From c03f86b389d00cf45edf133c9aa23479e6efc06e Mon Sep 17 00:00:00 2001
From: tenderlove <tenderlove@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 27 Apr 2018 00:13:51 +0000
Subject: [PATCH] Revert "Fix use of `rb_profile_frames` start parameter"

This reverts commit r63265.

ko1 said I should not have committed this! I'm sorry!

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63267 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 test/-ext-/debug/test_profile_frames.rb | 4 ----
 vm_backtrace.c                          | 3 ++-
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/test/-ext-/debug/test_profile_frames.rb b/test/-ext-/debug/test_profile_frames.rb
index 672c9c4b5a..5ea506046e 100644
--- a/test/-ext-/debug/test_profile_frames.rb
+++ b/test/-ext-/debug/test_profile_frames.rb
@@ -119,8 +119,4 @@ class TestProfileFrames < Test::Unit::TestCase
       a
     end;
   end
-
-  def test_start
-    assert_equal Bug::Debug.profile_frames(0, 10).tap(&:shift), Bug::Debug.profile_frames(1, 9)
-  end
 end
diff --git a/vm_backtrace.c b/vm_backtrace.c
index 3a13088855..59340292cf 100644
--- a/vm_backtrace.c
+++ b/vm_backtrace.c
@@ -1276,7 +1276,7 @@ rb_profile_frames(int start, int limit, VALUE *buff, int *lines)
     const rb_control_frame_t *cfp = ec->cfp, *end_cfp = RUBY_VM_END_CONTROL_FRAME(ec);
     const rb_callable_method_entry_t *cme;
 
-    for (i=0; i<limit && cfp != end_cfp; cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp)) {
+    for (i=0; i<limit && cfp != end_cfp;) {
 	if (cfp->iseq && cfp->pc) {
 	    if (start > 0) {
 		start--;
@@ -1296,6 +1296,7 @@ rb_profile_frames(int start, int limit, VALUE *buff, int *lines)
 
 	    i++;
 	}
+	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
     }
 
     return i;