* rtl.def (POST_MODIFY, PRE_MODIFY): New generalized operators for

  	addressing modes with side effects.  These are currently
  	placeholders for the C4x target.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@23228 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f1e6985..23b3802 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+Fri Oct 23 11:11:56 1998  Michael Hayes  <m.hayes@elec.canterbury.ac.nz>
+
+       * rtl.def (POST_MODIFY, PRE_MODIFY): New generalized operators for
+       addressing modes with side effects.  These are currently
+       placeholders for the C4x target.
+
 Thu Oct 22 16:46:35 1998  Bernd Schmidt <crux@pool.informatik.rwth-aachen.de>
 
        * loop.c (express_from): Make sure that when generating a PLUS of

diff --git a/gcc/rtl.def b/gcc/rtl.def
index 85a91e8..5273fdf 100644 (file)
--- a/gcc/rtl.def
+++ b/gcc/rtl.def
@@ -723,6 +723,14 @@ DEF_RTL_EXPR(PRE_INC, "pre_inc", "e", 'x')
 DEF_RTL_EXPR(POST_DEC, "post_dec", "e", 'x')
 DEF_RTL_EXPR(POST_INC, "post_inc", "e", 'x')
 
+/* These binary operations are used to represent generic address
+   side-effects in memory addresses, except for simple incrementation
+   or decrementation which use the above operations.  They are
+   created automatically by the life_analysis pass in flow.c. 
+   (Note that these operators are currently placeholders.)  */
+DEF_RTL_EXPR(PRE_MODIFY, "pre_modify", "ee", 'x')
+DEF_RTL_EXPR(POST_MODIFY, "post_modify", "ee", 'x')
+
 /* Comparison operations.  The ordered comparisons exist in two
    flavors, signed and unsigned.  */
 DEF_RTL_EXPR(NE, "ne", "ee", '<')

diff --git a/gcc/rtl.texi b/gcc/rtl.texi
index 61aeb85..2e8e69a 100644 (file)
--- a/gcc/rtl.texi
+++ b/gcc/rtl.texi
@@ -2036,7 +2036,7 @@ and of @var{min} and @var{max} to @var{base}.  See rtl.def for details.@refill
 @cindex RTL predecrement
 @cindex RTL postdecrement
 
-Four special side-effect expression codes appear as memory addresses.
+Six special side-effect expression codes appear as memory addresses.
 
 @table @code
 @findex pre_dec
@@ -2071,6 +2071,38 @@ being decremented.
 @findex post_inc
 @item (post_inc:@var{m} @var{x})
 Similar, but specifies incrementing @var{x} instead of decrementing it.
+
+@findex post_modify
+@item (post_modify:@var{m} @var{x} @var{y})
+
+Represents the side effect of setting @var{x} to @var{y} and
+represents @var{x} before @var{x} is modified.  @var{x} must be a
+@code{reg} or @code{mem}, but most machines allow only a @code{reg}.
+@var{m} must be the machine mode for pointers on the machine in use.
+The amount @var{x} is decremented by is the length in bytes of the
+machine mode of the containing memory reference of which this expression
+serves as the address.  Note that this is not currently implemented.
+
+The expression @var{y} must be one of three forms:
+@table @code
+@code{(plus:@var{m} @var{x} @var{z})},
+@code{(minus:@var{m} @var{x} @var{z})}, or
+@code{(plus:@var{m} @var{x} @var{i})},
+@end table
+where @var{z} is an index register and @var{i} is a constant.
+
+Here is an example of its use:@refill
+
+@example
+(mem:SF (post_modify:SI (reg:SI 42) (plus (reg:SI 42) (reg:SI 48))))
+@end example
+
+This says to modify pseudo register 42 by adding the contents of pseudo
+register 48 to it, after the use of what ever 42 points to.
+
+@findex post_modify
+@item (pre_modify:@var{m} @var{x} @var{expr})
+Similar except side effects happen before the use.
 @end table
 
 These embedded side effect expressions must be used with care.  Instruction