From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23240 invoked by alias); 3 Nov 2004 11:29:40 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 23203 invoked by uid 48); 3 Nov 2004 11:29:38 -0000 Date: Wed, 03 Nov 2004 11:29:00 -0000 Message-ID: <20041103112938.23201.qmail@sourceware.org> From: "nathan at gcc dot gnu dot org" To: gcc-bugs@gcc.gnu.org In-Reply-To: <20040728170038.16802.steinmtz@us.ibm.com> References: <20040728170038.16802.steinmtz@us.ibm.com> Reply-To: gcc-bugzilla@gcc.gnu.org Subject: [Bug rtl-optimization/16802] PowerPC - Unnecessary extsw X-Bugzilla-Reason: CC X-SW-Source: 2004-11/txt/msg00339.txt.bz2 List-Id: ------- Additional Comments From nathan at gcc dot gnu dot org 2004-11-03 11:29 ------- I believe this is a problem with the tree optimizers being ABI blind. on 64bit ppc integral parameters and return values are correctly extended to 64 bits. This sign extension is inserted during the tree->rtl translation, and therefore cannot leverage any ssa-vrp information. Unfortunately RTL does not have VRP itself, but only condition-code propagation. Combine does not track values across basic blocks, so it too is blind in this case, as the register is written in two blocks. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16802