merge revision(s) 4a7d6c2852aa734506be83c932168e8f974687b5: [Backport #18991]

	Fix false LocalJumpError when branch coverage is enabled

	`throw TAG_BREAK` instruction makes a jump only if the continuation of
	catch of TAG_BREAK exactly matches the instruction immediately following
	the "send" instruction that is currently being executed. Otherwise, it
	seems to determine break from proc-closure.

	Branch coverage may insert some recording instructions after "send"
	instruction, which broke the conditions for TAG_BREAK to work properly.

	This change forces to set the continuation of catch of TAG_BREAK
	immediately after "send" (or "invokesuper") instruction.

	[Bug #18991]
	---
	 compile.c                      | 25 ++++++++++++++++++++++++-
	 test/coverage/test_coverage.rb | 14 ++++++++++++++
	 2 files changed, 38 insertions(+), 1 deletion(-)

1 files changed, 24 insertions, 1 deletions

diff --git a/compile.c b/compile.c
index 2ebc6a7755..2641accc03 100644
--- a/compile.c
+++ b/compile.c
@@ -7216,7 +7216,30 @@ compile_iter(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node, in
 			   ISEQ_TYPE_BLOCK, line);
 	CHECK(COMPILE(ret, "iter caller", node->nd_iter));
     }
-    ADD_LABEL(ret, retry_end_l);
+
+    {
+        // We need to put the label "retry_end_l" immediately after the last "send" instruction.
+        // This because vm_throw checks if the break cont is equal to the index of next insn of the "send".
+        // (Otherwise, it is considered "break from proc-closure". See "TAG_BREAK" handling in "vm_throw_start".)
+        //
+        // Normally, "send" instruction is at the last.
+        // However, qcall under branch coverage measurement adds some instructions after the "send".
+        //
+        // Note that "invokesuper" appears instead of "send".
+        INSN *iobj;
+        LINK_ELEMENT *last_elem = LAST_ELEMENT(ret);
+        iobj = IS_INSN(last_elem) ? (INSN*) last_elem : (INSN*) get_prev_insn((INSN*) last_elem);
+        while (INSN_OF(iobj) != BIN(send) && INSN_OF(iobj) != BIN(invokesuper)) {
+            iobj = (INSN*) get_prev_insn(iobj);
+        }
+        ELEM_INSERT_NEXT(&iobj->link, (LINK_ELEMENT*) retry_end_l);
+
+        // LINK_ANCHOR has a pointer to the last element, but ELEM_INSERT_NEXT does not update it
+        // even if we add an insn to the last of LINK_ANCHOR. So this updates it manually.
+        if (&iobj->link == LAST_ELEMENT(ret)) {
+            ret->last = (LINK_ELEMENT*) retry_end_l;
+        }
+    }
 
     if (popped) {
 	ADD_INSN(ret, line_node, pop);