[pypy-svn] pypy ootype-virtualrefs: fix an obscure case which seems to be produced only with ootype translation. I didn't manage to write a test for it :-(

[antocuni]

Author: Antonio Cuni <anto.cuni at gmail.com>
Branch: ootype-virtualrefs
Changeset: r43173:67fec99826fb
Date: 2011-04-06 16:42 +0200
http://bitbucket.org/pypy/pypy/changeset/67fec99826fb/

Log:	fix an obscure case which seems to be produced only with ootype
	translation. I didn't manage to write a test for it :-(

diff --git a/pypy/translator/backendopt/merge_if_blocks.py b/pypy/translator/backendopt/merge_if_blocks.py
--- a/pypy/translator/backendopt/merge_if_blocks.py
+++ b/pypy/translator/backendopt/merge_if_blocks.py
@@ -75,14 +75,19 @@
             # False link
             checkvar = [var for var in current.operations[-1].args
                            if isinstance(var, Variable)][0]
+            resvar = current.operations[-1].result
             case = [var for var in current.operations[-1].args
                        if isinstance(var, Constant)][0]
-            chain.append((current, case))
             checkvars.append(checkvar)
             falseexit = current.exits[0]
             assert not falseexit.exitcase
             trueexit = current.exits[1]
             targetblock = falseexit.target
+            # if the result of the check is also passed through the link, we
+            # cannot construct the chain
+            if resvar in falseexit.args or resvar in trueexit.args:
+                break
+            chain.append((current, case))
             if len(entrymap[targetblock]) != 1:
                 break
             if checkvar not in falseexit.args: