[RS6000] Simplify setting of fixed_regs[RS6000_PIC_OFFSET_TABLE_REGNUM]

This makes the conditions look the same as other places that deal with
RS6000_PIC_OFFSET_TABLE_REGNUM, eg. first_reg_to_save.  No functional
changes.

	* config/rs6000/rs6000.c (rs6000_conditional_register_usage):
	Remove redundant PIC_OFFSET_TABLE_REGNUM test.  Replace with
	flag_pic test for Darwin.

From-SVN: r235669

gcc/ChangeLog

 2016-04-30  Alan Modra  <amodra@gmail.com>
 
+	* config/rs6000/rs6000.c (rs6000_conditional_register_usage):
+	Remove redundant PIC_OFFSET_TABLE_REGNUM test.  Replace with
+	flag_pic test for Darwin.
+
+2016-04-30  Alan Modra  <amodra@gmail.com>
+
 	* regs.h (struct reg_info_t): Delete freq_calls_crossed and
 	throw_calls_crossed.
 	(REG_FREQ_CALLS_CROSSED): Delete.

gcc/config/rs6000/rs6000.c

@@ -8650,21 +8650,16 @@ rs6000_conditional_register_usage (void)
   if (DEFAULT_ABI == ABI_AIX || DEFAULT_ABI == ABI_ELFv2)
     call_really_used_regs[2] = 0;
 
-  if (DEFAULT_ABI == ABI_V4
-      && PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
-      && flag_pic == 2)
+  if (DEFAULT_ABI == ABI_V4 && flag_pic == 2)
     fixed_regs[RS6000_PIC_OFFSET_TABLE_REGNUM] = 1;
 
-  if (DEFAULT_ABI == ABI_V4
-      && PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
-      && flag_pic == 1)
+  if (DEFAULT_ABI == ABI_V4 && flag_pic == 1)
     fixed_regs[RS6000_PIC_OFFSET_TABLE_REGNUM]
       = call_used_regs[RS6000_PIC_OFFSET_TABLE_REGNUM]
       = call_really_used_regs[RS6000_PIC_OFFSET_TABLE_REGNUM] = 1;
 
-  if (DEFAULT_ABI == ABI_DARWIN
-      && PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM)
-      fixed_regs[RS6000_PIC_OFFSET_TABLE_REGNUM]
+  if (DEFAULT_ABI == ABI_DARWIN && flag_pic)
+    fixed_regs[RS6000_PIC_OFFSET_TABLE_REGNUM]
       = call_used_regs[RS6000_PIC_OFFSET_TABLE_REGNUM]
       = call_really_used_regs[RS6000_PIC_OFFSET_TABLE_REGNUM] = 1;