PR66870 PowerPC64 Enable gold linker with split stack

A powerpc-linux/powerpc64-linux biarch compiler can default to either
-m32 or -m64, and we need to notice both -m32 and -m64 on the gccgo
command line.  It's also possible to build a -m64 only compiler, so in
that case we can define TARGET_CAN_SPLIT_STACK.

gcc/
	PR go/66870
	* config/rs6000/sysv4.h (TARGET_CAN_SPLIT_STACK_64BIT): Don't define.
	* config/rs6000/linux64.h (TARGET_CAN_SPLIT_STACK): Define.
	(TARGET_CAN_SPLIT_STACK_64BIT): Define.
gcc/go/
	PR go/66870
	* gospec.c (saw_opt_m32): Rename to..
	(is_m64): ..this, initialised by TARGET_CAN_SPLIT_STACK_64BIT.
	Update uses.
	(lang_specific_driver): Set is_m64 if OPT_m64, clear if OPT_m32.

From-SVN: r229009

gcc/ChangeLog

+2015-10-20  Alan Modra  <amodra@gmail.com>
+
+	PR go/66870
+	* config/rs6000/sysv4.h (TARGET_CAN_SPLIT_STACK_64BIT): Don't define.
+	* config/rs6000/linux64.h (TARGET_CAN_SPLIT_STACK): Define.
+	(TARGET_CAN_SPLIT_STACK_64BIT): Define.
+
 2015-10-19  Pierre-Marie de Rodat  <derodat@adacore.com>
 
 	PR rtl-optimization/66790

gcc/config/rs6000/linux64.h

@@ -245,6 +245,21 @@ extern int dot_symbols;
 #define MULTILIB_DEFAULTS { "m32" }
 #endif
 
+/* Split stack is only supported for 64 bit, and requires glibc >= 2.18.  */
+#if TARGET_GLIBC_MAJOR * 1000 + TARGET_GLIBC_MINOR >= 2018
+# ifndef RS6000_BI_ARCH
+#  define TARGET_CAN_SPLIT_STACK
+# else
+#  if DEFAULT_ARCH64_P
+/* Supported, and the default is -m64  */
+#   define TARGET_CAN_SPLIT_STACK_64BIT 1
+#  else
+/* Supported, and the default is -m32  */
+#   define TARGET_CAN_SPLIT_STACK_64BIT 0
+#  endif
+# endif
+#endif
+
 #ifndef RS6000_BI_ARCH
 
 /* 64-bit PowerPC Linux always has a TOC.  */

gcc/config/rs6000/sysv4.h

@@ -940,14 +940,6 @@ ncrtn.o%s"
 #undef TARGET_ASAN_SHADOW_OFFSET
 #define TARGET_ASAN_SHADOW_OFFSET rs6000_asan_shadow_offset
 
-/* On ppc64 and ppc64le, split stack is only support for
-   64 bit. */
-#undef TARGET_CAN_SPLIT_STACK_64BIT
-#if TARGET_GLIBC_MAJOR > 2 \
-  || (TARGET_GLIBC_MAJOR == 2 && TARGET_GLIBC_MINOR >= 18)
-#define TARGET_CAN_SPLIT_STACK_64BIT
-#endif
-
 /* This target uses the sysv4.opt file.  */
 #define TARGET_USES_SYSV4_OPT 1
 

gcc/go/ChangeLog

+2015-10-20  Alan Modra  <amodra@gmail.com>
+
+	PR go/66870
+	* gospec.c (saw_opt_m32): Rename to..
+	(is_m64): ..this, initialised by TARGET_CAN_SPLIT_STACK_64BIT.
+	Update uses.
+	(lang_specific_driver): Set is_m64 if OPT_m64, clear if OPT_m32.
+
 2015-10-01  Ian Lance Taylor  <iant@google.com>
 
 	PR go/66870

gcc/go/gospec.c

@@ -120,8 +120,10 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
   /* Whether the -S option was used.  */
   bool saw_opt_S = false;
 
-  /* Whether the -m32 option was used. */
-  bool saw_opt_m32 ATTRIBUTE_UNUSED = false;
+#ifdef TARGET_CAN_SPLIT_STACK_64BIT
+  /* Whether the -m64 option is in force. */
+  bool is_m64 = TARGET_CAN_SPLIT_STACK_64BIT;
+#endif
 
   /* The first input file with an extension of .go.  */
   const char *first_go_file = NULL;  
@@ -160,7 +162,11 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
 
 #ifdef TARGET_CAN_SPLIT_STACK_64BIT
 	case OPT_m32:
-	  saw_opt_m32 = true;
+	  is_m64 = false;
+	  break;
+
+	case OPT_m64:
+	  is_m64 = true;
 	  break;
 #endif
 
@@ -253,7 +259,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
 #endif
 
 #ifdef TARGET_CAN_SPLIT_STACK_64BIT
-  if (!saw_opt_m32)
+  if (is_m64)
     supports_split_stack = 1;
 #endif