From: "Максим Корякшин via Tarantool-patches" <tarantool-patches@dev.tarantool.org> To: "Sergey Kaplun" <skaplun@tarantool.org> Cc: "Maxim Kokryashkin" <max.kokryashkin@gmail.com>, tarantool-patches@dev.tarantool.org Subject: Re: [Tarantool-patches] [PATCH luajit] luajit-gdb: support dualnum mode Date: Fri, 13 Aug 2021 17:29:27 +0300 [thread overview] Message-ID: <1628864967.181226130@f723.i.mail.ru> (raw) In-Reply-To: <YROJ6jRfGaiOZzD3@root> [-- Attachment #1: Type: text/plain, Size: 7147 bytes --] Hi, Sergey! Thanks for the comments, here is the new commit message: ======================================================= luajit-gdb: support dualnum mode luajit-gdb.py displays integers in LJ_DUALNUM mode as nan-s. The dumper function produces output thinking of any input value as of a double. However, in DUALNUM mode, integers and doubles are stored differently, so the `itype` of a float number must be less than `LJ_TISNUM`, and the `itype` of an integer must be `LJ_TISNUM`. With this fact in mind, we can easily differentiate one from another. Closes tarantool/tarantool#6224 ======================================================= And here is the diff: ======================================================= diff --git a/src/luajit-gdb.py b/src/luajit-gdb.py index 5f79c277..d4882dd7 100644 --- a/src/luajit-gdb.py +++ b/src/luajit-gdb.py @@ -238,8 +238,11 @@ def jit_state(g): 0x15: 'ERR', }.get(int(J(g)['state']), 'INVALID') +def tvisint(o): + return LJ_DUALNUM and itype(o) == LJ_TISNUM + def tvisnumber(o): - return itype(o) <= (0xfffeffff if LJ_64 and not LJ_GC64 else LJ_T['NUMX']) + return itype(o) <= LJ_TISNUM def tvislightud(o): if LJ_64 and not LJ_GC64: @@ -343,9 +346,8 @@ def dump_lj_tudata(tv): return 'userdata @ {}'.format(strx64(gcval(tv['gcr']))) def dump_lj_tnumx(tv): - if itype(tv) == (0xfffeffff if LJ_64 and not LJ_GC64 else LJ_T['NUMX']): - integer = cast('int32_t', cast('uint64_t', cast('void*', tv['n'])) & 0xFFFFFFFF) - return 'number {}'.format(integer) + if tvisint(tv): + return 'number {}'.format(cast('int32_t', tv['i'])) else: return 'number {}'.format(cast('double', tv['n'])) @@ -687,7 +689,7 @@ The command requires no args and dumps current GC stats: )) def init(commands): - global LJ_64, LJ_GC64, LJ_FR2, PADDING + global LJ_64, LJ_GC64, LJ_DUALNUM, LJ_TISNUM, LJ_FR2, PADDING # XXX Fragile: though connecting the callback looks like a crap but it # respects both Python 2 and Python 3 (see #4828). @@ -728,6 +730,7 @@ def init(commands): try: LJ_64 = str(gdb.parse_and_eval('IRT_PTR')) == 'IRT_P64' LJ_FR2 = LJ_GC64 = str(gdb.parse_and_eval('IRT_PGC')) == 'IRT_P64' + LJ_DUALNUM = lookup('lj_lib_checknumber') is not None except: gdb.write('luajit-gdb.py failed to load: ' 'no debugging symbols found for libluajit\n') @@ -737,6 +740,7 @@ def init(commands): command(name) PADDING = ' ' * len(':' + hex((1 << (47 if LJ_GC64 else 32)) - 1)) + LJ_TISNUM = 0xfffeffff if LJ_64 and not LJ_GC64 else LJ_T['NUMX'] gdb.write('luajit-gdb.py is successfully loaded\n') ======================================================= >Среда, 11 августа 2021, 11:28 +03:00 от Sergey Kaplun <skaplun@tarantool.org>: > >Hi, Maxim! > >Thanks for the patch! > >Please consider my comments below. > >Side note: First of all, I'm very disappointed, that there this patch >[1] isn't merged (in any form) into gdb. Those work with the expanding >of macros is very helpful... > >On 31.07.21, Maxim Kokryashkin wrote: >> For x86/x64 LJ_DUALNUM mode is disabled. But for some other arches > >Nit: It can be enabled by corresponding configuration options for >x86/x64, too, IINM. So I suggest to drop the first and the second >sentence. > >> (arm or arm64, for example) it is enabled by default. luajit-gdb.py >> displays integers in LJ_DUALNUM mode as nan-s. >> > >Nit: This paragraph may be joined to the next after suggesting changes. > >> As it turned out, luajit-gdb detects those integers as integers, but >> there was a problem with the dumper function itself. > >Nit: The next sentence is about the problem with the dumping function, so >I suggest to drop this opening sentence:) >Feel free to ignore. > >> The dumper >> function produces output thinking of any input value as of a double. >> However, in DUALNUM mode, integers and floats are stored differently, > >Typo: s/floats/doubles/ >Here and below. > >> so the `itype` of a float number must be less than `LJ_TISNUM`, and the >> `itype` of an integer must be `LJ_TISNUM`. With this fact in mind, we >> can easily differentiate one from another. >> >> But in any mode, lua numbers are stored as doubles on the C side, so it > >Typo: s/lua/Lua/ > >Do you mean LuaJIT here? Because this is not true for LuaJIT. See ><lj_obj.h> for details. > >> takes an ugly cast chain on the Python side to perform the some sort of >> the `reinterpret_cast` because the gdb module doesn't have any >> mechanism to get the address of a symbol. > >This sentence isn't clear to me. What symbol do you mean? > >> >> Closes tarantool/tarantool#6224 > >Side note: You can say that it really closes the issue, because we use >luajit-gdb from this fork. OTOH, maybe one uses it as a part of >third_party from Tarantool repo. >"Closes" is good to me, but I'm not sure what is idiomatically correct. > >> --- >> Github branch: https://github.com/tarantool/luajit/tree/fckxorg/gh-6224-support-dulanum >> Issue: https://github.com/tarantool/tarantool/issues/6224 >> For more info, see line 273 in lj_obj.h >> >> src/luajit-gdb.py | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/src/luajit-gdb.py b/src/luajit-gdb.py >> index c50405ad..5f79c277 100644 >> --- a/src/luajit-gdb.py >> +++ b/src/luajit-gdb.py >> @@ -343,7 +343,11 @@ def dump_lj_tudata(tv): >> return 'userdata @ {}'.format(strx64(gcval(tv['gcr']))) >> >> def dump_lj_tnumx(tv): >> - return 'number {}'.format(cast('double', tv['n'])) >> + if itype(tv) == (0xfffeffff if LJ_64 and not LJ_GC64 else LJ_T['NUMX']): > >This is true only in LJ_DUALNUM mode. So I suggest we can add another >one global constant for this: LJ_DUALNUM. We can set it via hack with >lookuping symbol `lj_lib_checknumber` -- it is compiled only for >LJ_DUALNUM mode for now. So, if a result of lookup() isn't None we are >in LJ_DUALNUM mode. > >Also, I suggest to create another global constant for LJ_TISNUM, like it >is done for PADDING constant. > >I suppose we want to do something similar to tvisint() macro for this check: >| LJ_DUALNUM && itype(tv) == LJ_TISNUM > >> + integer = cast('int32_t', cast('uint64_t', cast('void*', tv['n'])) & 0xFFFFFFFF) > >I don't get this cast to uint64_t and mask. Why can't we just take >`(int32_t)(o)->i` value, like it is done for `intV()` macro? > >> + return 'number {}'.format(integer) > >Nit: I suppose, it is better to highlight the fact that TValue stores >integer here with corresponding return. It may be helpful for debugging >some issues, related to storing type, I suppose. > >But I'm not so sure at this point. Wait for Igor's opinion. > >> + else: >> + return 'number {}'.format(cast('double', tv['n'])) >> >> def dump_lj_invalid(tv): >> return 'not valid type @ {}'.format(strx64(gcval(tv['gcr']))) >> -- >> 2.32.0 >> > >[1]: https://sourceware.org/legacy-ml/gdb-patches/2011-08/msg00441.html > >-- >Best regards, >Sergey Kaplun [-- Attachment #2: Type: text/html, Size: 8942 bytes --]
next prev parent reply other threads:[~2021-08-13 14:29 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-31 13:36 Maxim Kokryashkin via Tarantool-patches 2021-08-11 8:27 ` Sergey Kaplun via Tarantool-patches 2021-08-13 14:29 ` Максим Корякшин via Tarantool-patches [this message] 2021-08-14 11:38 ` [Tarantool-patches] [PATCH luajit v2] " Maxim Kokryashkin via Tarantool-patches 2021-08-14 13:36 ` Максим Корякшин via Tarantool-patches 2021-08-14 13:47 ` Sergey Kaplun via Tarantool-patches 2021-08-14 17:26 ` Максим Корякшин via Tarantool-patches 2021-08-17 7:56 ` Igor Munkin via Tarantool-patches 2021-08-16 8:49 ` Igor Munkin via Tarantool-patches 2021-08-16 10:01 ` Максим Корякшин via Tarantool-patches 2021-08-16 16:23 ` Vitaliia Ioffe via Tarantool-patches 2021-08-17 7:47 ` Igor Munkin via Tarantool-patches 2021-08-17 9:23 ` [Tarantool-patches] [PATCH luajit] " Igor Munkin via Tarantool-patches
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