xtensa: Optimize boolean evaluation when SImode EQ/NE to zero if TARGET_MINMAX

This patch optimizes the boolean evaluation for equality to 0 in SImode
using the MINU (Minimum Value Unsigned) machine instruction available
when TARGET_MINMAX is configured, for example, (x != 0) to MINU(x, 1)
and (x == 0) to (MINU(x, 1) ^ 1).

    /* example */
    int test0(int x) {
      return x == 0;
    }
    int test1(int x) {
      return x != 0;
    }

    ;; before
    test0:
	mov.n	a10, a2
	movi.n	a9, 1
	movi.n	a2, 0
	moveqz	a2, a9, a10
	ret.n
    test1:
	mov.n	a10, a2
	movi.n	a9, 1
	movi.n	a2, 0
	movnez	a2, a9, a10
	ret.n

    ;; after (prereq. TARGET_MINMAX)
    test0:
	movi.n	a9, 1
	minu	a2, a2, a9
	xor	a2, a2, a9
	ret.n
    test1:
	movi.n	a9, 1
	minu	a2, a2, a9
	ret.n

gcc/ChangeLog:

	* config/xtensa/xtensa.cc (xtensa_expand_scc):
	Add code for particular constants (only 0 and INT_MIN for now)
	for EQ/NE boolean evaluation in SImode.
	* config/xtensa/xtensa.md (*eqne_INT_MIN): Remove because its
	implementation has been integrated into the above.

2 files changed, 37 insertions, 40 deletions

diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index af71e21..1afaa1c 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -994,15 +994,46 @@ xtensa_expand_scc (rtx operands[4], machine_mode cmp_mode)
   rtx cmp;
   rtx one_tmp, zero_tmp;
   rtx (*gen_fn) (rtx, rtx, rtx, rtx, rtx);
+  enum rtx_code code = GET_CODE (operands[1]);
 
-  if (!(cmp = gen_conditional_move (GET_CODE (operands[1]), cmp_mode,
-				    operands[2], operands[3])))
+  if (cmp_mode == SImode && CONST_INT_P (operands[3])
+      && (code == EQ || code == NE))
+    switch (INTVAL (operands[3]))
+      {
+      case 0:
+	if (TARGET_MINMAX)
+	  {
+	    one_tmp = force_reg (SImode, const1_rtx);
+	    emit_insn (gen_uminsi3 (dest, operands[2], one_tmp));
+	    if (code == EQ)
+	      emit_insn (gen_xorsi3 (dest, dest, one_tmp));
+	    return 1;
+	  }
+	break;
+      case -2147483648:
+	if (TARGET_ABS)
+	  {
+	    emit_insn (gen_abssi2 (dest, operands[2]));
+	    if (code == EQ)
+	      emit_insn (gen_lshrsi3 (dest, dest, GEN_INT (31)));
+	    else
+	      {
+		emit_insn (gen_ashrsi3 (dest, dest, GEN_INT (31)));
+		emit_insn (gen_addsi3 (dest, dest, const1_rtx));
+	      }
+	    return 1;
+	  }
+	break;
+      default:
+	break;
+      }
+
+  if (! (cmp = gen_conditional_move (code, cmp_mode,
+				     operands[2], operands[3])))
     return 0;
 
-  one_tmp = gen_reg_rtx (SImode);
-  zero_tmp = gen_reg_rtx (SImode);
-  emit_insn (gen_movsi (one_tmp, const_true_rtx));
-  emit_insn (gen_movsi (zero_tmp, const0_rtx));
+  one_tmp = force_reg (SImode, const1_rtx);
+  zero_tmp = force_reg (SImode, const0_rtx);
 
   gen_fn = (cmp_mode == SImode
 	    ? gen_movsicc_internal0
diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 5386e45..d6505e7 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -3188,40 +3188,6 @@
 		      (const_int 5)
 		      (const_int 6)))])
 
-
-(define_insn_and_split "*eqne_INT_MIN"
-  [(set (match_operand:SI 0 "register_operand" "=a")
-	(match_operator:SI 2 "boolean_operator"
-		[(match_operand:SI 1 "register_operand" "r")
-		 (const_int -2147483648)]))]
-  "TARGET_ABS"
-  "#"
-  "&& 1"
-  [(set (match_dup 0)
-	(abs:SI (match_dup 1)))
-   (set (match_dup 0)
-	(match_op_dup:SI 2
-		[(match_dup 0)
-		 (const_int 31)]))
-   (match_dup 3)]
-{
-  enum rtx_code code = GET_CODE (operands[2]);
-  operands[2] = gen_rtx_fmt_ee ((code == EQ) ? LSHIFTRT : ASHIFTRT,
-				SImode, XEXP (operands[2], 0),
-				XEXP (operands[2], 1));
-  operands[3] = (code != EQ) ? gen_addsi3 (operands[0],
-					   operands[0], const1_rtx)
-			     : const0_rtx;
-}
-  [(set_attr "type"	"move")
-   (set_attr "mode"	"SI")
-   (set (attr "length")
-	(if_then_else (match_test "GET_CODE (operands[2]) == EQ")
-		      (const_int 3)
-		      (if_then_else (match_test "TARGET_DENSITY")
-				    (const_int 5)
-				    (const_int 6))))])
-
 (define_peephole2
   [(set (match_operand:SI 0 "register_operand")
 	(match_operand:SI 6 "reload_operand"))