From 982503f45786fa64a081b8a656eea7efaba10655 Mon Sep 17 00:00:00 2001
From: Thomas Jarosch <thomas.jarosch@intra2net.com>
Date: Wed, 9 Jan 2013 18:56:00 +0100
Subject: [PATCH] Match compiler: Workaround broken optimizations in verify
 mode

If the match compiler uses the 'verify' mode and we
compile with -O2, some tests comparing the on-the-fly-parser
to the compiled match fail.

Small functions are inlined by the -O2 compile flag.
If we disable function inlining and still compile with -O2,
everything is back to normal.

gdb didn't show anything useful during the mismatch
since the needed variables are optimized out. Once
we start printing them, the problem vanishes, too.
-> Can only be diagnosed at the x86 assembly level.

The problem vanished by switching the invocation order
of Token::Match() and the compiled match, so just swap them.

Also add commented out helper code
to better diagnose mismatch problems.
---
 tools/matchcompiler.py | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/tools/matchcompiler.py b/tools/matchcompiler.py
index 29a1c7b7f..433822659 100755
--- a/tools/matchcompiler.py
+++ b/tools/matchcompiler.py
@@ -259,12 +259,12 @@ class MatchCompiler:
             origMatchName = 'simpleMatch'
             assert(varId == None)
 
-        ret += '    bool res_parsed_match = Token::' + origMatchName + '(tok, "' + pattern + '"'
+        ret += '    bool res_compiled_match = match'+str(patternNumber)+'(tok'
         if varId:
             ret += ', varid'
         ret += ');\n'
 
-        ret += '    bool res_compiled_match = match'+str(patternNumber)+'(tok'
+        ret += '    bool res_parsed_match = Token::' + origMatchName + '(tok, "' + pattern + '"'
         if varId:
             ret += ', varid'
         ret += ');\n'
@@ -272,8 +272,14 @@ class MatchCompiler:
         ret += '\n'
         # Don't use assert() here, it's disabled for optimized builds.
         # We also need to verify builds in 'release' mode
-        ret += '    if (res_parsed_match != res_compiled_match)\n'
+        ret += '    if (res_parsed_match != res_compiled_match) {\n'
+#        ret += '        std::cout << "res_parsed_match' + str(verifyNumber) + ': " << res_parsed_match << ", res_compiled_match: " << res_compiled_match << "\\n";\n'
+#        ret += '        if (tok)\n'
+#        ret += '            std::cout << "tok: " << tok->str();\n'
+#        ret += '        if (tok->next())\n'
+#        ret += '            std::cout << "tok next: " << tok->next()->str();\n'
         ret += '        throw InternalError(tok, "Internal error. compiled match returned different result than parsed match");\n'
+        ret += '    }\n'
         ret += '    return res_compiled_match;\n'
         ret += '}\n'
 
@@ -432,6 +438,7 @@ class MatchCompiler:
         header += '#include "errorlogger.h"\n'
         header += '#include <string>\n'
         header += '#include <cstring>\n'
+        # header += '#include <iostream>\n'
         code = ''
 
         for line in srclines: