combine.c (try_combine): Canonicalize (plus (mult X pow2) Y) into (plus (ashift X log2) Y) if...

	* combine.c (try_combine): Canonicalize (plus (mult X pow2) Y) into
	(plus (ashift X log2) Y) if it is a split point.

	* gcc.target/hppa/shadd-3.c: New test.

From-SVN: r223583

gcc/ChangeLog

 2015-05-22  Jeff Law  <law@redhat.com>
 
+	* combine.c (try_combine): Canonicalize (plus (mult X pow2) Y) into
+	(plus (ashift X log2) Y) if it is a split point.
+
 	* pa.c (mem_shadd_or_shadd_rtx_p): New function factored out
 	of hppa_legitimize_address to handle both forms of a multiply
 	by 2, 4 or 8.

gcc/combine.c

@@ -3746,6 +3746,21 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
 	      split_code = GET_CODE (*split);
 	    }
 
+	  /* Similarly for (plus (mult FOO (const_int pow2))).  */
+	  if (split_code == PLUS
+	      && GET_CODE (XEXP (*split, 0)) == MULT
+	      && CONST_INT_P (XEXP (XEXP (*split, 0), 1))
+	      && INTVAL (XEXP (XEXP (*split, 0), 1)) > 0
+	      && (i = exact_log2 (UINTVAL (XEXP (XEXP (*split, 0), 1)))) >= 0)
+	    {
+	      rtx nsplit = XEXP (*split, 0);
+	      SUBST (XEXP (*split, 0), gen_rtx_ASHIFT (GET_MODE (nsplit),
+					     XEXP (nsplit, 0), GEN_INT (i)));
+	      /* Update split_code because we may not have a multiply
+		 anymore.  */
+	      split_code = GET_CODE (*split);
+	    }
+
 #ifdef INSN_SCHEDULING
 	  /* If *SPLIT is a paradoxical SUBREG, when we split it, it should
 	     be written as a ZERO_EXTEND.  */

gcc/testsuite/ChangeLog

@@ -209,6 +209,7 @@
 
 2015-05-21  Jeff Law  <law@redhat.com>
 
+	* gcc.target/hppa/shadd-3.c: New test.
 	* gcc.target/hppa/shadd-4.c: New test.
 
 2015-05-21  Michael Matz  <matz@suse.de>

gcc/testsuite/gcc.target/hppa/shadd-3.c

+/* { dg-do compile }  */
+/* { dg-options "-O2" }  */
+/* In this test we want to verify that combine canonicalizes the
+   MULT into an ASHIFT which in turn allows postreload-gcse to
+   find the common subexpression.
+
+   Neither pass dumps stuff in a format that is particularly good
+   for parsing here, so we count the shadd insns.  More is not
+   necessarily better in this test.  If this test is too fragile
+   over time we'll have to revisit the combine and/or postreload
+   dumps.  */
+/* { dg-final { scan-assembler-times "sh.add" 5 } }  */
+
+extern void oof (void);
+typedef struct simple_bitmap_def *sbitmap;
+struct simple_bitmap_def
+{
+  unsigned char *popcount;
+  unsigned int n_bits;
+  unsigned long elms[1];
+};
+__inline__ void
+SET_BIT (sbitmap map, unsigned int bitno)
+{
+  if (map->popcount)
+    {
+      unsigned char oldbit;
+      oldbit =
+	((map)->elms[bitno / 64]);
+      if (!oldbit)
+	oof ();
+    }
+  map->elms[bitno / 64] |= 1;
+}
+
+void
+fix_bb_placements (int indx1, int indx2, sbitmap in_queue)
+{
+  SET_BIT (in_queue, indx1);
+  SET_BIT (in_queue, indx2);
+}