[RFC PATCH v1 03/10] RISC-V: Generate czero.eqz/nez on noce_try_store_flag_mask if-conversion

[Philipp Tomsich <philipp.tomsich@vrull.eu>]

Adds a pattern to map the output of noce_try_store_flag_mask
if-conversion in the combiner onto vt.maskc<n>; the input patterns
supported are similar to the following:
  (set (reg/v/f:DI 75 [ <retval> ])
       (and:DI (neg:DI (ne:DI (reg:DI 82)
		       (const_int 0 [0])))
	       (reg/v/f:DI 75 [ <retval> ])))

To ensure that the combine-pass doesn't get confused about
profitability, we recognize the idiom as requiring a single
instruction when the Zicond extension is present.

gcc/ChangeLog:

	* config/riscv/riscv.cc (riscv_rtx_costs): Recongnize the idiom
	for conditional-zero as a single instruction for TARGET_ZICOND
	* config/riscv/riscv.md: Include zicond.md.
	* config/riscv/zicond.md: New file.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/zicond-ne-03.c: New test.
	* gcc.target/riscv/zicond-ne-04.c: New test.

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

 gcc/config/riscv/riscv.cc                     | 15 ++++++++++
 gcc/config/riscv/riscv.md                     |  1 +
 gcc/config/riscv/zicond.md                    | 30 +++++++++++++++++++
 gcc/testsuite/gcc.target/riscv/zicond-ne-03.c | 13 ++++++++
 gcc/testsuite/gcc.target/riscv/zicond-ne-04.c | 13 ++++++++
 5 files changed, 72 insertions(+)
 create mode 100644 gcc/config/riscv/zicond.md
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-ne-03.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/zicond-ne-04.c

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index e4d3e1a3229..7e69a652fc5 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -2331,6 +2331,21 @@ riscv_rtx_costs (rtx x, machine_mode mode, int outer_code, int opno ATTRIBUTE_UN
       return false;
 
     case AND:
+      /* czero.eqz/nez */
+      if ((TARGET_ZICOND)
+	  && mode == word_mode
+	  && GET_CODE (XEXP (x, 0)) == NEG)
+	{
+	  rtx inner = XEXP (XEXP (x, 0), 0);
+
+	  if ((GET_CODE (inner) == EQ || GET_CODE (inner) == NE)
+	      && CONST_INT_P (XEXP (inner, 1))
+	      && INTVAL (XEXP (inner, 1)) == 0)
+	    {
+	      *total = COSTS_N_INSNS (1);
+	      return true;
+	    }
+	}
       /* slli.uw pattern for zba.  */
       if (TARGET_ZBA && TARGET_64BIT && mode == DImode
 	  && GET_CODE (XEXP (x, 0)) == ASHIFT)
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index e8b5fc6644d..7c632bb4d65 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -3228,3 +3228,4 @@ (define_insn "riscv_prefetchi_<mode>"
 (include "generic.md")
 (include "sifive-7.md")
 (include "vector.md")
+(include "zicond.md")
diff --git a/gcc/config/riscv/zicond.md b/gcc/config/riscv/zicond.md
new file mode 100644
index 00000000000..278e3a67802
--- /dev/null
+++ b/gcc/config/riscv/zicond.md
@@ -0,0 +1,30 @@
+;; Machine description for the RISC-V Zicond extension
+;; Copyright (C) 2022-23 Free Software Foundation, Inc.
+
+;; This file is part of GCC.
+
+;; GCC is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+
+;; GCC is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GCC; see the file COPYING3.  If not see
+;; <http://www.gnu.org/licenses/>.
+
+(define_code_iterator eq_or_ne [eq ne])
+(define_code_attr eqz [(eq "nez") (ne "eqz")])
+
+(define_insn "*czero.<eqz>"
+  [(set (match_operand:DI 0 "register_operand" "=r")
+	(and:DI (neg:DI (eq_or_ne:DI
+			(match_operand:DI 1 "register_operand" "r")
+			(const_int 0)))
+		(match_operand:DI 2 "register_operand" "r")))]
+  "TARGET_ZICOND"
+  "czero.<eqz>\t%0,%2,%1")
diff --git a/gcc/testsuite/gcc.target/riscv/zicond-ne-03.c b/gcc/testsuite/gcc.target/riscv/zicond-ne-03.c
new file mode 100644
index 00000000000..887b1273ce7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/zicond-ne-03.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc_zicond -mabi=lp64 -mtune=thead-c906" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-O1" "-Os" "-Oz" } } */
+
+long long ne3(long long a, long long b)
+{
+  if (a != 0)
+    return b;
+
+  return 0;
+}
+
+/* { dg-final { scan-assembler-times "czero.eqz" 1 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/zicond-ne-04.c b/gcc/testsuite/gcc.target/riscv/zicond-ne-04.c
new file mode 100644
index 00000000000..6f6df06b4b9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/zicond-ne-04.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc_zicond -mabi=lp64 -mtune=thead-c906" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-Os" "-Oz" } } */
+
+long long ne4(long long a, long long b)
+{
+  if (a != 0)
+    return 0;
+
+  return b;
+}
+
+/* { dg-final { scan-assembler-times "czero.nez" 1 } } */
-- 
2.34.1