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[PATCH v2] riscv: Add helper to make NaN-boxing for FP register
From: |
Ian Jiang |
Subject: |
[PATCH v2] riscv: Add helper to make NaN-boxing for FP register |
Date: |
Tue, 28 Jan 2020 08:37:07 +0800 |
The function that makes NaN-boxing when a 32-bit value is assigned
to a 64-bit FP register is split out to a helper gen_nanbox_fpr().
Then it is applied in translating of the FLW instruction.
Signed-off-by: Ian Jiang <address@hidden>
---
target/riscv/insn_trans/trans_rvf.inc.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/target/riscv/insn_trans/trans_rvf.inc.c
b/target/riscv/insn_trans/trans_rvf.inc.c
index e23cd639a6..3bfd8881e7 100644
--- a/target/riscv/insn_trans/trans_rvf.inc.c
+++ b/target/riscv/insn_trans/trans_rvf.inc.c
@@ -23,6 +23,20 @@
return false; \
} while (0)
+/*
+ * 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. Thus this does not
+ * apply when the RVD extension is not present.
+ */
+static void gen_nanbox_fpr(DisasContext *ctx, int regno)
+{
+ if (has_ext(ctx, RVD)) {
+ tcg_gen_ori_i64(cpu_fpr[regno], cpu_fpr[regno],
+ MAKE_64BIT_MASK(32, 32));
+ }
+}
+
static bool trans_flw(DisasContext *ctx, arg_flw *a)
{
TCGv t0 = tcg_temp_new();
@@ -32,8 +46,7 @@ static bool trans_flw(DisasContext *ctx, arg_flw *a)
tcg_gen_addi_tl(t0, t0, a->imm);
tcg_gen_qemu_ld_i64(cpu_fpr[a->rd], t0, ctx->mem_idx, MO_TEUL);
- /* RISC-V requires NaN-boxing of narrower width floating point values */
- tcg_gen_ori_i64(cpu_fpr[a->rd], cpu_fpr[a->rd], 0xffffffff00000000ULL);
+ gen_nanbox_fpr(ctx, a->rd);
tcg_temp_free(t0);
mark_fs_dirty(ctx);
--
2.17.1
- [PATCH v2] riscv: Add helper to make NaN-boxing for FP register,
Ian Jiang <=