* genmodes.c: Include hashtab.h.

	(modes_by_name, hash_mode, eq_mode, struct mode_adjust)
	(adj_bytesize, adj_alignment, adj_format, new_adjust)
	(_ADD_ADJUST, ADJUST_BYTESIZE, ADJUST_ALIGNMENT, ADJUST_FORMAT)
	(print_maybe_const_decl, emit_mode_adjustments): New.
	(known_modes): Rename to modes.
	(find_mode): Kill class argument; look up in hash table.
	(new_mode): Insert into hash table also.
	(new_adjust): New.
	(reset_float_format, make_partial_integer_mode)
	(make_vector_mode): Tweak error reporting.
	(reset_float_format): Correct type of fourth argument.
	(emit_insn_modes_h): Add #defines to help make mode_size,
	mode_base_align, and real_format_for_mode conditionally const.
	(emit_mode_size, emit_mode_base_align): Use print_maybe_const_decl.
	(emit_real_format_for_mode): Likewise, but temporarily disabled.
	(emit_insn_modes_c): Call emit_mode_adjustments.
	(main): Initialize modes_by_name.
	* Makefile.in: Update dependencies.
	* machmode.def: Document EXPR arguments and new ADJUST_* statements.
	* machmode.h: Use CONST_MODE_SIZE and CONST_MODE_BASE_ALIGN in
	declarations of mode_size and mode_base_align.  Declare
	init_adjust_machine_modes.
	* toplev.c (backend_init): Call init_adjust_machine_modes.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@72534 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 18 insertions, 1 deletions

diff --git a/gcc/machmode.def b/gcc/machmode.def
index 72b1ec83644..0b762497d00 100644
--- a/gcc/machmode.def
+++ b/gcc/machmode.def
@@ -51,7 +51,13 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
    constant.
 
    A FORMAT argument must be one of the real_mode_format structures
-   declared in real.h, or else a literal 0.
+   declared in real.h, or else a literal 0.  Do not put a leading &
+   on the argument.
+
+   An EXPR argument must be a syntactically valid C expression.
+   If an EXPR contains commas, you may need to write an extra pair of
+   parentheses around it, so it appears to be a single argument to the
+   statement.
 
    This file defines only those modes which are of use on almost all
    machines.  Other modes can be defined in the target-specific
@@ -120,6 +126,17 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 	error if there is no 'F'.  For INT modes, the names are
 	derived by prefixing a C to the name.
 
+     ADJUST_BYTESIZE (MODE, EXPR);
+     ADJUST_ALIGNMENT (MODE, EXPR);
+     ADJUST_FLOAT_FORMAT (MODE, EXPR);
+        Arrange for the byte size, alignment, or floating point format
+	of MODE to be adjustable at run time.  EXPR will be executed
+	once after processing all command line options, and should
+	evaluate to the desired byte size, alignment, or format.
+
+	Unlike a FORMAT argument, if you are adjusting a float format
+	you must put an & in front of the name of each format structure.
+
    Note: If a mode is ever made which is more than 255 bytes wide,
    machmode.h and genmodes.c will have to be changed to allocate
    more space for the mode_size and mode_alignment arrays.  */