[PATCH 4/4] xtensa: Add clrsbsi2 insn pattern

[PATCH 4/4] xtensa: Add clrsbsi2 insn pattern

[Takayuki 'January June' Suwa]

 > (clrsb:m x)
 > Represents the number of redundant leading sign bits in x, represented
 > as an integer of mode m, starting at the most significant bit position.

This explanation is just what the NSA instruction (not ever emitted before)
calculates in Xtensa ISA.

gcc/ChangeLog:

	* config/xtensa/xtensa.md (clrsbsi2): New insn pattern.

libgcc/ChangeLog:

	* config/xtensa/lib1funcs.S (__clrsbsi2): New function.
	* config/xtensa/t-xtensa (LIB1ASMFUNCS): Add _clrsbsi2.
---
  gcc/config/xtensa/xtensa.md      | 12 +++++++++++-
  libgcc/config/xtensa/lib1funcs.S | 23 +++++++++++++++++++++++
  libgcc/config/xtensa/t-xtensa    |  2 +-
  3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 4aa128eab64..dec49cc942b 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -429,7 +429,17 @@
     (set_attr "length"	"3")])

  \f
-;; Count leading/trailing zeros and find first bit.
+;; Count redundant leading sign bits and leading/trailing zeros,
+;; and find first bit.
+
+(define_insn "clrsbsi2"
+  [(set (match_operand:SI 0 "register_operand" "=a")
+	(clrsb:SI (match_operand:SI 1 "register_operand" "r")))]
+  "TARGET_NSA"
+  "nsa\t%0, %1"
+  [(set_attr "type"	"arith")
+   (set_attr "mode"	"SI")
+   (set_attr "length"	"3")])

  (define_insn "clzsi2"
    [(set (match_operand:SI 0 "register_operand" "=a")
diff --git a/libgcc/config/xtensa/lib1funcs.S 
b/libgcc/config/xtensa/lib1funcs.S
index 5a2bd20534f..3932d206256 100644
--- a/libgcc/config/xtensa/lib1funcs.S
+++ b/libgcc/config/xtensa/lib1funcs.S
@@ -456,6 +456,29 @@ __nsau_data:
  #endif /* L_clz */


+#ifdef L_clrsbsi2
+	.align	4
+	.global	__clrsbsi2
+	.type	__clrsbsi2, @function
+__clrsbsi2:
+	leaf_entry sp, 16
+#if XCHAL_HAVE_NSA
+	nsa	a2, a2
+#else
+	srai	a3, a2, 31
+	xor	a3, a3, a2
+	movi	a2, 31
+	beqz	a3, .Lreturn
+	do_nsau	a2, a3, a4, a5
+	addi	a2, a2, -1
+.Lreturn:
+#endif
+	leaf_return
+	.size	__clrsbsi2, . - __clrsbsi2
+
+#endif /* L_clrsbsi2 */
+
+
  #ifdef L_clzsi2
  	.align	4
  	.global	__clzsi2
diff --git a/libgcc/config/xtensa/t-xtensa b/libgcc/config/xtensa/t-xtensa
index 9836c96aefc..084618b382e 100644
--- a/libgcc/config/xtensa/t-xtensa
+++ b/libgcc/config/xtensa/t-xtensa
@@ -1,6 +1,6 @@
  LIB1ASMSRC = xtensa/lib1funcs.S
  LIB1ASMFUNCS = _mulsi3 _divsi3 _modsi3 _udivsi3 _umodsi3 \
-	_umulsidi3 _clz _clzsi2 _ctzsi2 _ffssi2 \
+	_umulsidi3 _clz _clrsbsi2 _clzsi2 _ctzsi2 _ffssi2 \
  	_ashldi3 _ashrdi3 _lshrdi3 \
  	_bswapsi2 _bswapdi2 \
  	_negsf2 _addsubsf3 _mulsf3 _divsf3 _cmpsf2 _fixsfsi _fixsfdi \
-- 
2.20.1

Re: [PATCH 4/4] xtensa: Add clrsbsi2 insn pattern

[Max Filippov]

On Sun, May 29, 2022 at 4:00 AM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
>
>  > (clrsb:m x)
>  > Represents the number of redundant leading sign bits in x, represented
>  > as an integer of mode m, starting at the most significant bit position.
>
> This explanation is just what the NSA instruction (not ever emitted before)
> calculates in Xtensa ISA.
>
> gcc/ChangeLog:
>
>         * config/xtensa/xtensa.md (clrsbsi2): New insn pattern.
>
> libgcc/ChangeLog:
>
>         * config/xtensa/lib1funcs.S (__clrsbsi2): New function.
>         * config/xtensa/t-xtensa (LIB1ASMFUNCS): Add _clrsbsi2.
> ---
>   gcc/config/xtensa/xtensa.md      | 12 +++++++++++-
>   libgcc/config/xtensa/lib1funcs.S | 23 +++++++++++++++++++++++
>   libgcc/config/xtensa/t-xtensa    |  2 +-
>   3 files changed, 35 insertions(+), 2 deletions(-)

Regtested for target=xtensa-linux-uclibc, no new regressions.
Committed to master.

-- 
Thanks.
-- Max