GIMPLE code which performs a narrowing truncation on the result of a
vector concatenation currently results in an unnecessary XTN being
emitted following a UZP1 to concate the operands. In cases such as this,
UZP1 should instead use a smaller arrangement specifier to replace the
XTN instruction. This is seen in cases such as in this GIMPLE example:
int32x2_t foo (svint64_t a, svint64_t b)
{
vector(2) int vect__2.8;
long int _1;
long int _3;
vector(2) long int _12;
<bb 2> [local count: 1073741824]:
_1 = svaddv_s64 ({ -1, 0, 0, 0, 0, 0, 0, 0, ... }, a_6(D));
_3 = svaddv_s64 ({ -1, 0, 0, 0, 0, 0, 0, 0, ... }, b_7(D));
_12 = {_1, _3};
vect__2.8_13 = (vector(2) int) _12;
return vect__2.8_13;
}
Original assembly generated:
bar:
ptrue p3.b, all
uaddv d0, p3, z0.d
uaddv d1, p3, z1.d
uzp1 v0.2d, v0.2d, v1.2d
xtn v0.2s, v0.2d
ret
This patch therefore defines the *aarch64_trunc_concat<mode> insn which
truncates the concatenation result, rather than concatenating the
truncated operands (such as in *aarch64_narrow_trunc<mode>), resulting
in the following optimised assembly being emitted:
bar:
ptrue p3.b, all
uaddv d0, p3, z0.d
uaddv d1, p3, z1.d
uzp1 v0.2s, v0.2s, v1.2s
ret
This patch passes all regression tests on aarch64 with no new failures.
A supporting test for this optimisation is also written and passes.
OK for master? I do not have commit rights so I cannot push the patch
myself.
gcc/ChangeLog:
* config/aarch64/aarch64-simd.md: (*aarch64_trunc_concat) new
insn definition.
* config/aarch64/iterators.md: (VDQHSD_F): new mode iterator.
(VTRUNCD): new mode attribute for truncated modes.
(Vtruncd): new mode attribute for arrangement specifier.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/sve/truncated_concatenation_1.c: new test
for the above example and the int64x2 version of the above.
---
gcc/config/aarch64/aarch64-simd.md | 16 ++++++++++++++
gcc/config/aarch64/iterators.md | 12 ++++++++++
.../aarch64/sve/truncated_concatenation_1.c | 22 +++++++++++++++++++
3 files changed, 50 insertions(+)
create mode 100644
gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
diff --git a/gcc/config/aarch64/aarch64-simd.md
b/gcc/config/aarch64/aarch64-simd.md
index cfe95bd4c31..de3dd444ecd 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -1872,6 +1872,22 @@
[(set_attr "type" "neon_permute<q>")]
)
+(define_insn "*aarch64_trunc_concat<mode>"
+ [(set (match_operand:<VTRUNCD> 0 "register_operand" "=w")
+ (truncate:<VTRUNCD>
+ (vec_concat:VDQHSD_F
+ (match_operand:<VHALF> 1 "register_operand" "w")
+ (match_operand:<VHALF> 2 "register_operand" "w"))))]
+ "TARGET_SIMD"
+{
+ if (!BYTES_BIG_ENDIAN)
+ return "uzp1\\t%0.<Vtruncd>, %1.<Vtruncd>, %2.<Vtruncd>";
+ else
+ return "uzp1\\t%0.<Vtruncd>, %2.<Vtruncd>, %1.<Vtruncd>";
+}
+ [(set_attr "type" "neon_permute<q>")]
+)
+
;; Packing doubles.
(define_expand "vec_pack_trunc_<mode>"
diff --git a/gcc/config/aarch64/iterators.md b/gcc/config/aarch64/iterators.md
index d7cb27e1885..3b28b2fae0c 100644
--- a/gcc/config/aarch64/iterators.md
+++ b/gcc/config/aarch64/iterators.md
@@ -290,6 +290,10 @@
;; Advanced SIMD modes for H, S and D types.
(define_mode_iterator VDQHSD [V4HI V8HI V2SI V4SI V2DI])
+;; Advanced SIMD modes that can be truncated whilst preserving
+;; the number of vector elements.
+(define_mode_iterator VDQHSD_F [V8HI V4SI V2DI V2SF V4SF V2DF])
+
(define_mode_iterator VDQHSD_V1DI [VDQHSD V1DI])
;; Advanced SIMD and scalar integer modes for H and S.
@@ -1722,6 +1726,14 @@
(define_mode_attr Vnarrowq2 [(V8HI "v16qi") (V4SI "v8hi")
(V2DI "v4si")])
+;; Truncated Advanced SIMD modes which preserve the number of lanes.
+(define_mode_attr VTRUNCD [(V8HI "V8QI") (V4SI "V4HI")
+ (V2SF "V2HF") (V4SF "V4HF")
+ (V2DI "V2SI") (V2DF "V2SF")])
+(define_mode_attr Vtruncd [(V8HI "8b") (V4SI "4h")
+ (V2SF "2h") (V4SF "4h")
+ (V2DI "2s") (V2DF "2s")])
+
;; Narrowed modes of vector modes.
(define_mode_attr VNARROW [(VNx8HI "VNx16QI")
(VNx4SI "VNx8HI") (VNx4SF "VNx8HF")
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
b/gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
new file mode 100644
index 00000000000..e0ad4209206
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -Wall -march=armv8.2-a+sve" } */
+
+#include <arm_neon.h>
+#include <arm_sve.h>
+
+int32x2_t foo (svint64_t a, svint64_t b) {
+ int32x2_t ab = vdup_n_s32 (0);
+ ab = vset_lane_s32 ((int)svaddv_s64 (svptrue_b64 (), a), ab, 0);
+ ab = vset_lane_s32 ((int)svaddv_s64 (svptrue_b64 (), b), ab, 1);
+ return ab;
+}
+
+int64x2_t bar (svint64_t a, svint64_t b) {
+ int64x2_t ab = vdupq_n_s64(0);
+ ab = vsetq_lane_s64 ((int)svaddv_s64 (svptrue_b64 (), a), ab, 0);
+ ab = vsetq_lane_s64 ((int)svaddv_s64 (svptrue_b64 (), b), ab, 1);
+ return ab;
+}
+
+/* { dg-final { scan-assembler-not {\txtn\t} } }*/
+/* { dg-final { scan-assembler-times {\tuzp1\tv[0-9]+\.2s, v[0-9]+\.2s,
v[0-9]+\.2s} 2 } }*/
\ No newline at end of file
--
2.34.1
