From patchwork Thu May 7 02:17:40 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: dengjianbo X-Patchwork-Id: 134592 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from vm01.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id EFC194BA23D9 for ; Thu, 7 May 2026 02:18:36 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org EFC194BA23D9 X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by sourceware.org (Postfix) with ESMTP id B37634BA23CF for ; Thu, 7 May 2026 02:18:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org B37634BA23CF Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=loongson.cn ARC-Filter: OpenARC Filter v1.0.0 sourceware.org B37634BA23CF Authentication-Results: sourceware.org; arc=none smtp.remote-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1778120286; cv=none; b=BaWLUWu098CRPMk7wEdYM6jkVKmNlegOhrZaLrBrLx1y2NcjYCehvuCE01OxWsHYhHwcAwPUnmF1Ukh0nVDCNW6XTEBojkrNiFOkDE9v53wdkFQqJkTKkjmBXTEbEVfX/nAsv0Po3NNeTGVlc69g+tB7nVaDDbFKSpU3Dhjh5vc= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1778120286; c=relaxed/simple; bh=lKmKHHlvdh6KLuR5W5SbfZ/w7MOdbHOyg3rfy25iSOw=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=SZJKgFpyIdzS71RWCBOh7FRCwTNoiA49/6ijYMOB10EmL2UjUEjyE5VOjW7SXSoME3SSEHvq2cnplEDLUdPGOG1hODsJf7WYbgkZH/eXi9lrc+pW2vrL5OBHI9KZIokNfRfHGmBzdEU7e/iyBYRDuKhTSfN2f/BKN1kVV5tRo1c= ARC-Authentication-Results: i=1; sourceware.org DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B37634BA23CF Received: from loongson.cn (unknown [10.10.130.252]) by gateway (Coremail) with SMTP id _____8DxrOla9vtp1lYHAA--.22138S3; Thu, 07 May 2026 10:18:02 +0800 (CST) Received: from slurm-master.loongson.cn (unknown [10.10.130.252]) by front1 (Coremail) with SMTP id qMiowJBx78JZ9vtp4gB8AA--.39988S2; Thu, 07 May 2026 10:18:02 +0800 (CST) From: Deng Jianbo To: adhemerval.zanella@linaro.org, libc-alpha@sourceware.org, caiyinyu@loongson.cn, i.swmail@xen0n.name Cc: joseph_myers@mentor.com, carlos@redhat.com, xuchenghua@loongson.cn, Deng Jianbo Subject: [PATCH] LoongArch: Optimize math barriers Date: Thu, 7 May 2026 10:17:40 +0800 Message-Id: <20260507021740.16572-1-dengjianbo@loongson.cn> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-CM-TRANSID: qMiowJBx78JZ9vtp4gB8AA--.39988S2 X-CM-SenderInfo: pghqwyxldqu0o6or00hjvr0hdfq/ X-Coremail-Antispam: 1Uk129KBj93XoW7Kw1kXw1kGFW7tr4DtF1UJwc_yoW8Aw47pr Wfur15tF4DuwnrJ3srC347uFs7Jw4Fkr45ZFWYk348Zr1S9rn5XFsaya98Za45uw10yFZ0 gr15tw1fu3ZxJacCm3ZEXasCq-sJn29KB7ZKAUJUUUU5529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUkjb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_JFI_Gr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Jr0_Gr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_ Gr0_Gr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2x26I8E6xACxx1l5I 8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1Y6r17McIj6I8E87Iv67AK xVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41l42xK82IYc2Ij64 vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8G jcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2I x0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK 8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I 0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x07j1WlkUUUUU= X-Spam-Status: No, score=-12.2 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, 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 sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libc-alpha-bounces~patchwork=sourceware.org@sourceware.org The constraints 'frm' used in math_opt_barrier and math_force_eval cause GCC choose fixed-point registers with lower costs in some cases, because in LoongArch ira_reg_class_subunion[FP_REGS][GR_REGS] is initialized to GR_REGS, extra move costs will be added when choosing FP_REGS. This results in unnecessary instructions to move values between FP_REGS and GR_REGS. Most of cases in GLIBC math barriers related macros are invoked with floating-point type paramters, this patch removes "r" constraints, allowing GCC to keep values in floating-point registers and avoid the extra moves. Example from xflow function before the change: movfr2gr.d $t0, $fa0 beqz $a0, 12 # 69960 fneg.d $fa1, $fa0 movfr2gr.d $t0, $fa1 movgr2fr.d $fa1, $t0 fmul.d $fa0, $fa0, $fa1 b -56 # 69930 After the patch: fmov.d $fa1, $fa0 beqz $a0, 12 # 69ac0 fneg.d $fa1, $fa0 nop fmul.d $fa0, $fa0, $fa1 b -52 # 69a90 --- sysdeps/loongarch/fpu/math-barriers.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sysdeps/loongarch/fpu/math-barriers.h b/sysdeps/loongarch/fpu/math-barriers.h index 6a069ff41d..76835aa210 100644 --- a/sysdeps/loongarch/fpu/math-barriers.h +++ b/sysdeps/loongarch/fpu/math-barriers.h @@ -21,8 +21,8 @@ /* Generic code forces values to memory; we don't need to do that. */ #define math_opt_barrier(x) \ - ({ __typeof (x) __x = (x); __asm ("" : "+frm" (__x)); __x; }) + ({ __typeof (x) __x = (x); __asm ("" : "+fm" (__x)); __x; }) #define math_force_eval(x) \ - ({ __typeof (x) __x = (x); __asm __volatile__ ("" : : "frm" (__x)); }) + ({ __typeof (x) __x = (x); __asm __volatile__ ("" : : "fm" (__x)); }) #endif /* math-barriers.h */