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Darwin: Amend REAL_LIBGCC_SPEC comment [NFC].

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This comment had got out of sync with reality, partly due to merging
of patches.  Updated to reflect the current implementation.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

gcc/ChangeLog:

	* config/darwin.h (REAL_LIBGCC_SPEC): Update the comment block
	describing this macro.
This commit is contained in:
Iain Sandoe 2022-05-28 11:55:00 +01:00
parent 163fa9a648
commit 65aebf1987
1 changed files with 13 additions and 25 deletions
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38
gcc/config/darwin.h
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@ -465,48 +465,36 @@ extern GTY(()) int darwin_ms_struct;
#define LIB_SPEC "%{!static:-lSystem}"
/*
Note that by default, -lgcc_eh is not linked against.
This is because,in general, we need to unwind through system libraries that
are linked with the shared unwinder in libunwind (or libgcc_s for 10.4/5).
/* Note that by default, -lgcc_eh (which provides a statically-linked unwinder)
is not used. This is because, in general, we need to unwind through system
libraries that are linked with the shared unwinder in libunwind (or libgcc_s
for OSX 10.4/5 [darwin8/9]).
For -static-libgcc: < 10.6, use the unwinder in libgcc_eh (and find
the emultls impl. there too).
When -static-libgcc is forced: < 10.6, use the unwinder in libgcc_eh (and
find the emultls impl. there too).
For -static-libgcc: >= 10.6, the unwinder *still* comes from libSystem and
we find the emutls impl from lemutls_w. In either case, the builtins etc.
are linked from -lgcc.
are linked from -lgcc. The eh library is still available so that it could
be specified explicitly if there is some reason to do so.
When we have specified shared-libgcc or any case that might require
exceptions, we pull the libgcc content (including emulated tls) from
-lgcc_s.1 in GCC and the unwinder from /usr/lib/libgcc_s.1 for < 10.6 and
-lgcc_s.1.1 in GCC and the unwinder from /usr/lib/libgcc_s.1 for < 10.6 and
libSystem for >= 10.6 respectively.
Otherwise, we just link the emutls/builtins from convenience libs.
If we need exceptions, prior to 10.3.9, then we have to link the static
eh lib, since there's no shared version on the system.
In all cases, libgcc_s.1 will be installed with the compiler, or any app
built using it, so we can link the builtins and emutls shared on all.
We have to work around that DYLD_XXXX are disabled in macOS 10.11+ which
means that any bootstrap trying to use a shared libgcc with a bumped SO-
name will fail. This means that we do not accept shared libgcc for these
versions.
versions (the primary reason for forcing a shared libgcc was that it
contained the unwinder on Darwin8 and 9).
For -static-libgcc: >= 10.6, the unwinder *still* comes from libSystem and
we find the emutls impl from lemutls_w. In either case, the builtins etc.
are linked from -lgcc.
>
Otherwise, we just link the shared version of gcc_s.1.1 and pick up
exceptions:
When using the shared version of gcc_s.1.1 the unwinder is provided by:
* Prior to 10.3.9, then we have to link the static eh lib, since there
is no shared version on the system.
is no shared unwinder version on the system.
* from 10.3.9 to 10.5, from /usr/lib/libgcc_s.1.dylib
* from 10.6 onwards, from libSystem.dylib
In all cases, libgcc_s.1.1 will be installed with the compiler, or any app
built using it, so we can link the builtins and emutls shared on all.
*/
#undef REAL_LIBGCC_SPEC
#define REAL_LIBGCC_SPEC \