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[Qemu-devel] [PATCH] target/arm: Avoid an extra temporary for store_exclusive

Richard Henderson posted 1 patch 6 years, 7 months ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20170908163859.29820-1-richard.henderson@linaro.org
Test checkpatch passed
Test docker passed
Test s390x passed
target/arm/translate-a64.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
[Qemu-devel] [PATCH] target/arm: Avoid an extra temporary for store_exclusive
Posted by Richard Henderson 6 years, 7 months ago 
Instead of copying addr to a local temp, reuse the value (which we
have just compared as equal) already saved in cpu_exclusive_addr.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/translate-a64.c | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 9017e30510..114e21cc58 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -1894,7 +1894,7 @@ static void gen_load_exclusive(DisasContext *s, int rt, int rt2,
 }
 
 static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
-                                TCGv_i64 inaddr, int size, int is_pair)
+                                TCGv_i64 addr, int size, int is_pair)
 {
     /* if (env->exclusive_addr == addr && env->exclusive_val == [addr]
      *     && (!is_pair || env->exclusive_high == [addr + datasize])) {
@@ -1910,13 +1910,8 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
      */
     TCGLabel *fail_label = gen_new_label();
     TCGLabel *done_label = gen_new_label();
-    TCGv_i64 addr = tcg_temp_local_new_i64();
     TCGv_i64 tmp;
 
-    /* Copy input into a local temp so it is not trashed when the
-     * basic block ends at the branch insn.
-     */
-    tcg_gen_mov_i64(addr, inaddr);
     tcg_gen_brcond_i64(TCG_COND_NE, addr, cpu_exclusive_addr, fail_label);
 
     tmp = tcg_temp_new_i64();
@@ -1927,27 +1922,24 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
             } else {
                 tcg_gen_concat32_i64(tmp, cpu_reg(s, rt2), cpu_reg(s, rt));
             }
-            tcg_gen_atomic_cmpxchg_i64(tmp, addr, cpu_exclusive_val, tmp,
+            tcg_gen_atomic_cmpxchg_i64(tmp, cpu_exclusive_addr,
+                                       cpu_exclusive_val, tmp,
                                        get_mem_index(s),
                                        MO_64 | MO_ALIGN | s->be_data);
             tcg_gen_setcond_i64(TCG_COND_NE, tmp, tmp, cpu_exclusive_val);
         } else if (s->be_data == MO_LE) {
-            gen_helper_paired_cmpxchg64_le(tmp, cpu_env, addr, cpu_reg(s, rt),
-                                           cpu_reg(s, rt2));
+            gen_helper_paired_cmpxchg64_le(tmp, cpu_env, cpu_exclusive_addr,
+                                           cpu_reg(s, rt), cpu_reg(s, rt2));
         } else {
-            gen_helper_paired_cmpxchg64_be(tmp, cpu_env, addr, cpu_reg(s, rt),
-                                           cpu_reg(s, rt2));
+            gen_helper_paired_cmpxchg64_be(tmp, cpu_env, cpu_exclusive_addr,
+                                           cpu_reg(s, rt), cpu_reg(s, rt2));
         }
     } else {
-        TCGv_i64 val = cpu_reg(s, rt);
-        tcg_gen_atomic_cmpxchg_i64(tmp, addr, cpu_exclusive_val, val,
-                                   get_mem_index(s),
+        tcg_gen_atomic_cmpxchg_i64(tmp, cpu_exclusive_addr, cpu_exclusive_val,
+                                   cpu_reg(s, rt), get_mem_index(s),
                                    size | MO_ALIGN | s->be_data);
         tcg_gen_setcond_i64(TCG_COND_NE, tmp, tmp, cpu_exclusive_val);
     }
-
-    tcg_temp_free_i64(addr);
-
     tcg_gen_mov_i64(cpu_reg(s, rd), tmp);
     tcg_temp_free_i64(tmp);
     tcg_gen_br(done_label);
-- 
2.13.5
Re: [Qemu-devel] [PATCH] target/arm: Avoid an extra temporary for store_exclusive
Posted by Alistair Francis 6 years, 7 months ago 
On Fri, Sep 8, 2017 at 9:38 AM, Richard Henderson
<richard.henderson@linaro.org> wrote:
> Instead of copying addr to a local temp, reuse the value (which we
> have just compared as equal) already saved in cpu_exclusive_addr.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>

Thanks,
Alistair

> ---
>  target/arm/translate-a64.c | 26 +++++++++-----------------
>  1 file changed, 9 insertions(+), 17 deletions(-)
>
> diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
> index 9017e30510..114e21cc58 100644
> --- a/target/arm/translate-a64.c
> +++ b/target/arm/translate-a64.c
> @@ -1894,7 +1894,7 @@ static void gen_load_exclusive(DisasContext *s, int rt, int rt2,
>  }
>
>  static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
> -                                TCGv_i64 inaddr, int size, int is_pair)
> +                                TCGv_i64 addr, int size, int is_pair)
>  {
>      /* if (env->exclusive_addr == addr && env->exclusive_val == [addr]
>       *     && (!is_pair || env->exclusive_high == [addr + datasize])) {
> @@ -1910,13 +1910,8 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
>       */
>      TCGLabel *fail_label = gen_new_label();
>      TCGLabel *done_label = gen_new_label();
> -    TCGv_i64 addr = tcg_temp_local_new_i64();
>      TCGv_i64 tmp;
>
> -    /* Copy input into a local temp so it is not trashed when the
> -     * basic block ends at the branch insn.
> -     */
> -    tcg_gen_mov_i64(addr, inaddr);
>      tcg_gen_brcond_i64(TCG_COND_NE, addr, cpu_exclusive_addr, fail_label);
>
>      tmp = tcg_temp_new_i64();
> @@ -1927,27 +1922,24 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
>              } else {
>                  tcg_gen_concat32_i64(tmp, cpu_reg(s, rt2), cpu_reg(s, rt));
>              }
> -            tcg_gen_atomic_cmpxchg_i64(tmp, addr, cpu_exclusive_val, tmp,
> +            tcg_gen_atomic_cmpxchg_i64(tmp, cpu_exclusive_addr,
> +                                       cpu_exclusive_val, tmp,
>                                         get_mem_index(s),
>                                         MO_64 | MO_ALIGN | s->be_data);
>              tcg_gen_setcond_i64(TCG_COND_NE, tmp, tmp, cpu_exclusive_val);
>          } else if (s->be_data == MO_LE) {
> -            gen_helper_paired_cmpxchg64_le(tmp, cpu_env, addr, cpu_reg(s, rt),
> -                                           cpu_reg(s, rt2));
> +            gen_helper_paired_cmpxchg64_le(tmp, cpu_env, cpu_exclusive_addr,
> +                                           cpu_reg(s, rt), cpu_reg(s, rt2));
>          } else {
> -            gen_helper_paired_cmpxchg64_be(tmp, cpu_env, addr, cpu_reg(s, rt),
> -                                           cpu_reg(s, rt2));
> +            gen_helper_paired_cmpxchg64_be(tmp, cpu_env, cpu_exclusive_addr,
> +                                           cpu_reg(s, rt), cpu_reg(s, rt2));
>          }
>      } else {
> -        TCGv_i64 val = cpu_reg(s, rt);
> -        tcg_gen_atomic_cmpxchg_i64(tmp, addr, cpu_exclusive_val, val,
> -                                   get_mem_index(s),
> +        tcg_gen_atomic_cmpxchg_i64(tmp, cpu_exclusive_addr, cpu_exclusive_val,
> +                                   cpu_reg(s, rt), get_mem_index(s),
>                                     size | MO_ALIGN | s->be_data);
>          tcg_gen_setcond_i64(TCG_COND_NE, tmp, tmp, cpu_exclusive_val);
>      }
> -
> -    tcg_temp_free_i64(addr);
> -
>      tcg_gen_mov_i64(cpu_reg(s, rd), tmp);
>      tcg_temp_free_i64(tmp);
>      tcg_gen_br(done_label);
> --
> 2.13.5
>
>
Re: [Qemu-devel] [PATCH] target/arm: Avoid an extra temporary for store_exclusive
Posted by Peter Maydell 6 years, 7 months ago 
On 8 September 2017 at 18:46, Alistair Francis <alistair23@gmail.com> wrote:
> On Fri, Sep 8, 2017 at 9:38 AM, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>> Instead of copying addr to a local temp, reuse the value (which we
>> have just compared as equal) already saved in cpu_exclusive_addr.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>
> Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
>



Applied to target-arm.next, thanks.

-- PMM

Patchew 2.1-devel-0870f84

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