From f0226f0a3c836e9262c5cd2671860140878d6b75 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 11 Apr 2016 08:43:06 +0000
Subject: [PATCH] compile.c: disable tco with rescue

* compile.c (iseq_optimize): disable tail call optimization in
  rescued, rescue, and ensure blocks.
  [ruby-core:73871] [Bug #12082]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54542 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog                      |  6 +++++
 compile.c                      | 47 ++++++++++++++++++++++++++++++++--
 test/ruby/test_optimization.rb | 24 +++++++++++++++++
 3 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 3c91eafbcf..82b6081cc4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Mon Apr 11 17:43:04 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* compile.c (iseq_optimize): disable tail call optimization in
+	  rescued, rescue, and ensure blocks.
+	  [ruby-core:73871] [Bug #12082]
+
 Mon Apr 11 06:54:39 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* file.c (apply2files): apply to a VALUE vector instead of a
diff --git a/compile.c b/compile.c
index 860de31f9f..cd9426c230 100644
--- a/compile.c
+++ b/compile.c
@@ -47,6 +47,13 @@ typedef struct iseq_link_anchor {
     LINK_ELEMENT *last;
 } LINK_ANCHOR;
 
+typedef enum {
+    LABEL_RESCUE_NONE,
+    LABEL_RESCUE_BEG,
+    LABEL_RESCUE_END,
+    LABEL_RESCUE_TYPE_MAX
+} LABEL_RESCUE_TYPE;
+
 typedef struct iseq_label_data {
     LINK_ELEMENT link;
     int label_no;
@@ -55,6 +62,7 @@ typedef struct iseq_label_data {
     int sp;
     int refcnt;
     unsigned int set: 1;
+    unsigned int rescued: 2;
 } LABEL;
 
 typedef struct iseq_insn_data {
@@ -561,6 +569,9 @@ rb_iseq_compile_node(rb_iseq_t *iseq, NODE *node)
 		LABEL *start = ISEQ_COMPILE_DATA(iseq)->start_label = NEW_LABEL(0);
 		LABEL *end = ISEQ_COMPILE_DATA(iseq)->end_label = NEW_LABEL(0);
 
+		start->rescued = LABEL_RESCUE_BEG;
+		end->rescued = LABEL_RESCUE_END;
+
 		ADD_TRACE(ret, FIX2INT(iseq->body->location.first_lineno), RUBY_EVENT_B_CALL);
 		ADD_LABEL(ret, start);
 		COMPILE(ret, "block body", node->nd_body);
@@ -2357,20 +2368,37 @@ iseq_specialized_instruction(rb_iseq_t *iseq, INSN *iobj)
     return COMPILE_OK;
 }
 
+static inline int
+tailcallable_p(rb_iseq_t *iseq)
+{
+    switch (iseq->body->type) {
+      case ISEQ_TYPE_RESCUE:
+      case ISEQ_TYPE_ENSURE:
+	/* rescue block can't tail call because of errinfo */
+	return FALSE;
+      default:
+	return TRUE;
+    }
+}
+
 static int
 iseq_optimize(rb_iseq_t *iseq, LINK_ANCHOR *anchor)
 {
     LINK_ELEMENT *list;
     const int do_peepholeopt = ISEQ_COMPILE_DATA(iseq)->option->peephole_optimization;
-    const int do_tailcallopt = ISEQ_COMPILE_DATA(iseq)->option->tailcall_optimization;
+    const int do_tailcallopt = tailcallable_p(iseq) &&
+	ISEQ_COMPILE_DATA(iseq)->option->tailcall_optimization;
     const int do_si = ISEQ_COMPILE_DATA(iseq)->option->specialized_instruction;
     const int do_ou = ISEQ_COMPILE_DATA(iseq)->option->operands_unification;
+    int rescue_level = 0;
+    int tailcallopt = do_tailcallopt;
+
     list = FIRST_ELEMENT(anchor);
 
     while (list) {
 	if (list->type == ISEQ_ELEMENT_INSN) {
 	    if (do_peepholeopt) {
-		iseq_peephole_optimize(iseq, list, do_tailcallopt);
+		iseq_peephole_optimize(iseq, list, tailcallopt);
 	    }
 	    if (do_si) {
 		iseq_specialized_instruction(iseq, (INSN *)list);
@@ -2379,6 +2407,17 @@ iseq_optimize(rb_iseq_t *iseq, LINK_ANCHOR *anchor)
 		insn_operands_unification((INSN *)list);
 	    }
 	}
+	if (list->type == ISEQ_ELEMENT_LABEL) {
+	    switch (((LABEL *)list)->rescued) {
+	      case LABEL_RESCUE_BEG:
+		rescue_level++;
+		tailcallopt = FALSE;
+		break;
+	      case LABEL_RESCUE_END:
+		if (!--rescue_level) tailcallopt = do_tailcallopt;
+		break;
+	    }
+	}
 	list = list->next;
     }
     return COMPILE_OK;
@@ -3483,6 +3522,8 @@ defined_expr(rb_iseq_t *iseq, LINK_ANCHOR *ret,
 							       ("defined guard in "),
 							       iseq->body->location.label),
 						 ISEQ_TYPE_DEFINED_GUARD, 0);
+	lstart->rescued = LABEL_RESCUE_BEG;
+	lend->rescued = LABEL_RESCUE_END;
 	APPEND_LABEL(ret, lcur, lstart);
 	ADD_LABEL(ret, lend);
 	ADD_CATCH_ENTRY(CATCH_TYPE_RESCUE, lstart, lend, rescue, lfinish[1]);
@@ -4339,6 +4380,8 @@ iseq_compile_each(rb_iseq_t *iseq, LINK_ANCHOR *ret, NODE * node, int poped)
 						 rb_str_concat(rb_str_new2("rescue in "), iseq->body->location.label),
 						 ISEQ_TYPE_RESCUE, line);
 
+	lstart->rescued = LABEL_RESCUE_BEG;
+	lend->rescued = LABEL_RESCUE_END;
 	ADD_LABEL(ret, lstart);
 	COMPILE(ret, "rescue head", node->nd_head);
 	ADD_LABEL(ret, lend);
diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index 2b414ec5b5..ae5a2d799b 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -295,6 +295,30 @@ class TestRubyOptimization < Test::Unit::TestCase
     assert_equal(:ok, yield_result)
   end
 
+  def do_raise
+    raise "should be rescued"
+  end
+
+  def errinfo
+    $!
+  end
+
+  def test_tailcall_inhibited_by_rescue
+    bug12082 = '[ruby-core:73871] [Bug #12082]'
+
+    tailcall(<<-'end;')
+      def to_be_rescued
+        return do_raise
+        1 + 2
+      rescue
+        errinfo
+      end
+    end;
+    result = to_be_rescued
+    assert_instance_of(RuntimeError, result, bug12082)
+    assert_equal("should be rescued", result.message, bug12082)
+  end
+
   class Bug10557
     def [](_)
       block_given?