On Thu, Apr 14, 2022 at 04:15:22PM +0200, Jan Beulich wrote: > On 14.04.2022 15:31, Roger Pau Monné wrote: > > On Thu, Apr 14, 2022 at 02:52:47PM +0200, Jan Beulich wrote: > >> On 14.04.2022 14:40, Roger Pau Monné wrote: > >>> On Tue, Apr 12, 2022 at 12:27:34PM +0200, Jan Beulich wrote: > >>>> While future gas versions will allow line number information to be > >>>> generated for all instances of .irp and alike [1][2], the same isn't > >>>> true (nor immediately intended) for .macro [3]. Hence macros, when they > >>>> do more than just invoke another macro or issue an individual insn, want > >>>> to have .line directives (in header files also .file ones) in place. > >>>> > >>>> Signed-off-by: Jan Beulich <[email protected]> > >>>> > >>>> [1] > >>>> https://sourceware.org/git?p=binutils-gdb.git;a=commitdiff;h=7992631e8c0b0e711fbaba991348ef6f6e583725 > >>>> [2] > >>>> https://sourceware.org/git?p=binutils-gdb.git;a=commitdiff;h=2ee1792bec225ea19c71095cee5a3a9ae6df7c59 > >>>> [3] > >>>> https://sourceware.org/git?p=binutils-gdb.git;a=commitdiff;h=6d1ace6861e999361b30d1bc27459ab8094e0d4a > >>>> --- > >>>> Using .file has the perhaps undesirable side effect of generating a fair > >>>> amount of (all identical) STT_FILE entries in the symbol table. We also > >>>> can't use the supposedly assembler-internal (and hence undocumented) > >>>> .appfile anymore, as it was removed [4]. Note that .linefile (also > >>>> internal/undocumented) as well as the "# <line> <file>" constructs the > >>>> compiler emits, leading to .linefile insertion by the assembler, aren't > >>>> of use anyway as these are processed and purged when processing .macro > >>>> [3]. > >>>> > >>>> [4] > >>>> https://sourceware.org/git?p=binutils-gdb.git;a=commitdiff;h=c39e89c3aaa3a6790f85e80f2da5022bc4bce38b > >>>> > >>>> --- a/xen/arch/x86/include/asm/spec_ctrl_asm.h > >>>> +++ b/xen/arch/x86/include/asm/spec_ctrl_asm.h > >>>> @@ -24,6 +24,8 @@ > >>>> #include <asm/msr-index.h> > >>>> #include <asm/spec_ctrl.h> > >>>> > >>>> +#define FILE_AND_LINE .file __FILE__; .line __LINE__ > >>> > >>> Seeing as this seems to get added to all macros below, I guess you did > >>> consider (and discarded) introducing a preprocessor macro do to the > >>> asm macro definitons: > >>> > >>> #define DECLARE_MACRO(n, ...) \ > >>> .macro n __VA_ARGS__ \ > >>> .file __FILE__; .line __LINE__ > >> > >> No, I didn't even consider that. I view such as too obfuscating - there's > >> then e.g. no visual match with the .endm. Furthermore, as outlined in the > >> description, I don't think this wants applying uniformly. There are > >> macros which better don't have this added. Yet I also would prefer to not > >> end up with a mix of .macro and DECLARE_MACRO(). > > > > I think it's a dummy question, but why would we want to add this to > > some macros? > > > > Isn't it better to always have the file and line reference where the > > macro gets used? > > Like said in the description, a macro simply invoking another macro, > or a macro simply wrapping a single insn, is likely better to have > its generated code associated with the original line number. Complex > macros, otoh, are imo often better to have line numbers associated > with actual macro contents. IOW to some degree I support the cited > workaround in binutils (which has been there for many years).
Seems a bit ad-hoc policy, but it's you and Andrew that mostly deal with this stuff, so if you are fine with it. Acked-by: roger Pau Monné <[email protected]> Thanks, Roger.
