target/arm: Avoid an extra temporary for store_exclusive

Message ID 20170908163859.29820-1-richard.henderson@linaro.org
State Superseded
Headers show
Series
  • target/arm: Avoid an extra temporary for store_exclusive
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Commit Message

Richard Henderson Sept. 8, 2017, 4:38 p.m.
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(-)

-- 
2.13.5

Comments

Alistair Francis Sept. 8, 2017, 5:46 p.m. | #1
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

>

>
Peter Maydell Sept. 14, 2017, 12:47 p.m. | #2
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

Patch

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);