[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v9 10/26] tcg: Add generic helpers for saturating ar
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH v9 10/26] tcg: Add generic helpers for saturating arithmetic |
Date: |
Mon, 15 Jan 2018 19:33:48 -0800 |
No vector ops as yet. SSE only has direct support for 8- and 16-bit
saturation; handling 32- and 64-bit saturation is much more expensive.
Signed-off-by: Richard Henderson <address@hidden>
---
accel/tcg/tcg-runtime.h | 20 ++++
tcg/tcg-op-gvec.h | 10 ++
accel/tcg/tcg-runtime-gvec.c | 268 +++++++++++++++++++++++++++++++++++++++++++
tcg/tcg-op-gvec.c | 92 +++++++++++++++
4 files changed, 390 insertions(+)
diff --git a/accel/tcg/tcg-runtime.h b/accel/tcg/tcg-runtime.h
index d1b3542946..ec187a094b 100644
--- a/accel/tcg/tcg-runtime.h
+++ b/accel/tcg/tcg-runtime.h
@@ -157,6 +157,26 @@ DEF_HELPER_FLAGS_4(gvec_mul16, TCG_CALL_NO_RWG, void, ptr,
ptr, ptr, i32)
DEF_HELPER_FLAGS_4(gvec_mul32, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
DEF_HELPER_FLAGS_4(gvec_mul64, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_ssadd8, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_ssadd16, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_ssadd32, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_ssadd64, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+
+DEF_HELPER_FLAGS_4(gvec_sssub8, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_sssub16, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_sssub32, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_sssub64, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+
+DEF_HELPER_FLAGS_4(gvec_usadd8, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_usadd16, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_usadd32, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_usadd64, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+
+DEF_HELPER_FLAGS_4(gvec_ussub8, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_ussub16, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_ussub32, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_4(gvec_ussub64, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
+
DEF_HELPER_FLAGS_3(gvec_neg8, TCG_CALL_NO_RWG, void, ptr, ptr, i32)
DEF_HELPER_FLAGS_3(gvec_neg16, TCG_CALL_NO_RWG, void, ptr, ptr, i32)
DEF_HELPER_FLAGS_3(gvec_neg32, TCG_CALL_NO_RWG, void, ptr, ptr, i32)
diff --git a/tcg/tcg-op-gvec.h b/tcg/tcg-op-gvec.h
index f716c53be0..98fdab22f6 100644
--- a/tcg/tcg-op-gvec.h
+++ b/tcg/tcg-op-gvec.h
@@ -179,6 +179,16 @@ void tcg_gen_gvec_sub(unsigned vece, uint32_t dofs,
uint32_t aofs,
void tcg_gen_gvec_mul(unsigned vece, uint32_t dofs, uint32_t aofs,
uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+/* Saturated arithmetic. */
+void tcg_gen_gvec_ssadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+void tcg_gen_gvec_sssub(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+void tcg_gen_gvec_usadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+void tcg_gen_gvec_ussub(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
+
void tcg_gen_gvec_and(unsigned vece, uint32_t dofs, uint32_t aofs,
uint32_t bofs, uint32_t oprsz, uint32_t maxsz);
void tcg_gen_gvec_or(unsigned vece, uint32_t dofs, uint32_t aofs,
diff --git a/accel/tcg/tcg-runtime-gvec.c b/accel/tcg/tcg-runtime-gvec.c
index ff26be0744..e84c900670 100644
--- a/accel/tcg/tcg-runtime-gvec.c
+++ b/accel/tcg/tcg-runtime-gvec.c
@@ -614,3 +614,271 @@ DO_EXT(gvec_extu32, uint32_t, uint64_t)
DO_EXT(gvec_exts8, int8_t, int16_t)
DO_EXT(gvec_exts16, int16_t, int32_t)
DO_EXT(gvec_exts32, int32_t, int64_t)
+
+void HELPER(gvec_ssadd8)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(int8_t)) {
+ int r = *(int8_t *)(a + i) + *(int8_t *)(b + i);
+ if (r > INT8_MAX) {
+ r = INT8_MAX;
+ } else if (r < INT8_MIN) {
+ r = INT8_MIN;
+ }
+ *(int8_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_ssadd16)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(int16_t)) {
+ int r = *(int16_t *)(a + i) + *(int16_t *)(b + i);
+ if (r > INT16_MAX) {
+ r = INT16_MAX;
+ } else if (r < INT16_MIN) {
+ r = INT16_MIN;
+ }
+ *(int16_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_ssadd32)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(int32_t)) {
+ int32_t ai = *(int32_t *)(a + i);
+ int32_t bi = *(int32_t *)(b + i);
+ int32_t di = ai + bi;
+ if (((di ^ ai) &~ (ai ^ bi)) < 0) {
+ /* Signed overflow. */
+ di = (di < 0 ? INT32_MAX : INT32_MIN);
+ }
+ *(int32_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_ssadd64)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(int64_t)) {
+ int64_t ai = *(int64_t *)(a + i);
+ int64_t bi = *(int64_t *)(b + i);
+ int64_t di = ai + bi;
+ if (((di ^ ai) &~ (ai ^ bi)) < 0) {
+ /* Signed overflow. */
+ di = (di < 0 ? INT64_MAX : INT64_MIN);
+ }
+ *(int64_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_sssub8)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint8_t)) {
+ int r = *(int8_t *)(a + i) - *(int8_t *)(b + i);
+ if (r > INT8_MAX) {
+ r = INT8_MAX;
+ } else if (r < INT8_MIN) {
+ r = INT8_MIN;
+ }
+ *(uint8_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_sssub16)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(int16_t)) {
+ int r = *(int16_t *)(a + i) - *(int16_t *)(b + i);
+ if (r > INT16_MAX) {
+ r = INT16_MAX;
+ } else if (r < INT16_MIN) {
+ r = INT16_MIN;
+ }
+ *(int16_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_sssub32)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(int32_t)) {
+ int32_t ai = *(int32_t *)(a + i);
+ int32_t bi = *(int32_t *)(b + i);
+ int32_t di = ai - bi;
+ if (((di ^ ai) & (ai ^ bi)) < 0) {
+ /* Signed overflow. */
+ di = (di < 0 ? INT32_MAX : INT32_MIN);
+ }
+ *(int32_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_sssub64)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(int64_t)) {
+ int64_t ai = *(int64_t *)(a + i);
+ int64_t bi = *(int64_t *)(b + i);
+ int64_t di = ai - bi;
+ if (((di ^ ai) & (ai ^ bi)) < 0) {
+ /* Signed overflow. */
+ di = (di < 0 ? INT64_MAX : INT64_MIN);
+ }
+ *(int64_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_usadd8)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint8_t)) {
+ unsigned r = *(uint8_t *)(a + i) + *(uint8_t *)(b + i);
+ if (r > UINT8_MAX) {
+ r = UINT8_MAX;
+ }
+ *(uint8_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_usadd16)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint16_t)) {
+ unsigned r = *(uint16_t *)(a + i) + *(uint16_t *)(b + i);
+ if (r > UINT16_MAX) {
+ r = UINT16_MAX;
+ }
+ *(uint16_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_usadd32)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint32_t)) {
+ uint32_t ai = *(uint32_t *)(a + i);
+ uint32_t bi = *(uint32_t *)(b + i);
+ uint32_t di = ai + bi;
+ if (di < ai) {
+ di = UINT32_MAX;
+ }
+ *(uint32_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_usadd64)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint64_t)) {
+ uint64_t ai = *(uint64_t *)(a + i);
+ uint64_t bi = *(uint64_t *)(b + i);
+ uint64_t di = ai + bi;
+ if (di < ai) {
+ di = UINT64_MAX;
+ }
+ *(uint64_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_ussub8)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint8_t)) {
+ int r = *(uint8_t *)(a + i) - *(uint8_t *)(b + i);
+ if (r < 0) {
+ r = 0;
+ }
+ *(uint8_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_ussub16)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint16_t)) {
+ int r = *(uint16_t *)(a + i) - *(uint16_t *)(b + i);
+ if (r < 0) {
+ r = 0;
+ }
+ *(uint16_t *)(d + i) = r;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_ussub32)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint32_t)) {
+ uint32_t ai = *(uint32_t *)(a + i);
+ uint32_t bi = *(uint32_t *)(b + i);
+ uint32_t di = ai - bi;
+ if (ai < bi) {
+ di = 0;
+ }
+ *(uint32_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
+
+void HELPER(gvec_ussub64)(void *d, void *a, void *b, uint32_t desc)
+{
+ intptr_t oprsz = simd_oprsz(desc);
+ intptr_t i;
+
+ for (i = 0; i < oprsz; i += sizeof(uint64_t)) {
+ uint64_t ai = *(uint64_t *)(a + i);
+ uint64_t bi = *(uint64_t *)(b + i);
+ uint64_t di = ai - bi;
+ if (ai < bi) {
+ di = 0;
+ }
+ *(uint64_t *)(d + i) = di;
+ }
+ clear_high(d, oprsz, desc);
+}
diff --git a/tcg/tcg-op-gvec.c b/tcg/tcg-op-gvec.c
index 2c117a35f1..d65a5b1b82 100644
--- a/tcg/tcg-op-gvec.c
+++ b/tcg/tcg-op-gvec.c
@@ -1291,6 +1291,98 @@ void tcg_gen_gvec_mul(unsigned vece, uint32_t dofs,
uint32_t aofs,
tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
}
+void tcg_gen_gvec_ssadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+ static const GVecGen3 g[4] = {
+ { .fno = gen_helper_gvec_ssadd8, .vece = MO_8 },
+ { .fno = gen_helper_gvec_ssadd16, .vece = MO_16 },
+ { .fno = gen_helper_gvec_ssadd32, .vece = MO_32 },
+ { .fno = gen_helper_gvec_ssadd64, .vece = MO_64 }
+ };
+ tcg_debug_assert(vece <= MO_64);
+ tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
+void tcg_gen_gvec_sssub(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+ static const GVecGen3 g[4] = {
+ { .fno = gen_helper_gvec_sssub8, .vece = MO_8 },
+ { .fno = gen_helper_gvec_sssub16, .vece = MO_16 },
+ { .fno = gen_helper_gvec_sssub32, .vece = MO_32 },
+ { .fno = gen_helper_gvec_sssub64, .vece = MO_64 }
+ };
+ tcg_debug_assert(vece <= MO_64);
+ tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
+static void tcg_gen_vec_usadd32_i32(TCGv_i32 d, TCGv_i32 a, TCGv_i32 b)
+{
+ TCGv_i32 max = tcg_const_i32(-1);
+ tcg_gen_add_i32(d, a, b);
+ tcg_gen_movcond_i32(TCG_COND_LTU, d, d, a, max, d);
+ tcg_temp_free_i32(max);
+}
+
+static void tcg_gen_vec_usadd32_i64(TCGv_i64 d, TCGv_i64 a, TCGv_i64 b)
+{
+ TCGv_i64 max = tcg_const_i64(-1);
+ tcg_gen_add_i64(d, a, b);
+ tcg_gen_movcond_i64(TCG_COND_LTU, d, d, a, max, d);
+ tcg_temp_free_i64(max);
+}
+
+void tcg_gen_gvec_usadd(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+ static const GVecGen3 g[4] = {
+ { .fno = gen_helper_gvec_usadd8, .vece = MO_8 },
+ { .fno = gen_helper_gvec_usadd16, .vece = MO_16 },
+ { .fni4 = tcg_gen_vec_usadd32_i32,
+ .fno = gen_helper_gvec_usadd32,
+ .vece = MO_32 },
+ { .fni8 = tcg_gen_vec_usadd32_i64,
+ .fno = gen_helper_gvec_usadd64,
+ .vece = MO_64 }
+ };
+ tcg_debug_assert(vece <= MO_64);
+ tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
+static void tcg_gen_vec_ussub32_i32(TCGv_i32 d, TCGv_i32 a, TCGv_i32 b)
+{
+ TCGv_i32 min = tcg_const_i32(0);
+ tcg_gen_sub_i32(d, a, b);
+ tcg_gen_movcond_i32(TCG_COND_LTU, d, a, b, min, d);
+ tcg_temp_free_i32(min);
+}
+
+static void tcg_gen_vec_ussub32_i64(TCGv_i64 d, TCGv_i64 a, TCGv_i64 b)
+{
+ TCGv_i64 min = tcg_const_i64(0);
+ tcg_gen_sub_i64(d, a, b);
+ tcg_gen_movcond_i64(TCG_COND_LTU, d, a, b, min, d);
+ tcg_temp_free_i64(min);
+}
+
+void tcg_gen_gvec_ussub(unsigned vece, uint32_t dofs, uint32_t aofs,
+ uint32_t bofs, uint32_t oprsz, uint32_t maxsz)
+{
+ static const GVecGen3 g[4] = {
+ { .fno = gen_helper_gvec_ussub8, .vece = MO_8 },
+ { .fno = gen_helper_gvec_ussub16, .vece = MO_16 },
+ { .fni4 = tcg_gen_vec_ussub32_i32,
+ .fno = gen_helper_gvec_ussub32,
+ .vece = MO_32 },
+ { .fni8 = tcg_gen_vec_ussub32_i64,
+ .fno = gen_helper_gvec_ussub64,
+ .vece = MO_64 }
+ };
+ tcg_debug_assert(vece <= MO_64);
+ tcg_gen_gvec_3(dofs, aofs, bofs, oprsz, maxsz, &g[vece]);
+}
+
/* Perform a vector negation using normal negation and a mask.
Compare gen_subv_mask above. */
static void gen_negv_mask(TCGv_i64 d, TCGv_i64 b, TCGv_i64 m)
--
2.14.3
- [Qemu-devel] [PATCH v9 00/26] tcg: generic vector operations, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 01/26] tcg: Allow multiple word entries into the constant pool, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 03/26] tcg: Standardize integral arguments to expanders, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 02/26] tcg: Add types and basic operations for host vectors, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 05/26] tcg: Add generic vector ops for interleave, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 04/26] tcg: Add generic vector expanders, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 06/26] tcg: Add generic vector ops for constant shifts, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 08/26] tcg: Add generic vector ops for multiplication, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 09/26] tcg: Add generic vector ops for extension, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 07/26] tcg: Add generic vector ops for comparisons, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 10/26] tcg: Add generic helpers for saturating arithmetic,
Richard Henderson <=
- [Qemu-devel] [PATCH v9 11/26] tcg: Loosen vec_gen_op* typecheck rules, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 13/26] tcg: Add generic vector helpers with a scalar variable operand, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 12/26] tcg: Add generic vector helpers with a scalar immediate operand, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 14/26] tcg/optimize: Handle vector opcodes during optimize, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 15/26] target/arm: Align vector registers, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 16/26] target/arm: Use vector infrastructure for aa64 add/sub/logic, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 17/26] target/arm: Use vector infrastructure for aa64 mov/not/neg, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 18/26] target/arm: Use vector infrastructure for aa64 dup/movi, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 19/26] target/arm: Use vector infrastructure for aa64 zip/uzp/trn/xtn, Richard Henderson, 2018/01/15
- [Qemu-devel] [PATCH v9 21/26] target/arm: Use vector infrastructure for aa64 compares, Richard Henderson, 2018/01/15