65 lines
2.2 KiB
Plaintext
65 lines
2.2 KiB
Plaintext
Right now there is no documentation for the GCC tree -> rtl interfaces
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(or more generally the interfaces for adding new languages).
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Such documentation would be of great benefit to the project. Until such
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time as we can formally start documenting the interface this file will
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serve as a repository for information on these interface and any incompatible
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changes we've made.
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2004-09-09:
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In an effort to decrease execution time, single char tree code
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classes were changed to enumerated values.
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Old way:
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DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", 'd', 0)
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New way:
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DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", tcc_declaration, 0)
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2001-02-26:
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A DECL_INITIAL of NULL_TREE or error_mark_node in a VAR_DECL is no longer
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taken to signify a tentative definition which should not be emitted until
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end-of-file. Frontends which want that behavior should set
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DECL_DEFER_OUTPUT before calling rest_of_decl_compilation.
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Feb 1, 1998:
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GCC used to store structure sizes & offsets to elements as bitsize
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quantities. This causes problems because a structure can only be
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(target memsize / 8) bytes long (this may effect arrays too). This
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is particularly problematical on machines with small address spaces.
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So:
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All trees that represent sizes in bits should have a TREE_TYPE of
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bitsizetype (rather than sizetype).
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Accordingly, when such values are computed / initialized, care has to
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be takes to use / compute the proper type.
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When a size in bits is converted into a size in bytes, which is expressed
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in trees, care should be taken to change the tree's type again to sizetype.
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?? 1997:
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In an effort to decrease cache thrashing and useless loads we've changed the
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third argument to the DEFTREECODE macro to be a single char. This will
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affect languages that defined their own tree codes (usually in a .def file).
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Old way:
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DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", "d", 0)
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New way:
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DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", 'd', 0)
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Copyright (C) 1998-2017 Free Software Foundation, Inc.
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Copying and distribution of this file, with or without modification,
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are permitted in any medium without royalty provided the copyright
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notice and this notice are preserved.
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