From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 77768 invoked by alias); 17 Dec 2015 21:21:41 -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 77733 invoked by uid 89); 17 Dec 2015 21:21:41 -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_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=ubizjak@gmail.com, ubizjakgmailcom, horrible, our X-HELO: mail-oi0-f53.google.com Received: from mail-oi0-f53.google.com (HELO mail-oi0-f53.google.com) (209.85.218.53) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Thu, 17 Dec 2015 21:21:40 +0000 Received: by mail-oi0-f53.google.com with SMTP id o124so49860791oia.1 for ; Thu, 17 Dec 2015 13:21:39 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.202.208.68 with SMTP id h65mr39045053oig.111.1450387298065; Thu, 17 Dec 2015 13:21:38 -0800 (PST) Received: by 10.60.138.70 with HTTP; Thu, 17 Dec 2015 13:21:38 -0800 (PST) In-Reply-To: References: <20151216232951.GA17976@intel.com> Date: Thu, 17 Dec 2015 21:21:00 -0000 Message-ID: Subject: Re: [PATCH] PR target/68937: i686: -fno-plt produces wrong code (maybe only with tailcall From: Uros Bizjak To: "H.J. Lu" Cc: "gcc-patches@gcc.gnu.org" Content-Type: text/plain; charset=UTF-8 X-SW-Source: 2015-12/txt/msg01830.txt.bz2 On Thu, Dec 17, 2015 at 7:09 PM, H.J. Lu wrote: > On Thu, Dec 17, 2015 at 8:11 AM, H.J. Lu wrote: >> On Thu, Dec 17, 2015 at 7:50 AM, H.J. Lu wrote: >>> On Thu, Dec 17, 2015 at 5:42 AM, Uros Bizjak wrote: >>>> On Thu, Dec 17, 2015 at 2:00 PM, H.J. Lu wrote: >>>>> On Thu, Dec 17, 2015 at 2:04 AM, Uros Bizjak wrote: >>>>>> On Thu, Dec 17, 2015 at 12:29 AM, H.J. Lu wrote: >>>>>>> Since sibcall never returns, we can only use call-clobbered register >>>>>>> as GOT base. Otherwise, callee-saved register used as GOT base won't >>>>>>> be properly restored. >>>>>>> >>>>>>> Tested on x86-64 with -m32. OK for trunk? >>>>>> >>>>>> You don't have to add explicit clobber for members of "CLOBBERED_REGS" >>>>>> class, and register_no_elim_operand predicate should be used with "U" >>>>>> constraint. Also, please introduce new predicate, similar to how >>>>>> GOT_memory_operand is defined and handled. >>>>>> >>>>> >>>>> Here is the updated patch. There is a predicate already, >>>>> sibcall_memory_operand. It allows any registers to >>>>> be as GOT base, which is the root of our problem. >>>>> This patch removes GOT slot from it and handles >>>>> sibcall over GOT slot with *sibcall_GOT_32 and >>>>> *sibcall_value_GOT_32 patterns. Since I need to >>>>> expose constraints on GOT base register to RA, >>>>> I have to use 2 operands, GOT base and function >>>>> symbol, to describe sibcall over 32-bit GOT slot. >>>> >>>> Please use >>>> >>>> (mem:SI (plus:SI >>>> (match_operand:SI 0 "register_no_elim_operand" "U") >>>> (match_operand:SI 1 "GOT32_symbol_operand"))) >>>> ... >>>> >>>> to avoid manual rebuild of the operand. >>>> >>> >>> Is this OK? >>> >> >> An updated patch to allow sibcall_memory_operand for RTL >> expansion. OK for trunk if there is no regression? >> > > There is no regressions on x86-64 with -m32. OK for trunk? OK for mainline, with a following change: @@ -597,11 +597,17 @@ (match_operand 0 "memory_operand")))) ;; Return true if OP is a memory operands that can be used in sibcalls. +;; Since sibcall never returns, we can only use call-clobbered register +;; as GOT base. Allow GOT slot here only with pseudo register as GOT +;; base. Properly handle sibcall over GOT slot with *sibcall_GOT_32 +;; and *sibcall_value_GOT_32 patterns. (define_predicate "sibcall_memory_operand" (and (match_operand 0 "memory_operand") (match_test "CONSTANT_P (XEXP (op, 0)) || (GET_CODE (XEXP (op, 0)) == PLUS && REG_P (XEXP (XEXP (op, 0), 0)) + && (REGNO (XEXP (XEXP (op, 0), 0)) + >= FIRST_PSEUDO_REGISTER) && GET_CODE (XEXP (XEXP (op, 0), 1)) == CONST && GET_CODE (XEXP (XEXP (XEXP (op, 0), 1), 0)) == UNSPEC && XINT (XEXP (XEXP (XEXP (op, 0), 1), 0), 1) == UNSPEC_GOT)"))) You can use (!HARD_REGISTER_NUM_P (...) || call_used_regs[...]) here. Call-used hard regs are still allowed here. Can you please also rewrite this horrible match_test as a block of C code using GOT32_symbol_operand predicate? Thanks, Uros.