[PATCH] Add SVE to NEWS and GDB manual

[Alan Hayward <alan.hayward@arm.com>]

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
 
-- 
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