According to the Zvfofp8min extension, the vfwcvtbf16.f.f.v instruction
supports OFP8 to BF16 conversion when SEW is 8.
And the VTYPE.altfmt field is used to select the OFP8 format.
* altfmt = 0: OFP8.e4m3 to BF16
* altfmt = 1: OFP8.e5m2 to BF16
Signed-off-by: Max Chou <max.chou@sifive.com>
---
target/riscv/helper.h | 12 +++
target/riscv/insn_trans/trans_rvbf16.c.inc | 16 +++-
target/riscv/vector_helper.c | 97 ++++++++++++++++++++++
3 files changed, 121 insertions(+), 4 deletions(-)
diff --git a/target/riscv/helper.h b/target/riscv/helper.h
index eb0a488ba8..356c24d9fb 100644
--- a/target/riscv/helper.h
+++ b/target/riscv/helper.h
@@ -1247,6 +1247,18 @@ DEF_HELPER_5(vfwcvtbf16_f_f_v, void, ptr, ptr, ptr, env, i32)
DEF_HELPER_6(vfwmaccbf16_vv, void, ptr, ptr, ptr, ptr, env, i32)
DEF_HELPER_6(vfwmaccbf16_vf, void, ptr, ptr, i64, ptr, env, i32)
+/* OFP8 functions */
+DEF_HELPER_5(vfwcvtbf16_f_f_v_ofp8e4m3, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfwcvtbf16_f_f_v_ofp8e5m2, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvtbf16_f_f_w_ofp8e4m3, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvtbf16_f_f_w_ofp8e5m2, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvtbf16_sat_f_f_w_ofp8e4m3, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvtbf16_sat_f_f_w_ofp8e5m2, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvt_f_f_q_ofp8e4m3, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvt_f_f_q_ofp8e5m2, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvt_sat_f_f_q_ofp8e4m3, void, ptr, ptr, ptr, env, i32)
+DEF_HELPER_5(vfncvt_sat_f_f_q_ofp8e5m2, void, ptr, ptr, ptr, env, i32)
+
/* Vector crypto functions */
DEF_HELPER_6(vclmul_vv, void, ptr, ptr, ptr, ptr, env, i32)
DEF_HELPER_6(vclmul_vx, void, ptr, ptr, tl, ptr, env, i32)
diff --git a/target/riscv/insn_trans/trans_rvbf16.c.inc b/target/riscv/insn_trans/trans_rvbf16.c.inc
index 6cfda03d2e..9aafd4d2ef 100644
--- a/target/riscv/insn_trans/trans_rvbf16.c.inc
+++ b/target/riscv/insn_trans/trans_rvbf16.c.inc
@@ -92,11 +92,20 @@ static bool trans_vfncvtbf16_f_f_w(DisasContext *ctx, arg_vfncvtbf16_f_f_w *a)
static bool trans_vfwcvtbf16_f_f_v(DisasContext *ctx, arg_vfwcvtbf16_f_f_v *a)
{
REQUIRE_FPU;
- REQUIRE_ZVFBFMIN(ctx);
- if (opfv_widen_check(ctx, a) && (ctx->sew == MO_16)) {
+ if (opfv_widen_check(ctx, a) &&
+ ((ctx->sew == MO_16 && ctx->cfg_ptr->ext_zvfbfmin) ||
+ (ctx->sew == MO_8 && ctx->cfg_ptr->ext_zvfofp8min))) {
+ gen_helper_gvec_3_ptr *fn;
uint32_t data = 0;
+ if (ctx->sew == MO_16) {
+ fn = gen_helper_vfwcvtbf16_f_f_v;
+ } else {
+ fn = ctx->altfmt ? gen_helper_vfwcvtbf16_f_f_v_ofp8e5m2 :
+ gen_helper_vfwcvtbf16_f_f_v_ofp8e4m3;
+ }
+
gen_set_rm_chkfrm(ctx, RISCV_FRM_DYN);
data = FIELD_DP32(data, VDATA, VM, a->vm);
@@ -106,8 +115,7 @@ static bool trans_vfwcvtbf16_f_f_v(DisasContext *ctx, arg_vfwcvtbf16_f_f_v *a)
tcg_gen_gvec_3_ptr(vreg_ofs(ctx, a->rd), vreg_ofs(ctx, 0),
vreg_ofs(ctx, a->rs2), tcg_env,
ctx->cfg_ptr->vlenb,
- ctx->cfg_ptr->vlenb, data,
- gen_helper_vfwcvtbf16_f_f_v);
+ ctx->cfg_ptr->vlenb, data, fn);
finalize_rvv_inst(ctx);
return true;
}
diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
index ee5a1e595b..418212973d 100644
--- a/target/riscv/vector_helper.c
+++ b/target/riscv/vector_helper.c
@@ -5024,6 +5024,103 @@ GEN_VEXT_V_ENV(vfncvt_f_f_w_w, 4)
RVVCALL(OPFVV1, vfncvtbf16_f_f_w, NOP_UU_H, H2, H4, float32_to_bfloat16)
GEN_VEXT_V_ENV(vfncvtbf16_f_f_w, 2)
+/*
+ * OCP FP8 Narrowing Conversions (BF16/F32 -> FP8)
+ * 1. Initialize a local float_status with RISC-V specific NaN handling
+ * 2. Call the softfloat conversion function with saturation parameter
+ * 3. Merge exception flags back to the original status
+ */
+#define GEN_OCP_FP8_NARROW(NAME, CONVERT_FN, SATURATE, IN_TYPE) \
+static uint8_t NAME(IN_TYPE a, float_status *s) \
+{ \
+ float_status local = *s; \
+ local.default_nan_pattern = 0x70; \
+ local.default_nan_mode = true; \
+ uint8_t result = CONVERT_FN(a, SATURATE, &local); \
+ s->float_exception_flags |= local.float_exception_flags; \
+ return result; \
+}
+
+/* BF16 -> E4M3/E5M2 conversions */
+GEN_OCP_FP8_NARROW(vfncvt_bf16_to_e4m3, bfloat16_to_float8_e4m3, false,
+ uint16_t)
+GEN_OCP_FP8_NARROW(vfncvt_bf16_to_e5m2, bfloat16_to_float8_e5m2, false,
+ uint16_t)
+GEN_OCP_FP8_NARROW(vfncvt_bf16_to_e4m3_sat, bfloat16_to_float8_e4m3, true,
+ uint16_t)
+GEN_OCP_FP8_NARROW(vfncvt_bf16_to_e5m2_sat, bfloat16_to_float8_e5m2, true,
+ uint16_t)
+
+/* F32 -> E4M3/E5M2 conversions */
+GEN_OCP_FP8_NARROW(vfncvt_f32_to_e4m3, float32_to_float8_e4m3, false, uint32_t)
+GEN_OCP_FP8_NARROW(vfncvt_f32_to_e5m2, float32_to_float8_e5m2, false, uint32_t)
+GEN_OCP_FP8_NARROW(vfncvt_f32_to_e4m3_sat, float32_to_float8_e4m3, true,
+ uint32_t)
+GEN_OCP_FP8_NARROW(vfncvt_f32_to_e5m2_sat, float32_to_float8_e5m2, true,
+ uint32_t)
+
+/*
+ * OCP FP8 Widening Conversions (FP8 -> BF16)
+ * According to Zvfofp8min isa specification: "No rounding occurs, and no
+ * floating-point exception flags are set."
+ * 1. Initialize a local float_status with no_signaling_nans=true
+ * 2. Call the softfloat conversion function
+ * 3. Intentionally DISCARD exception flags (not merged back)
+ */
+#define GEN_OCP_FP8_WIDEN(NAME, CONVERT_FN) \
+static uint16_t NAME(uint8_t a, float_status *s) \
+{ \
+ float_status local = *s; \
+ local.no_signaling_nans = true; \
+ return CONVERT_FN(a, &local); \
+}
+
+GEN_OCP_FP8_WIDEN(vfwcvt_e4m3_to_bf16, float8_e4m3_to_bfloat16)
+GEN_OCP_FP8_WIDEN(vfwcvt_e5m2_to_bf16, float8_e5m2_to_bfloat16)
+
+/* vfwcvtbf16.f.f.w vd, vs2, vm # Convert OFP8 to BF16. */
+RVVCALL(OPFVV1, vfwcvtbf16_f_f_v_ofp8e4m3, WOP_UU_B, H2, H1,
+ vfwcvt_e4m3_to_bf16)
+RVVCALL(OPFVV1, vfwcvtbf16_f_f_v_ofp8e5m2, WOP_UU_B, H2, H1,
+ vfwcvt_e5m2_to_bf16)
+GEN_VEXT_V_ENV(vfwcvtbf16_f_f_v_ofp8e4m3, 2)
+GEN_VEXT_V_ENV(vfwcvtbf16_f_f_v_ofp8e5m2, 2)
+
+/* vfncvtbf16.f.f.w vd, vs2, vm # Convert BF16 to OFP8 without saturation. */
+RVVCALL(OPFVV1, vfncvtbf16_f_f_w_ofp8e4m3, NOP_UU_B, H1, H2,
+ vfncvt_bf16_to_e4m3)
+RVVCALL(OPFVV1, vfncvtbf16_f_f_w_ofp8e5m2, NOP_UU_B, H1, H2,
+ vfncvt_bf16_to_e5m2)
+GEN_VEXT_V_ENV(vfncvtbf16_f_f_w_ofp8e4m3, 1)
+GEN_VEXT_V_ENV(vfncvtbf16_f_f_w_ofp8e5m2, 1)
+
+/* vfncvtbf16.sat.f.f.w vd, vs2, vm # Convert BF16 to OFP8 with saturation. */
+RVVCALL(OPFVV1, vfncvtbf16_sat_f_f_w_ofp8e4m3, NOP_UU_B, H1, H2,
+ vfncvt_bf16_to_e4m3_sat)
+RVVCALL(OPFVV1, vfncvtbf16_sat_f_f_w_ofp8e5m2, NOP_UU_B, H1, H2,
+ vfncvt_bf16_to_e5m2_sat)
+GEN_VEXT_V_ENV(vfncvtbf16_sat_f_f_w_ofp8e4m3, 1)
+GEN_VEXT_V_ENV(vfncvtbf16_sat_f_f_w_ofp8e5m2, 1)
+
+/* Quad-width narrowing type for FP32 to OFP8 */
+#define QOP_UU_B uint8_t, uint32_t, uint32_t
+
+/* vfncvt.f.f.q vd, vs2, vm # Convert FP32 to OFP8. */
+RVVCALL(OPFVV1, vfncvt_f_f_q_ofp8e4m3, QOP_UU_B, H1, H4,
+ vfncvt_f32_to_e4m3)
+RVVCALL(OPFVV1, vfncvt_f_f_q_ofp8e5m2, QOP_UU_B, H1, H4,
+ vfncvt_f32_to_e5m2)
+GEN_VEXT_V_ENV(vfncvt_f_f_q_ofp8e4m3, 1)
+GEN_VEXT_V_ENV(vfncvt_f_f_q_ofp8e5m2, 1)
+
+/* vfncvt.sat.f.f.q vd, vs2, vm # Convert FP32 to OFP8 with saturation. */
+RVVCALL(OPFVV1, vfncvt_sat_f_f_q_ofp8e4m3, QOP_UU_B, H1, H4,
+ vfncvt_f32_to_e4m3_sat)
+RVVCALL(OPFVV1, vfncvt_sat_f_f_q_ofp8e5m2, QOP_UU_B, H1, H4,
+ vfncvt_f32_to_e5m2_sat)
+GEN_VEXT_V_ENV(vfncvt_sat_f_f_q_ofp8e4m3, 1)
+GEN_VEXT_V_ENV(vfncvt_sat_f_f_q_ofp8e5m2, 1)
+
/*
* Vector Reduction Operations
*/
--
2.52.0