From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f43.google.com (mail-wr1-f43.google.com [209.85.221.43]) by sourceware.org (Postfix) with ESMTPS id 899C3382D474; Fri, 27 May 2022 06:07:32 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 899C3382D474 Received: by mail-wr1-f43.google.com with SMTP id j25so4529948wrb.6; Thu, 26 May 2022 23:07:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=dvBKW7EK1eIFgpnCcnVrIeKTpIOTONmZ5rG7om8Fq7c=; b=xo3Q3hYHyxMS7eAfjgiEbwGY0ZzjD+pqRWo+gmI884VoOpl5LdAS6Fgvtz4iflwbxz /cfVRAHXpzvjA9Mtts0HEvuWz6pcOyTEViXZlgOl96O3RO5BG79D9PqfMLORCuMUuy0m jVY/W8KdJcb2F6eVfHkH0buReMeFimxanipbPH7DjAMjghMEKwXb6wnlTvPLAJsM4r7/ M3Dkz4ghVJhddWKXipR62yy6BkH4kERxawhW7aA3nFX3fZ7XAn2avF9KLqAGjB6PMi3F 8caNyNXkmZpjihM69FuuM8UVMppuiIlgMAcy5UY9YvG9uw/6jjQoZeJGqm9FgT1mQWFS NTuw== X-Gm-Message-State: AOAM532zttDoZUKjBTTAINTTpdOMGhPmzmjlfOh+UZMk1qqzkl4cEuhM 7NI2OmpkkummN0xGSxte+vJkBG9mxSS8cWFD X-Google-Smtp-Source: ABdhPJy8xfnb4TKqVUkejkEBQj0qA2p9086r71l45EmHg7qMkFt0i1K15T11Q60yXpdxZE4kRDB8IQ== X-Received: by 2002:a05:6000:1882:b0:20f:de1d:9fb9 with SMTP id a2-20020a056000188200b0020fde1d9fb9mr18878396wri.504.1653631651277; Thu, 26 May 2022 23:07:31 -0700 (PDT) Received: from beast.fritz.box (62-178-148-172.cable.dynamic.surfer.at. [62.178.148.172]) by smtp.gmail.com with ESMTPSA id t125-20020a1c4683000000b00395f15d993fsm1169860wma.5.2022.05.26.23.07.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 May 2022 23:07:30 -0700 (PDT) From: Christoph Muellner To: gcc-patches@gcc.gnu.org, Kito Cheng , Jim Wilson , Andrew Waterman , Philipp Tomsich , Christoph Muellner , Aaron Durbin , Patrick O'Neill , Vineet Gupta Subject: [PATCH v3 4/9] RISC-V: Use STORE instead of AMOSWAP for atomic stores [PR 100265] Date: Fri, 27 May 2022 08:07:18 +0200 Message-Id: <20220527060723.235095-5-cmuellner@gcc.gnu.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220527060723.235095-1-cmuellner@gcc.gnu.org> References: <20220527060723.235095-1-cmuellner@gcc.gnu.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-11.0 required=5.0 tests=BAYES_00, FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM, GIT_PATCH_0, HEADER_FROM_DIFFERENT_DOMAINS, KAM_DMARC_STATUS, KAM_MANYTO, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 May 2022 06:07:34 -0000 Using AMOSWAP as atomic store does not allow us to do sub-word accesses. Further, it is not consistent with our atomic_load () implementation. The benefit of AMOSWAP is that the resulting code sequence will be smaller (comapred to FENCE+STORE), however, this does not weight out for the lack of sub-word accesses. Additionally, HW implementors have claimed that an optimal implementation AMOSWAP is slightly more expensive than FENCE+STORE. So let's use STORE instead of AMOSWAP. gcc/ PR 100265 * config/riscv/sync.md (atomic_store): Remove. --- gcc/config/riscv/sync.md | 11 ----------- 1 file changed, 11 deletions(-) diff --git a/gcc/config/riscv/sync.md b/gcc/config/riscv/sync.md index ddaeda0116d..86f4cef6af9 100644 --- a/gcc/config/riscv/sync.md +++ b/gcc/config/riscv/sync.md @@ -57,17 +57,6 @@ (define_insn "mem_thread_fence_1" ;; Atomic memory operations. -;; Implement atomic stores with amoswap. Fall back to fences for atomic loads. -(define_insn "atomic_store" - [(set (match_operand:GPR 0 "memory_operand" "=A") - (unspec_volatile:GPR - [(match_operand:GPR 1 "reg_or_0_operand" "rJ") - (match_operand:SI 2 "const_int_operand")] ;; model - UNSPEC_ATOMIC_STORE))] - "TARGET_ATOMIC" - "amoswap.%A2 zero,%z1,%0" - [(set (attr "length") (const_int 8))]) - (define_insn "atomic_" [(set (match_operand:GPR 0 "memory_operand" "+A") (unspec_volatile:GPR -- 2.35.3