[Darwin] Back-port fix for PR71767.

gcc/

2016-12-11  Iain Sandoe  <iain@codesourcery.com>

	Backport from mainline
	2016-11-27  Iain Sandoe  <iain@codesourcery.com>

	PR target/71767
	* config/darwin-sections.def (picbase_thunk_section): New.
	* config/darwin.c (darwin_init_sections): Set up picbase thunk
	section. (darwin_rodata_section, darwin_objc2_section,
	machopic_select_section, darwin_asm_declare_constant_name,
	darwin_emit_weak_or_comdat, darwin_function_section): Don’t use
	coalesced with newer linkers.
	(darwin_override_options): Decide on usage of coalesed sections
	on the basis of the target linker version.
	* config/darwin.h (MIN_LD64_NO_COAL_SECTS): New.
	* config/darwin.opt  (mtarget-linker): New.
	* config/i386/i386.c (ix86_code_end): Do not force the thunks into
	a coalesced section, instead use a thunks section.

	Backport from mainline
	2016-11-28  Iain Sandoe  <iain@codesourcery.com>

	PR target/71767
	* configure.ac (with_ld64): Use portable method to extract the
	major part of the version number.
	* configure: Regenerated.

	Backport from mainline
	2016-11-27  Iain Sandoe  <iain@codesourcery.com>

	PR target/71767
	* configure.ac (with-ld64): New var, set for Darwin, set on
	detection of ld64, gcc_cv_ld64_export_dynamic: New, New test.
	* config/darwin.h: Use LD64_HAS_DYNAMIC export. DEF_LD64: New,
	define.
	* config/darwin10.h(DEF_LD64): Update for this target version.
	* config/darwin12.h(LINK_GCC_C_SEQUENCE_SPEC): Remove rdynamic
	test.  (DEF_LD64): Update for this target version.
	* configure: Regenerated.
	* config.in: Regenerated.

	Backport from mainline
	2016-11-27  Iain Sandoe  <iain@codesourcery.com>

	PR target/71767
	* config/darwin.c (imachopic_indirection_name): Make data
	section indirections linker-visible.
	* config/darwin.h (ASM_GENERATE_INTERNAL_LABEL): Make local
	constant labels linker-visible.

gcc/testsuite/

2016-12-11  Iain Sandoe  <iain@codesourcery.com>

	Backport from mainline
	2016-11-27  Dominique d'Humieres  <dominiq@lps.ens.fr>
		    Iain Sandoe  <iain@codesourcery.com>

	PR target/71767
	* g++.dg/abi/key2.C: Adjust for changed Darwin sections and
	linker-visible symbols.
	* g++.dg/torture/darwin-cfstring-3.C: Likewise.
	* gcc.dg/const-uniq-1.c: Likewise.
	* gcc.dg/torture/darwin-cfstring-3.c: Likewise.
	* gcc.target/i386/pr70799-1.c: Likewise.




git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-6-branch@243524 138bc75d-0d04-0410-961f-82ee72b054a4

16 files changed, 350 insertions, 42 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7d78c39c225..5eb4bad303a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,53 @@
+2016-12-11  Iain Sandoe  <iain@codesourcery.com>
+
+	Backport from mainline
+	2016-11-27  Iain Sandoe  <iain@codesourcery.com>
+
+	PR target/71767
+	* config/darwin-sections.def (picbase_thunk_section): New.
+	* config/darwin.c (darwin_init_sections): Set up picbase thunk
+	section. (darwin_rodata_section, darwin_objc2_section,
+	machopic_select_section, darwin_asm_declare_constant_name,
+	darwin_emit_weak_or_comdat, darwin_function_section): Don’t use
+	coalesced with newer linkers.
+	(darwin_override_options): Decide on usage of coalesed sections
+	on the basis of the target linker version.
+	* config/darwin.h (MIN_LD64_NO_COAL_SECTS): New.
+	* config/darwin.opt  (mtarget-linker): New.
+	* config/i386/i386.c (ix86_code_end): Do not force the thunks into
+	a coalesced section, instead use a thunks section.
+
+	Backport from mainline
+	2016-11-28  Iain Sandoe  <iain@codesourcery.com>
+
+	PR target/71767
+	* configure.ac (with_ld64): Use portable method to extract the
+	major part of the version number.
+	* configure: Regenerated.
+
+	Backport from mainline
+	2016-11-27  Iain Sandoe  <iain@codesourcery.com>
+
+	PR target/71767
+	* configure.ac (with-ld64): New var, set for Darwin, set on
+	detection of ld64, gcc_cv_ld64_export_dynamic: New, New test.
+	* config/darwin.h: Use LD64_HAS_DYNAMIC export. DEF_LD64: New,
+	define.
+	* config/darwin10.h(DEF_LD64): Update for this target version.
+	* config/darwin12.h(LINK_GCC_C_SEQUENCE_SPEC): Remove rdynamic
+	test.  (DEF_LD64): Update for this target version.
+	* configure: Regenerated.
+	* config.in: Regenerated.
+
+	Backport from mainline
+	2016-11-27  Iain Sandoe  <iain@codesourcery.com>
+
+	PR target/71767
+	* config/darwin.c (imachopic_indirection_name): Make data
+	section indirections linker-visible.
+	* config/darwin.h (ASM_GENERATE_INTERNAL_LABEL): Make local
+	constant labels linker-visible.
+
 2016-12-09  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	Backport from mainline
diff --git a/gcc/config.in b/gcc/config.in
index 86bd5b0dd53..cda0e281587 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -1908,6 +1908,18 @@
 #endif
 
 
+/* Define to 1 if ld64 supports '-export_dynamic'. */
+#ifndef USED_FOR_TARGET
+#undef LD64_HAS_EXPORT_DYNAMIC
+#endif
+
+
+/* Define to ld64 version. */
+#ifndef USED_FOR_TARGET
+#undef LD64_VERSION
+#endif
+
+
 /* Define to the linker option to ignore unused dependencies. */
 #ifndef USED_FOR_TARGET
 #undef LD_AS_NEEDED_OPTION
diff --git a/gcc/config/darwin-sections.def b/gcc/config/darwin-sections.def
index cbf3e41e9ac..8a7e985c85f 100644
--- a/gcc/config/darwin-sections.def
+++ b/gcc/config/darwin-sections.def
@@ -31,6 +31,11 @@ along with GCC; see the file COPYING3.  If not see
 DEF_SECTION (text_coal_section, SECTION_CODE|SECTION_NO_ANCHOR,
 	     ".section __TEXT,__textcoal_nt,coalesced,pure_instructions", 0)
 
+/* We define a picbase thunks section separately, so that we can override the
+   def to be '.text' for versions of ld64 that handle coalescing.  */
+DEF_SECTION (picbase_thunk_section, SECTION_CODE|SECTION_NO_ANCHOR,
+	     ".section __TEXT,__textcoal_nt,coalesced,pure_instructions", 0)
+
 DEF_SECTION (text_hot_section, SECTION_CODE,
 	     ".section __TEXT,__text_hot,regular,pure_instructions", 0)
 DEF_SECTION (text_cold_section, SECTION_CODE,
diff --git a/gcc/config/darwin.c b/gcc/config/darwin.c
index 0055d805441..fd27cdfb950 100644
--- a/gcc/config/darwin.c
+++ b/gcc/config/darwin.c
@@ -96,6 +96,10 @@ int darwin_running_cxx;
 /* Some code-gen now depends on OS major version numbers (at least).  */
 int generating_for_darwin_version ;
 
+/* For older linkers we need to emit special sections (marked 'coalesced') for
+   for weak or single-definition items.  */
+static bool ld_uses_coal_sects = false;
+
 /* Section names.  */
 section * darwin_sections[NUM_DARWIN_SECTIONS];
 
@@ -219,6 +223,11 @@ darwin_init_sections (void)
   readonly_data_section = darwin_sections[const_section];
   exception_section = darwin_sections[darwin_exception_section];
   eh_frame_section = darwin_sections[darwin_eh_frame_section];
+
+  /* If our linker is new enough to coalesce weak symbols, then we
+     can just put picbase_thunks into the text section.  */
+  if (! ld_uses_coal_sects )
+    darwin_sections[picbase_thunk_section] = text_section;
 }
 
 int
@@ -473,7 +482,31 @@ indirection_hasher::equal (machopic_indirection *s, const char *k)
 }
 
 /* Return the name of the non-lazy pointer (if STUB_P is false) or
-   stub (if STUB_B is true) corresponding to the given name.  */
+   stub (if STUB_B is true) corresponding to the given name.
+
+  If we have a situation like:
+
+global_weak_symbol:
+  ....
+Lnon_weak_local:
+  ....
+
+  ld64 will be unable to split this into two atoms (because the "L" makes
+  the second symbol 'invisible').  This means that legitimate direct accesses
+  to the second symbol will appear to be non-allowed direct accesses to an
+  atom of type weak, global which are not allowed.
+
+  To avoid this, we make the indirections have a leading 'l' (lower-case L)
+  which has a special meaning: linker can see this and use it to determine
+  atoms, but it is not placed into the final symbol table.
+
+  The implementation here is somewhat heavy-handed in that it will also mark
+  indirections to the __IMPORT,__pointers section the same way which is
+  really unnecessary, since ld64 _can_ split those into atoms as they are
+  fixed size.  FIXME: determine if this is a penalty worth extra code to
+  fix.
+
+*/
 
 const char *
 machopic_indirection_name (rtx sym_ref, bool stub_p)
@@ -484,6 +517,7 @@ machopic_indirection_name (rtx sym_ref, bool stub_p)
   machopic_indirection *p;
   bool needs_quotes;
   const char *suffix;
+  char L_or_l = 'L';
   const char *prefix = user_label_prefix;
   const char *quote = "";
   tree id;
@@ -518,9 +552,13 @@ machopic_indirection_name (rtx sym_ref, bool stub_p)
   if (stub_p)
     suffix = STUB_SUFFIX;
   else
-    suffix = NON_LAZY_POINTER_SUFFIX;
+    {
+      suffix = NON_LAZY_POINTER_SUFFIX;
+      /* Let the linker see this.  */
+      L_or_l = 'l';
+    }
 
-  buffer = XALLOCAVEC (char, strlen ("&L")
+  buffer = XALLOCAVEC (char, 2  /* strlen ("&L") or ("&l") */
 		   + strlen (prefix)
 		   + namelen
 		   + strlen (suffix)
@@ -528,7 +566,7 @@ machopic_indirection_name (rtx sym_ref, bool stub_p)
 		   + 1 /* '\0' */);
 
   /* Construct the name of the non-lazy pointer or stub.  */
-  sprintf (buffer, "&%sL%s%s%s%s", quote, prefix, name, suffix, quote);
+  sprintf (buffer, "&%s%c%s%s%s%s", quote, L_or_l, prefix, name, suffix, quote);
 
   if (!machopic_indirections)
     machopic_indirections = hash_table<indirection_hasher>::create_ggc (37);
@@ -1217,9 +1255,9 @@ darwin_mark_decl_preserved (const char *name)
 }
 
 static section *
-darwin_rodata_section (int weak, bool zsize)
+darwin_rodata_section (int use_coal, bool zsize)
 {
-  return (weak
+  return (use_coal
 	  ? darwin_sections[const_coal_section]
 	  : (zsize ? darwin_sections[zobj_const_section]
 		   : darwin_sections[const_section]));
@@ -1388,7 +1426,8 @@ darwin_objc2_section (tree decl ATTRIBUTE_UNUSED, tree meta, section * base)
     return darwin_sections[objc2_image_info_section];
 
   else if (!strncmp (p, "V2_EHTY", 7))
-    return darwin_sections[data_coal_section];
+    return ld_uses_coal_sects ? darwin_sections[data_coal_section]
+                              : data_section;
 
   else if (!strncmp (p, "V2_CSTR", 7))
     return darwin_sections[objc2_constant_string_object_section];
@@ -1487,21 +1526,23 @@ machopic_select_section (tree decl,
 			 int reloc,
 			 unsigned HOST_WIDE_INT align)
 {
-  bool zsize, one, weak, ro;
+  bool zsize, one, weak, use_coal, ro;
   section *base_section = NULL;
 
   weak = (DECL_P (decl)
 	  && DECL_WEAK (decl)
 	  && !lookup_attribute ("weak_import", DECL_ATTRIBUTES (decl)));
 
-  zsize = (DECL_P (decl) 
+  zsize = (DECL_P (decl)
 	   && (TREE_CODE (decl) == VAR_DECL || TREE_CODE (decl) == CONST_DECL) 
 	   && tree_to_uhwi (DECL_SIZE_UNIT (decl)) == 0);
 
-  one = DECL_P (decl) 
+  one = DECL_P (decl)
 	&& TREE_CODE (decl) == VAR_DECL 
 	&& DECL_COMDAT_GROUP (decl);
 
+  use_coal = (weak || one) && ld_uses_coal_sects;
+
   ro = TREE_READONLY (decl) || TREE_CONSTANT (decl) ;
 
   switch (categorize_decl_for_section (decl, reloc))
@@ -1512,7 +1553,7 @@ machopic_select_section (tree decl,
 
     case SECCAT_RODATA:
     case SECCAT_SRODATA:
-      base_section = darwin_rodata_section (weak, zsize);
+      base_section = darwin_rodata_section (use_coal, zsize);
       break;
 
     case SECCAT_RODATA_MERGE_STR:
@@ -1534,7 +1575,7 @@ machopic_select_section (tree decl,
     case SECCAT_DATA_REL_RO_LOCAL:
     case SECCAT_SDATA:
     case SECCAT_TDATA:
-      if (weak || one)
+      if (use_coal)
 	{
 	  if (ro)
 	    base_section = darwin_sections[const_data_coal_section];
@@ -1563,7 +1604,7 @@ machopic_select_section (tree decl,
     case SECCAT_BSS:
     case SECCAT_SBSS:
     case SECCAT_TBSS:
-      if (weak || one) 
+      if (use_coal)
 	base_section = darwin_sections[data_coal_section];
       else
 	{
@@ -2259,14 +2300,18 @@ darwin_asm_declare_constant_name (FILE *file, const char *name,
 static void
 darwin_emit_weak_or_comdat (FILE *fp, tree decl, const char *name,
 				  unsigned HOST_WIDE_INT size, 
+				  bool use_coal,
 				  unsigned int align)
 {
-  /* Since the sections used here are coalesed, they will not be eligible
-     for section anchors, and therefore we don't need to break that out.  */
+  /* Since the sections used here are coalesced, they will not be eligible
+     for section anchors, and therefore we don't need to break that out.
+     CHECKME: for modern linker on PowerPC.  */
  if (TREE_READONLY (decl) || TREE_CONSTANT (decl))
-    switch_to_section (darwin_sections[const_data_coal_section]);
+    switch_to_section (use_coal ? darwin_sections[const_data_coal_section]
+				: darwin_sections[const_data_section]);
   else
-    switch_to_section (darwin_sections[data_coal_section]);
+    switch_to_section (use_coal ? darwin_sections[data_coal_section]
+				: data_section);
 
   /* To be consistent, we'll allow darwin_asm_declare_object_name to assemble
      the align info for zero-sized items... but do it here otherwise.  */
@@ -2485,7 +2530,7 @@ fprintf (fp, "# albss: %s (%lld,%d) ro %d cst %d stat %d com %d"
     {
       /* Weak or COMDAT objects are put in mergeable sections.  */
       darwin_emit_weak_or_comdat (fp, decl, name, size, 
-					DECL_ALIGN (decl));
+				  ld_uses_coal_sects, DECL_ALIGN (decl));
       return;
     } 
 
@@ -2599,7 +2644,7 @@ fprintf (fp, "# adcom: %s (%lld,%d) ro %d cst %d stat %d com %d pub %d"
     {
       /* Weak or COMDAT objects are put in mergable sections.  */
       darwin_emit_weak_or_comdat (fp, decl, name, size, 
-					DECL_ALIGN (decl));
+				  ld_uses_coal_sects, DECL_ALIGN (decl));
       return;
     } 
 
@@ -2669,7 +2714,7 @@ fprintf (fp, "# adloc: %s (%lld,%d) ro %d cst %d stat %d one %d pub %d"
     {
       /* Weak or COMDAT objects are put in mergable sections.  */
       darwin_emit_weak_or_comdat (fp, decl, name, size, 
-					DECL_ALIGN (decl));
+				  ld_uses_coal_sects, DECL_ALIGN (decl));
       return;
     } 
 
@@ -3051,6 +3096,12 @@ darwin_override_options (void)
       /* Earlier versions are not specifically accounted, until required.  */
     }
 
+  /* Older Darwin ld could not coalesce weak entities without them being
+     placed in special sections.  */
+  if (darwin_target_linker
+      && (strverscmp (darwin_target_linker, MIN_LD64_NO_COAL_SECTS) < 0))
+    ld_uses_coal_sects = true;
+
   /* In principle, this should be c-family only.  However, we really need to
      set sensible defaults for LTO as well, since the section selection stuff
      should check for correctness re. the ABI.  TODO: check and provide the
@@ -3576,12 +3627,13 @@ darwin_function_section (tree decl, enum node_frequency freq,
 			  bool startup, bool exit)
 {
   /* Decide if we need to put this in a coalescable section.  */
-  bool weak = (decl 
+  bool weak = (decl
 	       && DECL_WEAK (decl)
 	       && (!DECL_ATTRIBUTES (decl)
 		   || !lookup_attribute ("weak_import", 
 					  DECL_ATTRIBUTES (decl))));
 
+  bool use_coal = weak && ld_uses_coal_sects;
   /* If there is a specified section name, we should not be trying to
      override.  */
   if (decl && DECL_SECTION_NAME (decl) != NULL)
@@ -3589,8 +3641,8 @@ darwin_function_section (tree decl, enum node_frequency freq,
 
   /* We always put unlikely executed stuff in the cold section.  */
   if (freq == NODE_FREQUENCY_UNLIKELY_EXECUTED)
-    return (weak) ? darwin_sections[text_cold_coal_section]
-		  : darwin_sections[text_cold_section];
+    return (use_coal) ? darwin_sections[text_cold_coal_section]
+		      : darwin_sections[text_cold_section];
 
   /* If we have LTO *and* feedback information, then let LTO handle
      the function ordering, it makes a better job (for normal, hot,
@@ -3600,23 +3652,23 @@ darwin_function_section (tree decl, enum node_frequency freq,
 
   /* Non-cold startup code should go to startup subsection.  */
   if (startup)
-    return (weak) ? darwin_sections[text_startup_coal_section]
-		  : darwin_sections[text_startup_section];
+    return (use_coal) ? darwin_sections[text_startup_coal_section]
+		      : darwin_sections[text_startup_section];
 
   /* Similarly for exit.  */
   if (exit)
-    return (weak) ? darwin_sections[text_exit_coal_section]
-		  : darwin_sections[text_exit_section];
+    return (use_coal) ? darwin_sections[text_exit_coal_section]
+		      : darwin_sections[text_exit_section];
 
   /* Place hot code.  */
   if (freq == NODE_FREQUENCY_HOT)
-    return (weak) ? darwin_sections[text_hot_coal_section]
-		  : darwin_sections[text_hot_section];
+    return (use_coal) ? darwin_sections[text_hot_coal_section]
+		      : darwin_sections[text_hot_section];
 
   /* Otherwise, default to the 'normal' non-reordered sections.  */
 default_function_sections:
-  return (weak) ? darwin_sections[text_coal_section]
-		: text_section;
+  return (use_coal) ? darwin_sections[text_coal_section]
+		    : text_section;
 }
 
 /* When a function is partitioned between sections, we need to insert a label
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index 0277cf2238b..3cfb876813e 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -165,6 +165,12 @@ extern GTY(()) int darwin_ms_struct;
    specifying the handling of options understood by generic Unix
    linkers, and for positional arguments like libraries.  */
 
+#if LD64_HAS_EXPORT_DYNAMIC
+#define DARWIN_EXPORT_DYNAMIC " %{rdynamic:-export_dynamic}"
+#else
+#define DARWIN_EXPORT_DYNAMIC " %{rdynamic: %nrdynamic is not supported}"
+#endif
+
 #define LINK_COMMAND_SPEC_A \
    "%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
     %(linker)" \
@@ -185,7 +191,9 @@ extern GTY(()) int darwin_ms_struct;
     %{!nostdlib:%{!nodefaultlibs:\
       %{%:sanitize(address): -lasan } \
       %{%:sanitize(undefined): -lubsan } \
-      %(link_ssp) %(link_gcc_c_sequence)\
+      %(link_ssp) \
+      " DARWIN_EXPORT_DYNAMIC " %<rdynamic \
+      %(link_gcc_c_sequence) \
     }}\
     %{!nostdlib:%{!nostartfiles:%E}} %{T*} %{F*} }}}}}}}"
 
@@ -718,9 +726,16 @@ extern GTY(()) section * darwin_sections[NUM_DARWIN_SECTIONS];
   { "weak_import", 0, 0, true, false, false,				     \
     darwin_handle_weak_import_attribute, false }
 
+/* Make local constant labels linker-visible, so that if one follows a
+   weak_global constant, ld64 will be able to separate the atoms.  */
 #undef ASM_GENERATE_INTERNAL_LABEL
 #define ASM_GENERATE_INTERNAL_LABEL(LABEL,PREFIX,NUM)	\
-  sprintf (LABEL, "*%s%ld", PREFIX, (long)(NUM))
+  do {							\
+    if (strcmp ("LC", PREFIX) == 0)			\
+      sprintf (LABEL, "*%s%ld", "lC", (long)(NUM));	\
+    else						\
+      sprintf (LABEL, "*%s%ld", PREFIX, (long)(NUM));	\
+  } while (0)
 
 #undef TARGET_ASM_MARK_DECL_PRESERVED
 #define TARGET_ASM_MARK_DECL_PRESERVED darwin_mark_decl_preserved
@@ -930,4 +945,15 @@ extern void darwin_driver_init (unsigned int *,struct cl_decoded_option **);
    fall-back default.  */
 #define DEF_MIN_OSX_VERSION "10.5"
 
+/* Later versions of ld64 support coalescing weak code/data without requiring
+   that they be placed in specially identified sections.  This is the earliest
+   _tested_ version known to support this so far.  */
+#define MIN_LD64_NO_COAL_SECTS "236.4"
+
+#ifndef LD64_VERSION
+#define LD64_VERSION "85.2"
+#else
+#define DEF_LD64 LD64_VERSION
+#endif
+
 #endif /* CONFIG_DARWIN_H */
diff --git a/gcc/config/darwin.opt b/gcc/config/darwin.opt
index 50937315438..7f2e394ae79 100644
--- a/gcc/config/darwin.opt
+++ b/gcc/config/darwin.opt
@@ -391,5 +391,11 @@ Driver Separate
 sub_umbrella
 Driver Separate
 
+; Certain aspects of code-gen may be improved / adjusted if the version of ld64
+; is sufficiently modern.
+mtarget-linker
+Target RejectNegative Joined Separate Report Var(darwin_target_linker) Init(LD64_VERSION)
+The version of ld64 in use for this toolchain.
+
 undefined
 Driver Separate
diff --git a/gcc/config/darwin10.h b/gcc/config/darwin10.h
index 5829d788eb9..a81fbdccdc8 100644
--- a/gcc/config/darwin10.h
+++ b/gcc/config/darwin10.h
@@ -32,3 +32,8 @@ along with GCC; see the file COPYING3.  If not see
 
 #undef DEF_MIN_OSX_VERSION
 #define DEF_MIN_OSX_VERSION "10.6"
+
+#ifndef LD64_VERSION
+#undef DEF_LD64
+#define DEF_LD64 "97.7"
+#endif
diff --git a/gcc/config/darwin12.h b/gcc/config/darwin12.h
index e3669826dc3..f88e2a46901 100644
--- a/gcc/config/darwin12.h
+++ b/gcc/config/darwin12.h
@@ -21,10 +21,15 @@ along with GCC; see the file COPYING3.  If not see
 #undef  LINK_GCC_C_SEQUENCE_SPEC
 #define LINK_GCC_C_SEQUENCE_SPEC \
 "%:version-compare(>= 10.6 mmacosx-version-min= -no_compact_unwind) \
-   %{rdynamic:-export_dynamic} %{!static:%{!static-libgcc: \
+   %{!static:%{!static-libgcc: \
       %:version-compare(>= 10.6 mmacosx-version-min= -lSystem) } } \
    %{fno-pic|fno-PIC|fno-pie|fno-PIE|fapple-kext|mkernel|static|mdynamic-no-pic: \
       %:version-compare(>= 10.7 mmacosx-version-min= -no_pie) } %G %L"
 
 #undef DEF_MIN_OSX_VERSION
 #define DEF_MIN_OSX_VERSION "10.8"
+
+#ifndef LD64_VERSION
+#undef DEF_LD64
+#define DEF_LD64 "236.4"
+#endif
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 93f6470d412..9cbc4ccf4c1 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -11050,7 +11050,7 @@ ix86_code_end (void)
 #if TARGET_MACHO
       if (TARGET_MACHO)
 	{
-	  switch_to_section (darwin_sections[text_coal_section]);
+	  switch_to_section (darwin_sections[picbase_thunk_section]);
 	  fputs ("\t.weak_definition\t", asm_out_file);
 	  assemble_name (asm_out_file, name);
 	  fputs ("\n\t.private_extern\t", asm_out_file);
diff --git a/gcc/configure b/gcc/configure
index 40418310b03..3f91d011a8f 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -3631,6 +3631,11 @@ else
 fi
 
 
+case $target in
+    *darwin*) ld64_flag=yes;; # Darwin can only use a ld64-compatible linker.
+    *) ld64_flag=no;;
+esac
+
 # With pre-defined ld
 
 # Check whether --with-ld was given.
@@ -3643,6 +3648,8 @@ if test x"${DEFAULT_LINKER+set}" = x"set"; then
     as_fn_error "cannot execute: $DEFAULT_LINKER: check --with-ld or env. var. DEFAULT_LINKER" "$LINENO" 5
   elif $DEFAULT_LINKER -v < /dev/null 2>&1 | grep GNU > /dev/null; then
     gnu_ld_flag=yes
+  elif $DEFAULT_LINKER -v < /dev/null 2>&1 | grep ld64- > /dev/null; then
+    ld64_flag=yes
   fi
 
 cat >>confdefs.h <<_ACEOF
@@ -18453,7 +18460,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18456 "configure"
+#line 18463 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -18559,7 +18566,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18562 "configure"
+#line 18569 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -28069,6 +28076,71 @@ _ACEOF
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld_compress_debug" >&5
 $as_echo "$gcc_cv_ld_compress_debug" >&6; }
 
+if test x"$ld64_flag" = x"yes"; then
+
+  # Set defaults for possibly untestable items.
+  gcc_cv_ld64_export_dynamic=0
+
+  if test "$build" = "$host"; then
+    darwin_try_test=1
+  else
+    darwin_try_test=0
+  fi
+
+  # On Darwin, because of FAT library support, it is often possible to execute
+  # exes from compatible archs even when the host differs from the build system.
+  case "$build","$host" in
+    x86_64-*-darwin*,i?86-*-darwin* | powerpc64*-*-darwin*,powerpc*-*-darwin*)
+	darwin_try_test=1;;
+    *) ;;
+  esac
+
+  # If the configurer specified a minimum ld64 version to be supported, then use
+  # that to determine feature support.
+  if test x"${gcc_cv_ld64_version}" != x; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking ld64 specified version" >&5
+$as_echo_n "checking ld64 specified version... " >&6; }
+    gcc_cv_ld64_major=`echo "$gcc_cv_ld64_version" | sed -e 's/\..*//'`
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld64_major" >&5
+$as_echo "$gcc_cv_ld64_major" >&6; }
+   if test "$gcc_cv_ld64_major" -ge 236; then
+      gcc_cv_ld64_export_dynamic=1
+    fi
+  elif test -x "$gcc_cv_ld" -a "$darwin_try_test" -eq 1; then
+    # If the version was not specified, try to find it.
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking linker version" >&5
+$as_echo_n "checking linker version... " >&6; }
+    if test x"${gcc_cv_ld64_version}" = x; then
+      gcc_cv_ld64_version=`$gcc_cv_ld -v 2>&1 | grep ld64 | sed s/.*ld64-// | awk '{print $1}'`
+    fi
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld64_version" >&5
+$as_echo "$gcc_cv_ld64_version" >&6; }
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking linker for -export_dynamic support" >&5
+$as_echo_n "checking linker for -export_dynamic support... " >&6; }
+    gcc_cv_ld64_export_dynamic=1
+    if $gcc_cv_ld -export_dynamic < /dev/null 2>&1 | grep 'unknown option' > /dev/null; then
+      gcc_cv_ld64_export_dynamic=0
+    fi
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld64_export_dynamic" >&5
+$as_echo "$gcc_cv_ld64_export_dynamic" >&6; }
+  fi
+
+  if test x"${gcc_cv_ld64_version}" != x; then
+
+cat >>confdefs.h <<_ACEOF
+#define LD64_VERSION "${gcc_cv_ld64_version}"
+_ACEOF
+
+  fi
+
+
+cat >>confdefs.h <<_ACEOF
+#define LD64_HAS_EXPORT_DYNAMIC $gcc_cv_ld64_export_dynamic
+_ACEOF
+
+fi
+
 # --------
 # UNSORTED
 # --------
diff --git a/gcc/configure.ac b/gcc/configure.ac
index d426791ae6d..4475e5c338e 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -271,6 +271,11 @@ AC_ARG_WITH(gnu-ld,
 gnu_ld_flag="$with_gnu_ld",
 gnu_ld_flag=no)
 
+case $target in
+    *darwin*) ld64_flag=yes;; # Darwin can only use a ld64-compatible linker.
+    *) ld64_flag=no;;
+esac
+
 # With pre-defined ld
 AC_ARG_WITH(ld,
 [AS_HELP_STRING([--with-ld], [arrange to use the specified ld (full pathname)])],
@@ -280,6 +285,8 @@ if test x"${DEFAULT_LINKER+set}" = x"set"; then
     AC_MSG_ERROR([cannot execute: $DEFAULT_LINKER: check --with-ld or env. var. DEFAULT_LINKER])
   elif $DEFAULT_LINKER -v < /dev/null 2>&1 | grep GNU > /dev/null; then
     gnu_ld_flag=yes
+  elif $DEFAULT_LINKER -v < /dev/null 2>&1 | grep ld64- > /dev/null; then
+    ld64_flag=yes
   fi
   AC_DEFINE_UNQUOTED(DEFAULT_LINKER,"$DEFAULT_LINKER",
 	[Define to enable the use of a default linker.])
@@ -5148,6 +5155,59 @@ AC_DEFINE_UNQUOTED(LD_COMPRESS_DEBUG_OPTION, "$gcc_cv_ld_compress_debug_option",
 [Define to the linker option to enable compressed debug sections.])
 AC_MSG_RESULT($gcc_cv_ld_compress_debug)
 
+if test x"$ld64_flag" = x"yes"; then
+
+  # Set defaults for possibly untestable items.
+  gcc_cv_ld64_export_dynamic=0
+
+  if test "$build" = "$host"; then
+    darwin_try_test=1
+  else
+    darwin_try_test=0
+  fi
+
+  # On Darwin, because of FAT library support, it is often possible to execute
+  # exes from compatible archs even when the host differs from the build system.
+  case "$build","$host" in
+    x86_64-*-darwin*,i?86-*-darwin* | powerpc64*-*-darwin*,powerpc*-*-darwin*)
+	darwin_try_test=1;;
+    *) ;;
+  esac
+
+  # If the configurer specified a minimum ld64 version to be supported, then use
+  # that to determine feature support.
+  if test x"${gcc_cv_ld64_version}" != x; then
+    AC_MSG_CHECKING(ld64 specified version)
+    gcc_cv_ld64_major=`echo "$gcc_cv_ld64_version" | sed -e 's/\..*//'`
+    AC_MSG_RESULT($gcc_cv_ld64_major)
+   if test "$gcc_cv_ld64_major" -ge 236; then
+      gcc_cv_ld64_export_dynamic=1
+    fi
+  elif test -x "$gcc_cv_ld" -a "$darwin_try_test" -eq 1; then
+    # If the version was not specified, try to find it.
+    AC_MSG_CHECKING(linker version)
+    if test x"${gcc_cv_ld64_version}" = x; then
+      gcc_cv_ld64_version=`$gcc_cv_ld -v 2>&1 | grep ld64 | sed s/.*ld64-// | awk '{print $1}'`
+    fi
+    AC_MSG_RESULT($gcc_cv_ld64_version)
+
+    AC_MSG_CHECKING(linker for -export_dynamic support)
+    gcc_cv_ld64_export_dynamic=1
+    if $gcc_cv_ld -export_dynamic < /dev/null 2>&1 | grep 'unknown option' > /dev/null; then
+      gcc_cv_ld64_export_dynamic=0
+    fi
+    AC_MSG_RESULT($gcc_cv_ld64_export_dynamic)
+  fi
+
+  if test x"${gcc_cv_ld64_version}" != x; then
+    AC_DEFINE_UNQUOTED(LD64_VERSION, "${gcc_cv_ld64_version}",
+      [Define to ld64 version.])
+  fi
+
+  AC_DEFINE_UNQUOTED(LD64_HAS_EXPORT_DYNAMIC, $gcc_cv_ld64_export_dynamic,
+  [Define to 1 if ld64 supports '-export_dynamic'.])
+fi
+
 # --------
 # UNSORTED
 # --------
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 21b6839c592..97148591382 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,17 @@
+2016-12-11  Iain Sandoe  <iain@codesourcery.com>
+
+	Backport from mainline
+	2016-11-27  Dominique d'Humieres  <dominiq@lps.ens.fr>
+		    Iain Sandoe  <iain@codesourcery.com>
+
+	PR target/71767
+	* g++.dg/abi/key2.C: Adjust for changed Darwin sections and
+	linker-visible symbols.
+	* g++.dg/torture/darwin-cfstring-3.C: Likewise.
+	* gcc.dg/const-uniq-1.c: Likewise.
+	* gcc.dg/torture/darwin-cfstring-3.c: Likewise.
+	* gcc.target/i386/pr70799-1.c: Likewise.
+
 2016-12-09  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	Backport from mainline
diff --git a/gcc/testsuite/g++.dg/abi/key2.C b/gcc/testsuite/g++.dg/abi/key2.C
index 0d1347aaaa0..c79b3b2a20c 100644
--- a/gcc/testsuite/g++.dg/abi/key2.C
+++ b/gcc/testsuite/g++.dg/abi/key2.C
@@ -2,6 +2,7 @@
 // PR darwin/25908
 
 // { dg-do compile { target *-*-darwin* } }
+// { dg-options "-mtarget-linker 85.2" }
 // { dg-final { scan-assembler ".globl __ZTV1f\\n	.weak_definition __ZTV1f(\\n	.section __DATA,__const_coal,coalesced)?\\n	.align" } }
 // { dg-final { scan-assembler ".globl __ZTS1f\\n	.weak_definition __ZTS1f\\n	.section __TEXT,__const_coal,coalesced" } }
 // { dg-final { scan-assembler ".globl __ZTI1f\\n	.weak_definition __ZTI1f(\\n	.section __DATA,__const_coal,coalesced)?\\n	.align" } }
diff --git a/gcc/testsuite/g++.dg/torture/darwin-cfstring-3.C b/gcc/testsuite/g++.dg/torture/darwin-cfstring-3.C
index 2d755ec8dd0..ee4b385b17f 100644
--- a/gcc/testsuite/g++.dg/torture/darwin-cfstring-3.C
+++ b/gcc/testsuite/g++.dg/torture/darwin-cfstring-3.C
@@ -24,7 +24,7 @@ void foo(void) {
   s0 = s1;
 }
 
-/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+LC.*\n\[ \\t\]*\\.long\[ \\t\]+4\n" { target { *-*-darwin* && { ! lp64 } } } } } */
-/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+LC.*\n\[ \\t\]*\\.long\[ \\t\]+10\n" { target { *-*-darwin* && { ! lp64 } } } } } */
+/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+\[lL\]C.*\n\[ \\t\]*\\.long\[ \\t\]+4\n" { target { *-*-darwin* && { ! lp64 } } } } } */
+/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+\[lL\]C.*\n\[ \\t\]*\\.long\[ \\t\]+10\n" { target { *-*-darwin* && { ! lp64 } } } } } */
 /* { dg-final { scan-assembler ".quad\t___CFConstantStringClassReference\n\t.long\t1992\n\t.space 4\n\t.quad\t.*\n\t.quad\t4\n" { target { *-*-darwin* && {  lp64 } } } } } */
 /* { dg-final { scan-assembler ".quad\t___CFConstantStringClassReference\n\t.long\t1992\n\t.space 4\n\t.quad\t.*\n\t.quad\t10\n" { target { *-*-darwin* && {  lp64 } } } } } */
diff --git a/gcc/testsuite/gcc.dg/const-uniq-1.c b/gcc/testsuite/gcc.dg/const-uniq-1.c
index 2cb4f8a56cd..0e0718bf505 100644
--- a/gcc/testsuite/gcc.dg/const-uniq-1.c
+++ b/gcc/testsuite/gcc.dg/const-uniq-1.c
@@ -20,4 +20,4 @@ int lookup2 (int i)
   return a[i+1];
 }
 
-/* { dg-final { scan-tree-dump-times "L\\\$?C\\\.*0" 2 "gimple" } } */
+/* { dg-final { scan-tree-dump-times "\[lL\]\\\$?C\\\.*0" 2 "gimple" } } */
diff --git a/gcc/testsuite/gcc.dg/torture/darwin-cfstring-3.c b/gcc/testsuite/gcc.dg/torture/darwin-cfstring-3.c
index 2d755ec8dd0..ee4b385b17f 100644
--- a/gcc/testsuite/gcc.dg/torture/darwin-cfstring-3.c
+++ b/gcc/testsuite/gcc.dg/torture/darwin-cfstring-3.c
@@ -24,7 +24,7 @@ void foo(void) {
   s0 = s1;
 }
 
-/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+LC.*\n\[ \\t\]*\\.long\[ \\t\]+4\n" { target { *-*-darwin* && { ! lp64 } } } } } */
-/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+LC.*\n\[ \\t\]*\\.long\[ \\t\]+10\n" { target { *-*-darwin* && { ! lp64 } } } } } */
+/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+\[lL\]C.*\n\[ \\t\]*\\.long\[ \\t\]+4\n" { target { *-*-darwin* && { ! lp64 } } } } } */
+/* { dg-final { scan-assembler "\\.long\[ \\t\]+___CFConstantStringClassReference\n\[ \\t\]*\\.long\[ \\t\]+1992\n\[ \\t\]*\\.long\[ \\t\]+\[lL\]C.*\n\[ \\t\]*\\.long\[ \\t\]+10\n" { target { *-*-darwin* && { ! lp64 } } } } } */
 /* { dg-final { scan-assembler ".quad\t___CFConstantStringClassReference\n\t.long\t1992\n\t.space 4\n\t.quad\t.*\n\t.quad\t4\n" { target { *-*-darwin* && {  lp64 } } } } } */
 /* { dg-final { scan-assembler ".quad\t___CFConstantStringClassReference\n\t.long\t1992\n\t.space 4\n\t.quad\t.*\n\t.quad\t10\n" { target { *-*-darwin* && {  lp64 } } } } } */