From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by sourceware.org (Postfix) with ESMTPS id C46073858414 for ; Fri, 10 Feb 2023 11:21:07 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org C46073858414 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=suse.de Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id BAFB338C05; Fri, 10 Feb 2023 11:21:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1676028065; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Y1tJrDvvfDeeqmKVwu+2wwWc7H4RQ6ZIdL6RFbCBNSA=; b=PdVGsGUjIvnWCTWl/rz0Uk1ULJVRxKd0af1GrRdC1B9h8wtXgvRRgBDVGXaRGYx66Us4R5 wDTngKSES5cYsZ1iwmfD9gRmLR3BgUJ24mASEBsn62c7zH2KrcXWWiaM7cJrvWlk0uhqlU TuzQ207QVMTjQg3Az6WS1HgYXB/OjR4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1676028065; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Y1tJrDvvfDeeqmKVwu+2wwWc7H4RQ6ZIdL6RFbCBNSA=; b=+DSkLs6utbj0vDQLKrUgBRjNCotkgP2PjdoqBJpF6t/SvSh27rqyUz+RnQ2hNcs/FiDEJc e7TXlcyklZfosxCQ== Received: from wotan.suse.de (wotan.suse.de [10.160.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id A91B22C141; Fri, 10 Feb 2023 11:21:05 +0000 (UTC) Date: Fri, 10 Feb 2023 11:21:05 +0000 (UTC) From: Richard Biener To: Richard Sandiford cc: Richard Biener via Gcc-patches Subject: Re: [PATCH] tree-optimization/108724 - vectorized code getting piecewise expanded In-Reply-To: Message-ID: References: <20230210110251.62A5B385B52C@sourceware.org> User-Agent: Alpine 2.22 (LSU 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-11.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,KAM_SHORT,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Fri, 10 Feb 2023, Richard Sandiford wrote: > Richard Biener via Gcc-patches writes: > > This fixes an oversight to when removing the hard limits on using > > generic vectors for the vectorizer to enable both SLP and BB > > vectorization to use those. The vectorizer relies on vector lowering > > to expand plus, minus and negate to bit operations but vector > > lowering has a hard limit on the minimum number of elements per > > work item. Vectorizer costs for the testcase at hand work out > > to vectorize a loop with just two work items per vector and that > > causes element wise expansion and spilling. > > > > The fix for now is to re-instantiate the hard limit, matching what > > vector lowering does. For the future the way to go is to emit the > > lowered sequence directly from the vectorizer instead. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK? > > LGTM after reading the vector lowering stuff in the PR trail. > > TBH I don't remember when the hard limit was removed though. I removed it as part of fixing PR101801 but didn't anticipate the close connection with vector lowering. Richard. > Thanks, > Richard > > > > > Thanks, > > Richard. > > > > PR tree-optimization/108724 > > * tree-vect-stmts.cc (vectorizable_operation): Avoid > > using word_mode vectors when vector lowering will > > decompose them to elementwise operations. > > > > * gcc.target/i386/pr108724.c: New testcase. > > --- > > gcc/testsuite/gcc.target/i386/pr108724.c | 15 +++++++++++++++ > > gcc/tree-vect-stmts.cc | 14 ++++++++++++++ > > 2 files changed, 29 insertions(+) > > create mode 100644 gcc/testsuite/gcc.target/i386/pr108724.c > > > > diff --git a/gcc/testsuite/gcc.target/i386/pr108724.c b/gcc/testsuite/gcc.target/i386/pr108724.c > > new file mode 100644 > > index 00000000000..c4e0e918610 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/i386/pr108724.c > > @@ -0,0 +1,15 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-O3 -mno-sse" } */ > > + > > +int a[16], b[16], c[16]; > > +void foo() > > +{ > > + for (int i = 0; i < 16; i++) { > > + a[i] = b[i] + c[i]; > > + } > > +} > > + > > +/* When this is vectorized this shouldn't be expanded piecewise again > > + which will result in spilling for the upper half access. */ > > + > > +/* { dg-final { scan-assembler-not "\\\[er\\\]sp" } } */ > > diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc > > index c86249adcc3..09b5af603d2 100644 > > --- a/gcc/tree-vect-stmts.cc > > +++ b/gcc/tree-vect-stmts.cc > > @@ -6315,6 +6315,20 @@ vectorizable_operation (vec_info *vinfo, > > return false; > > } > > > > + /* ??? We should instead expand the operations here, instead of > > + relying on vector lowering which has this hard cap on the number > > + of vector elements below it performs elementwise operations. */ > > + if (using_emulated_vectors_p > > + && (code == PLUS_EXPR || code == MINUS_EXPR || code == NEGATE_EXPR) > > + && ((BITS_PER_WORD / vector_element_bits (vectype)) < 4 > > + || maybe_lt (nunits_out, 4U))) > > + { > > + if (dump_enabled_p ()) > > + dump_printf (MSG_NOTE, "not using word mode for +- and less than " > > + "four vector elements\n"); > > + return false; > > + } > > + > > int reduc_idx = STMT_VINFO_REDUC_IDX (stmt_info); > > vec_loop_masks *masks = (loop_vinfo ? &LOOP_VINFO_MASKS (loop_vinfo) : NULL); > > internal_fn cond_fn = get_conditional_internal_fn (code); > -- Richard Biener SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg, Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman; HRB 36809 (AG Nuernberg)