MySQL Bugs: #9342: Calling functions fails when compiled with Sun C compiler

Bug #9342	Calling functions fails when compiled with Sun C compiler
Submitted:	22 Mar 2005 18:04	Modified:	7 Jul 2005 16:09
Reporter:	Jim Winstead	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Compiling	Severity:	S2 (Serious)
Version:	5.0	OS:	Sun Solaris 10 on AMD64
Assigned to:	Jim Winstead	CPU Architecture:	Any

Description:
When compiled using the Sun C compiler's -xO3 flag, the server fails to handle calls to built-in functions correctly. It appears that the get_hash_symbol() function defined in sql/lex_hash.h is optimized in a way that causes it to fail to work. (This was determined by adding extra debug output to that function.)

How to repeat:
1. Download the 5.0.3 source (once released).
2. Configure on Solaris AMD64 using:

   CC=cc CXX=CC CFLAGS="-xO3 -mt -fsimple=1 -ftrap=%none -nofstore -xbuiltin=%all -xlibmil -xlibmopt -xtarget=opteron -xarch=amd64" CXXFLAGS="-xO3 -mt -fsimple=1 -ftrap=%none -nofstore -xbuiltin=%all -xlibmil -xlibmopt -xtarget=opteron -xarch=amd64"  ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-comment="MySQL Community Edition - Debug (GPL)" --with-extra-charsets=complex --with-server-suffix="-debug" --enable-thread-safe-client --enable-local-infile --with-named-curses=-lcurses --disable-shared --with-debug --with-readline --with-embedded-server --with-archive-storage-engine --with-innodb

  (This is our standard debug build.)

  cc is Sun C 5.7 2005/01/07.

3. Run the server, and try to call a function like "SELECT VERSION()". (Or just run one of the many tests that call functions.)

Suggested fix:
Compiling with "-xO1" instead of "-xO3" avoids the issue. It appears to be a bug in the optimizations done by the Sun compiler.

I have re-produced the problems of using "-xO3" with Sun Studio 10 to build the 64-bit MySQL on the Sol 10 x86 box. However, when I ran some test, for example,"mysql-run-test alias", looks like the "get_hash_symbol()" was not called duing the test by my adding some
debug messages on the get_hash_symbol()(it shows that get_hash_symbol() was called and exit before the "alias" test). So please let me know how come you get the conclusion that it is the get_hash_symbol() cause that using optimization level "-xO3" failed with the test. Could you attach the file defining get_hash_symbol() added with the debug messages, and let me know by running which test, it show the get_hash_symbol() failed?

With this patch to lex_casecmp() to see where it is being called:

@@ -72,9 +72,11 @@
 
 inline int lex_casecmp(const char *s, const char *t, uint len)
 {
+  DBUG_ENTER("lex_casecmp");
+  DBUG_PRINT("info",("check '%s' against '%s' (%d)", s, t, len));
   while (len-- != 0 &&
         to_upper_lex[(uchar) *s++] == to_upper_lex[(uchar) *t++]) ;
-  return (int) len+1;
+  DBUG_RETURN((int) len+1);
 }

And then running mysql-test-run --debug on a simple test that just calls 'SELECT VERSION()', I get this in the mysql-test/var/log/master.trace file:

T@10   : | | >lex_casecmp
T@10   : | | | info: check 'ect version()' against 'ECT' (3)
T@10   : | | <lex_casecmp
T@10   : | | >lex_casecmp
T@10   : | | | info: check 'rsion()' against 'EA' (5)
T@10   : | | <lex_casecmp

With a version of the server compiled with -Ox1, I get:

T@10   : | | >lex_casecmp
T@10   : | | | info: check 'ect version()' against 'ECT' (3)
T@10   : | | <lex_casecmp
T@10   : | | >lex_casecmp
T@10   : | | | info: check 'rsion()' against 'RSION' (5)
T@10   : | | <lex_casecmp

This means that get_hash_symbol() has gone astray. In the optimized (broken) case, it has gone taken 'VE' and matched it up with the 'AR' in AREA for some reason.

The compiler bug is in Sun's hands, and in the meantime we have cranked down the optimization setting to produce Solaris x86_64 builds.

According to Sun:

The patch to fix the problem of compiling MySQL with "-xO3" was just            
available on the website:                                                       
                                                                                
http://developers.sun.com/prodtech/cc/downloads/patches/ss10_patches.html       
                                                                                
Please select patch 117846-06.

We applied the patch on our Solaris10/AMD64 build machine and the code now compiles and passes the tests with -x03 enabled.