[Darwin] The need for picsym stubs is dependent on linker used, not OS rev.

272356 For very old toolchains, the compiler generated pic symbol stubs that
provide the necessary indirections. We no longer need this (since xcode
3 era) and it's more efficient for the linker to make one stub when it
knows a symbol is needed that for us to emit them speculatively in every
object.

Our current codegen is making the assumption that a specific OS version
uses a specific linker version - and therefore the presence of support
could be based on the target OS rev. Of course, that's way too simplistic
(most likely bogus for cross-toolchains) and we want to make things explict.

Since we have detection of the linker version, we can use that directly
(A config test for support for stub-less linking might also be feasible
but much more involved).

Finally, should the user wish to generate code that caters for export to
use in an environment with an older toolchain, the generation of stubs
can be forced from the command line.

In addition to the points above, branch islanding and a long branch opt
for PowerPC Darwin has become conflated with the emission of these stubs.

274379 There is no need to distinguish PIC/non-PIC symbol stubs.

So we can use a single flag for both.

gcc/

2019-11-01  Iain Sandoe  <iain@sandoe.co.uk>

	Backport from mainline
	2019-08-13 Iain Sandoe <iain@sandoe.co.uk>

	* config/darwin.c (machopic_indirect_call_target): Rename symbol stub
	flag.
	(darwin_override_options): Likewise.
	* config/darwin.h: Likewise.
	* config/darwin.opt: Likewise.
	* config/i386/i386.c (output_pic_addr_const): Likewise.
	* config/rs6000/darwin.h: Likewise.
	* config/rs6000/rs6000.c (rs6000_call_darwin_1): Likewise.
	* config/i386/darwin.h (TARGET_MACHO_PICSYM_STUBS): Rename to ...
	... this TARGET_MACHO_SYMBOL_STUBS.
	(FUNCTION_PROFILER):Likewise.
	* config/i386/i386.h: Likewise.

	Backport from mainline
	2019-06-16  Iain Sandoe  <iain@sandoe.co.uk>

	* config/darwin.c (machopic_indirect_call_target): Use renamed
	darwin_picsymbol_stubs to decide on output.
	(darwin_override_options): Handle darwin_picsymbol_stubs.
	* config/darwin.h (MIN_LD64_OMIT_STUBS): New.
	(LD64_VERSION): Revise default.
	* config/darwin.opt: (mpic-symbol-stubs): New option.
	(darwin_picsymbol_stubs): New variable.
	* config/i386/darwin.h (TARGET_MACHO_BRANCH_ISLANDS):
	rename to TARGET_MACHO_PICSYM_STUBS.
	* config/i386/i386.c (output_pic_addr_const): Likewise.
	* config/i386/i386.h Likewise.
	* config/rs6000/darwin.h: Likewise.
	* config/rs6000/rs6000.c (rs6000_call_darwin_1): Use renamed
	darwin_picsymbol_stubs.

gcc/testsuite/

2019-11-01  Iain Sandoe  <iain@sandoe.co.uk>

	Backport from mainline.
	2019-08-13  Iain Sandoe  <iain@sandoe.co.uk>

	* obj-c++.dg/stubify-1.mm: Rename symbol stub option.
	* obj-c++.dg/stubify-2.mm: Likewise.
	* objc.dg/stubify-1.m: Likewise.
	* objc.dg/stubify-2.m: Likewise.



git-svn-id: https://gcc.gnu.org/svn/gcc/branches/gcc-7-branch@277721 138bc75d-0d04-0410-961f-82ee72b054a4

14 files changed, 103 insertions, 40 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c3eea050d30..f343586ceab 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,42 @@
 2019-11-01  Iain Sandoe  <iain@sandoe.co.uk>
 
 	Backport from mainline
+	2019-08-13 Iain Sandoe <iain@sandoe.co.uk>
+
+	* config/darwin.c (machopic_indirect_call_target): Rename symbol stub
+	flag.
+	(darwin_override_options): Likewise.
+	* config/darwin.h: Likewise.
+	* config/darwin.opt: Likewise.
+	* config/i386/i386.c (output_pic_addr_const): Likewise.
+	* config/rs6000/darwin.h: Likewise.
+	* config/rs6000/rs6000.c (rs6000_call_darwin_1): Likewise.
+	* config/i386/darwin.h (TARGET_MACHO_PICSYM_STUBS): Rename to ...
+	... this TARGET_MACHO_SYMBOL_STUBS.
+	(FUNCTION_PROFILER):Likewise.
+	* config/i386/i386.h: Likewise.
+
+	Backport from mainline
+	2019-06-16  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* config/darwin.c (machopic_indirect_call_target): Use renamed
+	darwin_picsymbol_stubs to decide on output.
+	(darwin_override_options): Handle darwin_picsymbol_stubs.
+	* config/darwin.h (MIN_LD64_OMIT_STUBS): New.
+	(LD64_VERSION): Revise default.
+	* config/darwin.opt: (mpic-symbol-stubs): New option.
+	(darwin_picsymbol_stubs): New variable.
+	* config/i386/darwin.h (TARGET_MACHO_BRANCH_ISLANDS):
+	rename to TARGET_MACHO_PICSYM_STUBS.
+	* config/i386/i386.c (output_pic_addr_const): Likewise.
+	* config/i386/i386.h Likewise.
+	* config/rs6000/darwin.h: Likewise.
+	* config/rs6000/rs6000.c (rs6000_call_darwin_1): Use renamed
+	darwin_picsymbol_stubs.
+
+2019-11-01  Iain Sandoe  <iain@sandoe.co.uk>
+
+	Backport from mainline
 	2019-06-28  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* config.gcc (powerpc-*-darwin*, powerpc64-*-darwin*): Remove
diff --git a/gcc/config/darwin.c b/gcc/config/darwin.c
index 541f4589465..ba0506cf353 100644
--- a/gcc/config/darwin.c
+++ b/gcc/config/darwin.c
@@ -74,12 +74,6 @@ along with GCC; see the file COPYING3.  If not see
    of MACHO_SYMBOL_FLAG_STATIC for the code that handles @code{static}
    symbol indirection.  */
 
-/* For darwin >= 9  (OSX 10.5) the linker is capable of making the necessary
-   branch islands and we no longer need to emit darwin stubs.
-   However, if we are generating code for earlier systems (or for use in the 
-   kernel) the stubs might still be required, and this will be set true.  */
-int darwin_emit_branch_islands = false;
-
 typedef struct GTY(()) cdtor_record {
   rtx symbol;
   int priority;		/* [con/de]structor priority */
@@ -806,7 +800,7 @@ machopic_indirect_data_reference (rtx orig, rtx reg)
 rtx
 machopic_indirect_call_target (rtx target)
 {
-  if (! darwin_emit_branch_islands)
+  if (! darwin_symbol_stubs)
     return target;
 
   if (GET_CODE (target) != MEM)
@@ -3306,11 +3300,31 @@ darwin_override_options (void)
       flag_pic = 2;
     }
 
-  /* It is assumed that branch island stubs are needed for earlier systems.  */
-  if (generating_for_darwin_version < 9)
-    darwin_emit_branch_islands = true;
-  else
-    emit_aligned_common = true; /* Later systems can support aligned common.  */
+  /* Linkers >= ld64-62.1 (at least) are capable of making the necessary PIC
+     indirections and we no longer need to emit pic symbol stubs.
+     However, if we are generating code for earlier ones (or for use in the
+     kernel) the stubs might still be required, and this will be set true.
+     If the user sets it on or off - then that takes precedence. */
+
+  if (!global_options_set.x_darwin_symbol_stubs)
+    {
+      if (darwin_target_linker) {
+	if (strverscmp (darwin_target_linker, MIN_LD64_OMIT_STUBS) < 0)
+	  darwin_symbol_stubs = true;
+      } else if (generating_for_darwin_version < 9)
+	/* We know no better than to assume the use of an earlier linker.  */
+	darwin_symbol_stubs = true;
+    }
+  else if (DARWIN_X86 && darwin_symbol_stubs && TARGET_64BIT)
+    {
+      inform (input_location,
+	      "%<-msymbol-stubs%> is not required for 64b code (ignored)");
+      darwin_symbol_stubs = false;
+    }
+
+  if (generating_for_darwin_version >= 9)
+    /* Later systems can support aligned common.  */
+    emit_aligned_common = true;
 
   /* The c_dialect...() macros are not available to us here.  */
   darwin_running_cxx = (strstr (lang_hooks.name, "C++") != 0);
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index 5b2eb97d432..b83e36aeecd 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -1016,8 +1016,12 @@ extern void darwin_driver_init (unsigned int *,struct cl_decoded_option **);
    _tested_ version known to support this so far.  */
 #define MIN_LD64_NO_COAL_SECTS "236.4"
 
+/* From at least version 62.1, ld64 can build symbol indirection stubs as
+   needed, and there is no need for the compiler to emit them.  */
+#define MIN_LD64_OMIT_STUBS "85.2"
+
 #ifndef LD64_VERSION
-#define LD64_VERSION "85.2"
+#define LD64_VERSION "62.1"
 #else
 #define DEF_LD64 LD64_VERSION
 #endif
diff --git a/gcc/config/darwin.opt b/gcc/config/darwin.opt
index 0df8fe4fc56..018cb2cadcf 100644
--- a/gcc/config/darwin.opt
+++ b/gcc/config/darwin.opt
@@ -75,6 +75,10 @@ mone-byte-bool
 Target RejectNegative Report Var(darwin_one_byte_bool)
 Set sizeof(bool) to 1.
 
+msymbol-stubs
+Target Report Var(darwin_symbol_stubs) Init(0)
+Force generation of external symbol indirection stubs.
+
 ; Some code-gen may be improved / adjusted if the linker is sufficiently modern.
 mtarget-linker=
 Target RejectNegative Joined Report Alias(mtarget-linker)
diff --git a/gcc/config/i386/darwin.h b/gcc/config/i386/darwin.h
index f0d3cd1d338..234e892e6ba 100644
--- a/gcc/config/i386/darwin.h
+++ b/gcc/config/i386/darwin.h
@@ -89,14 +89,12 @@ along with GCC; see the file COPYING3.  If not see
 #undef WCHAR_TYPE_SIZE
 #define WCHAR_TYPE_SIZE 32
 
-/* Generate branch islands stubs if this is true.  */
-extern int darwin_emit_branch_islands;
-
-#undef TARGET_MACHO_BRANCH_ISLANDS
-#define TARGET_MACHO_BRANCH_ISLANDS darwin_emit_branch_islands
+/* Generate pic symbol indirection stubs if this is true.  */
+#undef TARGET_MACHO_SYMBOL_STUBS
+#define TARGET_MACHO_SYMBOL_STUBS (darwin_symbol_stubs)
 
 /* For compatibility with OSX system tools, use the new style of pic stub
-   if this is set.  */
+   if this is set (default).  */
 #undef  MACHOPIC_ATT_STUB
 #define MACHOPIC_ATT_STUB (darwin_macho_att_stub)
 
@@ -241,16 +239,16 @@ extern int darwin_emit_branch_islands;
 /* Darwin profiling -- call mcount.  */
 #undef FUNCTION_PROFILER
 #define FUNCTION_PROFILER(FILE, LABELNO)				\
-    do {								\
-      if (TARGET_MACHO_BRANCH_ISLANDS 					\
-	   && MACHOPIC_INDIRECT && !TARGET_64BIT)			\
-	{								\
-	  const char *name = machopic_mcount_stub_name ();		\
-	  fprintf (FILE, "\tcall %s\n", name+1);  /*  skip '&'  */	\
-	  machopic_validate_stub_or_non_lazy_ptr (name);		\
-	}								\
-      else fprintf (FILE, "\tcall mcount\n");				\
-    } while (0)
+  do {									\
+    if (TARGET_MACHO_SYMBOL_STUBS 					\
+	&& MACHOPIC_INDIRECT && !TARGET_64BIT)				\
+      {									\
+	const char *name = machopic_mcount_stub_name ();		\
+	fprintf (FILE, "\tcall %s\n", name+1);  /*  skip '&'  */	\
+	machopic_validate_stub_or_non_lazy_ptr (name);			\
+      }									\
+    else fprintf (FILE, "\tcall mcount\n");				\
+  } while (0)
 
 #define C_COMMON_OVERRIDE_OPTIONS					\
   do {									\
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 97bbb2477d7..de71f56be6b 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -17394,7 +17394,7 @@ output_pic_addr_const (FILE *file, rtx x, int code)
       break;
 
     case SYMBOL_REF:
-      if (TARGET_64BIT || ! TARGET_MACHO_BRANCH_ISLANDS)
+      if (TARGET_64BIT || ! TARGET_MACHO_SYMBOL_STUBS)
 	output_addr_const (file, x);
       else
 	{
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 0fe4c8b2caa..8e31c30787d 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -590,7 +590,7 @@ extern tree x86_mfence;
 /* Replace MACH-O, ifdefs by in-line tests, where possible. 
    (a) Macros defined in config/i386/darwin.h  */
 #define TARGET_MACHO 0
-#define TARGET_MACHO_BRANCH_ISLANDS 0
+#define TARGET_MACHO_SYMBOL_STUBS 0
 #define MACHOPIC_ATT_STUB 0
 /* (b) Macros defined in config/darwin.h  */
 #define MACHO_DYNAMIC_NO_PIC_P 0
diff --git a/gcc/config/rs6000/darwin.h b/gcc/config/rs6000/darwin.h
index 8f4f6e7d61c..58a2b811ea7 100644
--- a/gcc/config/rs6000/darwin.h
+++ b/gcc/config/rs6000/darwin.h
@@ -75,9 +75,6 @@
     }							\
   while (0)
 
-/* Generate branch islands stubs if this is true.  */
-extern int darwin_emit_branch_islands;
-
 #define SUBTARGET_OVERRIDE_OPTIONS darwin_rs6000_override_options ()
 
 #define C_COMMON_OVERRIDE_OPTIONS do {					\
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 93d7c714862..af0c7ce1656 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -24096,7 +24096,7 @@ print_operand (FILE *file, rtx x, int code)
 	{
 	  const char *name = XSTR (x, 0);
 #if TARGET_MACHO
-	  if (darwin_emit_branch_islands
+	  if (darwin_symbol_stubs
 	      && MACHOPIC_INDIRECT
 	      && machopic_classify_symbol (x) == MACHOPIC_UNDEFINED_FUNCTION)
 	    name = machopic_indirection_name (x, /*stub_p=*/true);
@@ -36025,7 +36025,7 @@ output_call (rtx_insn *insn, rtx *operands, int dest_operand_number,
 	     int cookie_operand_number)
 {
   static char buf[256];
-  if (darwin_emit_branch_islands
+  if (darwin_symbol_stubs
       && GET_CODE (operands[dest_operand_number]) == SYMBOL_REF
       && (INTVAL (operands[cookie_operand_number]) & CALL_LONG))
     {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b93a8cce8de..54690a22d33 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,16 @@
 2019-11-01  Iain Sandoe  <iain@sandoe.co.uk>
 
 	Backport from mainline.
+	2019-08-13  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* obj-c++.dg/stubify-1.mm: Rename symbol stub option.
+	* obj-c++.dg/stubify-2.mm: Likewise.
+	* objc.dg/stubify-1.m: Likewise.
+	* objc.dg/stubify-2.m: Likewise.
+
+2019-11-01  Iain Sandoe  <iain@sandoe.co.uk>
+
+	Backport from mainline.
 	2019-05-15  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* lib/target-supports.exp 
diff --git a/gcc/testsuite/obj-c++.dg/stubify-1.mm b/gcc/testsuite/obj-c++.dg/stubify-1.mm
index c2355437afc..46ce3fb8158 100644
--- a/gcc/testsuite/obj-c++.dg/stubify-1.mm
+++ b/gcc/testsuite/obj-c++.dg/stubify-1.mm
@@ -4,7 +4,7 @@
 /* { dg-do compile { target *-*-darwin* } } */
 /* { dg-skip-if "" { *-*-* } { "-fgnu-runtime" } { "" } } */
 /* { dg-require-effective-target ilp32 } */
-/* { dg-options "-Os -mdynamic-no-pic -fno-exceptions -mmacosx-version-min=10.4" } */
+/* { dg-options "-Os -mdynamic-no-pic -fno-exceptions -mmacosx-version-min=10.4 -msymbol-stubs" } */
 
 typedef struct objc_object { } *id ;
 int x = 41 ;
diff --git a/gcc/testsuite/obj-c++.dg/stubify-2.mm b/gcc/testsuite/obj-c++.dg/stubify-2.mm
index a9f66cac5d2..dd88974e259 100644
--- a/gcc/testsuite/obj-c++.dg/stubify-2.mm
+++ b/gcc/testsuite/obj-c++.dg/stubify-2.mm
@@ -4,7 +4,7 @@
 /* { dg-do compile { target *-*-darwin* } } */
 /* { dg-skip-if "" { *-*-* } { "-fgnu-runtime" } { "" } } */
 /* { dg-require-effective-target ilp32 } */
-/* { dg-options "-mdynamic-no-pic -fdump-rtl-jump -mmacosx-version-min=10.4" } */
+/* { dg-options "-mdynamic-no-pic -fdump-rtl-jump -mmacosx-version-min=10.4 -msymbol-stubs" } */
 
 typedef struct objc_object { } *id ;
 int x = 41 ;
diff --git a/gcc/testsuite/objc.dg/stubify-1.m b/gcc/testsuite/objc.dg/stubify-1.m
index 91bf73a14f7..97d5b598380 100644
--- a/gcc/testsuite/objc.dg/stubify-1.m
+++ b/gcc/testsuite/objc.dg/stubify-1.m
@@ -4,7 +4,7 @@
 /* { dg-do compile { target *-*-darwin* } } */
 /* { dg-skip-if "" { *-*-* } { "-fgnu-runtime" } { "" } } */
 /* { dg-require-effective-target ilp32 } */
-/* { dg-options "-Os -mdynamic-no-pic -mmacosx-version-min=10.4" } */
+/* { dg-options "-Os -mdynamic-no-pic -mmacosx-version-min=10.4 -msymbol-stubs" } */
 
 typedef struct objc_object { } *id ;
 int x = 41 ;
diff --git a/gcc/testsuite/objc.dg/stubify-2.m b/gcc/testsuite/objc.dg/stubify-2.m
index eaf4b964e4b..a07992a5a9e 100644
--- a/gcc/testsuite/objc.dg/stubify-2.m
+++ b/gcc/testsuite/objc.dg/stubify-2.m
@@ -4,7 +4,7 @@
 /* { dg-do compile { target powerpc*-*-darwin* } } */
 /* { dg-skip-if "" { *-*-* } { "-fgnu-runtime" } { "" } } */
 /* { dg-require-effective-target ilp32 } */
-/* { dg-options "-mdynamic-no-pic -fdump-rtl-jump -mmacosx-version-min=10.4" } */
+/* { dg-options "-mdynamic-no-pic -fdump-rtl-jump -mmacosx-version-min=10.4 -msymbol-stubs" } */
 
 typedef struct objc_object { } *id ;
 int x = 41 ;