Date: Thu, 21 Sep 2017 16:00:00 -0700 From: <soralx@cydem.org> To: <vbox@FreeBSD.org> Subject: Re: [virtualbox-ose] Build failure: global register variable Message-ID: <20170921160000.689755f8@mscad14> In-Reply-To: <20170920191710.58d335df@mscad14> References: <20170917195419.431341e7@mscad14> <20170920191710.58d335df@mscad14>
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> > [...]
> > kBuild: Compiling VBoxRemPrimary
> > - /usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.28/src/recompiler/target-i386/op_helper.c
> > In file included
> > from /usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.28/src/recompiler/target-i386/op_helper.c:29:
> > /usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.28/src/recompiler/target-i386/exec.h:41:38:
> > error: register 'r14' unsuitable for global register variables on this
> > target register struct CPUX86State *env asm(AREG0); ^
> > /usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.28/src/recompiler/dyngen-exec.h:81:15:
> > note: expanded from macro 'AREG0'
> > #define AREG0 "r14"
>
> Turns out that the fix for this is to make sure that devel/kBuild
> is compiled with GCC, not clang; thus, that module of VBox that
> has global register variable (and fails to build with clang) is
> automagically built with gcc. So some parts of VBox are built
> with base clang, some with gcc from ports; it is awkward, but
> it all works somehow.
Alternatively, one can try changing 'r14' to 'rbp' in definition
of "AREG0" for amd64 at src/recompiler/dyngen-exec.h:81. This is
the only place where gcc is needed, as clang cannot handle r14
for now [0].
I recompiled kBuild with clang, and succeeded compiling virtualbox-ose
with 'r14' to 'rbp' change. It seems to work normally, but I don't know
what are the performance implications of using up rbp.
[0] clang/lib/Basic/Targets/X86.h:
860 bool validateGlobalRegisterVariable(StringRef RegName, unsigned RegSize,
861 bool &HasSizeMismatch) const override {
862 // rsp and rbp are the only 64-bit registers the x86 backend can currently
863 // handle.
864 if (RegName.equals("rsp") || RegName.equals("rbp")) {
865 // Check that the register size is 64-bit.
866 HasSizeMismatch = RegSize != 64;
867 return true;
868 }
--
[SorAlx] ridin' VN2000 Classic LT
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