33 lines
1.2 KiB
Plaintext
33 lines
1.2 KiB
Plaintext
|
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.
|
||
|
|
|
||
|
|
|