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Re: [PATCH] riscv: do not set the rounding mode via `gen_set_rm`
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From: |
Bin Meng |
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Subject: |
Re: [PATCH] riscv: do not set the rounding mode via `gen_set_rm` |
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Date: |
Sun, 8 Jan 2023 11:52:08 +0800 |
On Fri, Dec 30, 2022 at 2:20 AM Saleem Abdulrasool <abdulras@google.com> wrote:
>
> From: Saleem Abdulrasool <compnerd@compnerd.org>
>
> Setting the rounding mode via the `gen_set_rm` call would alter the
> state of the disassembler, resetting the `TransOp` in the assembler
> context. When we subsequently set the rounding mode to the desired
> value, we would trigger an assertion in `decode_save_opc`. Instead
> we can set the rounding mode via the `gen_helper_set_rounding_mode`
> which will still trigger the exception in the case of an invalid RM
> without altering the CPU disassembler state.
>
> Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org>
> ---
> target/riscv/insn_trans/trans_rvv.c.inc | 69 +++++++++++++------------
> 1 file changed, 36 insertions(+), 33 deletions(-)
>
> diff --git a/target/riscv/insn_trans/trans_rvv.c.inc
> b/target/riscv/insn_trans/trans_rvv.c.inc
> index 4dea4413ae..73f6fab1c5 100644
> --- a/target/riscv/insn_trans/trans_rvv.c.inc
> +++ b/target/riscv/insn_trans/trans_rvv.c.inc
> @@ -2679,8 +2679,10 @@ static bool do_opfv(DisasContext *s, arg_rmr *a,
> int rm)
> {
> if (checkfn(s, a)) {
> + // the helper will raise an exception if the rounding mode is invalid
nits: use /* */
> if (rm != RISCV_FRM_DYN) {
> - gen_set_rm(s, RISCV_FRM_DYN);
> + gen_helper_set_rounding_mode(cpu_env,
> + tcg_constant_i32(RISCV_FRM_DYN));
> }
>
> uint32_t data = 0;
> @@ -3001,38 +3003,39 @@ static bool opffv_narrow_check(DisasContext *s,
> arg_rmr *a)
> require_scale_zve64f(s);
> }
>
> -#define GEN_OPFV_NARROW_TRANS(NAME, CHECK, HELPER, FRM) \
> -static bool trans_##NAME(DisasContext *s, arg_rmr *a) \
> -{ \
> - if (CHECK(s, a)) { \
> - if (FRM != RISCV_FRM_DYN) { \
> - gen_set_rm(s, RISCV_FRM_DYN); \
> - } \
> - \
> - uint32_t data = 0; \
> - static gen_helper_gvec_3_ptr * const fns[2] = { \
> - gen_helper_##HELPER##_h, \
> - gen_helper_##HELPER##_w, \
> - }; \
> - TCGLabel *over = gen_new_label(); \
> - gen_set_rm(s, FRM); \
> - tcg_gen_brcondi_tl(TCG_COND_EQ, cpu_vl, 0, over); \
> - tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over); \
> - \
> - data = FIELD_DP32(data, VDATA, VM, a->vm); \
> - data = FIELD_DP32(data, VDATA, LMUL, s->lmul); \
> - data = FIELD_DP32(data, VDATA, VTA, s->vta); \
> - data = FIELD_DP32(data, VDATA, VMA, s->vma); \
> - tcg_gen_gvec_3_ptr(vreg_ofs(s, a->rd), vreg_ofs(s, 0), \
> - vreg_ofs(s, a->rs2), cpu_env, \
> - s->cfg_ptr->vlen / 8, \
> - s->cfg_ptr->vlen / 8, data, \
> - fns[s->sew - 1]); \
> - mark_vs_dirty(s); \
> - gen_set_label(over); \
> - return true; \
> - } \
> - return false; \
> +#define GEN_OPFV_NARROW_TRANS(NAME, CHECK, HELPER, FRM) \
> +static bool trans_##NAME(DisasContext *s, arg_rmr *a) \
> +{ \
> + if (CHECK(s, a)) { \
> + if (FRM != RISCV_FRM_DYN) { \
> + gen_helper_set_rounding_mode(cpu_env, \
> + tcg_constant_i32(RISCV_FRM_DYN)); \
> + } \
> + \
> + uint32_t data = 0; \
> + static gen_helper_gvec_3_ptr * const fns[2] = { \
> + gen_helper_##HELPER##_h, \
> + gen_helper_##HELPER##_w, \
> + }; \
> + TCGLabel *over = gen_new_label(); \
> + gen_set_rm(s, FRM); \
> + tcg_gen_brcondi_tl(TCG_COND_EQ, cpu_vl, 0, over); \
> + tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over); \
> + \
> + data = FIELD_DP32(data, VDATA, VM, a->vm); \
> + data = FIELD_DP32(data, VDATA, LMUL, s->lmul); \
> + data = FIELD_DP32(data, VDATA, VTA, s->vta); \
> + data = FIELD_DP32(data, VDATA, VMA, s->vma); \
> + tcg_gen_gvec_3_ptr(vreg_ofs(s, a->rd), vreg_ofs(s, 0), \
> + vreg_ofs(s, a->rs2), cpu_env, \
> + s->cfg_ptr->vlen / 8, \
> + s->cfg_ptr->vlen / 8, data, \
> + fns[s->sew - 1]); \
> + mark_vs_dirty(s); \
> + gen_set_label(over); \
> + return true; \
> + } \
> + return false; \
> }
>
> GEN_OPFV_NARROW_TRANS(vfncvt_f_xu_w, opfxv_narrow_check, vfncvt_f_xu_w,
> --
Is it possible to create a test case (tests/tcg/riscv64) for this?
Regards,
Bin
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