Fix infinite loop by ensure

* compile.c (iseq_insert_nop_between_end_and_cont): insert nop so
  that the end of rescue and continuing points are not same, to
  get rid of infinite loop.  [Bug #15385]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66326 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 35 insertions, 9 deletions

diff --git a/compile.c b/compile.c
index f3ed917f4b..512f6df1a8 100644
--- a/compile.c
+++ b/compile.c
@@ -1298,6 +1298,27 @@ update_catch_except_flags(struct rb_iseq_constant_body *body)
     }
 }
 
+static void
+iseq_insert_nop_between_end_and_cont(rb_iseq_t *iseq)
+{
+    VALUE catch_table_ary = ISEQ_COMPILE_DATA(iseq)->catch_table_ary;
+    unsigned int i, tlen = (unsigned int)RARRAY_LEN(catch_table_ary);
+    const VALUE *tptr = RARRAY_CONST_PTR_TRANSIENT(catch_table_ary);
+    for (i = 0; i < tlen; i++) {
+        const VALUE *ptr = RARRAY_CONST_PTR_TRANSIENT(tptr[i]);
+        LINK_ELEMENT *end = (LINK_ELEMENT *)(ptr[2] & ~1);
+        LINK_ELEMENT *cont = (LINK_ELEMENT *)(ptr[4] & ~1);
+        LINK_ELEMENT *e;
+        for (e = end; e && (IS_LABEL(e) || IS_TRACE(e)); e = e->next) {
+            if (e == cont) {
+                INSN *nop = new_insn_core(iseq, 0, BIN(nop), 0, 0);
+                ELEM_INSERT_NEXT(end, &nop->link);
+                break;
+            }
+        }
+    }
+}
+
 static int
 iseq_setup_insn(rb_iseq_t *iseq, LINK_ANCHOR *const anchor)
 {
@@ -1329,6 +1350,9 @@ iseq_setup_insn(rb_iseq_t *iseq, LINK_ANCHOR *const anchor)
 	    dump_disasm_list(FIRST_ELEMENT(anchor));
     }
 
+    debugs("[compile step 3.4 (iseq_insert_nop_between_end_and_cont)]\n");
+    iseq_insert_nop_between_end_and_cont(iseq);
+
     return COMPILE_OK;
 }
 
@@ -5763,15 +5787,8 @@ compile_ensure(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node,
     ADD_LABEL(ret, lstart);
     CHECK(COMPILE_(ret, "ensure head", node->nd_head, (popped | last_leave)));
     ADD_LABEL(ret, lend);
-    if (LIST_INSN_SIZE_ZERO(ensr)) {
-	ADD_INSN(ret, line, nop);
-    }
-    else {
-	ADD_SEQ(ret, ensr);
-	if (!popped && last_leave) {
-	    ADD_INSN(ret, line, putnil);
-	}
-    }
+    ADD_SEQ(ret, ensr);
+    if (!popped && last_leave) ADD_INSN(ret, line, putnil);
     ADD_LABEL(ret, lcont);
     if (last_leave) ADD_INSN(ret, line, pop);
 
diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index 46bce922b9..5609602c1a 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -800,4 +800,13 @@ class TestRubyOptimization < Test::Unit::TestCase
     %w(1) || 2 while (i += 1) < 100
     assert_equal(100, i)
   end
+
+  def test_optimized_empty_ensure
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}", timeout: 1)
+    begin;
+      assert_raise(RuntimeError) {
+        begin raise ensure nil if nil end
+      }
+    end;
+  end
 end