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The CTF deduplicator was not considering enumerators inside enum types to be
things that caused type conflicts, so if the following two TUs were linked
together, you would end up with the following in the resulting dict:
1.c:
enum foo { A, B };
2.c:
enum bar { A, B };
linked:
enum foo { A, B };
enum bar { A, B };
This does work -- but it's not something that's valid C, and the general
point of the shared dict is that it is something that you could potentially
get from any valid C TU.
So consider such types to be conflicting, but obviously don't consider
actually identical enums to be conflicting, even though they too have (all)
their identifiers in common. This involves surprisingly little code. The
deduplicator detects conflicting types by counting types in a hash table of
hash tables:
decorated identifier -> (type hash -> count)
where the COUNT is the number of times a given hash has been observed: any
name with more than one hash associated with it is considered conflicting
(the count is used to identify the most common such name for promotion to
the shared dict).
Before now, those identifiers were all the identifiers of types (possibly
decorated with their namespace on the front for enumerator identifiers), but
we can equally well put *enumeration constant names* in there, undecorated
like the identifiers of types in the global namespace, with the type hash
being the hash of each enum containing that enumerator. The existing
conflicting-type-detection code will then accurately identify distinct enums
with enumeration constants in common. The enum that contains the most
commonly-appearing enumerators will be promoted to the shared dict.
libctf/
* ctf-impl.h (ctf_dedup_t) <cd_name_counts>: Extend comment.
* ctf-dedup.c (ctf_dedup_count_name): New, split out of...
(ctf_dedup_populate_mappings): ... here. Call it for all
* enumeration constants in an enum as well as types.
ld/
* testsuite/ld-ctf/enum-3.c: New test CTF.
* testsuite/ld-ctf/enum-4.c: Likewise.
* testsuite/ld-ctf/overlapping-enums.d: New test.
* testsuite/ld-ctf/overlapping-enums-2.d: Likewise.
README for LD
This is the GNU linker. It is distributed with other "binary
utilities" which should be in ../binutils. See ../binutils/README for
more general notes, including where to send bug reports.
There are many features of the linker:
* The linker uses a Binary File Descriptor library (../bfd)
that it uses to read and write object files. This helps
insulate the linker itself from the format of object files.
* The linker supports a number of different object file
formats. It can even handle multiple formats at once:
Read two input formats and write a third.
* The linker can be configured for cross-linking.
* The linker supports a control language.
* There is a user manual (ld.texi), as well as the
beginnings of an internals manual (ldint.texi).
Installation
============
See ../binutils/README.
If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.
To build just the linker, make the target all-ld from the top level
directory (one directory above this one).
Porting to a new target
=======================
See the ldint.texi manual.
Reporting bugs etc
===========================
See ../binutils/README.
Known problems
==============
The Solaris linker normally exports all dynamic symbols from an
executable. The GNU linker does not do this by default. This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets). This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl. You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.
HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly. The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages. There are various
workarounds to this:
* Build and install bash, and build with "make SHELL=bash".
* Update to a version of HP/UX with a working shell (e.g., 9.05).
* Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
emulparams script used exports any shell variables it sets.
Copyright (C) 2012-2024 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.