diff mbox series

[v3,02/21] target/riscv: Clean up division helpers

Message ID 20210819090502.428068-3-richard.henderson@linaro.org
State New
Headers show
Series target/riscv: Use tcg_constant_* | expand

Commit Message

Richard Henderson Aug. 19, 2021, 9:04 a.m. UTC 
Utilize the condition in the movcond more; this allows some of
the setcond that were feeding into movcond to be removed.
Do not write into source1 and source2.  Re-name "condN" to "tempN"
and use the temporaries for more than holding conditions.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 target/riscv/translate.c | 146 +++++++++++++++++++--------------------
 1 file changed, 71 insertions(+), 75 deletions(-)

-- 
2.25.1

Comments

Bin Meng Aug. 19, 2021, 11 a.m. UTC | #1 
On Thu, Aug 19, 2021 at 5:07 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> Utilize the condition in the movcond more; this allows some of

> the setcond that were feeding into movcond to be removed.

> Do not write into source1 and source2.  Re-name "condN" to "tempN"

> and use the temporaries for more than holding conditions.

>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>  target/riscv/translate.c | 146 +++++++++++++++++++--------------------

>  1 file changed, 71 insertions(+), 75 deletions(-)

>

> diff --git a/target/riscv/translate.c b/target/riscv/translate.c

> index 20a55c92fb..b52181538f 100644

> --- a/target/riscv/translate.c

> +++ b/target/riscv/translate.c

> @@ -213,106 +213,102 @@ static void gen_mulhsu(TCGv ret, TCGv arg1, TCGv arg2)

>

>  static void gen_div(TCGv ret, TCGv source1, TCGv source2)

>  {

> -    TCGv cond1, cond2, zeroreg, resultopt1;

> +    TCGv temp1, temp2, zero, one, mone, min;

> +

>      /*

>       * Handle by altering args to tcg_gen_div to produce req'd results:

> -     * For overflow: want source1 in source1 and 1 in source2

> -     * For div by zero: want -1 in source1 and 1 in source2 -> -1 result

> +     * For overflow: want source1 in temp1 and 1 in temp2

> +     * For div by zero: want -1 in temp1 and 1 in temp2 -> -1 result

>       */

> -    cond1 = tcg_temp_new();

> -    cond2 = tcg_temp_new();

> -    zeroreg = tcg_constant_tl(0);

> -    resultopt1 = tcg_temp_new();

> +    temp1 = tcg_temp_new();

> +    temp2 = tcg_temp_new();

> +    zero = tcg_constant_tl(0);

> +    one = tcg_constant_tl(1);

> +    mone = tcg_constant_tl(-1);

> +    min = tcg_constant_tl(1ull << (TARGET_LONG_BITS - 1));

>

> -    tcg_gen_movi_tl(resultopt1, (target_ulong)-1);

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond2, source2, (target_ulong)(~0L));

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source1,

> -                        ((target_ulong)1) << (TARGET_LONG_BITS - 1));

> -    tcg_gen_and_tl(cond1, cond1, cond2); /* cond1 = overflow */

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond2, source2, 0); /* cond2 = div 0 */

> -    /* if div by zero, set source1 to -1, otherwise don't change */

> -    tcg_gen_movcond_tl(TCG_COND_EQ, source1, cond2, zeroreg, source1,

> -            resultopt1);

> -    /* if overflow or div by zero, set source2 to 1, else don't change */

> -    tcg_gen_or_tl(cond1, cond1, cond2);

> -    tcg_gen_movi_tl(resultopt1, (target_ulong)1);

> -    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond1, zeroreg, source2,

> -            resultopt1);

> -    tcg_gen_div_tl(ret, source1, source2);

> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp1, source1, min);

> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, mone);

> +    tcg_gen_and_tl(temp1, temp1, temp2); /* temp1 = overflow */

> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, zero); /* temp2 = div0 */

> +    tcg_gen_or_tl(temp2, temp2, temp1);  /* temp2 = overflow | div0 */

>

> -    tcg_temp_free(cond1);

> -    tcg_temp_free(cond2);

> -    tcg_temp_free(resultopt1);

> +    /* if div by zero, set temp1 to -1, else source1. */

> +    tcg_gen_movcond_tl(TCG_COND_EQ, temp1, source2, zero, mone, source1);

> +

> +    /* if overflow or div by zero, set temp2 to 1, else source2 */

> +    tcg_gen_movcond_tl(TCG_COND_NE, temp2, temp2, zero, one, source2);

> +

> +    tcg_gen_div_tl(ret, temp1, temp2);

> +

> +    tcg_temp_free(temp1);

> +    tcg_temp_free(temp2);

>  }

>

>  static void gen_divu(TCGv ret, TCGv source1, TCGv source2)

>  {

> -    TCGv cond1, zeroreg, resultopt1;

> -    cond1 = tcg_temp_new();

> +    TCGv temp1, temp2, zero, one, max;

>

> -    zeroreg = tcg_constant_tl(0);

> -    resultopt1 = tcg_temp_new();

> +    temp1 = tcg_temp_new();

> +    temp2 = tcg_temp_new();

> +    zero = tcg_constant_tl(0);

> +    one = tcg_constant_tl(1);

> +    max = tcg_constant_tl(~0);

>

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source2, 0);

> -    tcg_gen_movi_tl(resultopt1, (target_ulong)-1);

> -    tcg_gen_movcond_tl(TCG_COND_EQ, source1, cond1, zeroreg, source1,

> -            resultopt1);

> -    tcg_gen_movi_tl(resultopt1, (target_ulong)1);

> -    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond1, zeroreg, source2,

> -            resultopt1);

> -    tcg_gen_divu_tl(ret, source1, source2);

> +    tcg_gen_movcond_tl(TCG_COND_EQ, temp1, source2, zero, max, source1);

> +    tcg_gen_movcond_tl(TCG_COND_EQ, temp2, source2, zero, one, source2);

> +    tcg_gen_divu_tl(ret, temp1, temp2);

>

> -    tcg_temp_free(cond1);

> -    tcg_temp_free(resultopt1);

> +    tcg_temp_free(temp1);

> +    tcg_temp_free(temp2);

>  }

>

>  static void gen_rem(TCGv ret, TCGv source1, TCGv source2)

>  {

> -    TCGv cond1, cond2, zeroreg, resultopt1;

> +    TCGv temp1, temp2, zero, one, mone, min;

>

> -    cond1 = tcg_temp_new();

> -    cond2 = tcg_temp_new();

> -    zeroreg = tcg_constant_tl(0);

> -    resultopt1 = tcg_temp_new();

> +    temp1 = tcg_temp_new();

> +    temp2 = tcg_temp_new();

> +    zero = tcg_constant_tl(0);

> +    one = tcg_constant_tl(1);

> +    mone = tcg_constant_tl(-1);

> +    min = tcg_constant_tl(1ull << (TARGET_LONG_BITS - 1));

>

> -    tcg_gen_movi_tl(resultopt1, 1L);

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond2, source2, (target_ulong)-1);

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source1,

> -                        (target_ulong)1 << (TARGET_LONG_BITS - 1));

> -    tcg_gen_and_tl(cond2, cond1, cond2); /* cond1 = overflow */

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source2, 0); /* cond2 = div 0 */

> -    /* if overflow or div by zero, set source2 to 1, else don't change */

> -    tcg_gen_or_tl(cond2, cond1, cond2);

> -    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond2, zeroreg, source2,

> -            resultopt1);

> -    tcg_gen_rem_tl(resultopt1, source1, source2);

> -    /* if div by zero, just return the original dividend */

> -    tcg_gen_movcond_tl(TCG_COND_EQ, ret, cond1, zeroreg, resultopt1,

> -            source1);

> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp1, source1, min);

> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, mone);

> +    tcg_gen_and_tl(temp1, temp1, temp2); /* temp1 = overflow */

> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, zero); /* temp2 = div0 */

> +    tcg_gen_or_tl(temp2, temp2, temp1);  /* temp2 = overflow | div0 */

>

> -    tcg_temp_free(cond1);

> -    tcg_temp_free(cond2);

> -    tcg_temp_free(resultopt1);

> +    /*

> +     * if overflow or div by zero, set temp2 to 1, else source2

> +     * this automatically takes care of returning the original

> +     * dividend for div by zero.

> +     */

> +    tcg_gen_movcond_tl(TCG_COND_NE, temp2, temp2, zero, one, source2);


What about the overflow case? The return value should be 0.

> +

> +    tcg_gen_rem_tl(ret, source1, temp2);

> +

> +    tcg_temp_free(temp1);

> +    tcg_temp_free(temp2);

>  }

>

>  static void gen_remu(TCGv ret, TCGv source1, TCGv source2)

>  {

> -    TCGv cond1, zeroreg, resultopt1;

> -    cond1 = tcg_temp_new();

> -    zeroreg = tcg_constant_tl(0);

> -    resultopt1 = tcg_temp_new();

> +    TCGv temp2, zero, one;

>

> -    tcg_gen_movi_tl(resultopt1, (target_ulong)1);

> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source2, 0);

> -    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond1, zeroreg, source2,

> -            resultopt1);

> -    tcg_gen_remu_tl(resultopt1, source1, source2);

> -    /* if div by zero, just return the original dividend */

> -    tcg_gen_movcond_tl(TCG_COND_EQ, ret, cond1, zeroreg, resultopt1,

> -            source1);

> +    temp2 = tcg_temp_new();

> +    zero = tcg_constant_tl(0);

> +    one = tcg_constant_tl(1);

>

> -    tcg_temp_free(cond1);

> -    tcg_temp_free(resultopt1);

> +    /*

> +     * if div by zero, set temp2 to 1, else source2

> +     * this automatically takes care of returning the original dividend.

> +     */

> +    tcg_gen_movcond_tl(TCG_COND_EQ, temp2, source2, zero, one, source2);

> +    tcg_gen_remu_tl(ret, source1, temp2);

> +

> +    tcg_temp_free(temp2);

>  }

>

>  static void gen_jal(DisasContext *ctx, int rd, target_ulong imm)


Regards,
Bin
Richard Henderson Aug. 19, 2021, 5:23 p.m. UTC | #2 
On 8/19/21 1:00 AM, Bin Meng wrote:
>>   static void gen_rem(TCGv ret, TCGv source1, TCGv source2)

>>   {

>> -    TCGv cond1, cond2, zeroreg, resultopt1;

>> +    TCGv temp1, temp2, zero, one, mone, min;

>>

>> -    cond1 = tcg_temp_new();

>> -    cond2 = tcg_temp_new();

>> -    zeroreg = tcg_constant_tl(0);

>> -    resultopt1 = tcg_temp_new();

>> +    temp1 = tcg_temp_new();

>> +    temp2 = tcg_temp_new();

>> +    zero = tcg_constant_tl(0);

>> +    one = tcg_constant_tl(1);

>> +    mone = tcg_constant_tl(-1);

>> +    min = tcg_constant_tl(1ull << (TARGET_LONG_BITS - 1));

>>

>> -    tcg_gen_movi_tl(resultopt1, 1L);

>> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond2, source2, (target_ulong)-1);

>> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source1,

>> -                        (target_ulong)1 << (TARGET_LONG_BITS - 1));

>> -    tcg_gen_and_tl(cond2, cond1, cond2); /* cond1 = overflow */

>> -    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source2, 0); /* cond2 = div 0 */

>> -    /* if overflow or div by zero, set source2 to 1, else don't change */

>> -    tcg_gen_or_tl(cond2, cond1, cond2);

>> -    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond2, zeroreg, source2,

>> -            resultopt1);

>> -    tcg_gen_rem_tl(resultopt1, source1, source2);

>> -    /* if div by zero, just return the original dividend */

>> -    tcg_gen_movcond_tl(TCG_COND_EQ, ret, cond1, zeroreg, resultopt1,

>> -            source1);

>> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp1, source1, min);

>> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, mone);

>> +    tcg_gen_and_tl(temp1, temp1, temp2); /* temp1 = overflow */

>> +    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, zero); /* temp2 = div0 */

>> +    tcg_gen_or_tl(temp2, temp2, temp1);  /* temp2 = overflow | div0 */

>>

>> -    tcg_temp_free(cond1);

>> -    tcg_temp_free(cond2);

>> -    tcg_temp_free(resultopt1);

>> +    /*

>> +     * if overflow or div by zero, set temp2 to 1, else source2

>> +     * this automatically takes care of returning the original

>> +     * dividend for div by zero.

>> +     */

>> +    tcg_gen_movcond_tl(TCG_COND_NE, temp2, temp2, zero, one, source2);

> 

> What about the overflow case? The return value should be 0.


Hmm.  I see that in the table, yes, but I don't see that the original code got that 
correct either.  I'll send a follow-up patch.

r~
diff mbox series

Patch

diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 20a55c92fb..b52181538f 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -213,106 +213,102 @@  static void gen_mulhsu(TCGv ret, TCGv arg1, TCGv arg2)
 
 static void gen_div(TCGv ret, TCGv source1, TCGv source2)
 {
-    TCGv cond1, cond2, zeroreg, resultopt1;
+    TCGv temp1, temp2, zero, one, mone, min;
+
     /*
      * Handle by altering args to tcg_gen_div to produce req'd results:
-     * For overflow: want source1 in source1 and 1 in source2
-     * For div by zero: want -1 in source1 and 1 in source2 -> -1 result
+     * For overflow: want source1 in temp1 and 1 in temp2
+     * For div by zero: want -1 in temp1 and 1 in temp2 -> -1 result
      */
-    cond1 = tcg_temp_new();
-    cond2 = tcg_temp_new();
-    zeroreg = tcg_constant_tl(0);
-    resultopt1 = tcg_temp_new();
+    temp1 = tcg_temp_new();
+    temp2 = tcg_temp_new();
+    zero = tcg_constant_tl(0);
+    one = tcg_constant_tl(1);
+    mone = tcg_constant_tl(-1);
+    min = tcg_constant_tl(1ull << (TARGET_LONG_BITS - 1));
 
-    tcg_gen_movi_tl(resultopt1, (target_ulong)-1);
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond2, source2, (target_ulong)(~0L));
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source1,
-                        ((target_ulong)1) << (TARGET_LONG_BITS - 1));
-    tcg_gen_and_tl(cond1, cond1, cond2); /* cond1 = overflow */
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond2, source2, 0); /* cond2 = div 0 */
-    /* if div by zero, set source1 to -1, otherwise don't change */
-    tcg_gen_movcond_tl(TCG_COND_EQ, source1, cond2, zeroreg, source1,
-            resultopt1);
-    /* if overflow or div by zero, set source2 to 1, else don't change */
-    tcg_gen_or_tl(cond1, cond1, cond2);
-    tcg_gen_movi_tl(resultopt1, (target_ulong)1);
-    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond1, zeroreg, source2,
-            resultopt1);
-    tcg_gen_div_tl(ret, source1, source2);
+    tcg_gen_setcond_tl(TCG_COND_EQ, temp1, source1, min);
+    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, mone);
+    tcg_gen_and_tl(temp1, temp1, temp2); /* temp1 = overflow */
+    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, zero); /* temp2 = div0 */
+    tcg_gen_or_tl(temp2, temp2, temp1);  /* temp2 = overflow | div0 */
 
-    tcg_temp_free(cond1);
-    tcg_temp_free(cond2);
-    tcg_temp_free(resultopt1);
+    /* if div by zero, set temp1 to -1, else source1. */
+    tcg_gen_movcond_tl(TCG_COND_EQ, temp1, source2, zero, mone, source1);
+
+    /* if overflow or div by zero, set temp2 to 1, else source2 */
+    tcg_gen_movcond_tl(TCG_COND_NE, temp2, temp2, zero, one, source2);
+
+    tcg_gen_div_tl(ret, temp1, temp2);
+
+    tcg_temp_free(temp1);
+    tcg_temp_free(temp2);
 }
 
 static void gen_divu(TCGv ret, TCGv source1, TCGv source2)
 {
-    TCGv cond1, zeroreg, resultopt1;
-    cond1 = tcg_temp_new();
+    TCGv temp1, temp2, zero, one, max;
 
-    zeroreg = tcg_constant_tl(0);
-    resultopt1 = tcg_temp_new();
+    temp1 = tcg_temp_new();
+    temp2 = tcg_temp_new();
+    zero = tcg_constant_tl(0);
+    one = tcg_constant_tl(1);
+    max = tcg_constant_tl(~0);
 
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source2, 0);
-    tcg_gen_movi_tl(resultopt1, (target_ulong)-1);
-    tcg_gen_movcond_tl(TCG_COND_EQ, source1, cond1, zeroreg, source1,
-            resultopt1);
-    tcg_gen_movi_tl(resultopt1, (target_ulong)1);
-    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond1, zeroreg, source2,
-            resultopt1);
-    tcg_gen_divu_tl(ret, source1, source2);
+    tcg_gen_movcond_tl(TCG_COND_EQ, temp1, source2, zero, max, source1);
+    tcg_gen_movcond_tl(TCG_COND_EQ, temp2, source2, zero, one, source2);
+    tcg_gen_divu_tl(ret, temp1, temp2);
 
-    tcg_temp_free(cond1);
-    tcg_temp_free(resultopt1);
+    tcg_temp_free(temp1);
+    tcg_temp_free(temp2);
 }
 
 static void gen_rem(TCGv ret, TCGv source1, TCGv source2)
 {
-    TCGv cond1, cond2, zeroreg, resultopt1;
+    TCGv temp1, temp2, zero, one, mone, min;
 
-    cond1 = tcg_temp_new();
-    cond2 = tcg_temp_new();
-    zeroreg = tcg_constant_tl(0);
-    resultopt1 = tcg_temp_new();
+    temp1 = tcg_temp_new();
+    temp2 = tcg_temp_new();
+    zero = tcg_constant_tl(0);
+    one = tcg_constant_tl(1);
+    mone = tcg_constant_tl(-1);
+    min = tcg_constant_tl(1ull << (TARGET_LONG_BITS - 1));
 
-    tcg_gen_movi_tl(resultopt1, 1L);
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond2, source2, (target_ulong)-1);
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source1,
-                        (target_ulong)1 << (TARGET_LONG_BITS - 1));
-    tcg_gen_and_tl(cond2, cond1, cond2); /* cond1 = overflow */
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source2, 0); /* cond2 = div 0 */
-    /* if overflow or div by zero, set source2 to 1, else don't change */
-    tcg_gen_or_tl(cond2, cond1, cond2);
-    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond2, zeroreg, source2,
-            resultopt1);
-    tcg_gen_rem_tl(resultopt1, source1, source2);
-    /* if div by zero, just return the original dividend */
-    tcg_gen_movcond_tl(TCG_COND_EQ, ret, cond1, zeroreg, resultopt1,
-            source1);
+    tcg_gen_setcond_tl(TCG_COND_EQ, temp1, source1, min);
+    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, mone);
+    tcg_gen_and_tl(temp1, temp1, temp2); /* temp1 = overflow */
+    tcg_gen_setcond_tl(TCG_COND_EQ, temp2, source2, zero); /* temp2 = div0 */
+    tcg_gen_or_tl(temp2, temp2, temp1);  /* temp2 = overflow | div0 */
 
-    tcg_temp_free(cond1);
-    tcg_temp_free(cond2);
-    tcg_temp_free(resultopt1);
+    /*
+     * if overflow or div by zero, set temp2 to 1, else source2
+     * this automatically takes care of returning the original
+     * dividend for div by zero.
+     */
+    tcg_gen_movcond_tl(TCG_COND_NE, temp2, temp2, zero, one, source2);
+
+    tcg_gen_rem_tl(ret, source1, temp2);
+
+    tcg_temp_free(temp1);
+    tcg_temp_free(temp2);
 }
 
 static void gen_remu(TCGv ret, TCGv source1, TCGv source2)
 {
-    TCGv cond1, zeroreg, resultopt1;
-    cond1 = tcg_temp_new();
-    zeroreg = tcg_constant_tl(0);
-    resultopt1 = tcg_temp_new();
+    TCGv temp2, zero, one;
 
-    tcg_gen_movi_tl(resultopt1, (target_ulong)1);
-    tcg_gen_setcondi_tl(TCG_COND_EQ, cond1, source2, 0);
-    tcg_gen_movcond_tl(TCG_COND_EQ, source2, cond1, zeroreg, source2,
-            resultopt1);
-    tcg_gen_remu_tl(resultopt1, source1, source2);
-    /* if div by zero, just return the original dividend */
-    tcg_gen_movcond_tl(TCG_COND_EQ, ret, cond1, zeroreg, resultopt1,
-            source1);
+    temp2 = tcg_temp_new();
+    zero = tcg_constant_tl(0);
+    one = tcg_constant_tl(1);
 
-    tcg_temp_free(cond1);
-    tcg_temp_free(resultopt1);
+    /*
+     * if div by zero, set temp2 to 1, else source2
+     * this automatically takes care of returning the original dividend.
+     */
+    tcg_gen_movcond_tl(TCG_COND_EQ, temp2, source2, zero, one, source2);
+    tcg_gen_remu_tl(ret, source1, temp2);
+
+    tcg_temp_free(temp2);
 }
 
 static void gen_jal(DisasContext *ctx, int rd, target_ulong imm)