re PR target/51244 ([SH] Inefficient conditional branch and code around T bit)

	PR target/51244
	* config/sh/sh.md (*cset_zero): New insns.

	PR target/51244
	* gcc.target/sh/pr51244-11.c: New.

From-SVN: r190544

gcc/ChangeLog

+2012-08-20  Oleg Endo  <olegendo@gcc.gnu.org>
+
+	PR target/51244
+	* config/sh/sh.md (*cset_zero): New insns.
+
 2012-08-20  Mark Wielaard  <mjw@redhat.com>
 
 	* dwarf2out.h (enum dw_val_class): Add dw_val_class_high_pc.

gcc/config/sh/sh.md

@@ -10409,6 +10409,41 @@ label:
   operands[0] = gen_reg_rtx (SImode);
 })
 
+;; The *cset_zero patterns convert optimizations such as
+;;	"if (test) x = 0;" to "x &= -(test == 0);"
+;; back to conditional branch sequences if zero-displacement branches
+;; are enabled.
+;; FIXME: These patterns can be removed when conditional execution patterns
+;; are implemented, since ifcvt will not perform these optimizations if
+;; conditional execution is supported.
+(define_insn "*cset_zero"
+  [(set (match_operand:SI 0 "arith_reg_dest" "=r")
+	(and:SI (plus:SI (match_operand:SI 1 "t_reg_operand")
+			 (const_int -1))
+		(match_operand:SI 2 "arith_reg_operand" "0")))]
+  "TARGET_SH1 && TARGET_ZDCBRANCH"
+{
+  return       "bf	0f"	"\n"
+	 "	mov	#0,%0"	"\n"
+	 "0:";
+}
+  [(set_attr "type" "arith") ;; poor approximation
+   (set_attr "length" "4")])
+
+(define_insn "*cset_zero"
+  [(set (match_operand:SI 0 "arith_reg_dest" "=r")
+	(if_then_else:SI (match_operand:SI 1 "t_reg_operand")
+			 (match_operand:SI 2 "arith_reg_operand" "0")
+			 (const_int 0)))]
+  "TARGET_SH1 && TARGET_ZDCBRANCH"
+{
+  return       "bt	0f"	"\n"
+	 "	mov	#0,%0"	"\n"
+	 "0:";
+}
+  [(set_attr "type" "arith") ;; poor approximation
+   (set_attr "length" "4")])
+
 (define_expand "cstoresf4"
   [(set (match_operand:SI 0 "register_operand" "=r")
 	(match_operator:SI 1 "sh_float_comparison_operator"

gcc/testsuite/ChangeLog

+2012-08-20  Oleg Endo  <olegendo@gcc.gnu.org>
+
+	PR target/51244
+	* gcc.target/sh/pr51244-11.c: New.
+
 2012-08-20  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/54301

gcc/testsuite/gcc.target/sh/pr51244-11.c

+/* Check that zero-displacement branches are used instead of branch-free
+   execution patterns.  */
+/* { dg-do compile { target "sh*-*-*" } } */
+/* { dg-options "-O1 -mzdcbranch" } */
+/* { dg-skip-if "" { "sh*-*-*" } { "-m5*" } { "" } } */
+/* { dg-final { scan-assembler-not "subc|and" } } */
+
+int*
+test_00 (int* s)
+{
+  if (s[0] == 0)
+    if (!s[3])
+      s = 0;
+  return s;
+}
+
+int*
+test_01 (int* s)
+{
+  if (s[0] == 0)
+    if (s[3])
+      s = 0;
+  return s;
+}