Darwin: Rework handling for unwinder code in libgcc_s and specs [PR80556].

This addresses a long-standing problem where a work-around for an unwinder
issue (also a regression) regresses other functionality.  The patch replaces
several work-arounds with a fix for PR80556 and a work-around for PR88590.

* The fix for PR80556 requires a bump to the SO name for libgcc_s, since we
need to remove the unwinder symbols from it.  This would trigger PR88590
hence the work-around for that.

* We weaken the symbols for emulated TLS support so that it is possible
for a DSO linked with static-libgcc to interoperate with a DSO linked with
libgcc_s.  Likewise main exes.

* We remove all the gcc-4.2.1 era stubs machinery and workarounds.

* libgcc is always now linked ahead of libc, which avoids fails where the
libc (libSystem) builtins implementations are not up to date.

* The unwinder now always comes from the system
 - for Darwin9 from /usr/lib/libgcc_s.1.dylib
 - for Darwin10 from /usr/lib/libSystem.dylib
 - for Darwin11+ from /usr/lib/system/libunwind.dylib.

 We still insert a shim on Darwin10 to fix an omitted unwind function, but
 the underlying unwinder remains the system one.

* The work-around for PR88590 has two parts (1) we always link libgcc from
its convenience lib on affected system versions (avoiding the need to find
the DSO path); (2) we add and export the emutls functions from DSOs - this
makes a relatively small (20k) addition to a DSO.  These can be backed out
when a proper fix for PR88590 is committed.

For distributions that wish to install a libgcc_s.1.dylib to satisfy linkage
from exes that linked against the stubs can use a reexported libgcc_s.1.1
(since that contains all the symbols that were previously exported via the
 stubs).

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

gcc/ChangeLog:

	PR target/80556
	* config/darwin-driver.c (darwin_driver_init): Handle exported
	symbols and symbol lists (suppress automatic export of the TLS
	symbols).
	* config/darwin.c (darwin_rename_builtins): Remove workaround.
	* config/darwin.h (LINK_GCC_C_SEQUENCE_SPEC): Likewise.
	(REAL_LIBGCC_SPEC): Handle revised library uses.
	* config/darwin.opt (nodefaultexport): New.
	* config/i386/darwin.h (PR80556_WORKAROUND): Remove.
	* config/i386/darwin32-biarch.h (PR80556_WORKAROUND): Likewise.
	* config/i386/darwin64-biarch.h (PR80556_WORKAROUND): Likewise.

libgcc/ChangeLog:

	* config.host: Add weak emutls crt to the extra_parts.
	* config/i386/darwin-lib.h (DECLARE_LIBRARY_RENAMES): Remove
	workaround.
	* config/libgcc-libsystem.ver: Add exclude list for the system-
	provided unwinder.
	* config/t-slibgcc-darwin: Bump SO version, remove stubs code.
	* config/i386/libgcc-darwin.10.4.ver: Removed.
	* config/i386/libgcc-darwin.10.5.ver: Removed.
	* config/rs6000/libgcc-darwin.10.4.ver: Removed.
	* config/rs6000/libgcc-darwin.10.5.ver: Removed.
	* config/t-darwin-noeh: New file.

gcc/testsuite/ChangeLog:

	* gcc.dg/torture/fp-int-convert-timode-3.c: Remove XFAIL.
	* gcc.dg/torture/fp-int-convert-timode-4.c: Likewise.

9 files changed, 87 insertions, 116 deletions

diff --git a/gcc/config/darwin-driver.c b/gcc/config/darwin-driver.c
index 4f0c6ba..7fa80ab 100644
--- a/gcc/config/darwin-driver.c
+++ b/gcc/config/darwin-driver.c
@@ -281,6 +281,7 @@ darwin_driver_init (unsigned int *decoded_options_count,
   const char *vers_string = NULL;
   bool seen_version_min = false;
   bool seen_sysroot_p = false;
+  bool noexport_p = true;
 
   for (i = 1; i < *decoded_options_count; i++)
     {
@@ -349,6 +350,13 @@ darwin_driver_init (unsigned int *decoded_options_count,
 	  seen_sysroot_p = true;
 	  break;
 
+	case OPT_Xlinker:
+	case OPT_Wl_:
+	  gcc_checking_assert ((*decoded_options)[i].arg);
+	  if (startswith ((*decoded_options)[i].arg, "-exported_symbol"))
+	    noexport_p = false;
+	  break;
+
 	default:
 	  break;
 	}
@@ -474,4 +482,14 @@ darwin_driver_init (unsigned int *decoded_options_count,
 			  &(*decoded_options)[*decoded_options_count - 1]);
         }
     }
+
+  if (noexport_p)
+    {
+      ++*decoded_options_count;
+      *decoded_options = XRESIZEVEC (struct cl_decoded_option,
+				     *decoded_options,
+				     *decoded_options_count);
+      generate_option (OPT_nodefaultexport, NULL, 1, CL_DRIVER,
+		       &(*decoded_options)[*decoded_options_count - 1]);
+    }
 }
diff --git a/gcc/config/darwin.c b/gcc/config/darwin.c
index 204114c..c5ba792 100644
--- a/gcc/config/darwin.c
+++ b/gcc/config/darwin.c
@@ -3637,30 +3637,6 @@ darwin_fold_builtin (tree fndecl, int n_args, tree *argp,
 void
 darwin_rename_builtins (void)
 {
-  /* The system ___divdc3 routine in libSystem on darwin10 is not
-     accurate to 1ulp, ours is, so we avoid ever using the system name
-     for this routine and instead install a non-conflicting name that
-     is accurate.
-
-     When -ffast-math or -funsafe-math-optimizations is given, we can
-     use the faster version.  */
-  if (!flag_unsafe_math_optimizations)
-    {
-      enum built_in_function dcode
-	= (enum built_in_function)(BUILT_IN_COMPLEX_DIV_MIN
-				   + DCmode - MIN_MODE_COMPLEX_FLOAT);
-      tree fn = builtin_decl_explicit (dcode);
-      /* Fortran and c call TARGET_INIT_BUILTINS and
-	 TARGET_INIT_LIBFUNCS at different times, so we have to put a
-	 call into each to ensure that at least one of them is called
-	 after build_common_builtin_nodes.  A better fix is to add a
-	 new hook to run after build_common_builtin_nodes runs.  */
-      if (fn)
-	set_user_assembler_name (fn, "___ieee_divdc3");
-      fn = builtin_decl_implicit (dcode);
-      if (fn)
-	set_user_assembler_name (fn, "___ieee_divdc3");
-    }
 }
 
 /* Implementation for the TARGET_LIBC_HAS_FUNCTION hook.  */
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index 7ed01ef..8d8d402 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -378,6 +378,16 @@ extern GTY(()) int darwin_ms_struct;
       %(link_ssp) \
       %:version-compare(>< 10.6 10.7 mmacosx-version-min= -ld10-uwfef) \
       %(link_gcc_c_sequence) \
+      %{!nodefaultexport:%{dylib|dynamiclib|bundle: \
+	%:version-compare(>= 10.11 asm_macosx_version_min= -U) \
+	%:version-compare(>= 10.11 asm_macosx_version_min= ___emutls_get_address) \
+	%:version-compare(>= 10.11 asm_macosx_version_min= -exported_symbol) \
+	%:version-compare(>= 10.11 asm_macosx_version_min= ___emutls_get_address) \
+	%:version-compare(>= 10.11 asm_macosx_version_min= -U) \
+	%:version-compare(>= 10.11 asm_macosx_version_min= ___emutls_register_common) \
+	%:version-compare(>= 10.11 asm_macosx_version_min= -exported_symbol) \
+	%:version-compare(>= 10.11 asm_macosx_version_min= ___emutls_register_common) \
+      }} \
     }}}\
     %{!r:%{!nostdlib:%{!nostartfiles:%E}}} %{T*} %{F*} "\
     DARWIN_PIE_SPEC \
@@ -404,14 +414,11 @@ extern GTY(()) int darwin_ms_struct;
 /* Tell collect2 to run dsymutil for us as necessary.  */
 #define COLLECT_RUN_DSYMUTIL 1
 
-/* Fix PR47558 by linking against libSystem ahead of libgcc. See also
-   PR 80556 and the fallout from this.  */
-
+/* We only want one instance of %G, since libSystem (Darwin's -lc) does not
+   depend on libgcc. */
 #undef  LINK_GCC_C_SEQUENCE_SPEC
 #define LINK_GCC_C_SEQUENCE_SPEC \
-"%{!static:%{!static-libgcc: \
-    %:version-compare(>= 10.6 mmacosx-version-min= -lSystem) } } \
-  %G %{!nolibc:%L}"
+ "%G %{!nolibc:%L} "
 
 /* ld64 supports a sysroot, it just has a different name and there's no easy
    way to check for it at config time.  */
@@ -456,37 +463,62 @@ extern GTY(()) int darwin_ms_struct;
 
 #define LIB_SPEC "%{!static:-lSystem}"
 
-/* Support -mmacosx-version-min by supplying different (stub) libgcc_s.dylib
-   libraries to link against, and by not linking against libgcc_s on
-   earlier-than-10.3.9.  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.
-
-   Note that by default, except as above, -lgcc_eh is not linked against.
+/*
+   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).
 
-   The static version of the current libgcc unwinder (which differs from the
-   implementation in libunwind.dylib on systems Darwin10 [10.6]+) can be used
-   by specifying -static-libgcc.
-
-   If libgcc_eh is linked against, it has to be before -lgcc, because it might
-   need symbols from -lgcc.  */
-
+   For -static-libgcc: < 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.
+
+   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
+   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.
+
+   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:
+     * Prior to 10.3.9, then we have to link the static eh lib, since there
+       is no shared 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						   \
-   "%{static-libgcc|static: -lgcc_eh -lgcc;				   \
-      shared-libgcc|fexceptions|fobjc-exceptions|fgnu-runtime:		   \
-       %:version-compare(!> 10.3.9 mmacosx-version-min= -lgcc_eh)	   \
-       %:version-compare(>< 10.3.9 10.5 mmacosx-version-min= -lgcc_s.10.4) \
-       %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lgcc_s.10.5)   \
-       %:version-compare(>< 10.3.9 10.5 mmacosx-version-min= -lgcc_ext.10.4) \
-       %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_ext.10.5)	   \
-       -lgcc ;								   \
-      :%:version-compare(>< 10.3.9 10.5 mmacosx-version-min= -lgcc_s.10.4) \
-       %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lgcc_s.10.5)   \
-       %:version-compare(>< 10.3.9 10.5 mmacosx-version-min= -lgcc_ext.10.4) \
-       %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_ext.10.5)	   \
-       -lgcc }"
+#define REAL_LIBGCC_SPEC \
+"%{static-libgcc|static:						  \
+    %:version-compare(!> 10.6 mmacosx-version-min= -lgcc_eh)		  \
+    %:version-compare(>= 10.6 mmacosx-version-min= -lemutls_w);		  \
+   shared-libgcc|fexceptions|fobjc-exceptions|fgnu-runtime:		  \
+    %:version-compare(!> 10.11 mmacosx-version-min= -lgcc_s.1.1)	  \
+    %:version-compare(>= 10.11 mmacosx-version-min= -lemutls_w)		  \
+    %:version-compare(!> 10.3.9 mmacosx-version-min= -lgcc_eh)		  \
+    %:version-compare(>< 10.3.9 10.5 mmacosx-version-min= -lgcc_s.10.4)   \
+    %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lgcc_s.10.5);	  \
+   : -lemutls_w								  \
+  } -lgcc "
 
 /* We specify crt0.o as -lcrt0.o so that ld will search the library path.  */
 
diff --git a/gcc/config/darwin.opt b/gcc/config/darwin.opt
index d1d1f81..48d3aa9 100644
--- a/gcc/config/darwin.opt
+++ b/gcc/config/darwin.opt
@@ -233,6 +233,10 @@ no_dead_strip_inits_and_terms
 Driver RejectNegative
 (Obsolete) Current linkers never dead-strip these items, so the option is not needed.
 
+nodefaultexport
+Driver RejectNegative
+Do not add a default symbol exports to modules or dynamic libraries.
+
 nofixprebinding
 Driver RejectNegative
 (Obsolete after 10.3.9) Set MH_NOPREFIXBINDING, in an executable.
diff --git a/gcc/config/i386/darwin.h b/gcc/config/i386/darwin.h
index 741f29a..e946a8b 100644
--- a/gcc/config/i386/darwin.h
+++ b/gcc/config/i386/darwin.h
@@ -25,37 +25,6 @@ along with GCC; see the file COPYING3.  If not see
 #undef DARWIN_X86
 #define DARWIN_X86 1
 
-/* WORKAROUND pr80556:
-   For x86_64 Darwin10 and later, the unwinder is in libunwind (redirected
-   from libSystem).  This doesn't use the keymgr (see keymgr.c) and therefore
-   the calls that libgcc makes to obtain the KEYMGR_GCC3_DW2_OBJ_LIST are not
-   updated to include new images, and might not even be valid for a single
-   image.
-   Therefore, for 64b exes at least, we must use the libunwind implementation,
-   even when static-libgcc is specified.  We put libSystem first so that
-   unwinder symbols are satisfied from there.
-   We default to 64b for single-arch builds, so apply this unconditionally. */
-#ifndef PR80556_WORKAROUND
-#define PR80556_WORKAROUND \
-" %:version-compare(>= 10.6 mmacosx-version-min= -lSystem) "
-#endif
-#undef REAL_LIBGCC_SPEC
-#define REAL_LIBGCC_SPEC						   \
-   "%{static-libgcc|static: "						   \
-       PR80556_WORKAROUND						   \
-      " -lgcc_eh -lgcc;							   \
-      shared-libgcc|fexceptions|fgnu-runtime:				   \
-       %:version-compare(!> 10.5 mmacosx-version-min= -lgcc_s.10.4)	   \
-       %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lgcc_s.10.5)   \
-       %:version-compare(!> 10.5 mmacosx-version-min= -lgcc_ext.10.4)	   \
-       %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_ext.10.5)	   \
-       -lgcc ;								   \
-      :%:version-compare(>< 10.3.9 10.5 mmacosx-version-min= -lgcc_s.10.4) \
-       %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lgcc_s.10.5)   \
-       %:version-compare(!> 10.5 mmacosx-version-min= -lgcc_ext.10.4)	   \
-       %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_ext.10.5)	   \
-       -lgcc }"
-
 /* Size of the Obj-C jump buffer.  */
 #define OBJC_JBLEN ((TARGET_64BIT) ? ((9 * 2) + 3 + 16) : (18))
 
diff --git a/gcc/config/i386/darwin32-biarch.h b/gcc/config/i386/darwin32-biarch.h
index 5470edf..ee15082 100644
--- a/gcc/config/i386/darwin32-biarch.h
+++ b/gcc/config/i386/darwin32-biarch.h
@@ -24,19 +24,6 @@ along with GCC; see the file COPYING3.  If not see
 #define TARGET_64BIT_DEFAULT 0
 #define TARGET_BI_ARCH 1
 
-/* WORKAROUND pr80556:
-   For x86_64 Darwin10 and later, the unwinder is in libunwind (redirected
-   from libSystem).  This doesn't use the keymgr (see keymgr.c) and therefore
-   the calls that libgcc makes to obtain the KEYMGR_GCC3_DW2_OBJ_LIST are not
-   updated to include new images, and might not even be valid for a single
-   image.
-   Therefore, for 64b exes at least, we must use the libunwind implementation,
-   even when static-libgcc is specified.  We put libSystem first so that
-   unwinder symbols are satisfied from there. */
-#undef PR80556_WORKAROUND
-#define PR80556_WORKAROUND \
-" %{m64:%:version-compare(>= 10.6 mmacosx-version-min= -lSystem)} "
-
 #undef  DARWIN_SUBARCH_SPEC
 #define DARWIN_SUBARCH_SPEC DARWIN_ARCH_SPEC
 
diff --git a/gcc/config/i386/darwin64-biarch.h b/gcc/config/i386/darwin64-biarch.h
index f5bc3d6..d02f7fc 100644
--- a/gcc/config/i386/darwin64-biarch.h
+++ b/gcc/config/i386/darwin64-biarch.h
@@ -25,19 +25,6 @@ along with GCC; see the file COPYING3.  If not see
 #define TARGET_64BIT_DEFAULT (OPTION_MASK_ISA_64BIT | OPTION_MASK_ABI_64)
 #define TARGET_BI_ARCH 1
 
-/* WORKAROUND pr80556:
-   For x86_64 Darwin10 and later, the unwinder is in libunwind (redirected
-   from libSystem).  This doesn't use the keymgr (see keymgr.c) and therefore
-   the calls that libgcc makes to obtain the KEYMGR_GCC3_DW2_OBJ_LIST are not
-   updated to include new images, and might not even be valid for a single
-   image.
-   Therefore, for 64b exes at least, we must use the libunwind implementation,
-   even when static-libgcc is specified.  We put libSystem first so that
-   unwinder symbols are satisfied from there. */
-#undef PR80556_WORKAROUND
-#define PR80556_WORKAROUND \
-" %{!m32:%:version-compare(>= 10.6 mmacosx-version-min= -lSystem)} "
-
 #undef  DARWIN_SUBARCH_SPEC
 #define DARWIN_SUBARCH_SPEC DARWIN_ARCH_SPEC
 
diff --git a/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-3.c b/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-3.c
index 1070230..707d539 100644
--- a/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-3.c
+++ b/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-3.c
@@ -4,7 +4,6 @@
 /* { dg-require-effective-target int128 } */
 /* { dg-require-effective-target fenv } */
 /* { dg-options "-frounding-math" } */
-/* { dg-xfail-run-if "see PR80556 c63" { x86_64-*-darwin* i68?-*-darwin* } { "*" } { "" } } */
 
 #include <fenv.h>
 #include <stdlib.h>
diff --git a/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-4.c b/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-4.c
index 3facf32..09600f9 100644
--- a/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-4.c
+++ b/gcc/testsuite/gcc.dg/torture/fp-int-convert-timode-4.c
@@ -4,7 +4,6 @@
 /* { dg-require-effective-target int128 } */
 /* { dg-require-effective-target fenv } */
 /* { dg-options "-frounding-math" } */
-/* { dg-xfail-run-if "see PR80556 c63" { x86_64-*-darwin* i68?-*-darwin* } { "*" } { "" } } */
 
 #include <fenv.h>
 #include <stdlib.h>