[RFC PATCH v5 4/5] target/riscv: rvv: Provide group continuous ld/st flow for unit-stride ld/st instructions

[Max Chou]

The vector unmasked unit-stride and whole register load/store
instructions will load/store continuous memory. If the endian of both
the host and guest architecture are the same, then we can group the
element load/store to load/store more data at a time.

Signed-off-by: Max Chou <max.chou@sifive.com>
---
 target/riscv/vector_helper.c | 72 +++++++++++++++++++++++++++++-------
 1 file changed, 58 insertions(+), 14 deletions(-)

diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
index 5343a08e6ad..2e675b4220c 100644
--- a/target/riscv/vector_helper.c
+++ b/target/riscv/vector_helper.c
@@ -188,6 +188,40 @@ GEN_VEXT_ST_ELEM(ste_h, uint16_t, H2, stw)
 GEN_VEXT_ST_ELEM(ste_w, uint32_t, H4, stl)
 GEN_VEXT_ST_ELEM(ste_d, uint64_t, H8, stq)
 
+static inline QEMU_ALWAYS_INLINE void
+vext_continus_ldst_tlb(CPURISCVState *env, vext_ldst_elem_fn_tlb *ldst_tlb,
+                       void *vd, uint32_t evl, target_ulong addr,
+                       uint32_t reg_start, uintptr_t ra, uint32_t esz,
+                       bool is_load)
+{
+    uint32_t i;
+    for (i = env->vstart; i < evl; env->vstart = ++i, addr += esz) {
+        ldst_tlb(env, adjust_addr(env, addr), i * esz, vd, ra);
+    }
+}
+
+static inline QEMU_ALWAYS_INLINE void
+vext_continus_ldst_host(CPURISCVState *env, vext_ldst_elem_fn_host *ldst_host,
+                        void *vd, uint32_t evl, uint32_t reg_start, void *host,
+                        uint32_t esz, bool is_load)
+{
+#if TARGET_BIG_ENDIAN != HOST_BIG_ENDIAN
+    for (; reg_start < evl; reg_start++, host += esz) {
+        uint32_t byte_off = reg_start * esz;
+        ldst_host(vd, byte_off, host);
+    }
+#else
+    uint32_t byte_offset = reg_start * esz;
+    uint32_t size = (evl - reg_start) * esz;
+
+    if (is_load) {
+        memcpy(vd + byte_offset, host, size);
+    } else {
+        memcpy(host, vd + byte_offset, size);
+    }
+#endif
+}
+
 static void vext_set_tail_elems_1s(target_ulong vl, void *vd,
                                    uint32_t desc, uint32_t nf,
                                    uint32_t esz, uint32_t max_elems)
@@ -299,24 +333,34 @@ vext_page_ldst_us(CPURISCVState *env, void *vd, 
target_ulong addr,
                                mmu_index, true, &host, ra);
 
     if (host && flags == 0) {
-        for (i = env->vstart; i < evl; ++i) {
-            k = 0;
-            while (k < nf) {
-                ldst_host(vd, (i + k * max_elems) << log2_esz, host);
-                host += esz;
-                k++;
+        if (nf == 1) {
+            vext_continus_ldst_host(env, ldst_host, vd, evl, env->vstart, host,
+                                    esz, is_load);
+        } else {
+            for (i = env->vstart; i < evl; ++i) {
+                k = 0;
+                while (k < nf) {
+                    ldst_host(vd, (i + k * max_elems) << log2_esz, host);
+                    host += esz;
+                    k++;
+                }
             }
         }
         env->vstart += elems;
     } else {
-        /* load bytes from guest memory */
-        for (i = env->vstart; i < evl; env->vstart = ++i) {
-            k = 0;
-            while (k < nf) {
-                ldst_tlb(env, adjust_addr(env, addr),
-                         (i + k * max_elems) << log2_esz, vd, ra);
-                addr += esz;
-                k++;
+        if (nf == 1) {
+            vext_continus_ldst_tlb(env, ldst_tlb, vd, evl, addr, env->vstart,
+                                   ra, esz, is_load);
+        } else {
+            /* load bytes from guest memory */
+            for (i = env->vstart; i < evl; env->vstart = ++i) {
+                k = 0;
+                while (k < nf) {
+                    ldst_tlb(env, adjust_addr(env, addr),
+                            (i + k * max_elems) << log2_esz, vd, ra);
+                    addr += esz;
+                    k++;
+                }
             }
         }
     }
-- 
2.34.1