1 files changed, 29 insertions, 0 deletions
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index d0485c0750..3919f570f7 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -90,6 +90,35 @@ static inline bool has_ext(DisasContext *ctx, uint32_t ext)
     return ctx->misa & ext;
 }
 
+/*
+ * RISC-V requires NaN-boxing of narrower width floating point values.
+ * This applies when a 32-bit value is assigned to a 64-bit FP register.
+ * For consistency and simplicity, we nanbox results even when the RVD
+ * extension is not present.
+ */
+static void gen_nanbox_s(TCGv_i64 out, TCGv_i64 in)
+{
+    tcg_gen_ori_i64(out, in, MAKE_64BIT_MASK(32, 32));
+}
+
+/*
+ * A narrow n-bit operation, where n < FLEN, checks that input operands
+ * are correctly Nan-boxed, i.e., all upper FLEN - n bits are 1.
+ * If so, the least-significant bits of the input are used, otherwise the
+ * input value is treated as an n-bit canonical NaN (v2.2 section 9.2).
+ *
+ * Here, the result is always nan-boxed, even the canonical nan.
+ */
+static void gen_check_nanbox_s(TCGv_i64 out, TCGv_i64 in)
+{
+    TCGv_i64 t_max = tcg_const_i64(0xffffffff00000000ull);
+    TCGv_i64 t_nan = tcg_const_i64(0xffffffff7fc00000ull);
+
+    tcg_gen_movcond_i64(TCG_COND_GEU, out, in, t_max, in, t_nan);
+    tcg_temp_free_i64(t_max);
+    tcg_temp_free_i64(t_nan);
+}
+
 static void generate_exception(DisasContext *ctx, int excp)
 {
     tcg_gen_movi_tl(cpu_pc, ctx->base.pc_next);