[gcc r10-10779] Darwin, PPC : Fix R13 for PPC64.

[gcc r10-10779] Darwin, PPC : Fix R13 for PPC64.

[Iain D Sandoe]

https://gcc.gnu.org/g:18cb0117150855224da0e73776a3e0d2bb68e7e6

commit r10-10779-g18cb0117150855224da0e73776a3e0d2bb68e7e6
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Fri Dec 11 00:29:42 2020 +0000

    Darwin, PPC : Fix R13 for PPC64.
    
    We have a somewhat unusual situation in that for PPC64, R13 is
    both reserved and callee-saved (it is used internally by the
    pthreads implementation to contain pthread_self).
    
    So add R13 to the fixed regs, but also keep it in the callee-
    saved set.
    
    gcc/ChangeLog:
    
            * config/rs6000/darwin.h (FIXED_R13): Add for PPC64.
            (FIRST_SAVED_GP_REGNO): Save from R13 even when it is one
            of the fixed regs.
    
    (cherry picked from commit b12d6e79899fd27833c53ffc3c973538244f62e1)

Diff:
---
 gcc/config/rs6000/darwin.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gcc/config/rs6000/darwin.h b/gcc/config/rs6000/darwin.h
index ce27508afcb..627ca805498 100644
--- a/gcc/config/rs6000/darwin.h
+++ b/gcc/config/rs6000/darwin.h
@@ -203,7 +203,7 @@
 
 /* Make both r2 and r13 available for allocation.  */
 #define FIXED_R2 0
-#define FIXED_R13 0
+#define FIXED_R13 TARGET_64BIT
 
 /* Base register for access to local variables of the function.  */
 
@@ -213,6 +213,9 @@
 #undef  RS6000_PIC_OFFSET_TABLE_REGNUM
 #define RS6000_PIC_OFFSET_TABLE_REGNUM 31
 
+#undef FIRST_SAVED_GP_REGNO
+#define FIRST_SAVED_GP_REGNO 13
+
 /* Darwin's stack must remain 16-byte aligned for both 32 and 64 bit
    ABIs.  */