[Darwin] Some TLC for older Darwin versions.

The library handling and some of the options for creating the crts for
the older PPC Darwin versions had bit-rotted somewhat.  This adjusts the
build criteria for the crts to avoid newer ld64 versions warnings about
mismatches in build and object versions.

Added to some of the comments that it's documented why the specs are as
they are.

2019-07-03  Iain Sandoe  <iain@sandoe.co.uk>

gcc/

	* config/darwin.h (REAL_LIBGCC_SPEC): Adjust for earlier Darwin.
	(STARTFILE_SPEC): Split crt3 into a separate spec.
	(DARWIN_EXTRA_SPECS): Add crt2 and crt3 spec.
	(DARWIN_CRT2_SPEC): New.
	(DARWIN_CRT3_SPEC): New.
	(MIN_LD64_OMIT_STUBS): Revise to 62.1.
	* config/rs6000/darwin.h (DARWIN_CRT2_SPEC): Revise conditions.
	(DARWIN_CRT3_SPEC): New.

libgcc/

2019-07-03  Iain Sandoe  <iain@sandoe.co.uk>

	* config.host (powerpc-*-darwin*,powerpc64-*-darwin*): Revise crt
	list.
	* config/rs6000/t-darwin: Build crt3_2 for older systems.  Revise
	mmacosx-version-min for crts to run across all system versions.
	* config/rs6000/t-darwin64 (LIB2ADD): Remove.
	* config/t-darwin: Revise mmacosx-version-min for crts to run across
	system versions >= 10.4.

From-SVN: r273016

3 files changed, 75 insertions, 30 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e407904..f1794c8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2019-07-03  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* config/darwin.h (REAL_LIBGCC_SPEC): Adjust for earlier Darwin.
+	(STARTFILE_SPEC): Split crt3 into a separate spec.
+	(DARWIN_EXTRA_SPECS): Add crt2 and crt3 spec.
+	(DARWIN_CRT2_SPEC): New.
+	(DARWIN_CRT3_SPEC): New.
+	(MIN_LD64_OMIT_STUBS): Revise to 62.1.
+	* config/rs6000/darwin.h (DARWIN_CRT2_SPEC): Revise conditions.
+	(DARWIN_CRT3_SPEC): New.
+
 2019-07-03  Michael Meissner  <meissner@linux.ibm.com>
 
 	* config/rs6000/altivec.md (altivec_mov<mode>, VM2 iterator):
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index ae324f1..72215ce 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -189,8 +189,15 @@ extern GTY(()) int darwin_ms_struct;
 #define DARWIN_NOCOMPACT_UNWIND \
 " %:version-compare(>= 10.6 mmacosx-version-min= -no_compact_unwind) "
 
-/* This is mostly a clone of the standard LINK_COMMAND_SPEC, plus
-   precomp, libtool, and fat build additions.
+/* In Darwin linker specs we can put -lcrt0.o and ld will search the library
+   path for crt0.o or -lcrtx.a and it will search for for libcrtx.a.  As for
+   other ports, we can also put xxx.{o,a}%s and get the appropriate complete
+   startfile absolute directory.  This latter point is important when we want
+   to override ld's rule of .dylib being found ahead of .a and the user wants
+   the convenience library to be linked.  */
+
+/* The LINK_COMMAND spec is mostly a clone of the standard LINK_COMMAND_SPEC,
+   plus precomp, libtool, and fat build additions.
 
    In general, random Darwin linker flags should go into LINK_SPEC
    instead of LINK_COMMAND_SPEC.  The command spec is better for
@@ -352,43 +359,42 @@ extern GTY(()) int darwin_ms_struct;
 
 /* 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.
+   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.
+   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 is not linked against!  This is
-   because in a future version of Darwin the EH frame information may
-   be in a new format, or the fallback routine might be changed; if
-   you want to explicitly link against the static version of those
-   routines, because you know you don't need to unwind through system
-   libraries, you need to explicitly say -static-libgcc.
+   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 it is linked against, it has to be before -lgcc, because it may
+   If libgcc_eh is linked against, it has to be before -lgcc, because it might
    need symbols from -lgcc.  */
+
 #undef REAL_LIBGCC_SPEC
 #define REAL_LIBGCC_SPEC						   \
    "%{static-libgcc|static: -lgcc_eh -lgcc;				   \
-      shared-libgcc|fexceptions|fgnu-runtime:				   \
-       %:version-compare(!> 10.5 mmacosx-version-min= -lgcc_s.10.4)	   \
+      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(!> 10.5 mmacosx-version-min= -lgcc_ext.10.4)	   \
+       %: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(!> 10.5 mmacosx-version-min= -lgcc_ext.10.4)	   \
+       %: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 }"
 
-/* We specify crt0.o as -lcrt0.o so that ld will search the library path.
-
-   crt3.o provides __cxa_atexit on systems that don't have it.  Since
-   it's only used with C++, which requires passing -shared-libgcc, key
-   off that to avoid unnecessarily adding a destructor to every
-   powerpc program built.  */
+/* We specify crt0.o as -lcrt0.o so that ld will search the library path.  */
 
 #undef  STARTFILE_SPEC
 #define STARTFILE_SPEC							    \
-  "%{Zdynamiclib: %(darwin_dylib1) %{fgnu-tm: -lcrttms.o}}		    \
-   %{!Zdynamiclib:%{Zbundle:%{!static:					    \
+"%{Zdynamiclib: %(darwin_dylib1) %{fgnu-tm: -lcrttms.o}}		    \
+ %{!Zdynamiclib:%{Zbundle:%{!static:					    \
 	%:version-compare(< 10.6 mmacosx-version-min= -lbundle1.o)	    \
 	%{fgnu-tm: -lcrttms.o}}}					    \
      %{!Zbundle:%{pg:%{static:-lgcrt0.o}				    \
@@ -402,7 +408,7 @@ extern GTY(()) int darwin_ms_struct;
                                 %{!object:%{preload:-lcrt0.o}		    \
                                   %{!preload: %(darwin_crt1)		    \
 					      %(darwin_crt2)}}}}}}	    \
-  %{shared-libgcc:%:version-compare(< 10.5 mmacosx-version-min= crt3.o%s)}"
+ %(darwin_crt3)"
 
 /* We want a destructor last in the list.  */
 #define TM_DESTRUCTOR "%{fgnu-tm: -lcrttme.o}"
@@ -410,18 +416,30 @@ extern GTY(()) int darwin_ms_struct;
 
 #define DARWIN_EXTRA_SPECS						\
   { "darwin_crt1", DARWIN_CRT1_SPEC },					\
+  { "darwin_crt2", DARWIN_CRT2_SPEC },					\
+  { "darwin_crt3", DARWIN_CRT3_SPEC },					\
   { "darwin_dylib1", DARWIN_DYLIB1_SPEC },
 
-#define DARWIN_DYLIB1_SPEC						\
-  "%:version-compare(!> 10.5 mmacosx-version-min= -ldylib1.o)		\
-   %:version-compare(>< 10.5 10.6 mmacosx-version-min= -ldylib1.10.5.o)"
-
 #define DARWIN_CRT1_SPEC						\
   "%:version-compare(!> 10.5 mmacosx-version-min= -lcrt1.o)		\
    %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lcrt1.10.5.o)	\
    %:version-compare(>< 10.6 10.8 mmacosx-version-min= -lcrt1.10.6.o)	\
    %{fgnu-tm: -lcrttms.o}"
 
+#define DARWIN_CRT2_SPEC ""
+
+/* crt3.o provides __cxa_atexit on systems that don't have it (and a fix
+   up for faulty versions on 10.4).  Since it's only used with C++, which
+   requires passing -shared-libgcc, key off that to avoid unnecessarily
+   adding a destructor to every program built for 10.4 or earlier.  */
+
+#define DARWIN_CRT3_SPEC \
+"%{shared-libgcc:%:version-compare(< 10.5 mmacosx-version-min= crt3.o%s)}"
+
+#define DARWIN_DYLIB1_SPEC						\
+  "%:version-compare(!> 10.5 mmacosx-version-min= -ldylib1.o)		\
+   %:version-compare(>< 10.5 10.6 mmacosx-version-min= -ldylib1.10.5.o)"
+
 #ifdef HAVE_AS_MMACOSX_VERSION_MIN_OPTION
 /* Emit macosx version (but only major).  */
 #define ASM_MMACOSX_VERSION_MIN_SPEC \
@@ -996,7 +1014,7 @@ extern void darwin_driver_init (unsigned int *,struct cl_decoded_option **);
 
 /* From at least version 62.1, ld64 can build PIC indirection stubs as
    needed, and there is no need for the compiler to emit them.  */
-#define MIN_LD64_OMIT_STUBS "85.2"
+#define MIN_LD64_OMIT_STUBS "62.1"
 
 #ifndef LD64_VERSION
 #define LD64_VERSION "62.1"
diff --git a/gcc/config/rs6000/darwin.h b/gcc/config/rs6000/darwin.h
index 7b3b232..b0b5047 100644
--- a/gcc/config/rs6000/darwin.h
+++ b/gcc/config/rs6000/darwin.h
@@ -128,9 +128,25 @@ extern int darwin_emit_picsym_stub;
    %:version-compare(>< 10.5 10.7 mmacosx-version-min= -lcrt1.10.5.o)	\
    %{fgnu-tm: -lcrttms.o}"
 
-/* crt2.o is at least partially required for 10.3.x and earlier.  */
+/* crt2.o is at least partially required for 10.3.x and earlier.
+   It deals with registration of the unwind frames, where this is not
+   automatically provided by the system.  So we need it for any case that
+   might use exceptions.  */
+#undef DARWIN_CRT2_SPEC
 #define DARWIN_CRT2_SPEC \
-  "%{!m64:%:version-compare(!> 10.4 mmacosx-version-min= crt2.o%s)}"
+"%{!m64:%{shared-libgcc|static-libstdc++|fexceptions|fobjc-exceptions|fgnu-runtime: \
+   %:version-compare(!> 10.4 mmacosx-version-min= crt2.o%s) \
+  }}"
+
+/* crt3 deals with providing cxa_atexit on earlier systems (or fixing it up,
+   for broken versions).  It's only needed for c++ code, so we can make it
+   conditional on shared-libgcc since that's forced on for c++.  */
+#undef DARWIN_CRT3_SPEC
+#define DARWIN_CRT3_SPEC \
+"%{!m64:%{shared-libgcc|static-libstdc++:							\
+   %:version-compare(>< 10.4 10.5 mmacosx-version-min= crt3.o%s) \
+   %:version-compare(!> 10.4 mmacosx-version-min= crt3_2.o%s) \
+  }}"
 
 /* The PPC regs save/restore functions are leaves and could, conceivably
    be used by the tm destructor.  */