[PATCH][rs6000][PR target/87474] fix strncmp expansion with -mno-power8-vector

[Aaron Sawdey]

PR/87474 happens because I didn't check that both vector and VSX instructions
were enabled, so insns that are disabled get generated with -mno-power8-vector.

Regstrap passes on ppc64le, ok for trunk?

Thanks!
  Aaron



2018-10-01  Aaron Sawdey  <acsawdey@linux.ibm.com>

	PR target/87474
	* config/rs6000/rs6000-string.c (expand_strn_compare): Check that both
	vector and VSX are enabled.


Index: gcc/config/rs6000/rs6000-string.c
===================================================================
--- gcc/config/rs6000/rs6000-string.c	(revision 264760)
+++ gcc/config/rs6000/rs6000-string.c	(working copy)
@@ -2205,6 +2205,7 @@
     }
   else
     {
+      /* Implies TARGET_P8_VECTOR here. */
       rtx diffix = gen_reg_rtx (DImode);
       rtx result_gbbd = gen_reg_rtx (V16QImode);
       /* Since each byte of the input is either 00 or FF, the bytes in
@@ -2313,9 +2314,12 @@
   /* Is it OK to use vec/vsx for this. TARGET_VSX means we have at
      least POWER7 but we use TARGET_EFFICIENT_UNALIGNED_VSX which is
      at least POWER8.  That way we can rely on overlapping compares to
-     do the final comparison of less than 16 bytes.  Also I do not want
-     to deal with making this work for 32 bits.  */
-  int use_vec = (bytes >= 16 && !TARGET_32BIT && TARGET_EFFICIENT_UNALIGNED_VSX);
+     do the final comparison of less than 16 bytes.  Also I do not
+     want to deal with making this work for 32 bits.  In addition, we
+     have to make sure that we have at least P8_VECTOR (we don't allow
+     P9_VECTOR without P8_VECTOR).  */
+  int use_vec = (bytes >= 16 && !TARGET_32BIT
+		 && TARGET_EFFICIENT_UNALIGNED_VSX && TARGET_P8_VECTOR);

   if (use_vec)
     required_align = 16;


-- 
Aaron Sawdey, Ph.D.  acsawdey@linux.vnet.ibm.com
050-2/C113  (507) 253-7520 home: 507/263-0782
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