (VALUE)(lc) | 1);			\
     LABEL_UNREMOVABLE(ls);							\
-    LABEL_UNREMOVABLE(le);							\
-    LABEL_UNREMOVABLE(lc);							\
+    LABEL_REF(le);								\
+    LABEL_REF(lc);								\
     rb_ary_push(ISEQ_COMPILE_DATA(iseq)->catch_table_ary, freeze_hide_obj(_e));	\
 } while (0)
 
@@ -2295,33 +2295,58 @@ replace_destination(INSN *dobj, INSN *nobj)
     if (!dl->refcnt) ELEM_REMOVE(&dl->link);
 }
 
+static LABEL*
+find_destination(INSN *i)
+{
+    int pos, len = insn_len(i->insn_id);
+    for (pos = 0; pos < len; ++pos) {
+	if (insn_op_types(i->insn_id)[pos] == TS_OFFSET) {
+	    return (LABEL *)OPERAND_AT(i, pos);
+	}
+    }
+    return 0;
+}
+
 static int
 remove_unreachable_chunk(rb_iseq_t *iseq, LINK_ELEMENT *i)
 {
     LINK_ELEMENT *first = i, *end;
+    int *unref_counts = 0, nlabels = ISEQ_COMPILE_DATA(iseq)->label_no;
 
     if (!i) return 0;
-    while (i) {
+    unref_counts = ALLOCA_N(int, nlabels);
+    MEMZERO(unref_counts, int, nlabels);
+    end = i;
+    do {
+	LABEL *lab;
 	if (IS_INSN(i)) {
-	    if (IS_INSN_ID(i, jump) || IS_INSN_ID(i, leave)) {
+	    if (IS_INSN_ID(i, leave)) {
+		end = i;
 		break;
 	    }
+	    else if ((lab = find_destination((INSN *)i)) != 0) {
+		if (lab->unremovable) break;
+		unref_counts[lab->label_no]++;
+	    }
 	}
 	else if (IS_LABEL(i)) {
-	    if (((LABEL *)i)->unremovable) return 0;
-	    if (((LABEL *)i)->refcnt > 0) {
+	    lab = (LABEL *)i;
+	    if (lab->unremovable) return 0;
+	    if (lab->refcnt > unref_counts[lab->label_no]) {
 		if (i == first) return 0;
-		i = i->prev;
 		break;
 	    }
+	    continue;
 	}
 	else if (IS_TRACE(i)) {
 	    /* do nothing */
 	}
-	else return 0;
-	i = i->next;
-    }
-    end = i;
+	else if (IS_ADJUST(i)) {
+	    LABEL *dest = ((ADJUST *)i)->label;
+	    if (dest && dest->unremovable) return 0;
+	}
+	end = i;
+    } while ((i = i->next) != 0);
     i = first;
     do {
 	if (IS_INSN(i)) {
@@ -2416,6 +2441,7 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
 	    goto again;
 	}
 	else if (IS_INSN_ID(diobj, leave)) {
+	    INSN *pop;
 	    /*
 	     *  jump LABEL
 	     *  ...
@@ -2423,6 +2449,7 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
 	     *  leave
 	     * =>
 	     *  leave
+	     *  pop
 	     *  ...
 	     * LABEL:
 	     *  leave
@@ -2432,6 +2459,9 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
 	    iobj->insn_id = BIN(leave);
 	    iobj->operand_size = 0;
 	    iobj->insn_info = diobj->insn_info;
+	    /* adjust stack depth */
+	    pop = new_insn_body(iseq, diobj->insn_info.line_no, BIN(pop), 0);
+	    ELEM_INSERT_NEXT(&iobj->link, &pop->link);
 	    goto again;
 	}
 	else if ((piobj = (INSN *)get_prev_insn(iobj)) != 0 &&
@@ -5064,6 +5094,7 @@ compile_next(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node, in
 	add_ensure_iseq(ret, iseq, 0);
 	ADD_INSNL(ret, line, jump, ISEQ_COMPILE_DATA(iseq)->end_label);
 	ADD_ADJUST_RESTORE(ret, splabel);
+	splabel->unremovable = FALSE;
 
 	if (!popped) {
 	    ADD_INSN(ret, line, putnil);
diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index e1a035704e..6d8d8f5f32 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -1134,6 +1134,15 @@ eom
     assert_equal(:begin, result)
   end
 
+  def test_return_in_loop
+    obj = Object.new
+    def obj.test
+      x = nil
+      return until x unless x
+    end
+    assert_nil obj.test
+  end
+
   private
 
   def not_label(x) @result = x; @not_label ||= nil end
diff --git a/version.h b/version.h
index 005c770ba5..c11322024d 100644
--- a/version.h
+++ b/version.h
@@ -1,10 +1,10 @@
 #define RUBY_VERSION "2.5.1"
-#define RUBY_RELEASE_DATE "2018-03-24"
-#define RUBY_PATCHLEVEL 52
+#define RUBY_RELEASE_DATE "2018-03-25"
+#define RUBY_PATCHLEVEL 53
 
 #define RUBY_RELEASE_YEAR 2018
 #define RUBY_RELEASE_MONTH 3
-#define RUBY_RELEASE_DAY 24
+#define RUBY_RELEASE_DAY 25
 
 #include "ruby/version.h"