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From: "pluto at agmk dot net" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/26457] -fstack-protector leaks the upper bits of RAX Date: Thu, 02 Mar 2006 14:32:00 -0000 [thread overview] Message-ID: <20060302143202.16194.qmail@sourceware.org> (raw) In-Reply-To: <bug-26457-12259@http.gcc.gnu.org/bugzilla/> ------- Comment #4 from pluto at agmk dot net 2006-03-02 14:32 ------- http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/24592.pdf page 33: [ Zero-Extension of 32-Bit Results. ] (...) when performing 32-bit operations with a GPR destination in 64-bit mode, the processor zero-extends the 32-bit result into the full 64-bit destination. 8-bit and 16-bit operations on GPRs preserve all unwritten upper bits of the destination GPR. This is consistent with legacy 16-bit and 32-bit semantics for partial-width results. Software should explicitly sign-extend the results of 8-bit, 16- bit, and 32-bit operations to the full 64-bit width before using the results in 64-bit address calculations. -- pluto at agmk dot net changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |pluto at agmk dot net http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26457
next prev parent reply other threads:[~2006-03-02 14:32 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2006-02-24 15:08 [Bug c/26457] New: " arjan at linux dot intel dot com 2006-02-24 15:12 ` [Bug target/26457] " jakub at gcc dot gnu dot org 2006-02-24 15:20 ` pinskia at gcc dot gnu dot org 2006-03-02 14:00 ` pinskia at gcc dot gnu dot org 2006-03-02 14:32 ` pluto at agmk dot net [this message] 2006-03-02 14:48 ` jakub at gcc dot gnu dot org
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