From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=2607:f8b0:4864:20::144; helo=mail-it1-x144.google.com; envelope-from=ard.biesheuvel@linaro.org; receiver=edk2-devel@lists.01.org Received: from mail-it1-x144.google.com (mail-it1-x144.google.com [IPv6:2607:f8b0:4864:20::144]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 7347421197B32 for ; Wed, 12 Dec 2018 03:51:24 -0800 (PST) Received: by mail-it1-x144.google.com with SMTP id g76so8595540itg.2 for ; Wed, 12 Dec 2018 03:51:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=1lTrYadw/3DDiXFGbwifQdwe1VacIk08hBPu1qDTENQ=; b=Tuojz0pgLyGJAa2eS+T0QjYPi8MAx8Oiqq3mF91KazeZT4GxRsQOs5YWQyHtUleclt 4DLEbgSur+HzbJwmNkItPStPz8RM0i8S/GdEZLftODPSjI6lg7aKPR+e0L2rLttU2T8X UMW3yUQ3OLbQuAIrGAAwaQ4TBkdU3BKEtd2OE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=1lTrYadw/3DDiXFGbwifQdwe1VacIk08hBPu1qDTENQ=; b=QwRbWVXM+4hOkEKM3KkgzTo0b208RYmFDAr2O2T6HYLMuIcNrVXs81xtDlkrQiDv4Y AiptVxw0GrlzVpTKN0i0DsBjJ//5iOVBKaTpwxYn2UDWlAK2uj+3G0dhcqt4BRh0d0BU /QkUkN5Z3uNzjB6xZccVFPvmFMhw2kgdxXmZhIF5TmC6c3E/4+98Uw+uXuP3Zcu3u3kQ 29SoNuNzyY0VEGFgjF03q/yaIjSzIqg9RpTmZq9bN127mA8lX8ntk/0mHx7SRQEMI7Mk NXWYvTuRq1fxcWso7x27dN8FFtnIXKgd/THpTUQqi8tsd7QX2bEYTMDqqMBp/+LHYe7Q JnTA== X-Gm-Message-State: AA+aEWaIqAWZ2Pdf3PYKEe0E4aVWVJ2gSwS+TdH2BhnMVP//D7RzFGOi T2M9a49rZ2AHRH1/cXxbYOQD5nfVwPr/0cWzrORvAA== X-Google-Smtp-Source: AFSGD/UDm0wTGgfuHIif7Rs80YV20cZ+U7yDi2uwVkW7ZgsUV66UBu9ybv2/6eb5WG4LmpVKv7qyIx39tBL+LgQYMXQ= X-Received: by 2002:a02:4c9:: with SMTP id 192mr18681311jab.2.1544615483892; Wed, 12 Dec 2018 03:51:23 -0800 (PST) MIME-Version: 1.0 References: <20181212103308.8099-1-ard.biesheuvel@linaro.org> <20181212103308.8099-3-ard.biesheuvel@linaro.org> <0f1b613c-e027-e025-ccc1-d2526653d0ca@redhat.com> In-Reply-To: <0f1b613c-e027-e025-ccc1-d2526653d0ca@redhat.com> From: Ard Biesheuvel Date: Wed, 12 Dec 2018 12:51:12 +0100 Message-ID: To: Laszlo Ersek Cc: "edk2-devel@lists.01.org" , "Kinney, Michael D" , "Gao, Liming" , "Feng, Bob C" , Leif Lindholm Subject: Re: [PATCH 2/3] BaseTools/tools_def ARM CLANG35: work around -mno-movt option name change X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Dec 2018 11:51:25 -0000 Content-Type: text/plain; charset="UTF-8" On Wed, 12 Dec 2018 at 12:50, Laszlo Ersek wrote: > > On 12/12/18 11:33, Ard Biesheuvel wrote: > > PE/COFF only has a very limited id space for runtime relocations, and > > so it defines only a single relocation for movw/movt instruction pairs, > > which can be combined to load a 32-bit symbol reference into a register. > > For this to work as expected, these instructions must always appear in > > the same order and adjacently, and this is something few compilers take > > into account, unless they target PE/COFF explicitly (and this is not the > > case for our ELF based toolchains) > > > > For Clang 3.6 and later, we can pass the -mno-movt option to suppress > > movw/movt pairs entirely, which works around the issue. Unfortunately, > > for Clang 3.5, the option is called differently (-mllvm -arm-use-movt=0) > > and mutually incompatible between 3.5 and 3.6. > > > > Since it is desirable for the CLANG35 toolchain to be usable on newer > > versions of Clang as well (given that it is the only non-LTO alternative > > to CLANG38), let's work around this issue in a way that permits versions > > 3.5 and newer of Clang to be used with the CLANG35 profile. > > > > So pass the -mkernel flag instead (and drop the -mno-unaligned-access > > in *_CLANG35_ARM_CC_XIPFLAGS which now becomes redundant, and which > > Clang complains about). This also inhibits movw/movt generation, along > > with some other changes (e.g., long calls) which do affect code generation > > but not in a undesirable manner. > > > > Contributed-under: TianoCore Contribution Agreement 1.1 > > Signed-off-by: Ard Biesheuvel > > --- > > BaseTools/Conf/tools_def.template | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template > > index ac2b95e0f5ba..2ba833e1fb06 100755 > > --- a/BaseTools/Conf/tools_def.template > > +++ b/BaseTools/Conf/tools_def.template > > @@ -5249,7 +5249,7 @@ DEFINE CLANG35_AARCH64_CC_FLAGS = DEF(GCC_AARCH64_CC_FLAGS) DEF(CLANG35_AARCH64 > > *_CLANG35_ARM_ASM_FLAGS = DEF(GCC_ASM_FLAGS) DEF(CLANG35_ARM_TARGET) $(ARCHASM_FLAGS) $(PLATFORM_FLAGS) -Qunused-arguments > > *_CLANG35_ARM_DLINK_FLAGS = DEF(CLANG35_ARM_TARGET) DEF(GCC_ARM_DLINK_FLAGS) > > *_CLANG35_ARM_DLINK2_FLAGS = DEF(GCC_DLINK2_FLAGS_COMMON) -Wl,--defsym=PECOFF_HEADER_SIZE=0x220 > > -*_CLANG35_ARM_PLATFORM_FLAGS = -march=armv7-a > > +*_CLANG35_ARM_PLATFORM_FLAGS = -march=armv7-a -mkernel -Qunused-arguments > > *_CLANG35_ARM_PP_FLAGS = DEF(GCC_PP_FLAGS) DEF(CLANG35_ARM_TARGET) $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) > > *_CLANG35_ARM_RC_FLAGS = DEF(GCC_ARM_RC_FLAGS) > > *_CLANG35_ARM_VFRPP_FLAGS = DEF(GCC_VFRPP_FLAGS) DEF(CLANG35_ARM_TARGET) $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) > > > > The commit message speaks about adding -mkernel, and removing > -mno-unaligned-access (elsewhere). In the patch, I only see -mkernel > (plus an un-announced -Qunused-arguments option). > > Is the commit message slightly out-of-date relative to the code? (Or > perhaps the other way around?) > Ah yes. The -mno-unaligned-access became redundant, but instead of removing it, i ended up adding the -Qunused-arguments to stop Clang from complaining about it.