* expr.c (get_inner_reference): Use sbitsizetype for type sizes.

        * fold-const.c (size_int): Replace with
        (size_int_wide).
        (make_bit_field_ref): Use bitsize_int for bit position.
        * stor-layout.c (sizetype): Delete.
        (sizetype_tab, sbitsizetype, ubitsizetype): Declare.
        (layout_record, layout_union, layout_type):
        Use bitsize_int for bit size.
        (set_sizetype): New function.
        (make_signed_type, make_unsigned_type): Use it.
        * c-decl.c (init_decl_processing): Likewise.
        * tree.h (size_int): Don't delcare, #define.
        (size_int_wide, sizetype_tab, sbitsize, ubitsize): Declare.
        (set_sizetype): Declare.
        (bitsize_int, size_int_2, BITS_PER_UNIT_LOG, sizetype, bitsizetype):
        Define.
        * c-typeck.c (c_sizeof, c_sizeof_nowarn, c_size_in_bytes):
        Convert result to sizetype.
        (really_start_incremental_init, push_init_level):
        Set type of constructor_bit_index to sbitsizetype.
        (push_init_level): Use unsigned arithmetic to determine padding.
        (output_init_element): Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@17577 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 32 insertions, 0 deletions

diff --git a/gcc/LANGUAGES b/gcc/LANGUAGES
new file mode 100644
index 00000000000..31bae9fd477
--- /dev/null
+++ b/gcc/LANGUAGES
@@ -0,0 +1,32 @@
+Right now there is no documentation for the GCC tree -> rtl interfaces
+(or more generally the interfaces for adding new languages).
+
+Such documentation would be of great benefit to the project.  Until such
+time as we can formally start documenting the interface this file will
+serve as a repository for information on these interface and any incompatable
+changes we've made.
+
+
+Feb 1, 1998:
+
+  GCC used to store structure sizes & offsets to elements as bitsize
+  quantities.  This causes problems because a structure can only be
+  (target memsize / 8) bytes long (this may effect arrays too).  This
+  is particularly problematical on machines with small address spaces.
+
+  So:
+
+    All trees that represent sizes in bits should have a TREE_TYPE of
+    bitsizetype (rather than sizetype).
+
+    Accordingly, when such values are computed / initialized, care has to
+    be takes to use / compute the proper type.
+
+    When a size in bits is converted into a size in bytes, which is expressed
+    in trees, care should be taken to change the tree's type again to sizetype.
+
+    We've updated C, C++, Fortran & Objective-C to work with the new
+    scheme.  Other languages will need to be updated accordingly.
+    Contact amylaar@cygnus.com for additional information.
+
+