S/390: Allow to use r2 to r4 as literal pool base.

gcc/ChangeLog

	* config/s390/s390.c (s390_init_frame_layout): Try r4 to r2 for the
	literal pool pointer.

gcc/testsuite/ChangeLog

	* gcc.target/s390/litpool-r3-1.c: New test.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@231813 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 10 insertions, 3 deletions

diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index ed684af1a66..cba88bbb0fc 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -9584,10 +9584,17 @@ s390_init_frame_layout (void)
 	 as base register to avoid save/restore overhead.  */
       if (!base_used)
 	cfun->machine->base_reg = NULL_RTX;
-      else if (crtl->is_leaf && !df_regs_ever_live_p (5))
-	cfun->machine->base_reg = gen_rtx_REG (Pmode, 5);
       else
-	cfun->machine->base_reg = gen_rtx_REG (Pmode, BASE_REGNUM);
+	{
+	  int br = 0;
+
+	  if (crtl->is_leaf)
+	    /* Prefer r5 (most likely to be free).  */
+	    for (br = 5; br >= 2 && df_regs_ever_live_p (br); br--)
+	      ;
+	  cfun->machine->base_reg =
+	    gen_rtx_REG (Pmode, (br > 0) ? br : BASE_REGNUM);
+	}
 
       s390_register_info ();
       s390_frame_info ();