[PATCH, rs6000] Don't mark the TOC reg as set up in prologue

[Pat Haugen]

Revision 235876 inadvertently caused the TOC reg to be marked as set up
in prologue, which prevents shrink-wrapping from moving the prologue
past a TOC reference. The following patch corrects the situation.

Bootstrap/regtest on powerpc64le-linux and powerpc64-linux(-m32/-m64)
with no new regressions. Ok for trunk?

-Pat


2017-09-14  Pat Haugen  <pthau...@us.ibm.com>

        * config/rs6000/rs6000.c (rs6000_set_up_by_prologue): Make sure the TOC
        reg (r2) isn't in the set of registers defined in the prologue.


testsuite/ChangeLog:
2017-09-14  Pat Haugen  <pthau...@us.ibm.com>

        * gcc.target/powerpc/r2_shrink-wrap.c: New.


Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c	(revision 252029)
+++ gcc/config/rs6000/rs6000.c	(working copy)
@@ -37807,6 +37807,11 @@ rs6000_set_up_by_prologue (struct hard_r
     add_to_hard_reg_set (&set->set, Pmode, RS6000_PIC_OFFSET_TABLE_REGNUM);
   if (cfun->machine->split_stack_argp_used)
     add_to_hard_reg_set (&set->set, Pmode, 12);
+
+  /* Make sure the hard reg set doesn't include r2, which was possibly added
+     via PIC_OFFSET_TABLE_REGNUM.  */
+  if (TARGET_TOC)
+    remove_from_hard_reg_set (&set->set, Pmode, TOC_REGNUM);
 }
 
 
Index: gcc/testsuite/gcc.target/powerpc/r2_shrink-wrap.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/r2_shrink-wrap.c	(nonexistent)
+++ gcc/testsuite/gcc.target/powerpc/r2_shrink-wrap.c	(working copy)
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-pro_and_epilogue" } */
+
+void bar();
+int j;
+void foo(int i)
+{
+  j = i;
+  if (i > 0)
+    {
+      bar();
+    }
+}
+
+/* { dg-final { scan-rtl-dump-times "Performing shrink-wrapping" 1 "pro_and_epilogue" } } */