#45215 [Opn->Fbk]: php_gmp.dll uses exotic instructions

ID: 45215 Updated by: pajoye@php.net Reported By: shaunspiller at gmail dot com -Status: Open +Status: Feedback Bug Type: Reproducible crash Operating System: Win32 PHP Version: 5.2.6 -Assigned To: +Assigned To: pajoye New Comment: "I'm using the latest precompiled Win32 binaries of PHP-5.2.6 (and have also tried PHP-5.1.6) and get a program crash with an #Undefined Opcode exception when loading php_gmp.dll." Do you mean that you get the same issue with 5.1.6? I think yes as the gmp library has not been changed since 5.1.6. About win9x support, which OS do you use? You may know that we plan to drop win9x support for 5.3+, only 2k+ will be supported. About i386 support, especially with GMP there is a real improvement by using 686+, see the gmp website for a detailed list. And finally good point about the documentation, we should document it asap. Previous Comments: ------------------------------------------------------------------------ [2008-06-09 14:29:25] shaunspiller at gmail dot com Description: ------------ I'm using the latest precompiled Win32 binaries of PHP-5.2.6 (and have also tried PHP-5.1.6) and get a program crash with an #Undefined Opcode exception when loading php_gmp.dll. I know what the problem is and I'm not sure if one would consider it a bug or not since it will only happen on very old machines, but I can't believe I'm the first person to have ever encountered this. The instruction in php_gmp.dll which causes the crash is CMOVZ EDX, EAX. The conditional move instructions were only added with the Pentium Pro. Tough luck for me -- my computer literally blew up last week and I'm stuck temporarally with a Pentium MMX and a K6 laptop, neither of which support CMOVcc. It's understandable that compiling for P6+ instructions might be a good tradeoff between performance and compatibility, but current versions of PHP are *stated* to work with even Windows 98 and up, and so are the precompiled binaries (other extensions seem to work just fine). I don't know how much CMOVcc is relied on in php_gmp.dll, and changing the build options to use generic I386+ might be undesirable, but the P6 instruction set requirement should at least be *mentioned* somewhere, and it isn't (not that I found). Disappointing for me in either case, because recompiling the DLL is a little beyond what I can do on this old system right now. I would normally have just used BCMath instead, but I need the base-conversion stuff, which that doesn't have. Reproduce code: --------------- <?php dl('php_gmp.dll'); echo 'hi!'; ?> Expected result: ---------------- hi! Actual result: -------------- Instant program crash. Windows provides the following info: PHP executed an invalid instruction in module PHP_GMP.DLL at 0187:01a760f4. Registers: EAX=01a7ced0 CS=0187 EIP=01a760f4 EFLGS=00010202 EBX=01a710e0 SS=018f ESP=00d3f904 EBP=01989c20 ECX=01a710c0 DS=018f ESI=0000001a FS=12c7 EDX=01a710b0 ES=018f EDI=01370ae0 GS=0000 Bytes at CS:EIP: 0f 44 d0 b8 60 cf a7 01 85 c9 0f 44 c8 85 db b8 Stack dump: 1001a380 01a710a4 01a710b0 01a710c0 01a710e0 01a8c2f0 0000000c 01a76120 00000003 0000001a 01370ae0 01a8c2fc 00000013 00000002 00000003 0000001a ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=45215&edit=1