[PATCH] Add SVE to NEWS and GDB manual

[PATCH] Add SVE to NEWS and GDB manual

[Alan Hayward]

I wasn't sure whether the vector length limitation should
get added to these files - I couldn't find any other limitations
stated in these files. Happy to remove those parts / move elsewhere.

Also corrected vector gradient to vector granule, as per DWARF spec.

Ok for 8.2 branch too?


2018-08-21  Alan Hayward  <alan.hayward@arm.com>

gdb/
	* NEWS: Add SVE to 8.2 section.
	* doc/gdb.texinfo: Add SVE to AArch64 section.
	* arch/aarch64.h (aarch64_regnum): Update comment.
---
 gdb/NEWS            |  3 +++
 gdb/arch/aarch64.h  |  4 ++--
 gdb/doc/gdb.texinfo | 16 ++++++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 16d3d72589..3119d97d98 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -90,6 +90,9 @@ GNU/Linux/RISC-V		riscv*-*-linux*
 * C expressions can now use _Alignof, and C++ expressions can now use
   alignof.
 
+* Support for SVE on AArch64 Linux.  Note that in 8.2, GDB does not detect
+  changes to the vector length while the process is running.
+
 * New commands
 
 set debug fbsd-nat
diff --git a/gdb/arch/aarch64.h b/gdb/arch/aarch64.h
index e344a36770..d6b88e6d56 100644
--- a/gdb/arch/aarch64.h
+++ b/gdb/arch/aarch64.h
@@ -49,7 +49,7 @@ enum aarch64_regnum
   AARCH64_SVE_P15_REGNUM = AARCH64_SVE_P0_REGNUM + 15,	/* Last SVE predicate
 							   register.  */
   AARCH64_SVE_FFR_REGNUM,	/* SVE First Fault Register.  */
-  AARCH64_SVE_VG_REGNUM,	/* SVE Vector Gradient.  */
+  AARCH64_SVE_VG_REGNUM,	/* SVE Vector Granule.  */
 
   /* Other useful registers.  */
   AARCH64_LAST_X_ARG_REGNUM = AARCH64_X0_REGNUM + 7,
@@ -71,7 +71,7 @@ enum aarch64_regnum
 	The number of bytes in an SVE Z register.
    VQ : Vector Quotient.
 	The number of 128bit chunks in an SVE Z register.
-   VG : Vector Gradient.
+   VG : Vector Granule.
 	The number of 64bit chunks in an SVE Z register.  */
 
 #define sve_vg_from_vl(vl)	((vl) / 8)
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 433a2698a9..4526a385d0 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -23451,6 +23451,22 @@ Show whether AArch64 debugging messages are displayed.
 
 @end table
 
+@subsubsection AArch64 SVE.
+@cindex AArch64 SVE.
+
+When GDB is debugging the AArch64 architecture, if the Scalable Vector
+Extension (SVE) is present then GDB will provide the vector registers
+@code{$z0} through @code{$z31}, vector predicate registers @code{$p0} through
+@code{$p15}, and the @code{$ffr} register.  In addition the pseduo register
+@code{$vg} will be provided.  This is the vector granule for the current thread
+and represents the number of 64-bit chunks in a SVE Z register.
+
+If the vector length changes, then the @code{$vg} register will be updated,
+but the lengths of the @code{z} and @code{p} registers will not change.  This
+is a known limitation of GDB and does not affect the execution of the target
+process.
+
+
 @node i386
 @subsection x86 Architecture-specific Issues
 
-- 
2.15.2 (Apple Git-101.1)

Re: [PATCH] Add SVE to NEWS and GDB manual

[Pedro Alves]

On 08/21/2018 01:53 PM, Alan Hayward wrote:
> I wasn't sure whether the vector length limitation should
> get added to these files - I couldn't find any other limitations
> stated in these files. Happy to remove those parts / move elsewhere.
> 


> Also corrected vector gradient to vector granule, as per DWARF spec.

That seems unrelated, best to apply as a separate patch, I'd think.

> 
> Ok for 8.2 branch too?
> 
> 
> 2018-08-21  Alan Hayward  <alan.hayward@arm.com>
> 
> gdb/
> 	* NEWS: Add SVE to 8.2 section.
> 	* doc/gdb.texinfo: Add SVE to AArch64 section.
> 	* arch/aarch64.h (aarch64_regnum): Update comment.
> ---
>  gdb/NEWS            |  3 +++
>  gdb/arch/aarch64.h  |  4 ++--
>  gdb/doc/gdb.texinfo | 16 ++++++++++++++++
>  3 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 16d3d72589..3119d97d98 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -90,6 +90,9 @@ GNU/Linux/RISC-V		riscv*-*-linux*
>  * C expressions can now use _Alignof, and C++ expressions can now use
>    alignof.
>  
> +* Support for SVE on AArch64 Linux.  Note that in 8.2, GDB does not detect
> +  changes to the vector length while the process is running.

I assume this is the "new in 8.2" section, so is there a reason you're saying
"note that in 8.2" instead of "note that" ??  It seems redundant.
If it isn't redundant, and you mean to say that master (8.3) will
behave differently, then such behavior should instead get its own
news entry in 8.3.

> +
>  * New commands
>  
>  set debug fbsd-nat
> diff --git a/gdb/arch/aarch64.h b/gdb/arch/aarch64.h
> index e344a36770..d6b88e6d56 100644
> --- a/gdb/arch/aarch64.h
> +++ b/gdb/arch/aarch64.h
> @@ -49,7 +49,7 @@ enum aarch64_regnum
>    AARCH64_SVE_P15_REGNUM = AARCH64_SVE_P0_REGNUM + 15,	/* Last SVE predicate
>  							   register.  */
>    AARCH64_SVE_FFR_REGNUM,	/* SVE First Fault Register.  */
> -  AARCH64_SVE_VG_REGNUM,	/* SVE Vector Gradient.  */
> +  AARCH64_SVE_VG_REGNUM,	/* SVE Vector Granule.  */
>  
>    /* Other useful registers.  */
>    AARCH64_LAST_X_ARG_REGNUM = AARCH64_X0_REGNUM + 7,
> @@ -71,7 +71,7 @@ enum aarch64_regnum
>  	The number of bytes in an SVE Z register.
>     VQ : Vector Quotient.
>  	The number of 128bit chunks in an SVE Z register.
> -   VG : Vector Gradient.
> +   VG : Vector Granule.
>  	The number of 64bit chunks in an SVE Z register.  */
>  
>  #define sve_vg_from_vl(vl)	((vl) / 8)
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 433a2698a9..4526a385d0 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -23451,6 +23451,22 @@ Show whether AArch64 debugging messages are displayed.
>  
>  @end table
>  
> +@subsubsection AArch64 SVE.
> +@cindex AArch64 SVE.
> +
> +When GDB is debugging the AArch64 architecture, if the Scalable Vector

Throughout, you should use @value{GDBN} instead of "GDB".

> +Extension (SVE) is present then GDB will provide the vector registers
> +@code{$z0} through @code{$z31}, vector predicate registers @code{$p0} through
> +@code{$p15}, and the @code{$ffr} register.  In addition the pseduo register

Typo: "pseduo" -> "pseudo".

> +@code{$vg} will be provided.  This is the vector granule for the current thread
> +and represents the number of 64-bit chunks in a SVE Z register.

Should that be "an SVE" (as in, "an ess, vee, eee") ?  Or is SVE usually read
as "a ssssveeee"?

> +
> +If the vector length changes, then the @code{$vg} register will be updated,
> +but the lengths of the @code{z} and @code{p} registers will not change.  This
> +is a known limitation of GDB and does not affect the execution of the target
> +process.

Is the documentation for the "org.gnu.gdb.aarch64.sve" XML tdesc feature in the
branch already?

> +
> +
>  @node i386
>  @subsection x86 Architecture-specific Issues
>  
> 

Thanks,
Pedro Alves

Re: [PATCH] Add SVE to NEWS and GDB manual

[Alan Hayward]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 6333 bytes --]

Thanks for the review.

> On 21 Aug 2018, at 15:36, Pedro Alves <palves@redhat.com> wrote:
> 
> On 08/21/2018 01:53 PM, Alan Hayward wrote:
>> I wasn't sure whether the vector length limitation should
>> get added to these files - I couldn't find any other limitations
>> stated in these files. Happy to remove those parts / move elsewhere.
>> 
> 
> 
>> Also corrected vector gradient to vector granule, as per DWARF spec.
> 
> That seems unrelated, best to apply as a separate patch, I'd think.

Ok, I’ll post and push that as it’s own OBV patch.

> 
>> 
>> Ok for 8.2 branch too?
>> 
>> 
>> 2018-08-21  Alan Hayward  <alan.hayward@arm.com>
>> 
>> gdb/
>> 	* NEWS: Add SVE to 8.2 section.
>> 	* doc/gdb.texinfo: Add SVE to AArch64 section.
>> 	* arch/aarch64.h (aarch64_regnum): Update comment.
>> ---
>> gdb/NEWS            |  3 +++
>> gdb/arch/aarch64.h  |  4 ++--
>> gdb/doc/gdb.texinfo | 16 ++++++++++++++++
>> 3 files changed, 21 insertions(+), 2 deletions(-)
>> 
>> diff --git a/gdb/NEWS b/gdb/NEWS
>> index 16d3d72589..3119d97d98 100644
>> --- a/gdb/NEWS
>> +++ b/gdb/NEWS
>> @@ -90,6 +90,9 @@ GNU/Linux/RISC-V		riscv*-*-linux*
>> * C expressions can now use _Alignof, and C++ expressions can now use
>>   alignof.
>> 
>> +* Support for SVE on AArch64 Linux.  Note that in 8.2, GDB does not detect
>> +  changes to the vector length while the process is running.
> 
> I assume this is the "new in 8.2" section, so is there a reason you're saying
> "note that in 8.2" instead of "note that" ??  It seems redundant.
> If it isn't redundant, and you mean to say that master (8.3) will
> behave differently, then such behavior should instead get its own
> news entry in 8.3.
> 

My worry was that for 8.3 and onwards, anyone quickly reading the NEWS file
might miss the entry 8.3 saying it now works. But, agree with your comment.
Removed the redundancy.


>> +
>> * New commands
>> 
>> set debug fbsd-nat
>> diff --git a/gdb/arch/aarch64.h b/gdb/arch/aarch64.h
>> index e344a36770..d6b88e6d56 100644
>> --- a/gdb/arch/aarch64.h
>> +++ b/gdb/arch/aarch64.h
>> @@ -49,7 +49,7 @@ enum aarch64_regnum
>>   AARCH64_SVE_P15_REGNUM = AARCH64_SVE_P0_REGNUM + 15,	/* Last SVE predicate
>> 							   register.  */
>>   AARCH64_SVE_FFR_REGNUM,	/* SVE First Fault Register.  */
>> -  AARCH64_SVE_VG_REGNUM,	/* SVE Vector Gradient.  */
>> +  AARCH64_SVE_VG_REGNUM,	/* SVE Vector Granule.  */
>> 
>>   /* Other useful registers.  */
>>   AARCH64_LAST_X_ARG_REGNUM = AARCH64_X0_REGNUM + 7,
>> @@ -71,7 +71,7 @@ enum aarch64_regnum
>> 	The number of bytes in an SVE Z register.
>>    VQ : Vector Quotient.
>> 	The number of 128bit chunks in an SVE Z register.
>> -   VG : Vector Gradient.
>> +   VG : Vector Granule.
>> 	The number of 64bit chunks in an SVE Z register.  */
>> 
>> #define sve_vg_from_vl(vl)	((vl) / 8)
>> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
>> index 433a2698a9..4526a385d0 100644
>> --- a/gdb/doc/gdb.texinfo
>> +++ b/gdb/doc/gdb.texinfo
>> @@ -23451,6 +23451,22 @@ Show whether AArch64 debugging messages are displayed.
>> 
>> @end table
>> 
>> +@subsubsection AArch64 SVE.
>> +@cindex AArch64 SVE.
>> +
>> +When GDB is debugging the AArch64 architecture, if the Scalable Vector
> 
> Throughout, you should use @value{GDBN} instead of "GDB”.

Done.

> 
>> +Extension (SVE) is present then GDB will provide the vector registers
>> +@code{$z0} through @code{$z31}, vector predicate registers @code{$p0} through
>> +@code{$p15}, and the @code{$ffr} register.  In addition the pseduo register
> 
> Typo: "pseduo" -> "pseudo”.

Oops. Done.

> 
>> +@code{$vg} will be provided.  This is the vector granule for the current thread
>> +and represents the number of 64-bit chunks in a SVE Z register.
> 
> Should that be "an SVE" (as in, "an ess, vee, eee") ?  Or is SVE usually read
> as "a ssssveeee”?

Had a quick chat with our documentation team. Updated to “an”.

> 
>> +
>> +If the vector length changes, then the @code{$vg} register will be updated,
>> +but the lengths of the @code{z} and @code{p} registers will not change. This
>> +is a known limitation of GDB and does not affect the execution of the target
>> +process.
> 
> Is the documentation for the "org.gnu.gdb.aarch64.sve" XML tdesc feature in the
> branch already?
> 

Yes, added as part of the SVE target description patch.


Updated version below.
This version ok?



2018-08-21  Alan Hayward  <alan.hayward@arm.com>

gdb/
	* NEWS: Add SVE to 8.2 section.
	* doc/gdb.texinfo: Add SVE to AArch64 section.



diff --git a/gdb/NEWS b/gdb/NEWS
index 16d3d725897c8c06124709c0203be5d24c85f72b..bd03d72e9afb2b5413b5a322754fc352ee7c34dc 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -90,6 +90,9 @@ GNU/Linux/RISC-V		riscv*-*-linux*
 * C expressions can now use _Alignof, and C++ expressions can now use
   alignof.

+* Support for SVE on AArch64 Linux.  Note that GDB does not detect changes to
+  the vector length while the process is running.
+
 * New commands

 set debug fbsd-nat
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 433a2698a9264b352e560259f6157dc98a6777e3..e58d67283b341de9866ed1605f3285bf7c81ce78 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -23451,6 +23451,22 @@ Show whether AArch64 debugging messages are displayed.

 @end table

+@subsubsection AArch64 SVE.
+@cindex AArch64 SVE.
+
+When @value{GDBN} is debugging the AArch64 architecture, if the Scalable Vector
+Extension (SVE) is present then @value{GDBN} will provide the vector registers
+@code{$z0} through @code{$z31}, vector predicate registers @code{$p0} through
+@code{$p15}, and the @code{$ffr} register.  In addition the pseudo register
+@code{$vg} will be provided.  This is the vector granule for the current thread
+and represents the number of 64-bit chunks in an SVE @code{z} register.
+
+If the vector length changes, then the @code{$vg} register will be updated,
+but the lengths of the @code{z} and @code{p} registers will not change.  This
+is a known limitation of @value{GDBN} and does not affect the execution of the
+target process.
+
+
 @node i386
 @subsection x86 Architecture-specific Issues


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Re: [PATCH] Add SVE to NEWS and GDB manual

[Eli Zaretskii]

> From: Alan Hayward <Alan.Hayward@arm.com>
> CC: GDB Patches <gdb-patches@sourceware.org>, nd <nd@arm.com>
> Date: Tue, 21 Aug 2018 17:29:18 +0000
> 
> Updated version below.
> This version ok?
> 
> 
> 
> 2018-08-21  Alan Hayward  <alan.hayward@arm.com>
> 
> gdb/
> 	* NEWS: Add SVE to 8.2 section.
> 	* doc/gdb.texinfo: Add SVE to AArch64 section.

The gdb.texinfo entry should mention the node in which the changes are
made, as if it were a function.

> +When @value{GDBN} is debugging the AArch64 architecture, if the Scalable Vector
> +Extension (SVE) is present then @value{GDBN} will provide the vector registers
                             ^
Comma missing there.

> +@code{$z0} through @code{$z31}, vector predicate registers @code{$p0} through
> +@code{$p15}, and the @code{$ffr} register.  In addition the pseudo register
                                                          ^
And another.

OK with those gotchas fixed.

Thanks.