qemu-riscv
[Top][All Lists]
Advanced
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH for-9.0 v14 4/8] target/riscv/vector_helpers: do early exit w

From: Daniel Henrique Barboza
Subject: Re: [PATCH for-9.0 v14 4/8] target/riscv/vector_helpers: do early exit when vstart >= vl
Date: Thu, 14 Mar 2024 10:42:16 -0300
User-agent: Mozilla Thunderbird 


On 3/14/24 10:27, Daniel Henrique Barboza wrote:



On 3/14/24 10:14, Max Chou wrote:

According v spec section 7.9. Vector Load/Store Whole Register Instructions

"The instructions operate with an effective vector length, evl=NFIELDS*VLEN/EEW, 
regardless of current settings in vtype and vl. The usual property that no elements are 
written if vstart ≥ vl does not apply to these instructions. Instead, no elements are 
written if vstart ≥ evl."

The VSTART_CHECK_EARLY_EXIT in vext_ldst_whole function may causes unexpected 
result. We may replace the VSTART_CHECK_EARLY_EXIT function by

- VSTART_CHECK_EARLY_EXIT(env); + if (env->vstart >= ((vlenb * nf) >> log2_esz)) { 
+ env->vstart = 0; + return; + }


Do we need to do an early exit in this case? If the function is able to handle
gracefully whatever env->vstart value it faces (it seems to be the case) then we
should just remove the exit entirely.


Nevermind. Here's the guard that I am removing in the next patch for 
vext_lsdt_whole:

-    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);

If we just remove it and put nothing else in its place we'll end up breaking it.

To preserve the existing behavior we'll have to change the early exit to

if (vstart >= evl) {...}


'evl' is being calculated as

    uint32_t evl = s->cfg_ptr->vlenb * nf / width;


So yeah, your suggestion to exit the helper early with:

+ if (env->vstart >= ((vlenb * nf) >> log2_esz)) {
+     env->vstart = 0;
+     return;
+ }

Is correct. I'll change it in v15.


Thanks,


Daniel



In fact I removed all the early exits from all helpers that are guarded
by vstart_eq_zero: vcpop_m(), vfirst_m(), vmsetm(), GEN_VEXT_VIOTA_M(),
GEN_VEXT_VCOMPRESS_VM(), GEN_VEXT_RED() and GEN_VEXT_FRED(). For these case
the helpers can either do nothing if vl = 0 or throw some exception like
vcpop and first does.


Thanks,

Daniel






@@ -572,6 +580,8 @@ 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;
+    VSTART_CHECK_EARLY_EXIT(env);
+
      k = env->vstart / max_elems;
      off = env->vstart % max_elems;
@@ -877,6 +887,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void *vs2, 
  \
      uint32_t vta = vext_vta(desc);                            \
      uint32_t i;                                               \
                                                                \
+    VSTART_CHECK_EARLY_EXIT(env);                             \
+                                                              \
      for (i = env->vstart; i < vl; i++) {                      \
          ETYPE s1 = *((ETYPE *)vs1 + H(i));                    \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                    \
@@ -909,6 +921,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1, void 
*vs2,        \
      uint32_t vta = vext_vta(desc);                                       \
      uint32_t i;                                                          \
                                                                           \
+    VSTART_CHECK_EARLY_EXIT(env);                                        \
+                                                                         \
      for (i = env->vstart; i < vl; i++) {                                 \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                               \
          ETYPE carry = vext_elem_mask(v0, i);                             \
@@ -944,6 +958,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void *vs2, 
  \
      uint32_t vta_all_1s = vext_vta_all_1s(desc);              \
      uint32_t i;                                               \
                                                                \
+    VSTART_CHECK_EARLY_EXIT(env);                             \
+                                                              \
      for (i = env->vstart; i < vl; i++) {                      \
          ETYPE s1 = *((ETYPE *)vs1 + H(i));                    \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                    \
@@ -982,6 +998,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1,      
    \
      uint32_t vta_all_1s = vext_vta_all_1s(desc);                \
      uint32_t i;                                                 \
                                                                  \
+    VSTART_CHECK_EARLY_EXIT(env);                               \
+                                                                \
      for (i = env->vstart; i < vl; i++) {                        \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                      \
          ETYPE carry = !vm && vext_elem_mask(v0, i);             \
@@ -1078,6 +1096,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1,          
                \
      uint32_t vma = vext_vma(desc);                                        \
      uint32_t i;                                                           \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      for (i = env->vstart; i < vl; i++) {                                  \
          if (!vm && !vext_elem_mask(v0, i)) {                              \
              /* set masked-off elements to 1s */                           \
@@ -1125,6 +1145,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1,    
  \
      uint32_t vma = vext_vma(desc);                          \
      uint32_t i;                                             \
                                                              \
+    VSTART_CHECK_EARLY_EXIT(env);                           \
+                                                            \
      for (i = env->vstart; i < vl; i++) {                    \
          if (!vm && !vext_elem_mask(v0, i)) {                \
              /* set masked-off elements to 1s */             \
@@ -1187,6 +1209,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void 
*vs2,   \
      uint32_t vma = vext_vma(desc);                            \
      uint32_t i;                                               \
                                                                \
+    VSTART_CHECK_EARLY_EXIT(env);                             \
+                                                              \
      for (i = env->vstart; i < vl; i++) {                      \
          ETYPE s1 = *((ETYPE *)vs1 + H(i));                    \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                    \
@@ -1252,6 +1276,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1, 
void *vs2,   \
      uint32_t vma = vext_vma(desc);                                  \
      uint32_t i;                                                     \
                                                                      \
+    VSTART_CHECK_EARLY_EXIT(env);                                   \
+                                                                    \
      for (i = env->vstart; i < vl; i++) {                            \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                          \
          if (!vm && !vext_elem_mask(v0, i)) {                        \
@@ -1799,6 +1825,8 @@ void HELPER(NAME)(void *vd, void *vs1, CPURISCVState 
*env,           \
      uint32_t vta = vext_vta(desc);                                   \
      uint32_t i;                                                      \
                                                                       \
+    VSTART_CHECK_EARLY_EXIT(env);                                    \
+                                                                     \
      for (i = env->vstart; i < vl; i++) {                             \
          ETYPE s1 = *((ETYPE *)vs1 + H(i));                           \
          *((ETYPE *)vd + H(i)) = s1;                                  \
@@ -1823,6 +1851,8 @@ void HELPER(NAME)(void *vd, uint64_t s1, CPURISCVState 
*env,         \
      uint32_t vta = vext_vta(desc);                                   \
      uint32_t i;                                                      \
                                                                       \
+    VSTART_CHECK_EARLY_EXIT(env);                                    \
+                                                                     \
      for (i = env->vstart; i < vl; i++) {                             \
          *((ETYPE *)vd + H(i)) = (ETYPE)s1;                           \
      }                                                                \
@@ -1846,6 +1876,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void 
*vs2,          \
      uint32_t vta = vext_vta(desc);                                   \
      uint32_t i;                                                      \
                                                                       \
+    VSTART_CHECK_EARLY_EXIT(env);                                    \
+                                                                     \
      for (i = env->vstart; i < vl; i++) {                             \
          ETYPE *vt = (!vext_elem_mask(v0, i) ? vs2 : vs1);            \
          *((ETYPE *)vd + H(i)) = *(vt + H(i));                        \
@@ -1870,6 +1902,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1,    
           \
      uint32_t vta = vext_vta(desc);                                   \
      uint32_t i;                                                      \
                                                                       \
+    VSTART_CHECK_EARLY_EXIT(env);                                    \
+                                                                     \
      for (i = env->vstart; i < vl; i++) {                             \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                           \
          ETYPE d = (!vext_elem_mask(v0, i) ? s2 :                     \
@@ -1915,6 +1949,8 @@ vext_vv_rm_1(void *vd, void *v0, void *vs1, void *vs2,
               uint32_t vl, uint32_t vm, int vxrm,
               opivv2_rm_fn *fn, uint32_t vma, uint32_t esz)
  {
+    VSTART_CHECK_EARLY_EXIT(env);
+
      for (uint32_t i = env->vstart; i < vl; i++) {
          if (!vm && !vext_elem_mask(v0, i)) {
              /* set masked-off elements to 1s */
@@ -2040,6 +2076,8 @@ vext_vx_rm_1(void *vd, void *v0, target_long s1, void 
*vs2,
               uint32_t vl, uint32_t vm, int vxrm,
               opivx2_rm_fn *fn, uint32_t vma, uint32_t esz)
  {
+    VSTART_CHECK_EARLY_EXIT(env);
+
      for (uint32_t i = env->vstart; i < vl; i++) {
          if (!vm && !vext_elem_mask(v0, i)) {
              /* set masked-off elements to 1s */
@@ -2837,6 +2875,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1,          
\
      uint32_t vma = vext_vma(desc);                        \
      uint32_t i;                                           \
                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                         \
+                                                          \
      for (i = env->vstart; i < vl; i++) {                  \
          if (!vm && !vext_elem_mask(v0, i)) {              \
              /* set masked-off elements to 1s */           \
@@ -2880,6 +2920,8 @@ void HELPER(NAME)(void *vd, void *v0, uint64_t s1,        
\
      uint32_t vma = vext_vma(desc);                        \
      uint32_t i;                                           \
                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                         \
+                                                          \
      for (i = env->vstart; i < vl; i++) {                  \
          if (!vm && !vext_elem_mask(v0, i)) {              \
              /* set masked-off elements to 1s */           \
@@ -3466,6 +3508,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs2,       \
      uint32_t vma = vext_vma(desc);                     \
      uint32_t i;                                        \
                                                         \
+    VSTART_CHECK_EARLY_EXIT(env);                      \
+                                                       \
      if (vl == 0) {                                     \
          return;                                        \
      }                                                  \
@@ -3987,6 +4031,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void 
*vs2,   \
      uint32_t vma = vext_vma(desc);                            \
      uint32_t i;                                               \
                                                                \
+    VSTART_CHECK_EARLY_EXIT(env);                             \
+                                                              \
      for (i = env->vstart; i < vl; i++) {                      \
          ETYPE s1 = *((ETYPE *)vs1 + H(i));                    \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                    \
@@ -4027,6 +4073,8 @@ void HELPER(NAME)(void *vd, void *v0, uint64_t s1, void 
*vs2,       \
      uint32_t vma = vext_vma(desc);                                  \
      uint32_t i;                                                     \
                                                                      \
+    VSTART_CHECK_EARLY_EXIT(env);                                   \
+                                                                    \
      for (i = env->vstart; i < vl; i++) {                            \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                          \
          if (!vm && !vext_elem_mask(v0, i)) {                        \
@@ -4220,6 +4268,8 @@ void HELPER(NAME)(void *vd, void *v0, uint64_t s1, void 
*vs2, \
      uint32_t vta = vext_vta(desc);                            \
      uint32_t i;                                               \
                                                                \
+    VSTART_CHECK_EARLY_EXIT(env);                             \
+                                                              \
      for (i = env->vstart; i < vl; i++) {                      \
          ETYPE s2 = *((ETYPE *)vs2 + H(i));                    \
          *((ETYPE *)vd + H(i)) =                               \
@@ -4386,6 +4436,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1,          
\
      uint32_t i;                                           \
      TD s1 =  *((TD *)vs1 + HD(0));                        \
                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                         \
+                                                          \
      for (i = env->vstart; i < vl; i++) {                  \
          TS2 s2 = *((TS2 *)vs2 + HS2(i));                  \
          if (!vm && !vext_elem_mask(v0, i)) {              \
@@ -4472,6 +4524,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1,          
 \
      uint32_t i;                                            \
      TD s1 =  *((TD *)vs1 + HD(0));                         \
                                                             \
+    VSTART_CHECK_EARLY_EXIT(env);                          \
+                                                           \
      for (i = env->vstart; i < vl; i++) {                   \
          TS2 s2 = *((TS2 *)vs2 + HS2(i));                   \
          if (!vm && !vext_elem_mask(v0, i)) {               \
@@ -4544,6 +4598,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1,          
\
      uint32_t i;                                           \
      int a, b;                                             \
                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                         \
+                                                          \
      for (i = env->vstart; i < vl; i++) {                  \
          a = vext_elem_mask(vs1, i);                       \
          b = vext_elem_mask(vs2, i);                       \
@@ -4585,6 +4641,11 @@ target_ulong HELPER(vcpop_m)(void *v0, void *vs2, 
CPURISCVState *env,
      uint32_t vl = env->vl;
      int i;
+    if (env->vstart >= env->vl) {
+        env->vstart = 0;
+        return 0;
+    }
+
      for (i = env->vstart; i < vl; i++) {
          if (vm || vext_elem_mask(v0, i)) {
              if (vext_elem_mask(vs2, i)) {
@@ -4604,6 +4665,11 @@ target_ulong HELPER(vfirst_m)(void *v0, void *vs2, 
CPURISCVState *env,
      uint32_t vl = env->vl;
      int i;
+    if (env->vstart >= env->vl) {
+        env->vstart = 0;
+        return 0;
+    }
+
      for (i = env->vstart; i < vl; i++) {
          if (vm || vext_elem_mask(v0, i)) {
              if (vext_elem_mask(vs2, i)) {
@@ -4632,6 +4698,8 @@ static void vmsetm(void *vd, void *v0, void *vs2, 
CPURISCVState *env,
      int i;
      bool first_mask_bit = false;
+    VSTART_CHECK_EARLY_EXIT(env);
+
      for (i = env->vstart; i < vl; i++) {
          if (!vm && !vext_elem_mask(v0, i)) {
              /* set masked-off elements to 1s */
@@ -4704,6 +4772,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs2, 
CPURISCVState *env,      \
      uint32_t sum = 0;                                                     \
      int i;                                                                \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      for (i = env->vstart; i < vl; i++) {                                  \
          if (!vm && !vext_elem_mask(v0, i)) {                              \
              /* set masked-off elements to 1s */                           \
@@ -4737,6 +4807,8 @@ void HELPER(NAME)(void *vd, void *v0, CPURISCVState *env, 
uint32_t desc)  \
      uint32_t vma = vext_vma(desc);                                        \
      int i;                                                                \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      for (i = env->vstart; i < vl; i++) {                                  \
          if (!vm && !vext_elem_mask(v0, i)) {                              \
              /* set masked-off elements to 1s */                           \
@@ -4772,6 +4844,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1, 
void *vs2,         \
      uint32_t vma = vext_vma(desc);                                        \
      target_ulong offset = s1, i_min, i;                                   \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      i_min = MAX(env->vstart, offset);                                     \
      for (i = i_min; i < vl; i++) {                                        \
          if (!vm && !vext_elem_mask(v0, i)) {                              \
@@ -4805,6 +4879,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1, 
void *vs2,         \
      uint32_t vma = vext_vma(desc);                                        \
      target_ulong i_max, i_min, i;                                         \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      i_min = MIN(s1 < vlmax ? vlmax - s1 : 0, vl);                         \
      i_max = MAX(i_min, env->vstart);                                      \
      for (i = env->vstart; i < i_max; ++i) {                               \
@@ -4847,6 +4923,8 @@ static void vslide1up_##BITWIDTH(void *vd, void *v0, 
uint64_t s1,           \
      uint32_t vma = vext_vma(desc);                                          \
      uint32_t i;                                                             \
                                                                              \
+    VSTART_CHECK_EARLY_EXIT(env);                                           \
+                                                                            \
      for (i = env->vstart; i < vl; i++) {                                    \
          if (!vm && !vext_elem_mask(v0, i)) {                                \
              /* set masked-off elements to 1s */                             \
@@ -4896,6 +4974,8 @@ static void vslide1down_##BITWIDTH(void *vd, void *v0, 
uint64_t s1,           \
      uint32_t vma = vext_vma(desc);                                            
\
      uint32_t i;                                                               
\
                                                                                
\
+    VSTART_CHECK_EARLY_EXIT(env);                                             \
+                                                                              \
      for (i = env->vstart; i < vl; i++) {                                      
\
          if (!vm && !vext_elem_mask(v0, i)) {                                  
\
              /* set masked-off elements to 1s */                               
\
@@ -4971,6 +5051,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void 
*vs2,               \
      uint64_t index;                                                       \
      uint32_t i;                                                           \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      for (i = env->vstart; i < vl; i++) {                                  \
          if (!vm && !vext_elem_mask(v0, i)) {                              \
              /* set masked-off elements to 1s */                           \
@@ -5014,6 +5096,8 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1, 
void *vs2,         \
      uint64_t index = s1;                                                  \
      uint32_t i;                                                           \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      for (i = env->vstart; i < vl; i++) {                                  \
          if (!vm && !vext_elem_mask(v0, i)) {                              \
              /* set masked-off elements to 1s */                           \
@@ -5048,6 +5132,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void 
*vs2,               \
      uint32_t vta = vext_vta(desc);                                        \
      uint32_t num = 0, i;                                                  \
                                                                            \
+    VSTART_CHECK_EARLY_EXIT(env);                                         \
+                                                                          \
      for (i = env->vstart; i < vl; i++) {                                  \
          if (!vext_elem_mask(vs1, i)) {                                    \
              continue;                                                     \
@@ -5100,6 +5186,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs2,          
       \
      uint32_t vma = vext_vma(desc);                               \
      uint32_t i;                                                  \
                                                                   \
+    VSTART_CHECK_EARLY_EXIT(env);                                \
+                                                                 \
      for (i = env->vstart; i < vl; i++) {                         \
          if (!vm && !vext_elem_mask(v0, i)) {                     \
              /* set masked-off elements to 1s */                  \
diff --git a/target/riscv/vector_internals.c b/target/riscv/vector_internals.c
index 12f5964fbb..996c21eb31 100644
--- a/target/riscv/vector_internals.c
+++ b/target/riscv/vector_internals.c
@@ -44,6 +44,8 @@ void do_vext_vv(void *vd, void *v0, void *vs1, void *vs2,
      uint32_t vma = vext_vma(desc);
      uint32_t i;
+    VSTART_CHECK_EARLY_EXIT(env);
+
      for (i = env->vstart; i < vl; i++) {
          if (!vm && !vext_elem_mask(v0, i)) {
              /* set masked-off elements to 1s */
@@ -68,6 +70,8 @@ void do_vext_vx(void *vd, void *v0, target_long s1, void *vs2,
      uint32_t vma = vext_vma(desc);
      uint32_t i;
+    VSTART_CHECK_EARLY_EXIT(env);
+
      for (i = env->vstart; i < vl; i++) {
          if (!vm && !vext_elem_mask(v0, i)) {
              /* set masked-off elements to 1s */
diff --git a/target/riscv/vector_internals.h b/target/riscv/vector_internals.h
index 842765f6c1..9e1e15b575 100644
--- a/target/riscv/vector_internals.h
+++ b/target/riscv/vector_internals.h
@@ -24,6 +24,13 @@
  #include "tcg/tcg-gvec-desc.h"
  #include "internals.h"
+#define VSTART_CHECK_EARLY_EXIT(env) do { \
+    if (env->vstart >= env->vl) {         \
+        env->vstart = 0;                  \
+        return;                           \
+    }                                     \
+} while (0)
+
  static inline uint32_t vext_nf(uint32_t desc)
  {
      return FIELD_EX32(simd_data(desc), VDATA, NF);
@@ -151,6 +158,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs2,       \
      uint32_t vma = vext_vma(desc);                     \
      uint32_t i;                                        \
                                                         \
+    VSTART_CHECK_EARLY_EXIT(env);                      \
+                                                       \
      for (i = env->vstart; i < vl; i++) {               \
          if (!vm && !vext_elem_mask(v0, i)) {           \
              /* set masked-off elements to 1s */        \
reply via email to
[Prev in Thread] Current Thread [Next in Thread]