On Thu, 2026-06-18 at 06:33 +0800, Xi Ruoyao wrote:
> A hot loop in SPEC 2026 stockfish_r calculates the dot product of a
> sign-extended vector and a zero-extended vector. Add the corresponding
> usdot_prod pattern to use the instructions with such a semantic, for
> example xvmulwev.h.bu.b, to optimize the loop.
>
> PR target/125474
>
> gcc/
>
> * config/loongarch/simd.md (usdot_prod<wvec_half><mode>): New
> define_expand.
> (usdot_prod<wvec_quarter><mode>): New define_expand.
>
> gcc/testsuite/
>
> * gcc.target/loongarch/vector/lasx/dot-prod-mixed-signedness.c:
> New test.
> ---
>
> Change from v1: rewrite the test in C and put it into
> gcc.target/loongarch/vector/lasx.
>
> Bootstrapped and regtested on loongarch64-linux-gnu. Ok for trunk?
Ping.
>
> gcc/config/loongarch/simd.md | 54 ++++++++++++++++
> .../vector/lasx/dot-prod-mixed-signedness.c | 63 +++++++++++++++++++
> 2 files changed, 117 insertions(+)
> create mode 100644
> gcc/testsuite/gcc.target/loongarch/vector/lasx/dot-prod-mixed-signedness.c
>
> diff --git a/gcc/config/loongarch/simd.md b/gcc/config/loongarch/simd.md
> index 377e94fb356..09e746c56e7 100644
> --- a/gcc/config/loongarch/simd.md
> +++ b/gcc/config/loongarch/simd.md
> @@ -934,6 +934,60 @@ (define_expand
> "<simd_isa>_<x>vmaddw<ev_od>_<simdfmt_w>_<simdfmt>u_<simdfmt>"
> DONE;
> })
>
> +(define_expand "usdot_prod<wvec_half><mode>"
> + [(match_operand:<WVEC_HALF> 0 "register_operand")
> + (match_operand:IVEC 1 "register_operand")
> + (match_operand:IVEC 2 "register_operand")
> + (match_operand:<WVEC_HALF> 3 "reg_or_0_operand")]
> + ""
> +{
> + rtx *op = operands;
> +
> + if (op[3] == CONST0_RTX (<WVEC_HALF>mode))
> + emit_insn (
> + gen_<simd_isa>_<x>vmulwev_<simdfmt_w>_<simdfmt>u_<simdfmt> (
> + op[0], op[1], op[2]));
> + else
> + emit_insn (
> + gen_<simd_isa>_<x>vmaddwev_<simdfmt_w>_<simdfmt>u_<simdfmt> (
> + op[0], op[3], op[1], op[2]));
> +
> + emit_insn (
> + gen_<simd_isa>_<x>vmaddwod_<simdfmt_w>_<simdfmt>u_<simdfmt> (
> + op[0], op[0], op[1], op[2]));
> + DONE;
> +})
> +
> +(define_expand "usdot_prod<wvec_quarter><mode>"
> + [(match_operand:<WVEC_QUARTER> 0 "register_operand")
> + (match_operand:IVEC_HB 1 "register_operand")
> + (match_operand:IVEC_HB 2 "register_operand")
> + (match_operand:<WVEC_QUARTER> 3 "reg_or_0_operand")]
> + ""
> +{
> + rtx *op = operands;
> + rtx res_mulev = gen_reg_rtx (<WVEC_HALF>mode);
> + rtx res_mulod = gen_reg_rtx (<WVEC_HALF>mode);
> + rtx res_addev = gen_reg_rtx (<WVEC_QUARTER>mode);
> + rtx res_addod = gen_reg_rtx (<WVEC_QUARTER>mode);
> + emit_insn (gen_<simd_isa>_<x>vmulwev_<simdfmt_w>_<simdfmt>u_<simdfmt>
> + (res_mulev, op[1], op[2]));
> + emit_insn (gen_<simd_isa>_<x>vmulwod_<simdfmt_w>_<simdfmt>u_<simdfmt>
> + (res_mulod, op[1], op[2]));
> + emit_insn (gen_<simd_isa>_<x>vhaddw_<simdfmt_qw>_<simdfmt_w>
> + (res_addev, res_mulev, res_mulev));
> + emit_insn (gen_<simd_isa>_<x>vhaddw_<simdfmt_qw>_<simdfmt_w>
> + (res_addod, res_mulod, res_mulod));
> +
> + rtx sum = gen_rtx_PLUS (<WVEC_QUARTER>mode, res_addev, res_addod);
> + if (op[3] == CONST0_RTX (<WVEC_QUARTER>mode))
> + emit_move_insn (op[0], sum);
> + else
> + emit_insn (gen_add<wvec_quarter>3 (
> + op[0], force_reg (<WVEC_QUARTER>mode, sum), op[3]));
> + DONE;
> +})
> +
> ; For "historical" reason we need a punned version of q_d variants.
> (define_mode_iterator DIVEC [(V2DI "ISA_HAS_LSX") (V4DI "ISA_HAS_LASX")])
>
> diff --git
> a/gcc/testsuite/gcc.target/loongarch/vector/lasx/dot-prod-mixed-signedness.c
> b/gcc/testsuite/gcc.target/loongarch/vector/lasx/dot-prod-mixed-signedness.c
> new file mode 100644
> index 00000000000..d5f42ebdc96
> --- /dev/null
> +++
> b/gcc/testsuite/gcc.target/loongarch/vector/lasx/dot-prod-mixed-signedness.c
> @@ -0,0 +1,63 @@
> +/* { dg-options "-O3 -mlasx -fno-unroll-loops -fdump-tree-optimized" } */
> +/* { dg-final { scan-tree-dump-times "DOT_PROD_EXPR" 1 "optimized" } } */
> +
> +typedef unsigned int uint32_t;
> +typedef int int32_t;
> +typedef unsigned char uint8_t;
> +typedef char int8_t;
> +typedef uint32_t IndexType;
> +
> +[[gnu::noipa]]
> +void transform(int32_t *__restrict__ output, const int8_t *weights,
> + const int32_t *biases, const uint8_t *input) {
> + for (IndexType i = 0; i < 0x10; ++i) {
> + const IndexType offset = i * 0x1000;
> +
> + int32_t sum = biases[i];
> + for (IndexType j = 0; j < 0x1000; ++j) {
> + sum += weights[offset + j] * input[j];
> + }
> + output[i] = sum;
> + }
> +}
> +
> +[[gnu::noipa]]
> +void transform_novec(int32_t *__restrict__ output,
> + const int8_t *weights,
> + const int32_t *biases,
> + const uint8_t *input) {
> +#pragma GCC novector
> + for (IndexType i = 0; i < 0x10; ++i) {
> + const IndexType offset = i * 0x1000;
> +
> + int32_t sum = biases[i];
> +#pragma GCC novector
> + for (IndexType j = 0; j < 0x1000; ++j) {
> + sum += weights[offset + j] * input[j];
> + }
> + output[i] = sum;
> + }
> +}
> +
> +int8_t w[0x11000];
> +uint8_t in[0x1000];
> +int32_t out[0x10];
> +int32_t out_novec[0x10];
> +int32_t b[0x10];
> +
> +int
> +main ()
> +{
> + for (unsigned i = 0; i < 0x11000; i++)
> + w[i] = (int8_t)(uint8_t)(i * i + 113 * i + 47);
> + for (unsigned i = 0x11000; i < 0x12000; i++)
> + in[i - 0x11000] = (uint8_t)(i * i + 113 * i + 47);
> + for (int i = 0; i < 0x10; i++)
> + b[i] = i;
> +
> + transform (out, w, b, in);
> + transform_novec (out_novec, w, b, in);
> +
> + if (__builtin_memcmp (out, out_novec, sizeof (out)))
> + __builtin_trap ();
> +}
--
Xi Ruoyao <[email protected]>
