Hi All,
When doing a (narrowing) right shift by half the width of the original type then
we are essentially shuffling the top bits from the first number down.
If we have a hi/lo pair we can just use a single shuffle instead of needing two
shifts.
i.e.
typedef short int16_t;
typedef unsigned short uint16_t;
void foo (uint16_t * restrict a, int16_t * restrict d, int n)
{
for( int i = 0; i < n; i++ )
d[i] = (a[i] * a[i]) >> 16;
}
now generates:
.L4:
ldr q0, [x0, x3]
umull v1.4s, v0.4h, v0.4h
umull2 v0.4s, v0.8h, v0.8h
uzp2 v0.8h, v1.8h, v0.8h
str q0, [x1, x3]
add x3, x3, 16
cmp x4, x3
bne .L4
instead of
.L4:
ldr q0, [x0, x3]
umull v1.4s, v0.4h, v0.4h
umull2 v0.4s, v0.8h, v0.8h
sshr v1.4s, v1.4s, 16
sshr v0.4s, v0.4s, 16
xtn v1.4h, v1.4s
xtn2 v1.8h, v0.4s
str q1, [x1, x3]
add x3, x3, 16
cmp x4, x3
bne .L4
Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
Ok for master?
Thanks,
Tamar
gcc/ChangeLog:
* config/aarch64/aarch64-simd.md
(*aarch64_<srn_op>topbits_shuffle<mode>,
*aarch64_topbits_shuffle<mode>): New.
* config/aarch64/predicates.md
(aarch64_simd_shift_imm_vec_exact_top): New.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/shrn-combine-2.c: New test.
* gcc.target/aarch64/shrn-combine-3.c: New test.
--- inline copy of patch --
diff --git a/gcc/config/aarch64/aarch64-simd.md
b/gcc/config/aarch64/aarch64-simd.md
index
d7b6cae424622d259f97a3d5fa9093c0fb0bd5ce..300bf001b59ca7fa197c580b10adb7f70f20d1e0
100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -1840,6 +1840,36 @@ (define_insn "*aarch64_<srn_op>shrn<mode>2_vect"
[(set_attr "type" "neon_shift_imm_narrow_q")]
)
+(define_insn "*aarch64_<srn_op>topbits_shuffle<mode>"
+ [(set (match_operand:<VNARROWQ2> 0 "register_operand" "=w")
+ (vec_concat:<VNARROWQ2>
+ (truncate:<VNARROWQ>
+ (SHIFTRT:VQN (match_operand:VQN 1 "register_operand" "w")
+ (match_operand:VQN 2 "aarch64_simd_shift_imm_vec_exact_top")))
+ (truncate:<VNARROWQ>
+ (SHIFTRT:VQN (match_operand:VQN 3 "register_operand" "w")
+ (match_dup 2)))))]
+ "TARGET_SIMD"
+ "uzp2\\t%0.<V2ntype>, %1.<V2ntype>, %3.<V2ntype>"
+ [(set_attr "type" "neon_permute<q>")]
+)
+
+(define_insn "*aarch64_topbits_shuffle<mode>"
+ [(set (match_operand:<VNARROWQ2> 0 "register_operand" "=w")
+ (vec_concat:<VNARROWQ2>
+ (unspec:<VNARROWQ> [
+ (match_operand:VQN 1 "register_operand" "w")
+ (match_operand:VQN 2 "aarch64_simd_shift_imm_vec_exact_top")
+ ] UNSPEC_RSHRN)
+ (unspec:<VNARROWQ> [
+ (match_operand:VQN 3 "register_operand" "w")
+ (match_dup 2)
+ ] UNSPEC_RSHRN)))]
+ "TARGET_SIMD"
+ "uzp2\\t%0.<V2ntype>, %1.<V2ntype>, %3.<V2ntype>"
+ [(set_attr "type" "neon_permute<q>")]
+)
+
(define_expand "aarch64_shrn<mode>"
[(set (match_operand:<VNARROWQ> 0 "register_operand")
(truncate:<VNARROWQ>
diff --git a/gcc/config/aarch64/predicates.md b/gcc/config/aarch64/predicates.md
index
49f02ae0381359174fed80c2a2264295c75bc189..7fd4f9e7d06d3082d6f3047290f0446789e1d0d2
100644
--- a/gcc/config/aarch64/predicates.md
+++ b/gcc/config/aarch64/predicates.md
@@ -545,6 +545,12 @@ (define_predicate "aarch64_simd_shift_imm_offset_di"
(and (match_code "const_int")
(match_test "IN_RANGE (INTVAL (op), 1, 64)")))
+(define_predicate "aarch64_simd_shift_imm_vec_exact_top"
+ (and (match_code "const_vector")
+ (match_test "aarch64_const_vec_all_same_in_range_p (op,
+ GET_MODE_UNIT_BITSIZE (GET_MODE (op)) / 2,
+ GET_MODE_UNIT_BITSIZE (GET_MODE (op)) / 2)")))
+
(define_predicate "aarch64_simd_shift_imm_vec_qi"
(and (match_code "const_vector")
(match_test "aarch64_const_vec_all_same_in_range_p (op, 1, 8)")))
diff --git a/gcc/testsuite/gcc.target/aarch64/shrn-combine-2.c
b/gcc/testsuite/gcc.target/aarch64/shrn-combine-2.c
new file mode 100644
index
0000000000000000000000000000000000000000..924b3b849e449082b8c0b7dc6b955a2bad8d0911
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/shrn-combine-2.c
@@ -0,0 +1,15 @@
+/* { dg-do assemble } */
+/* { dg-options "-O3 --save-temps --param=vect-epilogues-nomask=0" } */
+
+typedef short int16_t;
+typedef unsigned short uint16_t;
+
+void foo (uint16_t * restrict a, int16_t * restrict d, int n)
+{
+ for( int i = 0; i < n; i++ )
+ d[i] = (a[i] * a[i]) >> 16;
+}
+
+/* { dg-final { scan-assembler-times {\tuzp2\t} 1 } } */
+/* { dg-final { scan-assembler-not {\tshrn\t} } } */
+/* { dg-final { scan-assembler-not {\tshrn2\t} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/shrn-combine-3.c
b/gcc/testsuite/gcc.target/aarch64/shrn-combine-3.c
new file mode 100644
index
0000000000000000000000000000000000000000..929a55c5c338844e6a5c5ad249af482286ab9c61
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/shrn-combine-3.c
@@ -0,0 +1,14 @@
+/* { dg-do assemble } */
+/* { dg-options "-O3 --save-temps --param=vect-epilogues-nomask=0" } */
+
+
+#include <arm_neon.h>
+
+uint16x8_t foo (uint32x4_t a, uint32x4_t b)
+{
+ return vrshrn_high_n_u32 (vrshrn_n_u32 (a, 16), b, 16);
+}
+
+/* { dg-final { scan-assembler-times {\tuzp2\t} 1 } } */
+/* { dg-final { scan-assembler-not {\tshrn\t} } } */
+/* { dg-final { scan-assembler-not {\tshrn2\t} } } */
--
diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index d7b6cae424622d259f97a3d5fa9093c0fb0bd5ce..300bf001b59ca7fa197c580b10adb7f70f20d1e0 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -1840,6 +1840,36 @@ (define_insn "*aarch64_<srn_op>shrn<mode>2_vect"
[(set_attr "type" "neon_shift_imm_narrow_q")]
)
+(define_insn "*aarch64_<srn_op>topbits_shuffle<mode>"
+ [(set (match_operand:<VNARROWQ2> 0 "register_operand" "=w")
+ (vec_concat:<VNARROWQ2>
+ (truncate:<VNARROWQ>
+ (SHIFTRT:VQN (match_operand:VQN 1 "register_operand" "w")
+ (match_operand:VQN 2 "aarch64_simd_shift_imm_vec_exact_top")))
+ (truncate:<VNARROWQ>
+ (SHIFTRT:VQN (match_operand:VQN 3 "register_operand" "w")
+ (match_dup 2)))))]
+ "TARGET_SIMD"
+ "uzp2\\t%0.<V2ntype>, %1.<V2ntype>, %3.<V2ntype>"
+ [(set_attr "type" "neon_permute<q>")]
+)
+
+(define_insn "*aarch64_topbits_shuffle<mode>"
+ [(set (match_operand:<VNARROWQ2> 0 "register_operand" "=w")
+ (vec_concat:<VNARROWQ2>
+ (unspec:<VNARROWQ> [
+ (match_operand:VQN 1 "register_operand" "w")
+ (match_operand:VQN 2 "aarch64_simd_shift_imm_vec_exact_top")
+ ] UNSPEC_RSHRN)
+ (unspec:<VNARROWQ> [
+ (match_operand:VQN 3 "register_operand" "w")
+ (match_dup 2)
+ ] UNSPEC_RSHRN)))]
+ "TARGET_SIMD"
+ "uzp2\\t%0.<V2ntype>, %1.<V2ntype>, %3.<V2ntype>"
+ [(set_attr "type" "neon_permute<q>")]
+)
+
(define_expand "aarch64_shrn<mode>"
[(set (match_operand:<VNARROWQ> 0 "register_operand")
(truncate:<VNARROWQ>
diff --git a/gcc/config/aarch64/predicates.md b/gcc/config/aarch64/predicates.md
index 49f02ae0381359174fed80c2a2264295c75bc189..7fd4f9e7d06d3082d6f3047290f0446789e1d0d2 100644
--- a/gcc/config/aarch64/predicates.md
+++ b/gcc/config/aarch64/predicates.md
@@ -545,6 +545,12 @@ (define_predicate "aarch64_simd_shift_imm_offset_di"
(and (match_code "const_int")
(match_test "IN_RANGE (INTVAL (op), 1, 64)")))
+(define_predicate "aarch64_simd_shift_imm_vec_exact_top"
+ (and (match_code "const_vector")
+ (match_test "aarch64_const_vec_all_same_in_range_p (op,
+ GET_MODE_UNIT_BITSIZE (GET_MODE (op)) / 2,
+ GET_MODE_UNIT_BITSIZE (GET_MODE (op)) / 2)")))
+
(define_predicate "aarch64_simd_shift_imm_vec_qi"
(and (match_code "const_vector")
(match_test "aarch64_const_vec_all_same_in_range_p (op, 1, 8)")))
diff --git a/gcc/testsuite/gcc.target/aarch64/shrn-combine-2.c b/gcc/testsuite/gcc.target/aarch64/shrn-combine-2.c
new file mode 100644
index 0000000000000000000000000000000000000000..924b3b849e449082b8c0b7dc6b955a2bad8d0911
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/shrn-combine-2.c
@@ -0,0 +1,15 @@
+/* { dg-do assemble } */
+/* { dg-options "-O3 --save-temps --param=vect-epilogues-nomask=0" } */
+
+typedef short int16_t;
+typedef unsigned short uint16_t;
+
+void foo (uint16_t * restrict a, int16_t * restrict d, int n)
+{
+ for( int i = 0; i < n; i++ )
+ d[i] = (a[i] * a[i]) >> 16;
+}
+
+/* { dg-final { scan-assembler-times {\tuzp2\t} 1 } } */
+/* { dg-final { scan-assembler-not {\tshrn\t} } } */
+/* { dg-final { scan-assembler-not {\tshrn2\t} } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/shrn-combine-3.c b/gcc/testsuite/gcc.target/aarch64/shrn-combine-3.c
new file mode 100644
index 0000000000000000000000000000000000000000..929a55c5c338844e6a5c5ad249af482286ab9c61
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/shrn-combine-3.c
@@ -0,0 +1,14 @@
+/* { dg-do assemble } */
+/* { dg-options "-O3 --save-temps --param=vect-epilogues-nomask=0" } */
+
+
+#include <arm_neon.h>
+
+uint16x8_t foo (uint32x4_t a, uint32x4_t b)
+{
+ return vrshrn_high_n_u32 (vrshrn_n_u32 (a, 16), b, 16);
+}
+
+/* { dg-final { scan-assembler-times {\tuzp2\t} 1 } } */
+/* { dg-final { scan-assembler-not {\tshrn\t} } } */
+/* { dg-final { scan-assembler-not {\tshrn2\t} } } */
