From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10212 invoked by alias); 1 Jun 2011 20:17:50 -0000 Received: (qmail 10202 invoked by uid 22791); 1 Jun 2011 20:17:48 -0000 X-SWARE-Spam-Status: No, hits=-2.7 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 01 Jun 2011 20:17:22 +0000 From: "oleg.endo@t-online.de" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/49263] New: SH Target: underutilized "TST #imm, R0" instruction X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: oleg.endo@t-online.de X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Date: Wed, 01 Jun 2011 20:17:00 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2011-06/txt/msg00070.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49263 Summary: SH Target: underutilized "TST #imm, R0" instruction Product: gcc Version: 4.6.1 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: target AssignedTo: unassigned@gcc.gnu.org ReportedBy: oleg.endo@t-online.de Created attachment 24411 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24411 test for various integer types and constant values 0...255 The "TST #imm, R0" instruction is a bit underutilized on SH targets. For some bit patterns of the immediate constant it tries to extract the bits in question by various means and test the result against zero/non-zero and misses the straight forward instruction. In particular: * one single bit * n contiguous bits starting at bit 0 When testing a byte against 0x80 it uses "CMP/PZ", which is as good as a "TST" instruction (in terms of costs), so this is OK. I've spotted this in version around 4.4. It still happens with 4.6 and the following config: Using built-in specs. COLLECT_GCC=sh-elf-gcc COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/sh-elf/4.6.1/lto-wrapper Target: sh-elf Configured with: ../gcc-4.6-20110527/configure --target=sh-elf --prefix=/usr/local --enable-languages=c,c++ --enable-multilib --disable-libssp --without-headers --disable-nls --disable-werror --enable-lto --with-newlib --with-gnu-as --with-gnu-ld --with-system-zlib Thread model: single gcc version 4.6.1 20110527 (prerelease) (GCC)