RISC-V: Support noce_try_store_flag_mask as vt.maskc<n>

When if-conversion in noce_try_store_flag_mask starts the sequence off
with an order-operator, our patterns for vt.maskc<n> will receive the
result of the order-operator as a register argument; consequently,
they can't know that the result will be either 1 or 0.

To convey this information (and make vt.maskc<n> applicable), we wrap
the result of the order-operator in a eq/ne against (const_int 0).
This commit adds the split pattern to handle these cases.

gcc/ChangeLog:

	* config/riscv/xventanacondops.md: Add split to wrap an an
          order-operator suitably for generating vt.maskc<n>.

Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>

Ref vrull/gcc#157

RISC-V: Recognize 'ge<u>'/'le<u>' operators as 'slt<u>'/'sgt<u>'

During if-conversion, if noce_try_store_flag_mask succeeds, we may see
    if (cur < next) {
        next = 0;
    }
transformed into
   27: r82:SI=ltu(r76:DI,r75:DI)
      REG_DEAD r76:DI
   28: r81:SI=r82:SI^0x1
      REG_DEAD r82:SI
   29: r80:DI=zero_extend(r81:SI)
      REG_DEAD r81:SI

This currently escapes the combiner, as RISC-V does not have a pattern
to apply the 'slt' instruction to 'geu' verbs.  By adding a pattern in
this commit, we match such cases.

gcc/ChangeLog:

	* config/riscv/predicates.md (anyge_operator): Define.
	(anygt_operator): Define.
	(anyle_operator): Define.
	(anylt_operator): Define.
	* config/riscv/riscv.md (*sge<u>_<X:mode><GPR:mode>): Add a
	  pattern to map 'geu' onto slt w/ reversed operands.
	* config/riscv/riscv.md: Helpers for ge & le.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/xventanacondops-le-01.c: New test.
	* gcc.target/riscv/xventanacondops-lt-03.c: New test.

gcc/config/riscv/predicates.md

@@ -200,6 +200,18 @@
 (define_predicate "equality_operator"
   (match_code "eq,ne"))
 
+(define_predicate "anyge_operator"
+  (match_code "ge,geu"))
+
+(define_predicate "anygt_operator"
+  (match_code "gt,gtu"))
+
+(define_predicate "anyle_operator"
+  (match_code "le,leu"))
+
+(define_predicate "anylt_operator"
+  (match_code "lt,ltu"))
+
 (define_predicate "order_operator"
   (match_code "eq,ne,lt,ltu,le,leu,ge,geu,gt,gtu"))
 

gcc/config/riscv/riscv.md

@@ -2449,6 +2449,19 @@
   [(set_attr "type" "slt")
    (set_attr "mode" "<X:MODE>")])
 
+(define_split
+  [(set (match_operand:GPR 0 "register_operand")
+	(match_operator:GPR 1 "anyle_operator"
+	       [(match_operand:X 2 "register_operand")
+		(match_operand:X 3 "register_operand")]))]
+  "TARGET_XVENTANACONDOPS"
+  [(set (match_dup 0) (match_dup 4))
+   (set (match_dup 0) (eq:GPR (match_dup 0) (const_int 0)))]
+ {
+  operands[4] = gen_rtx_fmt_ee (GET_CODE (operands[1]) == LE ? LT : LTU,
+				<GPR:MODE>mode, operands[3], operands[2]);
+ })
+
 (define_insn "*slt<u>_<X:mode><GPR:mode>"
   [(set (match_operand:GPR           0 "register_operand" "= r")
 	(any_lt:GPR (match_operand:X 1 "register_operand" "  r")
@@ -2470,6 +2483,19 @@
   [(set_attr "type" "slt")
    (set_attr "mode" "<X:MODE>")])
 
+(define_split
+  [(set (match_operand:GPR 0 "register_operand")
+	(match_operator:GPR 1 "anyge_operator"
+	       [(match_operand:X 2 "register_operand")
+		(match_operand:X 3 "register_operand")]))]
+  "TARGET_XVENTANACONDOPS"
+  [(set (match_dup 0) (match_dup 4))
+   (set (match_dup 0) (eq:GPR (match_dup 0) (const_int 0)))]
+{
+  operands[4] = gen_rtx_fmt_ee (GET_CODE (operands[1]) == GE ? LT : LTU,
+				<GPR:MODE>mode, operands[2], operands[3]);
+})
+
 ;;
 ;;  ....................
 ;;

gcc/config/riscv/xventanacondops.md

@@ -28,3 +28,48 @@
 		(match_operand:DI 2 "register_operand" "r")))]
   "TARGET_XVENTANACONDOPS"
   "vt.maskc<n>\t%0,%2,%1")
+
+;; Make order operators digestible to the vt.maskc<n> logic by
+;; wrapping their result in a comparison against (const_int 0).
+
+;; "a >= b" is "!(a < b)"
+(define_split
+  [(set (match_operand:X 0 "register_operand")
+	(and:X (neg:X (match_operator:X 1 "anyge_operator"
+			     [(match_operand:X 2 "register_operand")
+			      (match_operand:X 3 "register_operand")]))
+	       (match_operand:X 4 "register_operand")))
+   (clobber (match_operand:X 5 "register_operand"))]
+  "TARGET_XVENTANACONDOPS"
+  [(set (match_dup 5) (match_dup 6))
+   (set (match_dup 0) (and:X (neg:X (eq:X (match_dup 5) (const_int 0)))
+			     (match_dup 4)))]
+{
+  operands[6] = gen_rtx_fmt_ee (GET_CODE (operands[1]) == GE ? LT : LTU,
+				<X:MODE>mode, operands[2], operands[3]);
+})
+
+;; "a > b"
+(define_split
+  [(set (match_operand:X 0 "register_operand")
+	(and:X (neg:X (match_operator:X 1 "anygt_operator"
+			     [(match_operand:X 2 "register_operand")
+			      (match_operand:X 3 "register_operand")]))
+	       (match_operand:X 4 "register_operand")))
+   (clobber (match_operand:X 5 "register_operand"))]
+  "TARGET_XVENTANACONDOPS"
+  [(set (match_dup 5) (match_dup 1))
+   (set (match_dup 0) (and:X (neg:X (ne:X (match_dup 5) (const_int 0)))
+			     (match_dup 4)))])
+
+;; "a <= b" is "!(a > b)"
+(define_split
+  [(set (match_operand:X 0 "register_operand")
+	(and:X (neg:X (match_operator:X 1 "anyle_operator"
+			     [(match_operand:X 2 "register_operand")
+			      (match_operand:X 3 "arith_operand")]))
+	       (match_operand:X 4 "register_operand")))
+   (clobber (match_operand:X 5 "register_operand"))]
+  "TARGET_XVENTANACONDOPS"
+  [(set (match_dup 5) (match_dup 1))
+   (set (match_dup 0) (and:X (neg:X (ne:X (match_dup 5) (const_int 0)))

gcc/testsuite/gcc.target/riscv/xventanacondops-le-01.c

@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc_zba_zbb_zbs_xventanacondops -mabi=lp64 -mbranch-cost=4" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-O1" "-Os" "-Oz"  } } */
+
+long long sink (long long);
+
+long long lt3 (long long a, long long b)
+{
+  if (a <= b) 
+    b = 0;
+
+  return sink(b);
+}
+
+/* { dg-final { scan-assembler-times "sgt\t" 1 } } */
+/* { dg-final { scan-assembler-times "vt.maskc\t" 1 } } */
+

gcc/testsuite/gcc.target/riscv/xventanacondops-lt-03.c

@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc_zba_zbb_zbs_xventanacondops -mabi=lp64 -mbranch-cost=4" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-O1" "-Os" "-Oz"  } } */
+
+long long sink (long long);
+
+long long lt3 (long long a, long long b)
+{
+  if (a < b) 
+    b = 0;
+
+  return sink(b);
+}
+
+/* { dg-final { scan-assembler-times "slt\t" 1 } } */
+/* { dg-final { scan-assembler-times "vt.maskcn\t" 1 } } */
+