> (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")])
-;; 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
