From: khan@xraylith.wisc.edu (Mumit Khan) Subject: egcs-1.1: i386 stdcall function codegen bug 28 Oct 1998 16:20:32 -0800 Message-ID: Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="1915750185-1360710587-909549652=:28077" To: egcs-bugs@cygnus.com, gnu-win32@cygnus.com This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. Send mail to mime@docserver.cac.washington.edu for more info. --1915750185-1360710587-909549652=:28077 Content-Type: TEXT/PLAIN; charset=US-ASCII egcs version : release and mainline binutils : 2.9.1 and 980830 snapshots There seems to be a i386 codegen bug that affects "stdcall" functions returning anything larger than an integer. For the following function, double __attribute__((stdcall)) foo_local1 (double f) { return f; } The assembly created (using -O2 -fomit-frame-pointer to cut noise), we get the following. This causes the return value to be garbage unless I comment out the "fstp" instruction. .globl _foo_local1@8 _foo_local1@8: fldl 4(%esp) fstp %st(0) ## <<<< offending instruction ret $8 Interestingly, for a "cdecl" function, the fstp instruction is missing and everything works as expected. double foo_local2 (double f) { return f; } .globl _foo_local2 _foo_local2: fldl 4(%esp) ## <<<< no fstp instruction ret I'm attaching a trivial, but complete, test program that shows the problem. Regards, Mumit --1915750185-1360710587-909549652=:28077 Content-Type: TEXT/PLAIN; charset=US-ASCII; name="stdcall-bug.c" Content-Transfer-Encoding: BASE64 Content-ID: Content-Description: bug test case I2luY2x1ZGUgPHN0ZGlvLmg+DQoNCiNkZWZpbmUgV0lOQVBJIF9fYXR0cmli dXRlX18oKHN0ZGNhbGwpKQ0KDQpkb3VibGUgV0lOQVBJDQpmb29fbG9jYWwx IChkb3VibGUgZikgew0KICByZXR1cm4gZjsNCn0NCg0KZG91YmxlIA0KZm9v X2xvY2FsMiAoZG91YmxlIGYpIHsNCiAgcmV0dXJuIGY7DQp9DQoNCmludCAN Cm1haW4gKCkgDQp7IA0KICBkb3VibGUgZjEsIGYyOw0KICBmMSA9IDUuMDsN CiAgZjIgPSBmb29fbG9jYWwxIChmMSk7DQogIHByaW50ZiAoImZvb19sb2Nh bDEgKCVmKSA9ICVmXG4iLCBmMSwgZjIpOw0KICBmMiA9IGZvb19sb2NhbDIg KGYxKTsNCiAgcHJpbnRmICgiZm9vX2xvY2FsMiAoJWYpID0gJWZcbiIsIGYx LCBmMik7DQogIHJldHVybiAwOw0KfQ0KDQo= --1915750185-1360710587-909549652=:28077-- - For help on using this list (especially unsubscribing), send a message to "gnu-win32-request@cygnus.com" with one line of text: "help".