rs6000.c (rs6000_gimple_fold_builtin): Return early if there is no lhs.

[gcc]

	2017-07-12  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Return
	early if there is no lhs.

[testsuite]

	2017-07-12  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* gcc.target/powerpc/fold-vec-missing-lhs: New.

From-SVN: r250185

gcc/ChangeLog

+	2017-07-13  Will Schmidt  <will_schmidt@vnet.ibm.com>
+
+	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Return
+	early if there is no lhs.
+
 2017-07-13  Martin Liska  <mliska@suse.cz>
 
 	* dwarf2out.c (gen_pointer_type_die): Remove dead code.

gcc/config/rs6000/rs6000.c

@@ -16302,6 +16302,10 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
     = (enum rs6000_builtins) DECL_FUNCTION_CODE (fndecl);
   tree arg0, arg1, lhs;
 
+  /* Generic solution to prevent gimple folding of code without a LHS.  */
+  if (!gimple_call_lhs (stmt))
+    return false;
+
   switch (fn_code)
     {
     /* Flavors of vec_add.  We deliberately don't expand

gcc/testsuite/ChangeLog

+	2017-07-13  Will Schmidt  <will_schmidt@vnet.ibm.com>
+
+	* gcc.target/powerpc/fold-vec-missing-lhs.c: New.
+
 2017-07-13  Martin Liska  <mliska@suse.cz>
 
 	* c-c++-common/ubsan/sanitize-all-1.c: Update scanned pattern.

gcc/testsuite/gcc.target/powerpc/fold-vec-missing-lhs.c

+/* This test is meant to verify that the gimple-folding does not
+   occur when the LHS portion of an expression is missing.
+   The intent of this test is to verify that we do not generate an ICE.
+   This was noticed during debug of PR81317.  */
+
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_altivec_ok } */
+/* { dg-options "-maltivec" } */
+
+#include <altivec.h>
+
+vector signed short
+test1_nolhs (vector bool short x, vector signed short y)
+{
+  vec_add (x, y);
+  return vec_add (x, y);
+}
+
+vector signed short
+test2_nolhs (vector signed short x, vector bool short y)
+{
+  vec_add (x, y);
+  return vec_add (x, y);
+}