[PATCH v8 12/17] hppa: Add memcopy.h

[Richard Henderson <richard.henderson@linaro.org>]

GCC's combine pass cannot merge (x >> c | y << (32 - c)) into a
double-word shift unless (1) the subtract is in the same basic block
and (2) the result of the subtract is used exactly once.  Neither
condition is true for any use of MERGE.

By forcing the use of a double-word shift, we not only reduce
contention on SAR, but also allow the setting of SAR to be hoisted
outside of a loop.

Checked on hppa-linux-gnu.
Message-Id: <20230111204558.2402155-13-adhemerval.zanella@linaro.org>
---
 sysdeps/hppa/memcopy.h | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 sysdeps/hppa/memcopy.h

diff --git a/sysdeps/hppa/memcopy.h b/sysdeps/hppa/memcopy.h
new file mode 100644
index 0000000000..0d4b4ac435
--- /dev/null
+++ b/sysdeps/hppa/memcopy.h
@@ -0,0 +1,42 @@
+/* Definitions for memory copy functions, PA-RISC version.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdeps/generic/memcopy.h>
+
+/* Use a single double-word shift instead of two shifts and an ior.
+   If the uses of MERGE were close to the computation of shl/shr,
+   the compiler might have been able to create this itself.
+   But instead that computation is well separated.
+
+   Using an inline function instead of a macro is the easiest way
+   to ensure that the types are correct.  */
+
+#undef MERGE
+
+static __always_inline op_t
+MERGE (op_t w0, int shl, op_t w1, int shr)
+{
+  _Static_assert (OPSIZ == 4 || OPSIZ == 8, "Invalid OPSIZE");
+
+  op_t res;
+  if (OPSIZ == 4)
+    asm ("shrpw %1,%2,%%sar,%0" : "=r"(res) : "r"(w0), "r"(w1), "q"(shr));
+  else if (OPSIZ == 8)
+    asm ("shrpd %1,%2,%%sar,%0" : "=r"(res) : "r"(w0), "r"(w1), "q"(shr));
+  return res;
+}
-- 
2.34.1