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

PR target/51244
	* config/sh/sh.md (*mov_t_msb_neg): New insn and two accompanying
	unnamed split patterns.

	PR target/51244
	* gcc.target/sh/pr51244-12.c: New.

From-SVN: r192052

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2012-10-03  Oleg Endo  <olegendo@gcc.gnu.org>
+
+	PR target/51244
+	* config/sh/sh.md (*mov_t_msb_neg): New insn and two accompanying
+	unnamed split patterns.
+
 2012-10-03  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/50457

gcc/config/sh/sh.md

@@ -10769,6 +10769,51 @@ label:
 	(set (reg:SI T_REG) (const_int 1))
 	(use (match_dup 2))])])
 
+;; Use negc to store the T bit in a MSB of a reg in the following way:
+;;	T = 1: 0x80000000 -> reg
+;;	T = 0: 0x7FFFFFFF -> reg
+;; This works because 0 - 0x80000000 = 0x80000000.
+(define_insn_and_split "*mov_t_msb_neg"
+  [(set (match_operand:SI 0 "arith_reg_dest")
+	(minus:SI (const_int -2147483648)  ;; 0x80000000
+		  (match_operand 1 "t_reg_operand")))
+   (clobber (reg:SI T_REG))]
+  "TARGET_SH1"
+  "#"
+  "&& can_create_pseudo_p ()"
+  [(set (match_dup 2) (const_int -2147483648))
+   (parallel [(set (match_dup 0) (minus:SI (neg:SI (match_dup 2))
+				 (reg:SI T_REG)))
+	      (clobber (reg:SI T_REG))])]
+{
+  operands[2] = gen_reg_rtx (SImode);
+})
+
+;; These are essentially the same as above, but with the inverted T bit.
+;; Combine recognizes the split patterns, but does not take them sometimes
+;; if the T_REG clobber is specified.  Instead it tries to split out the
+;; T bit negation.  Since these splits are supposed to be taken only by
+;; combine, it will see the T_REG clobber of the *mov_t_msb_neg insn, so this
+;; should be fine.
+(define_split
+  [(set (match_operand:SI 0 "arith_reg_dest")
+	(plus:SI (match_operand 1 "negt_reg_operand")
+		 (const_int 2147483647)))]  ;; 0x7fffffff
+  "TARGET_SH1 && can_create_pseudo_p ()"
+  [(parallel [(set (match_dup 0)
+		   (minus:SI (const_int -2147483648) (reg:SI T_REG)))
+	      (clobber (reg:SI T_REG))])])
+
+(define_split
+  [(set (match_operand:SI 0 "arith_reg_dest")
+	(if_then_else:SI (match_operand 1 "t_reg_operand")
+			 (const_int 2147483647)  ;; 0x7fffffff
+			 (const_int -2147483648)))]  ;; 0x80000000
+  "TARGET_SH1 && can_create_pseudo_p ()"
+  [(parallel [(set (match_dup 0)
+		   (minus:SI (const_int -2147483648) (reg:SI T_REG)))
+	      (clobber (reg:SI T_REG))])])
+
 ;; The *negnegt pattern helps the combine pass to figure out how to fold 
 ;; an explicit double T bit negation.
 (define_insn_and_split "*negnegt"

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2012-10-03  Oleg Endo  <olegendo@gcc.gnu.org>
+
+	PR target/51244
+	* gcc.target/sh/pr51244-12.c: New.
+
 2012-10-03  Dehao Chen  <dehao@google.com>
 
 	PR middle-end/54782

gcc/testsuite/gcc.target/sh/pr51244-12.c

@@ -0,0 +1,68 @@
+/* Check that the negc instruction is generated as expected for the cases
+   below.  If we see a movrt or #-1 negc sequence it means that the pattern
+   which handles the inverted case does not work properly.  */
+/* { dg-do compile { target "sh*-*-*" } } */
+/* { dg-options "-O1" } */
+/* { dg-skip-if "" { "sh*-*-*" } { "-m5*" } { "" } } */
+/* { dg-final { scan-assembler-times "negc" 10 } } */
+/* { dg-final { scan-assembler-not "movrt|#-1|add|sub" } } */
+
+int
+test00 (int a, int b, int* x)
+{
+  return (a == b) ? 0x7FFFFFFF : 0x80000000;
+}
+
+int
+test00_inv (int a, int b)
+{
+  return (a != b) ? 0x80000000 : 0x7FFFFFFF;
+}
+
+int
+test01 (int a, int b)
+{
+  return (a >= b) ? 0x7FFFFFFF : 0x80000000;
+}
+
+int
+test01_inv (int a, int b)
+{
+  return (a < b) ? 0x80000000 : 0x7FFFFFFF;
+}
+
+int
+test02 (int a, int b)
+{
+  return (a > b) ? 0x7FFFFFFF : 0x80000000;
+}
+
+int
+test02_inv (int a, int b)
+{
+  return (a <= b) ? 0x80000000 : 0x7FFFFFFF;
+}
+
+int
+test03 (int a, int b)
+{
+  return ((a & b) == 0) ? 0x7FFFFFFF : 0x80000000;
+}
+
+int
+test03_inv (int a, int b)
+{
+  return ((a & b) != 0) ? 0x80000000 : 0x7FFFFFFF;
+}
+
+int
+test04 (int a)
+{
+  return ((a & 0x55) == 0) ? 0x7FFFFFFF : 0x80000000;
+}
+
+int
+test04_inv (int a)
+{
+  return ((a & 0x55) != 0) ? 0x80000000 : 0x7FFFFFFF;
+}