[PATCH for 9.0 v15 05/10] target/riscv: always clear vstart for ldst_whole insns

[Daniel Henrique Barboza <dbarboza@ventanamicro.com>]

Commit 8ff8ac6329 added a conditional to guard the vext_ldst_whole()
helper if vstart >= evl. But by skipping the helper we're also not
setting vstart = 0 at the end of the insns, which is incorrect.

We'll move the conditional to vext_ldst_whole(), following in line with
the removal of all brconds vstart >= vl that the next patch will do. The
idea is to make the helpers responsible for their own vstart management.

Fix ldst_whole isns by:

- remove the brcond that skips the helper if vstart is >= evl;

- vext_ldst_whole() now does an early exit with the same check, where
  evl = (vlenb * nf) >> log2_esz, but the early exit will also clear
  vstart.

The 'width' param is now unneeded in ldst_whole_trans() and is also
removed. It was used for the evl calculation for the brcond and has no
other use now.  The 'width' is reflected in vext_ldst_whole() via
log2_esz, which is encoded by GEN_VEXT_LD_WHOLE() as
"ctzl(sizeof(ETYPE))".

Suggested-by: Max Chou <max.chou@sifive.com>
Fixes: 8ff8ac6329 ("target/riscv: rvv: Add missing early exit condition for whole register load/store")
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/insn_trans/trans_rvv.c.inc | 52 +++++++++++--------------
 target/riscv/vector_helper.c            |  5 +++
 2 files changed, 28 insertions(+), 29 deletions(-)

diff --git a/target/riscv/insn_trans/trans_rvv.c.inc b/target/riscv/insn_trans/trans_rvv.c.inc
index 52c26a7834..1366445e1f 100644
--- a/target/riscv/insn_trans/trans_rvv.c.inc
+++ b/target/riscv/insn_trans/trans_rvv.c.inc
@@ -1097,13 +1097,9 @@ GEN_VEXT_TRANS(vle64ff_v, MO_64, r2nfvm, ldff_op, ld_us_check)
 typedef void gen_helper_ldst_whole(TCGv_ptr, TCGv, TCGv_env, TCGv_i32);
 
 static bool ldst_whole_trans(uint32_t vd, uint32_t rs1, uint32_t nf,
-                             uint32_t width, gen_helper_ldst_whole *fn,
+                             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 +1116,6 @@ 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;
 }
 
@@ -1129,42 +1123,42 @@ static bool ldst_whole_trans(uint32_t vd, uint32_t rs1, uint32_t nf,
  * load and store whole register instructions ignore vtype and vl setting.
  * Thus, we don't need to check vill bit. (Section 7.9)
  */
-#define GEN_LDST_WHOLE_TRANS(NAME, ARG_NF, WIDTH)               \
+#define GEN_LDST_WHOLE_TRANS(NAME, ARG_NF)                                \
 static bool trans_##NAME(DisasContext *s, arg_##NAME * a)                 \
 {                                                                         \
     if (require_rvv(s) &&                                                 \
         QEMU_IS_ALIGNED(a->rd, ARG_NF)) {                                 \
-        return ldst_whole_trans(a->rd, a->rs1, ARG_NF, WIDTH,             \
+        return ldst_whole_trans(a->rd, a->rs1, ARG_NF,                    \
                                 gen_helper_##NAME, s);                    \
     }                                                                     \
     return false;                                                         \
 }
 
-GEN_LDST_WHOLE_TRANS(vl1re8_v,  1, 1)
-GEN_LDST_WHOLE_TRANS(vl1re16_v, 1, 2)
-GEN_LDST_WHOLE_TRANS(vl1re32_v, 1, 4)
-GEN_LDST_WHOLE_TRANS(vl1re64_v, 1, 8)
-GEN_LDST_WHOLE_TRANS(vl2re8_v,  2, 1)
-GEN_LDST_WHOLE_TRANS(vl2re16_v, 2, 2)
-GEN_LDST_WHOLE_TRANS(vl2re32_v, 2, 4)
-GEN_LDST_WHOLE_TRANS(vl2re64_v, 2, 8)
-GEN_LDST_WHOLE_TRANS(vl4re8_v,  4, 1)
-GEN_LDST_WHOLE_TRANS(vl4re16_v, 4, 2)
-GEN_LDST_WHOLE_TRANS(vl4re32_v, 4, 4)
-GEN_LDST_WHOLE_TRANS(vl4re64_v, 4, 8)
-GEN_LDST_WHOLE_TRANS(vl8re8_v,  8, 1)
-GEN_LDST_WHOLE_TRANS(vl8re16_v, 8, 2)
-GEN_LDST_WHOLE_TRANS(vl8re32_v, 8, 4)
-GEN_LDST_WHOLE_TRANS(vl8re64_v, 8, 8)
+GEN_LDST_WHOLE_TRANS(vl1re8_v,  1)
+GEN_LDST_WHOLE_TRANS(vl1re16_v, 1)
+GEN_LDST_WHOLE_TRANS(vl1re32_v, 1)
+GEN_LDST_WHOLE_TRANS(vl1re64_v, 1)
+GEN_LDST_WHOLE_TRANS(vl2re8_v,  2)
+GEN_LDST_WHOLE_TRANS(vl2re16_v, 2)
+GEN_LDST_WHOLE_TRANS(vl2re32_v, 2)
+GEN_LDST_WHOLE_TRANS(vl2re64_v, 2)
+GEN_LDST_WHOLE_TRANS(vl4re8_v,  4)
+GEN_LDST_WHOLE_TRANS(vl4re16_v, 4)
+GEN_LDST_WHOLE_TRANS(vl4re32_v, 4)
+GEN_LDST_WHOLE_TRANS(vl4re64_v, 4)
+GEN_LDST_WHOLE_TRANS(vl8re8_v,  8)
+GEN_LDST_WHOLE_TRANS(vl8re16_v, 8)
+GEN_LDST_WHOLE_TRANS(vl8re32_v, 8)
+GEN_LDST_WHOLE_TRANS(vl8re64_v, 8)
 
 /*
  * The vector whole register store instructions are encoded similar to
  * unmasked unit-stride store of elements with EEW=8.
  */
-GEN_LDST_WHOLE_TRANS(vs1r_v, 1, 1)
-GEN_LDST_WHOLE_TRANS(vs2r_v, 2, 1)
-GEN_LDST_WHOLE_TRANS(vs4r_v, 4, 1)
-GEN_LDST_WHOLE_TRANS(vs8r_v, 8, 1)
+GEN_LDST_WHOLE_TRANS(vs1r_v, 1)
+GEN_LDST_WHOLE_TRANS(vs2r_v, 2)
+GEN_LDST_WHOLE_TRANS(vs4r_v, 4)
+GEN_LDST_WHOLE_TRANS(vs8r_v, 8)
 
 /*
  *** Vector Integer Arithmetic Instructions
diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
index bcc553c0e2..1f4c276b21 100644
--- a/target/riscv/vector_helper.c
+++ b/target/riscv/vector_helper.c
@@ -572,6 +572,11 @@ vext_ldst_whole(void *vd, target_ulong base, CPURISCVState *env, uint32_t desc,
     uint32_t vlenb = riscv_cpu_cfg(env)->vlenb;
     uint32_t max_elems = vlenb >> log2_esz;
 
+    if (env->vstart >= ((vlenb * nf) >> log2_esz)) {
+        env->vstart = 0;
+        return;
+    }
+
     k = env->vstart / max_elems;
     off = env->vstart % max_elems;
 
-- 
2.44.0