From: Mark Kettenis <mark.kettenis@xs4all.nl>
To: hjl.tools@gmail.com
Cc: gdb-patches@sourceware.org
Subject: Re: PATCH: 3/6 [2nd try]: Add AVX support (i386 changes)
Date: Sun, 28 Mar 2010 11:55:00 -0000 [thread overview]
Message-ID: <201003281155.o2SBtYEk029587@glazunov.sibelius.xs4all.nl> (raw)
In-Reply-To: <6dc9ffc81003271837l761ac147t7ba88988cb99fcb0@mail.gmail.com> (hjl.tools@gmail.com)
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> Date: Sat, 27 Mar 2010 18:37:41 -0700
> From: "H.J. Lu" <hjl.tools@gmail.com>
>
> >> diff --git a/gdb/i386-linux-tdep.c b/gdb/i386-linux-tdep.c
> >> index b23c109..66ecf84 100644
> >> --- a/gdb/i386-linux-tdep.c
> >> +++ b/gdb/i386-linux-tdep.c
> >> +#include "i387-tdep.h"
> >> +#include "i386-xstate.h"
> >> +
> >> /* The syscall's XML filename for i386. */
> >> #define XML_SYSCALL_FILENAME_I386 "syscalls/i386-linux.xml"
> >>
> >> @@ -47,13 +50,15 @@
> >> #include <stdint.h>
> >>
> >> #include "features/i386/i386-linux.c"
> >> +#include "features/i386/i386-avx-linux.c"
> >>
> >> /* Supported register note sections. */
> >> -static struct core_regset_section i386_linux_regset_sections[] =
> >> +struct core_regset_section i386_linux_regset_sections[] =
> >
> > Why do you make this non-static?
>
> I need to change size of .reg-xstate section from i386-linux-nat.c.
But then, why do you have the i386_linux_update_xstateregs() function
if you still need to pass the array itself around?
Anyway, how about setting the size of the .reg-xstate to
I386_XSTATE_SSE_SIZE unconditionally? Tools will look at xcr0 value
encoded in there to determine what information in there is valid, so
dumping a little bit more than strictly necessary shouldn't be a
problem.
It would simplify things a bit. Less code is good!
> >> {
> >> { ".reg", 144, "general-purpose" },
> >> { ".reg2", 108, "floating-point" },
> >> { ".reg-xfp", 512, "extended floating-point" },
> >> + { ".reg-xstate", 0, "XSAVE extended state" },
> >> { NULL, 0 }
> >> };
> >> @@ -560,6 +566,66 @@ static int i386_linux_sc_reg_offset[] =
> >> 0 * 4 /* %gs */
> >> };
> >>
> >> +/* Update XSAVE extended state register note section. */
> >> +
> >> +void
> >> +i386_linux_update_xstateregset
> >> + (struct core_regset_section *regset_sections, unsigned int xstate_size)
> >> +{
> >> + int i;
> >> +
> >> + /* Update the XSAVE extended state register note section for "gcore".
> >> + Disable it if its size is 0. */
> >> + for (i = 0; regset_sections[i].sect_name != NULL; i++)
> >> + if (strcmp (regset_sections[i].sect_name, ".reg-xstate") == 0)
> >> + {
> >> + if (xstate_size)
> >> + regset_sections[i].size = xstate_size;
> >> + else
> >> + regset_sections[i].sect_name = NULL;
> >> + break;
> >> + }
> >> +}
> >
> > What will happen if you have a single GDB connected to two different
> > remote targets, one with AVX support and one without?
>
> The size of .reg-xstate section is used only for native gcore and
> won't be used for remote targets.
Ugh, yes you're right, gcore is a native-only feature.
> >> + /* Check extended state size. */
> >> + if (size < I386_XSTATE_AVX_SIZE)
> >> + xcr0 = I386_XSTATE_SSE_MASK;
> >> + else
> >> + {
> >> + char contents[8];
> >> +
> >> + if (! bfd_get_section_contents (abfd, xstate, contents,
> >> + (file_ptr) I386_LINUX_XSAVE_XCR0_OFFSET,
> >> + 8))
> >
> > Is that cast really necessary?
>
> I just follow the tradition. Most of bfd_get_section_contents calls have
> (file_ptr) cast. It may be used to avoid 32bit vs 64bit VMA warning.
Please don't use casts when they're not absolutely necessary; they
tend to hide bugs.
> >> diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
> >> index 05afa56..8ced34a 100644
> >> --- a/gdb/i386-tdep.c
> >> +++ b/gdb/i386-tdep.c
> >> @@ -2183,6 +2241,59 @@ i387_ext_type (struct gdbarch *gdbarch)
> >> return tdep->i387_ext_type;
> >> }
> >>
> >> +/* Construct vector type for pseudo XMM registers. We can't use
> >> + tdesc_find_type since XMM isn't described in target description. */
> >
> > I'm confused here. If you have a non-AVX target, why do you need a 256-bit vector type?
>
> i386_ymm_type is only called from
>
> else if (i386_ymm_regnum_p (gdbarch, regnum))
> return i386_ymm_type (gdbarch);
>
> It won't be called if you have a non-AVX target.
Sorry; that confuses me even more. Let me try to explain again what
puzzles me. The pseudo XMM registers are 128-bit, so why are you
building a 256-bit type? Is the problem simply that the comment is
wrong and you're talking about pseudo YMM registers here?
> >> @@ -5854,9 +6071,13 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
> >> set_tdesc_pseudo_register_type (gdbarch, i386_pseudo_register_type);
> >> set_tdesc_pseudo_register_name (gdbarch, i386_pseudo_register_name);
> >>
> >> - /* The default ABI includes general-purpose registers,
> >> - floating-point registers, and the SSE registers. */
> >> - set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS);
> >> + /* Override the normal target description method to make the AVX
> >> + upper halves anonymous. */
> >> + set_gdbarch_register_name (gdbarch, i386_register_name);
> >> +
> >> + /* The default ABI includes general-purpose registers, floating-point
> >> + registers, the SSE registers and the upper AVX registers. */
> >> + set_gdbarch_num_regs (gdbarch, I386_AVX_NUM_REGS);
> >
> > Isn't it better to leave the AVX registers out of the default target,
> > and only provide them if we're talking to a target (native or remote)
> > that indicates it supports them?
>
> That is set to a value higher enough to support AVX. The actual number
> of registers will be set properly later. See:
OK, then please adjust the comment to say something like:
/* Even though the default ABI only includes general-purpose registers,
floating-point registers and the SSE registers, we have to leave a
gap for the upper AVX registers. */
Thanks,
Mark
next prev parent reply other threads:[~2010-03-28 11:55 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-04 18:02 PATCH: 1/6: Add AVX support H.J. Lu
2010-03-04 18:05 ` PATCH: 2/6: Add AVX support (Update document) H.J. Lu
2010-03-04 18:06 ` PATCH: 3/6: Add AVX support (i386 changes) H.J. Lu
2010-03-06 22:21 ` PATCH: 3/6 [2nd try]: " H.J. Lu
2010-03-07 21:32 ` H.J. Lu
2010-03-11 22:37 ` Mark Kettenis
2010-03-12 0:00 ` H.J. Lu
2010-03-27 14:55 ` Mark Kettenis
2010-03-27 15:30 ` Daniel Jacobowitz
2010-03-27 16:05 ` Mark Kettenis
2010-03-27 15:33 ` H.J. Lu
2010-03-27 16:09 ` Mark Kettenis
2010-03-28 1:39 ` H.J. Lu
2010-03-12 16:49 ` H.J. Lu
2010-03-13 1:38 ` H.J. Lu
2010-03-29 1:11 ` PATCH: 3/6 [3rd " H.J. Lu
2010-04-02 14:31 ` H.J. Lu
2010-04-02 14:42 ` Mark Kettenis
2010-04-02 15:28 ` H.J. Lu
2010-04-07 10:13 ` Mark Kettenis
2010-04-07 14:56 ` H.J. Lu
2010-04-07 15:04 ` H.J. Lu
2010-04-07 15:19 ` Mark Kettenis
2010-04-07 16:55 ` H.J. Lu
2010-04-07 18:34 ` Mark Kettenis
2010-04-07 18:50 ` H.J. Lu
2010-03-27 15:48 ` PATCH: 3/6 [2nd " Mark Kettenis
2010-03-28 1:37 ` H.J. Lu
2010-03-28 11:55 ` Mark Kettenis [this message]
2010-03-28 14:25 ` H.J. Lu
2010-03-29 20:32 ` Mark Kettenis
2010-03-29 21:41 ` H.J. Lu
2010-03-04 18:08 ` PATCH: 4/6: Add AVX support (amd64 changes) H.J. Lu
2010-03-04 18:09 ` PATCH: 5/6: Add AVX support (i387 changes) H.J. Lu
2010-03-04 18:10 ` PATCH: 6/6: Add AVX support (gdbserver changes) H.J. Lu
2010-03-06 22:23 ` PATCH: 6/6 [2nd try]: " H.J. Lu
2010-03-12 17:25 ` H.J. Lu
2010-03-27 16:07 ` Daniel Jacobowitz
2010-03-28 1:11 ` H.J. Lu
2010-03-28 7:55 ` Pedro Alves
2010-03-28 14:56 ` H.J. Lu
2010-03-28 16:17 ` Pedro Alves
2010-03-28 16:37 ` H.J. Lu
2010-03-28 16:40 ` Daniel Jacobowitz
2010-03-28 16:47 ` Pedro Alves
2010-03-28 20:53 ` H.J. Lu
2010-03-28 21:27 ` Pedro Alves
2010-03-28 16:39 ` Daniel Jacobowitz
2010-03-28 19:31 ` H.J. Lu
2010-03-29 1:09 ` PATCH: 6/6 [3rd " H.J. Lu
2010-03-29 14:08 ` Eli Zaretskii
2010-03-29 14:42 ` H.J. Lu
2010-03-29 15:11 ` Eli Zaretskii
2010-03-29 15:42 ` H.J. Lu
2010-03-29 15:51 ` Eli Zaretskii
2010-03-30 16:48 ` H.J. Lu
2010-04-02 17:39 ` Daniel Jacobowitz
2010-04-07 4:37 ` H.J. Lu
2010-04-03 21:57 ` Jan Kratochvil
2010-04-07 4:12 ` H.J. Lu
2010-04-07 16:59 ` H.J. Lu
2010-03-05 3:20 ` PATCH: 5/6: Add AVX support (i387 changes) Hui Zhu
2010-03-05 3:54 ` H.J. Lu
2010-03-06 22:22 ` PATCH: 5/6 [2nd try]: " H.J. Lu
2010-03-12 17:24 ` H.J. Lu
2010-04-07 16:57 ` PATCH: 5/6 [3rd " H.J. Lu
2010-03-27 15:08 ` PATCH: 5/6 [2nd " Mark Kettenis
2010-03-27 15:15 ` H.J. Lu
2010-03-06 22:21 ` PATCH: 4/6 [2nd try]: Add AVX support (amd64 changes) H.J. Lu
2010-03-07 21:33 ` H.J. Lu
2010-03-12 17:01 ` H.J. Lu
2010-03-13 1:38 ` H.J. Lu
2010-03-29 1:07 ` PATCH: 4/6 [3rd " H.J. Lu
2010-04-02 14:32 ` H.J. Lu
2010-04-07 16:54 ` H.J. Lu
2010-03-05 10:33 ` PATCH: 2/6: Add AVX support (Update document) Eli Zaretskii
2010-03-05 14:08 ` H.J. Lu
2010-03-06 22:19 ` PATCH: 2/6 [2nd try]: " H.J. Lu
2010-03-12 11:11 ` Eli Zaretskii
2010-03-12 14:17 ` H.J. Lu
2010-03-12 15:28 ` Eli Zaretskii
2010-03-12 15:27 ` Eli Zaretskii
2010-03-12 16:46 ` H.J. Lu
2010-03-12 18:15 ` Eli Zaretskii
2010-03-29 0:18 ` PATCH: 2/6 [3rd " H.J. Lu
2010-03-30 16:41 ` H.J. Lu
2010-03-30 18:27 ` Eli Zaretskii
2010-03-30 18:37 ` H.J. Lu
2010-03-04 19:09 ` PATCH: 1/6: Add AVX support Daniel Jacobowitz
2010-03-04 19:29 ` H.J. Lu
2010-03-04 19:47 ` Daniel Jacobowitz
2010-03-04 21:27 ` H.J. Lu
2010-03-04 21:34 ` Nathan Froyd
2010-03-04 21:41 ` H.J. Lu
2010-03-04 21:59 ` Nathan Froyd
2010-03-04 21:47 ` Daniel Jacobowitz
2010-03-05 2:06 ` H.J. Lu
2010-03-05 7:29 ` Mark Kettenis
2010-03-06 22:16 ` PATCH: 0/6 [2nd try]: " H.J. Lu
2010-03-06 22:18 ` PATCH: 1/6 [2nd try]: Add AVX support (AVX XML files) H.J. Lu
2010-03-07 14:16 ` PATCH: 0/6 [2nd try]: Add AVX support Mark Kettenis
2010-03-07 14:37 ` H.J. Lu
2010-03-07 16:31 ` H.J. Lu
2010-03-07 16:40 ` H.J. Lu
2010-03-07 17:04 ` H.J. Lu
2010-03-07 17:39 ` H.J. Lu
2010-03-07 20:00 ` Mark Kettenis
2010-03-07 19:10 ` Nathan Froyd
2010-03-07 19:49 ` Mark Kettenis
2010-03-07 21:07 ` Nathan Froyd
2010-03-07 21:17 ` H.J. Lu
2010-03-07 20:29 ` Mark Kettenis
2010-03-07 21:04 ` H.J. Lu
2010-03-27 16:16 ` Daniel Jacobowitz
2010-03-29 0:16 ` PATCH: 0/6 [3nd " H.J. Lu
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