From 727ceb2a952de5279f65f039af058e246b0cf29a Mon Sep 17 00:00:00 2001
From: mame <mame@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 6 Jul 2018 04:52:33 +0000
Subject: Fix a bug of peephole optimization

```
  if   L1
L0:
  jump L2
L1:
  ...
L2:
```

was wrongly optimized to:

```
  unless L2
L0:
L1:
  ...
L2:
```

To make it conservative, this optimization is now disabled when there is
any label between `if` and `jump` instructions.
Fixes [Bug #14897].

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63868 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

diff --git a/bootstraptest/test_flow.rb b/bootstraptest/test_flow.rb
index 0390062..9da6d45 100644
--- a/bootstraptest/test_flow.rb
+++ b/bootstraptest/test_flow.rb
@@ -589,3 +589,13 @@ assert_equal "foo", %q{
   end
   Bug6460.new.m1
 }, '[ruby-dev:46372]'
+
+assert_equal "foo", %q{
+  obj = "foo"
+  if obj || any1
+    any2 = any2
+  else
+    raise obj.inspect
+  end
+  obj
+}, '[ruby-core:87830]'
diff --git a/compile.c b/compile.c
index ea6b74d..139a778 100644
--- a/compile.c
+++ b/compile.c
@@ -2730,7 +2730,8 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
 	    ELEM_INSERT_NEXT(&dniobj->link, &pop->link);
 	    goto again;
 	}
-	else if ((piobj = (INSN *)get_prev_insn(iobj)) != 0 &&
+	else if (IS_INSN(iobj->link.prev) &&
+                 (piobj = (INSN *)iobj->link.prev) &&
 		 (IS_INSN_ID(piobj, branchif) ||
 		  IS_INSN_ID(piobj, branchunless))) {
 	    INSN *pdiobj = (INSN *)get_destination_insn(piobj);
-- 
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