re PR target/85945 (ICE in resolve_subreg_use, at lower-subreg.c:751)

	PR target/85945
	* lower-subreg.c (find_decomposable_subregs): Don't decompose float
	subregs of multi-word pseudos unless the float mode has word size.

	* gcc.c-torture/compile/pr85945.c: New test.

From-SVN: r261593

gcc/ChangeLog

+2018-06-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/85945
+	* lower-subreg.c (find_decomposable_subregs): Don't decompose float
+	subregs of multi-word pseudos unless the float mode has word size.
+
 2018-06-14  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/86139

gcc/lower-subreg.c

@@ -497,7 +497,16 @@ find_decomposable_subregs (rtx *loc, enum classify_move_insn *pcmi)
 	     were the same number and size of pieces.  Hopefully this
 	     doesn't happen much.  */
 
-	  if (outer_words == 1 && inner_words > 1)
+	  if (outer_words == 1
+	      && inner_words > 1
+	      /* Don't allow to decompose floating point subregs of
+		 multi-word pseudos if the floating point mode does
+		 not have word size, because otherwise we'd generate
+		 a subreg with that floating mode from a different
+		 sized integral pseudo which is not allowed by
+		 validate_subreg.  */
+	      && (!FLOAT_MODE_P (GET_MODE (x))
+		  || outer_size == UNITS_PER_WORD))
 	    {
 	      bitmap_set_bit (decomposable_context, regno);
 	      iter.skip_subrtxes ();

gcc/testsuite/ChangeLog

+2018-06-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/85945
+	* gcc.c-torture/compile/pr85945.c: New test.
+
 2018-06-14  Richard Biener  <rguenther@suse.de>
 
 	PR ipa/86124

gcc/testsuite/gcc.c-torture/compile/pr85945.c

+/* PR target/85945 */
+
+typedef float V __attribute__((vector_size(16)));
+union U { V v; float f[4]; };
+int f;
+float g[4];
+
+void
+foo (void)
+{
+  V d;
+  union U i;
+  i.v = d;
+  for (f = 0; f < 4; f++)
+    g[f] = i.f[f];
+}