[AArch64 Doc] Clarify feature modifiers {no,}{fp,simd,crypto}

gcc:

	* doc/invoke.texi: Clarify AArch64 feature modifiers (no)fp, (no)simd
	and (no)crypto.

From-SVN: r224909

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index dc609a91f31b62abc4cfe8d100209cf5ea7c569b..bf4f27c3d519216de397050f97d5aaa1ed90d820 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2015-06-24  Alan Lawrence  <alan.lawrence@arm.com>
+
+       * doc/invoke.texi: Clarify AArch64 feature modifiers (no)fp, (no)simd
+       and (no)crypto.
+
 2015-06-24  Alan Lawrence  <alan.lawrence@arm.com>
 
        * config/aarch64/aarch64-protos.h (aarch64_err_no_fpadvsimd): New.

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index b99ab1ce6b61e9f5f445259f93cd0f33c097e3ae..053dd5dc2cf5115f39d36ee356f51ab962024a4e 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -12359,7 +12359,10 @@ Generate big-endian code.  This is the default when GCC is configured for an
 
 @item -mgeneral-regs-only
 @opindex mgeneral-regs-only
-Generate code which uses only the general registers.
+Generate code which uses only the general-purpose registers.  This is equivalent
+to feature modifier @option{nofp} of @option{-march} or @option{-mcpu}, except
+that @option{-mgeneral-regs-only} takes precedence over any conflicting feature
+modifier regardless of sequence.
 
 @item -mlittle-endian
 @opindex mlittle-endian
@@ -12498,20 +12501,22 @@ over the appropriate part of this option.
 @subsubsection @option{-march} and @option{-mcpu} Feature Modifiers
 @cindex @option{-march} feature modifiers
 @cindex @option{-mcpu} feature modifiers
-Feature modifiers used with @option{-march} and @option{-mcpu} can be one
-the following:
+Feature modifiers used with @option{-march} and @option{-mcpu} can be any of
+the following and their inverses @option{no@var{feature}}:
 
 @table @samp
 @item crc
 Enable CRC extension.
 @item crypto
-Enable Crypto extension.  This implies Advanced SIMD is enabled.
+Enable Crypto extension.  This also enables Advanced SIMD and floating-point
+instructions.
 @item fp
-Enable floating-point instructions.
+Enable floating-point instructions.  This is on by default for all possible
+values for options @option{-march} and @option{-mcpu}.
 @item simd
-Enable Advanced SIMD instructions.  This implies floating-point instructions
-are enabled.  This is the default for all current possible values for options
-@option{-march} and @option{-mcpu=}.
+Enable Advanced SIMD instructions.  This also enables floating-point
+instructions.  This is on by default for all possible values for options
+@option{-march} and @option{-mcpu}.
 @item lse
 Enable Large System Extension instructions.
 @item pan
@@ -12522,6 +12527,10 @@ Enable Limited Ordering Regions support.
 Enable ARMv8.1 Advanced SIMD instructions.
 @end table
 
+That is, @option{crypto} implies @option{simd} implies @option{fp}.
+Conversely, @option{nofp} (or equivalently, @option{-mgeneral-regs-only})
+implies @option{nosimd} implies @option{nocrypto}.
+
 @node Adapteva Epiphany Options
 @subsection Adapteva Epiphany Options