[PATCH v11 4/7] target/riscv: remove 'over' brconds from vector trans

Daniel Henrique Barboza posted 7 patches 8 months, 2 weeks ago
Maintainers: Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Bin Meng <bin.meng@windriver.com>, Weiwei Li <liwei1518@gmail.com>, Daniel Henrique Barboza <dbarboza@ventanamicro.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>
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[PATCH v11 4/7] target/riscv: remove 'over' brconds from vector trans
Posted by Daniel Henrique Barboza 8 months, 2 weeks ago
Most of the vector translations has this following pattern at the start:

    TCGLabel *over = gen_new_label();
    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);

And then right at the end:

     gen_set_label(over);
     return true;

This means that if vstart >= vl we'll not set vstart = 0 at the end of
the insns - this is done inside the helper that is being skipped.  The
reason why this pattern hasn't been a bigger problem is because the
conditional vstart >= vl is very rare.

Checking all the helpers in vector_helper.c we see all of them with a
pattern like this:

    for (i = env->vstart; i < vl; i++) {
        (...)
    }
    env->vstart = 0;

Thus they can handle vstart >= vl case gracefully, with the benefit of
setting env->vstart = 0 during the process.

Remove all 'over' conditionals and let the helper set env->vstart = 0
every time.

Note that not all insns uses helpers, and for those cases the 'brcond'
jump is the only way to filter vstart >= vl. This is the case of
trans_vmv_s_x() and trans_vfmv_s_f(). We won't remove the 'brcond'
conditionals from them.

While we're at it, remove the (vl == 0) brconds from trans_rvbf16.c.inc
too since they're unneeded.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/insn_trans/trans_rvbf16.c.inc |  12 ---
 target/riscv/insn_trans/trans_rvv.c.inc    | 108 ---------------------
 target/riscv/insn_trans/trans_rvvk.c.inc   |  18 ----
 3 files changed, 138 deletions(-)

diff --git a/target/riscv/insn_trans/trans_rvbf16.c.inc b/target/riscv/insn_trans/trans_rvbf16.c.inc
index 8ee99df3f3..a842e76a6b 100644
--- a/target/riscv/insn_trans/trans_rvbf16.c.inc
+++ b/target/riscv/insn_trans/trans_rvbf16.c.inc
@@ -71,11 +71,8 @@ static bool trans_vfncvtbf16_f_f_w(DisasContext *ctx, arg_vfncvtbf16_f_f_w *a)
 
     if (opfv_narrow_check(ctx, a) && (ctx->sew == MO_16)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
 
         gen_set_rm_chkfrm(ctx, RISCV_FRM_DYN);
-        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, ctx->lmul);
@@ -87,7 +84,6 @@ static bool trans_vfncvtbf16_f_f_w(DisasContext *ctx, arg_vfncvtbf16_f_f_w *a)
                            ctx->cfg_ptr->vlenb, data,
                            gen_helper_vfncvtbf16_f_f_w);
         mark_vs_dirty(ctx);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -100,11 +96,8 @@ static bool trans_vfwcvtbf16_f_f_v(DisasContext *ctx, arg_vfwcvtbf16_f_f_v *a)
 
     if (opfv_widen_check(ctx, a) && (ctx->sew == MO_16)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
 
         gen_set_rm_chkfrm(ctx, RISCV_FRM_DYN);
-        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, ctx->lmul);
@@ -116,7 +109,6 @@ static bool trans_vfwcvtbf16_f_f_v(DisasContext *ctx, arg_vfwcvtbf16_f_f_v *a)
                            ctx->cfg_ptr->vlenb, data,
                            gen_helper_vfwcvtbf16_f_f_v);
         mark_vs_dirty(ctx);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -130,11 +122,8 @@ static bool trans_vfwmaccbf16_vv(DisasContext *ctx, arg_vfwmaccbf16_vv *a)
     if (require_rvv(ctx) && vext_check_isa_ill(ctx) && (ctx->sew == MO_16) &&
         vext_check_dss(ctx, a->rd, a->rs1, a->rs2, a->vm)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
 
         gen_set_rm_chkfrm(ctx, RISCV_FRM_DYN);
-        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, ctx->lmul);
@@ -147,7 +136,6 @@ static bool trans_vfwmaccbf16_vv(DisasContext *ctx, arg_vfwmaccbf16_vv *a)
                            ctx->cfg_ptr->vlenb, data,
                            gen_helper_vfwmaccbf16_vv);
         mark_vs_dirty(ctx);
-        gen_set_label(over);
         return true;
     }
     return false;
diff --git a/target/riscv/insn_trans/trans_rvv.c.inc b/target/riscv/insn_trans/trans_rvv.c.inc
index 8c16a9f5b3..4c1a064cf6 100644
--- a/target/riscv/insn_trans/trans_rvv.c.inc
+++ b/target/riscv/insn_trans/trans_rvv.c.inc
@@ -616,9 +616,6 @@ static bool ldst_us_trans(uint32_t vd, uint32_t rs1, uint32_t data,
     TCGv base;
     TCGv_i32 desc;
 
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     dest = tcg_temp_new_ptr();
     mask = tcg_temp_new_ptr();
     base = get_gpr(s, rs1, EXT_NONE);
@@ -660,7 +657,6 @@ static bool ldst_us_trans(uint32_t vd, uint32_t rs1, uint32_t data,
         tcg_gen_mb(TCG_MO_ALL | TCG_BAR_LDAQ);
     }
 
-    gen_set_label(over);
     return true;
 }
 
@@ -802,9 +798,6 @@ static bool ldst_stride_trans(uint32_t vd, uint32_t rs1, uint32_t rs2,
     TCGv base, stride;
     TCGv_i32 desc;
 
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     dest = tcg_temp_new_ptr();
     mask = tcg_temp_new_ptr();
     base = get_gpr(s, rs1, EXT_NONE);
@@ -819,7 +812,6 @@ static bool ldst_stride_trans(uint32_t vd, uint32_t rs1, uint32_t rs2,
 
     fn(dest, mask, base, stride, tcg_env, desc);
 
-    gen_set_label(over);
     return true;
 }
 
@@ -906,9 +898,6 @@ static bool ldst_index_trans(uint32_t vd, uint32_t rs1, uint32_t vs2,
     TCGv base;
     TCGv_i32 desc;
 
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     dest = tcg_temp_new_ptr();
     mask = tcg_temp_new_ptr();
     index = tcg_temp_new_ptr();
@@ -924,7 +913,6 @@ static bool ldst_index_trans(uint32_t vd, uint32_t rs1, uint32_t vs2,
 
     fn(dest, mask, base, index, tcg_env, desc);
 
-    gen_set_label(over);
     return true;
 }
 
@@ -1044,9 +1032,6 @@ static bool ldff_trans(uint32_t vd, uint32_t rs1, uint32_t data,
     TCGv base;
     TCGv_i32 desc;
 
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     dest = tcg_temp_new_ptr();
     mask = tcg_temp_new_ptr();
     base = get_gpr(s, rs1, EXT_NONE);
@@ -1059,7 +1044,6 @@ static bool ldff_trans(uint32_t vd, uint32_t rs1, uint32_t data,
     fn(dest, mask, base, tcg_env, desc);
 
     mark_vs_dirty(s);
-    gen_set_label(over);
     return true;
 }
 
@@ -1100,10 +1084,6 @@ static bool ldst_whole_trans(uint32_t vd, uint32_t rs1, uint32_t nf,
                              uint32_t width, gen_helper_ldst_whole *fn,
                              DisasContext *s)
 {
-    uint32_t evl = s->cfg_ptr->vlenb * nf / width;
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcondi_tl(TCG_COND_GEU, cpu_vstart, evl, over);
-
     TCGv_ptr dest;
     TCGv base;
     TCGv_i32 desc;
@@ -1120,8 +1100,6 @@ static bool ldst_whole_trans(uint32_t vd, uint32_t rs1, uint32_t nf,
 
     fn(dest, base, tcg_env, desc);
 
-    gen_set_label(over);
-
     return true;
 }
 
@@ -1195,10 +1173,6 @@ static inline bool
 do_opivv_gvec(DisasContext *s, arg_rmrr *a, GVecGen3Fn *gvec_fn,
               gen_helper_gvec_4_ptr *fn)
 {
-    TCGLabel *over = gen_new_label();
-
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     if (a->vm && s->vl_eq_vlmax && !(s->vta && s->lmul < 0)) {
         gvec_fn(s->sew, vreg_ofs(s, a->rd),
                 vreg_ofs(s, a->rs2), vreg_ofs(s, a->rs1),
@@ -1216,7 +1190,6 @@ do_opivv_gvec(DisasContext *s, arg_rmrr *a, GVecGen3Fn *gvec_fn,
                            s->cfg_ptr->vlenb, data, fn);
     }
     mark_vs_dirty(s);
-    gen_set_label(over);
     return true;
 }
 
@@ -1248,9 +1221,6 @@ static bool opivx_trans(uint32_t vd, uint32_t rs1, uint32_t vs2, uint32_t vm,
     TCGv_i32 desc;
     uint32_t data = 0;
 
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     dest = tcg_temp_new_ptr();
     mask = tcg_temp_new_ptr();
     src2 = tcg_temp_new_ptr();
@@ -1271,7 +1241,6 @@ static bool opivx_trans(uint32_t vd, uint32_t rs1, uint32_t vs2, uint32_t vm,
     fn(dest, mask, src1, src2, tcg_env, desc);
 
     mark_vs_dirty(s);
-    gen_set_label(over);
     return true;
 }
 
@@ -1410,9 +1379,6 @@ static bool opivi_trans(uint32_t vd, uint32_t imm, uint32_t vs2, uint32_t vm,
     TCGv_i32 desc;
     uint32_t data = 0;
 
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     dest = tcg_temp_new_ptr();
     mask = tcg_temp_new_ptr();
     src2 = tcg_temp_new_ptr();
@@ -1433,7 +1399,6 @@ static bool opivi_trans(uint32_t vd, uint32_t imm, uint32_t vs2, uint32_t vm,
     fn(dest, mask, src1, src2, tcg_env, desc);
 
     mark_vs_dirty(s);
-    gen_set_label(over);
     return true;
 }
 
@@ -1495,8 +1460,6 @@ static bool do_opivv_widen(DisasContext *s, arg_rmrr *a,
 {
     if (checkfn(s, a)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
-        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);
@@ -1509,7 +1472,6 @@ static bool do_opivv_widen(DisasContext *s, arg_rmrr *a,
                            s->cfg_ptr->vlenb,
                            data, fn);
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -1571,8 +1533,6 @@ static bool do_opiwv_widen(DisasContext *s, arg_rmrr *a,
 {
     if (opiwv_widen_check(s, a)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
-        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);
@@ -1584,7 +1544,6 @@ static bool do_opiwv_widen(DisasContext *s, arg_rmrr *a,
                            tcg_env, s->cfg_ptr->vlenb,
                            s->cfg_ptr->vlenb, data, fn);
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -1643,8 +1602,6 @@ static bool opivv_trans(uint32_t vd, uint32_t vs1, uint32_t vs2, uint32_t vm,
                         gen_helper_gvec_4_ptr *fn, DisasContext *s)
 {
     uint32_t data = 0;
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
 
     data = FIELD_DP32(data, VDATA, VM, vm);
     data = FIELD_DP32(data, VDATA, LMUL, s->lmul);
@@ -1655,7 +1612,6 @@ static bool opivv_trans(uint32_t vd, uint32_t vs1, uint32_t vs2, uint32_t vm,
                        vreg_ofs(s, vs2), tcg_env, s->cfg_ptr->vlenb,
                        s->cfg_ptr->vlenb, data, fn);
     mark_vs_dirty(s);
-    gen_set_label(over);
     return true;
 }
 
@@ -1834,8 +1790,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)             \
             gen_helper_##NAME##_h,                                 \
             gen_helper_##NAME##_w,                                 \
         };                                                         \
-        TCGLabel *over = gen_new_label();                          \
-        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);             \
@@ -1848,7 +1802,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)             \
                            s->cfg_ptr->vlenb, data,                \
                            fns[s->sew]);                           \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -2045,14 +1998,11 @@ static bool trans_vmv_v_v(DisasContext *s, arg_vmv_v_v *a)
                 gen_helper_vmv_v_v_b, gen_helper_vmv_v_v_h,
                 gen_helper_vmv_v_v_w, gen_helper_vmv_v_v_d,
             };
-            TCGLabel *over = gen_new_label();
-            tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
 
             tcg_gen_gvec_2_ptr(vreg_ofs(s, a->rd), vreg_ofs(s, a->rs1),
                                tcg_env, s->cfg_ptr->vlenb,
                                s->cfg_ptr->vlenb, data,
                                fns[s->sew]);
-            gen_set_label(over);
         }
         mark_vs_dirty(s);
         return true;
@@ -2068,8 +2018,6 @@ static bool trans_vmv_v_x(DisasContext *s, arg_vmv_v_x *a)
         /* vmv.v.x has rs2 = 0 and vm = 1 */
         vext_check_ss(s, a->rd, 0, 1)) {
         TCGv s1;
-        TCGLabel *over = gen_new_label();
-        tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
 
         s1 = get_gpr(s, a->rs1, EXT_SIGN);
 
@@ -2102,7 +2050,6 @@ static bool trans_vmv_v_x(DisasContext *s, arg_vmv_v_x *a)
         }
 
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -2129,8 +2076,6 @@ static bool trans_vmv_v_i(DisasContext *s, arg_vmv_v_i *a)
                 gen_helper_vmv_v_x_b, gen_helper_vmv_v_x_h,
                 gen_helper_vmv_v_x_w, gen_helper_vmv_v_x_d,
             };
-            TCGLabel *over = gen_new_label();
-            tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
 
             s1 = tcg_constant_i64(simm);
             dest = tcg_temp_new_ptr();
@@ -2140,7 +2085,6 @@ static bool trans_vmv_v_i(DisasContext *s, arg_vmv_v_i *a)
             fns[s->sew](dest, s1, tcg_env, desc);
 
             mark_vs_dirty(s);
-            gen_set_label(over);
         }
         return true;
     }
@@ -2275,9 +2219,7 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)             \
             gen_helper_##NAME##_w,                                 \
             gen_helper_##NAME##_d,                                 \
         };                                                         \
-        TCGLabel *over = gen_new_label();                          \
         gen_set_rm(s, RISCV_FRM_DYN);                              \
-        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);             \
@@ -2292,7 +2234,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)             \
                            s->cfg_ptr->vlenb, data,                \
                            fns[s->sew - 1]);                       \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -2310,9 +2251,6 @@ static bool opfvf_trans(uint32_t vd, uint32_t rs1, uint32_t vs2,
     TCGv_i32 desc;
     TCGv_i64 t1;
 
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
-
     dest = tcg_temp_new_ptr();
     mask = tcg_temp_new_ptr();
     src2 = tcg_temp_new_ptr();
@@ -2330,7 +2268,6 @@ static bool opfvf_trans(uint32_t vd, uint32_t rs1, uint32_t vs2,
     fn(dest, mask, t1, src2, tcg_env, desc);
 
     mark_vs_dirty(s);
-    gen_set_label(over);
     return true;
 }
 
@@ -2393,9 +2330,7 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)           \
         static gen_helper_gvec_4_ptr * const fns[2] = {          \
             gen_helper_##NAME##_h, gen_helper_##NAME##_w,        \
         };                                                       \
-        TCGLabel *over = gen_new_label();                        \
         gen_set_rm(s, RISCV_FRM_DYN);                            \
-        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);           \
@@ -2408,7 +2343,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)           \
                            s->cfg_ptr->vlenb, data,              \
                            fns[s->sew - 1]);                     \
         mark_vs_dirty(s);                                        \
-        gen_set_label(over);                                     \
         return true;                                             \
     }                                                            \
     return false;                                                \
@@ -2467,9 +2401,7 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)             \
         static gen_helper_gvec_4_ptr * const fns[2] = {            \
             gen_helper_##NAME##_h, gen_helper_##NAME##_w,          \
         };                                                         \
-        TCGLabel *over = gen_new_label();                          \
         gen_set_rm(s, RISCV_FRM_DYN);                              \
-        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);             \
@@ -2482,7 +2414,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmrr *a)             \
                            s->cfg_ptr->vlenb, data,                \
                            fns[s->sew - 1]);                       \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -2584,9 +2515,7 @@ static bool do_opfv(DisasContext *s, arg_rmr *a,
 {
     if (checkfn(s, a)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
         gen_set_rm_chkfrm(s, rm);
-        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);
@@ -2597,7 +2526,6 @@ static bool do_opfv(DisasContext *s, arg_rmr *a,
                            s->cfg_ptr->vlenb,
                            s->cfg_ptr->vlenb, data, fn);
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -2696,8 +2624,6 @@ static bool trans_vfmv_v_f(DisasContext *s, arg_vfmv_v_f *a)
                 gen_helper_vmv_v_x_w,
                 gen_helper_vmv_v_x_d,
             };
-            TCGLabel *over = gen_new_label();
-            tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
 
             t1 = tcg_temp_new_i64();
             /* NaN-box f[rs1] */
@@ -2711,7 +2637,6 @@ static bool trans_vfmv_v_f(DisasContext *s, arg_vfmv_v_f *a)
             fns[s->sew - 1](dest, t1, tcg_env, desc);
 
             mark_vs_dirty(s);
-            gen_set_label(over);
         }
         return true;
     }
@@ -2773,9 +2698,7 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
             gen_helper_##HELPER##_h,                               \
             gen_helper_##HELPER##_w,                               \
         };                                                         \
-        TCGLabel *over = gen_new_label();                          \
         gen_set_rm_chkfrm(s, FRM);                                 \
-        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);             \
@@ -2787,7 +2710,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
                            s->cfg_ptr->vlenb, data,                \
                            fns[s->sew - 1]);                       \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -2824,9 +2746,7 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
             gen_helper_##NAME##_h,                                 \
             gen_helper_##NAME##_w,                                 \
         };                                                         \
-        TCGLabel *over = gen_new_label();                          \
         gen_set_rm(s, RISCV_FRM_DYN);                              \
-        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);             \
@@ -2838,7 +2758,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
                            s->cfg_ptr->vlenb, data,                \
                            fns[s->sew]);                           \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -2891,9 +2810,7 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
             gen_helper_##HELPER##_h,                               \
             gen_helper_##HELPER##_w,                               \
         };                                                         \
-        TCGLabel *over = gen_new_label();                          \
         gen_set_rm_chkfrm(s, FRM);                                 \
-        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);             \
@@ -2905,7 +2822,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
                            s->cfg_ptr->vlenb, data,                \
                            fns[s->sew - 1]);                       \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -2940,9 +2856,7 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
             gen_helper_##HELPER##_h,                               \
             gen_helper_##HELPER##_w,                               \
         };                                                         \
-        TCGLabel *over = gen_new_label();                          \
         gen_set_rm_chkfrm(s, FRM);                                 \
-        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);             \
@@ -2954,7 +2868,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
                            s->cfg_ptr->vlenb, data,                \
                            fns[s->sew]);                           \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -3031,8 +2944,6 @@ static bool trans_##NAME(DisasContext *s, arg_r *a)                \
         vext_check_isa_ill(s)) {                                   \
         uint32_t data = 0;                                         \
         gen_helper_gvec_4_ptr *fn = gen_helper_##NAME;             \
-        TCGLabel *over = gen_new_label();                          \
-        tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over); \
                                                                    \
         data = FIELD_DP32(data, VDATA, LMUL, s->lmul);             \
         data =                                                     \
@@ -3043,7 +2954,6 @@ static bool trans_##NAME(DisasContext *s, arg_r *a)                \
                            s->cfg_ptr->vlenb,                      \
                            s->cfg_ptr->vlenb, data, fn);           \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -3131,8 +3041,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
         s->vstart_eq_zero) {                                       \
         uint32_t data = 0;                                         \
         gen_helper_gvec_3_ptr *fn = gen_helper_##NAME;             \
-        TCGLabel *over = gen_new_label();                          \
-        tcg_gen_brcondi_tl(TCG_COND_EQ, cpu_vl, 0, over);          \
                                                                    \
         data = FIELD_DP32(data, VDATA, VM, a->vm);                 \
         data = FIELD_DP32(data, VDATA, LMUL, s->lmul);             \
@@ -3145,7 +3053,6 @@ static bool trans_##NAME(DisasContext *s, arg_rmr *a)              \
                            s->cfg_ptr->vlenb,                      \
                            data, fn);                              \
         mark_vs_dirty(s);                                          \
-        gen_set_label(over);                                       \
         return true;                                               \
     }                                                              \
     return false;                                                  \
@@ -3171,8 +3078,6 @@ static bool trans_viota_m(DisasContext *s, arg_viota_m *a)
         require_align(a->rd, s->lmul) &&
         s->vstart_eq_zero) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
-        tcg_gen_brcondi_tl(TCG_COND_EQ, cpu_vl, 0, over);
 
         data = FIELD_DP32(data, VDATA, VM, a->vm);
         data = FIELD_DP32(data, VDATA, LMUL, s->lmul);
@@ -3187,7 +3092,6 @@ static bool trans_viota_m(DisasContext *s, arg_viota_m *a)
                            s->cfg_ptr->vlenb,
                            s->cfg_ptr->vlenb, data, fns[s->sew]);
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -3201,8 +3105,6 @@ static bool trans_vid_v(DisasContext *s, arg_vid_v *a)
         require_align(a->rd, s->lmul) &&
         require_vm(a->vm, a->rd)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
-        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);
@@ -3217,7 +3119,6 @@ static bool trans_vid_v(DisasContext *s, arg_vid_v *a)
                            s->cfg_ptr->vlenb,
                            data, fns[s->sew]);
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -3630,8 +3531,6 @@ static bool trans_vcompress_vm(DisasContext *s, arg_r *a)
             gen_helper_vcompress_vm_b, gen_helper_vcompress_vm_h,
             gen_helper_vcompress_vm_w, gen_helper_vcompress_vm_d,
         };
-        TCGLabel *over = gen_new_label();
-        tcg_gen_brcondi_tl(TCG_COND_EQ, cpu_vl, 0, over);
 
         data = FIELD_DP32(data, VDATA, LMUL, s->lmul);
         data = FIELD_DP32(data, VDATA, VTA, s->vta);
@@ -3641,7 +3540,6 @@ static bool trans_vcompress_vm(DisasContext *s, arg_r *a)
                            s->cfg_ptr->vlenb, data,
                            fns[s->sew]);
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -3664,12 +3562,9 @@ static bool trans_##NAME(DisasContext *s, arg_##NAME * a)               \
                              vreg_ofs(s, a->rs2), maxsz, maxsz);        \
             mark_vs_dirty(s);                                           \
         } else {                                                        \
-            TCGLabel *over = gen_new_label();                           \
-            tcg_gen_brcondi_tl(TCG_COND_GEU, cpu_vstart, maxsz, over);  \
             tcg_gen_gvec_2_ptr(vreg_ofs(s, a->rd), vreg_ofs(s, a->rs2), \
                                tcg_env, maxsz, maxsz, 0, gen_helper_vmvr_v); \
             mark_vs_dirty(s);                                           \
-            gen_set_label(over);                                        \
         }                                                               \
         return true;                                                    \
     }                                                                   \
@@ -3698,8 +3593,6 @@ static bool int_ext_op(DisasContext *s, arg_rmr *a, uint8_t seq)
 {
     uint32_t data = 0;
     gen_helper_gvec_3_ptr *fn;
-    TCGLabel *over = gen_new_label();
-    tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
 
     static gen_helper_gvec_3_ptr * const fns[6][4] = {
         {
@@ -3744,7 +3637,6 @@ static bool int_ext_op(DisasContext *s, arg_rmr *a, uint8_t seq)
                        s->cfg_ptr->vlenb, data, fn);
 
     mark_vs_dirty(s);
-    gen_set_label(over);
     return true;
 }
 
diff --git a/target/riscv/insn_trans/trans_rvvk.c.inc b/target/riscv/insn_trans/trans_rvvk.c.inc
index a5cdd1b67f..6d640e4596 100644
--- a/target/riscv/insn_trans/trans_rvvk.c.inc
+++ b/target/riscv/insn_trans/trans_rvvk.c.inc
@@ -164,8 +164,6 @@ GEN_OPIVX_GVEC_TRANS_CHECK(vandn_vx, andcs, zvkb_vx_check)
                 gen_helper_##NAME##_w,                                     \
                 gen_helper_##NAME##_d,                                     \
             };                                                             \
-            TCGLabel *over = gen_new_label();                              \
-            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);                 \
@@ -177,7 +175,6 @@ GEN_OPIVX_GVEC_TRANS_CHECK(vandn_vx, andcs, zvkb_vx_check)
                                s->cfg_ptr->vlenb, s->cfg_ptr->vlenb,       \
                                data, fns[s->sew]);                         \
             mark_vs_dirty(s);                                              \
-            gen_set_label(over);                                           \
             return true;                                                   \
         }                                                                  \
         return false;                                                      \
@@ -249,14 +246,12 @@ GEN_OPIVI_WIDEN_TRANS(vwsll_vi, IMM_ZX, vwsll_vx, vwsll_vx_check)
             TCGv_ptr rd_v, rs2_v;                                             \
             TCGv_i32 desc, egs;                                               \
             uint32_t data = 0;                                                \
-            TCGLabel *over = gen_new_label();                                 \
                                                                               \
             if (!s->vstart_eq_zero || !s->vl_eq_vlmax) {                      \
                 /* save opcode for unwinding in case we throw an exception */ \
                 decode_save_opc(s);                                           \
                 egs = tcg_constant_i32(EGS);                                  \
                 gen_helper_egs_check(egs, tcg_env);                           \
-                tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);    \
             }                                                                 \
                                                                               \
             data = FIELD_DP32(data, VDATA, VM, a->vm);                        \
@@ -272,7 +267,6 @@ GEN_OPIVI_WIDEN_TRANS(vwsll_vi, IMM_ZX, vwsll_vx, vwsll_vx_check)
             tcg_gen_addi_ptr(rs2_v, tcg_env, vreg_ofs(s, a->rs2));            \
             gen_helper_##NAME(rd_v, rs2_v, tcg_env, desc);                    \
             mark_vs_dirty(s);                                                 \
-            gen_set_label(over);                                              \
             return true;                                                      \
         }                                                                     \
         return false;                                                         \
@@ -325,14 +319,12 @@ GEN_V_UNMASKED_TRANS(vaesem_vs, vaes_check_vs, ZVKNED_EGS)
             TCGv_ptr rd_v, rs2_v;                                             \
             TCGv_i32 uimm_v, desc, egs;                                       \
             uint32_t data = 0;                                                \
-            TCGLabel *over = gen_new_label();                                 \
                                                                               \
             if (!s->vstart_eq_zero || !s->vl_eq_vlmax) {                      \
                 /* save opcode for unwinding in case we throw an exception */ \
                 decode_save_opc(s);                                           \
                 egs = tcg_constant_i32(EGS);                                  \
                 gen_helper_egs_check(egs, tcg_env);                           \
-                tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);    \
             }                                                                 \
                                                                               \
             data = FIELD_DP32(data, VDATA, VM, a->vm);                        \
@@ -350,7 +342,6 @@ GEN_V_UNMASKED_TRANS(vaesem_vs, vaes_check_vs, ZVKNED_EGS)
             tcg_gen_addi_ptr(rs2_v, tcg_env, vreg_ofs(s, a->rs2));            \
             gen_helper_##NAME(rd_v, rs2_v, uimm_v, tcg_env, desc);            \
             mark_vs_dirty(s);                                                 \
-            gen_set_label(over);                                              \
             return true;                                                      \
         }                                                                     \
         return false;                                                         \
@@ -394,7 +385,6 @@ GEN_VI_UNMASKED_TRANS(vaeskf2_vi, vaeskf2_check, ZVKNED_EGS)
     {                                                                         \
         if (CHECK(s, a)) {                                                    \
             uint32_t data = 0;                                                \
-            TCGLabel *over = gen_new_label();                                 \
             TCGv_i32 egs;                                                     \
                                                                               \
             if (!s->vstart_eq_zero || !s->vl_eq_vlmax) {                      \
@@ -402,7 +392,6 @@ GEN_VI_UNMASKED_TRANS(vaeskf2_vi, vaeskf2_check, ZVKNED_EGS)
                 decode_save_opc(s);                                           \
                 egs = tcg_constant_i32(EGS);                                  \
                 gen_helper_egs_check(egs, tcg_env);                           \
-                tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);    \
             }                                                                 \
                                                                               \
             data = FIELD_DP32(data, VDATA, VM, a->vm);                        \
@@ -417,7 +406,6 @@ GEN_VI_UNMASKED_TRANS(vaeskf2_vi, vaeskf2_check, ZVKNED_EGS)
                                data, gen_helper_##NAME);                      \
                                                                               \
             mark_vs_dirty(s);                                                 \
-            gen_set_label(over);                                              \
             return true;                                                      \
         }                                                                     \
         return false;                                                         \
@@ -448,7 +436,6 @@ static bool trans_vsha2cl_vv(DisasContext *s, arg_rmrr *a)
 {
     if (vsha_check(s, a)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
         TCGv_i32 egs;
 
         if (!s->vstart_eq_zero || !s->vl_eq_vlmax) {
@@ -456,7 +443,6 @@ static bool trans_vsha2cl_vv(DisasContext *s, arg_rmrr *a)
             decode_save_opc(s);
             egs = tcg_constant_i32(ZVKNH_EGS);
             gen_helper_egs_check(egs, tcg_env);
-            tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
         }
 
         data = FIELD_DP32(data, VDATA, VM, a->vm);
@@ -472,7 +458,6 @@ static bool trans_vsha2cl_vv(DisasContext *s, arg_rmrr *a)
                 gen_helper_vsha2cl32_vv : gen_helper_vsha2cl64_vv);
 
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
@@ -482,7 +467,6 @@ static bool trans_vsha2ch_vv(DisasContext *s, arg_rmrr *a)
 {
     if (vsha_check(s, a)) {
         uint32_t data = 0;
-        TCGLabel *over = gen_new_label();
         TCGv_i32 egs;
 
         if (!s->vstart_eq_zero || !s->vl_eq_vlmax) {
@@ -490,7 +474,6 @@ static bool trans_vsha2ch_vv(DisasContext *s, arg_rmrr *a)
             decode_save_opc(s);
             egs = tcg_constant_i32(ZVKNH_EGS);
             gen_helper_egs_check(egs, tcg_env);
-            tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
         }
 
         data = FIELD_DP32(data, VDATA, VM, a->vm);
@@ -506,7 +489,6 @@ static bool trans_vsha2ch_vv(DisasContext *s, arg_rmrr *a)
                 gen_helper_vsha2ch32_vv : gen_helper_vsha2ch64_vv);
 
         mark_vs_dirty(s);
-        gen_set_label(over);
         return true;
     }
     return false;
-- 
2.43.2
Re: [PATCH v11 4/7] target/riscv: remove 'over' brconds from vector trans
Posted by Richard Henderson 8 months, 2 weeks ago
On 3/11/24 03:58, Daniel Henrique Barboza wrote:
> Most of the vector translations has this following pattern at the start:
> 
>      TCGLabel *over = gen_new_label();
>      tcg_gen_brcond_tl(TCG_COND_GEU, cpu_vstart, cpu_vl, over);
> 
> And then right at the end:
> 
>       gen_set_label(over);
>       return true;
> 
> This means that if vstart >= vl we'll not set vstart = 0 at the end of
> the insns - this is done inside the helper that is being skipped.  The
> reason why this pattern hasn't been a bigger problem is because the
> conditional vstart >= vl is very rare.
> 
> Checking all the helpers in vector_helper.c we see all of them with a
> pattern like this:
> 
>      for (i = env->vstart; i < vl; i++) {
>          (...)
>      }
>      env->vstart = 0;
> 
> Thus they can handle vstart >= vl case gracefully, with the benefit of
> setting env->vstart = 0 during the process.

You'll want to update this comment for VSTART_CHECK_EARLY_EXIT


r~