From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 76445 invoked by alias); 12 Aug 2015 01:11:57 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 76420 invoked by uid 89); 12 Aug 2015 01:11:57 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.2 required=5.0 tests=AWL,BAYES_00,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-pa0-f48.google.com Received: from mail-pa0-f48.google.com (HELO mail-pa0-f48.google.com) (209.85.220.48) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Wed, 12 Aug 2015 01:11:55 +0000 Received: by pacrr5 with SMTP id rr5so2212762pac.3 for ; Tue, 11 Aug 2015 18:11:53 -0700 (PDT) X-Received: by 10.66.222.68 with SMTP id qk4mr61088880pac.96.1439341913567; Tue, 11 Aug 2015 18:11:53 -0700 (PDT) Received: from bigtime.twiddle.net (50-194-63-110-static.hfc.comcastbusiness.net. [50.194.63.110]) by smtp.gmail.com with ESMTPSA id kv10sm4167810pbc.2.2015.08.11.18.11.52 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Aug 2015 18:11:52 -0700 (PDT) From: Richard Henderson To: gcc-patches@gcc.gnu.org Cc: David Edelsohn Subject: [PATCH 07/15] rs6000: Generalize left shift in constant generation Date: Wed, 12 Aug 2015 01:12:00 -0000 Message-Id: <1439341904-9345-8-git-send-email-rth@redhat.com> In-Reply-To: <1439341904-9345-1-git-send-email-rth@redhat.com> References: <1439341904-9345-1-git-send-email-rth@redhat.com> X-IsSubscribed: yes X-SW-Source: 2015-08/txt/msg00560.txt.bz2 Rather than always shift by 32, shift by the total number of zeros required. The improvement to also look to shift out ones comes from Kenner via alpha. Cc: David Edelsohn --- * config/rs6000/rs6000.c (genimm_ppc::exam_search): Use ctz to compute the shift. Also attempt to shift out ones. --- gcc/config/rs6000/rs6000.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c index 59c5014..b27e476 100644 --- a/gcc/config/rs6000/rs6000.c +++ b/gcc/config/rs6000/rs6000.c @@ -8145,6 +8145,7 @@ genimm_ppc::exam_search (HOST_WIDE_INT c, int budget) { const int sub_budget = budget - 1; HOST_WIDE_INT test; + int bits; /* Simple arithmetic on the low 32-bits. */ test = c & 0xffff; @@ -8181,11 +8182,23 @@ genimm_ppc::exam_search (HOST_WIDE_INT c, int budget) } /* Shift the constant left. */ - test = HOST_WIDE_INT_UC (0xffffffff00000000); - if ((c & test) == c && exam_sub (c >> 32, sub_budget)) + bits = ctz_hwi (c); + if (bits > 0) { - opN (ASHIFT, 32); /* SLDI */ - return true; + /* First try with zeros being shifted out. */ + HOST_WIDE_INT sub_c = (unsigned HOST_WIDE_INT)c >> bits; + bool ok = exam_sub (sub_c, sub_budget); + if (!ok) + { + /* If that failed, try with ones being shifted out. */ + sub_c |= ~(HOST_WIDE_INT_M1U >> bits); + ok = exam_sub (sub_c, sub_budget); + } + if (ok) + { + opN (ASHIFT, bits); /* SLDI */ + return true; + } } return false; -- 2.4.3