md.texi: Document the mnemonic attribute.

2013-10-10  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>

	* doc/md.texi: Document the mnemonic attribute.

From-SVN: r203354

2 files changed, 62 insertions, 9 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fdf0f2c..87ba2a2 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2013-10-10  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>
 
+	* doc/md.texi: Document the mnemonic attribute.
+
+2013-10-10  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>
+
 	PR target/57377
 	* gensupport.c (gen_mnemonic_attr): Handle (set (attr x) y) and
 	(set_attr_alternative x ...) when searching for user defined
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index c07663b..2a5a2e1 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -7698,6 +7698,7 @@ to track the condition codes.
 * Attr Example::        An example of assigning attributes.
 * Insn Lengths::        Computing the length of insns.
 * Constant Attributes:: Defining attributes that are constant.
+* Mnemonic Attribute::  Obtain the instruction mnemonic as attribute value.
 * Delay Slots::         Defining delay slots required for a machine.
 * Processor pipeline description:: Specifying information for insn scheduling.
 @end menu
@@ -7717,15 +7718,17 @@ by the target machine.  It looks like:
 (define_attr @var{name} @var{list-of-values} @var{default})
 @end smallexample
 
-@var{name} is a string specifying the name of the attribute being defined.
-Some attributes are used in a special way by the rest of the compiler. The
-@code{enabled} attribute can be used to conditionally enable or disable
-insn alternatives (@pxref{Disable Insn Alternatives}). The @code{predicable}
-attribute, together with a suitable @code{define_cond_exec}
-(@pxref{Conditional Execution}), can be used to automatically generate
-conditional variants of instruction patterns. The compiler internally uses
-the names @code{ce_enabled} and @code{nonce_enabled}, so they should not be
-used elsewhere as alternative names.
+@var{name} is a string specifying the name of the attribute being
+defined.  Some attributes are used in a special way by the rest of the
+compiler. The @code{enabled} attribute can be used to conditionally
+enable or disable insn alternatives (@pxref{Disable Insn
+Alternatives}). The @code{predicable} attribute, together with a
+suitable @code{define_cond_exec} (@pxref{Conditional Execution}), can
+be used to automatically generate conditional variants of instruction
+patterns. The @code{mnemonic} attribute can be used to check for the
+instruction mnemonic (@pxref{Mnemonic Attribute}).  The compiler
+internally uses the names @code{ce_enabled} and @code{nonce_enabled},
+so they should not be used elsewhere as alternative names.
 
 @var{list-of-values} is either a string that specifies a comma-separated
 list of values that can be assigned to the attribute, or a null string to
@@ -7789,6 +7792,11 @@ distances. @xref{Insn Lengths}.
 The @code{enabled} attribute can be defined to prevent certain
 alternatives of an insn definition from being used during code
 generation. @xref{Disable Insn Alternatives}.
+
+@item mnemonic
+The @code{mnemonic} attribute can be defined to implement instruction
+specific checks in e.g. the pipeline description.
+@xref{Mnemonic Attribute}.
 @end table
 
 For each of these special attributes, the corresponding
@@ -8341,6 +8349,47 @@ forms involving insn attributes.
 
 @end ifset
 @ifset INTERNALS
+@node Mnemonic Attribute
+@subsection Mnemonic Attribute
+@cindex mnemonic attribute
+
+The @code{mnemonic} attribute is a string type attribute holding the
+instruction mnemonic for an insn alternative.  The attribute values
+will automatically be generated by the machine description parser if
+there is an attribute definition in the md file:
+
+@smallexample
+(define_attr "mnemonic" "unknown" (const_string "unknown"))
+@end smallexample
+
+The default value can be freely chosen as long as it does not collide
+with any of the instruction mnemonics.  This value will be used
+whenever the machine description parser is not able to determine the
+mnemonic string.  This might be the case for output templates
+containing more than a single instruction as in
+@code{"mvcle\t%0,%1,0\;jo\t.-4"}.
+
+The @code{mnemonic} attribute set is not generated automatically if the
+instruction string is generated via C code.
+
+An existing @code{mnemonic} attribute set in an insn definition will not
+be overriden by the md file parser.  That way it is possible to
+manually set the instruction mnemonics for the cases where the md file
+parser fails to determine it automatically.
+
+The @code{mnemonic} attribute is useful for dealing with instruction
+specific properties in the pipeline description without defining
+additional insn attributes.
+
+@smallexample
+(define_attr "ooo_expanded" ""
+  (cond [(eq_attr "mnemonic" "dlr,dsgr,d,dsgf,stam,dsgfr,dlgr")
+         (const_int 1)]
+        (const_int 0)))
+@end smallexample
+
+@end ifset
+@ifset INTERNALS
 @node Delay Slots
 @subsection Delay Slot Scheduling
 @cindex delay slots, defining