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[PATCH v5 1/6] tcg/sparc: Add scratch argument to tcg_out_movi_int

Richard Henderson posted 6 patches 4 years ago
Maintainers: Richard Henderson <richard.henderson@linaro.org>
There is a newer version of this series
[PATCH v5 1/6] tcg/sparc: Add scratch argument to tcg_out_movi_int
Posted by Richard Henderson 4 years ago 
This will allow us to control exactly what scratch register is
used for loading the constant.  Also, fix a theoretical problem
in recursing through tcg_out_movi, which may provide a different
value for in_prologue.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/sparc/tcg-target.c.inc | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/tcg/sparc/tcg-target.c.inc b/tcg/sparc/tcg-target.c.inc
index 0c062c60eb..8c3671f56a 100644
--- a/tcg/sparc/tcg-target.c.inc
+++ b/tcg/sparc/tcg-target.c.inc
@@ -414,7 +414,8 @@ static void tcg_out_movi_imm13(TCGContext *s, TCGReg ret, int32_t arg)
 }
 
 static void tcg_out_movi_int(TCGContext *s, TCGType type, TCGReg ret,
-                             tcg_target_long arg, bool in_prologue)
+                             tcg_target_long arg, bool in_prologue,
+                             TCGReg scratch)
 {
     tcg_target_long hi, lo = (int32_t)arg;
     tcg_target_long test, lsb;
@@ -471,22 +472,25 @@ static void tcg_out_movi_int(TCGContext *s, TCGType type, TCGReg ret,
     /* A 64-bit constant decomposed into 2 32-bit pieces.  */
     if (check_fit_i32(lo, 13)) {
         hi = (arg - lo) >> 32;
-        tcg_out_movi(s, TCG_TYPE_I32, ret, hi);
+        tcg_out_movi_int(s, TCG_TYPE_I32, ret, hi, in_prologue, scratch);
         tcg_out_arithi(s, ret, ret, 32, SHIFT_SLLX);
         tcg_out_arithi(s, ret, ret, lo, ARITH_ADD);
     } else {
+        tcg_debug_assert(scratch != TCG_REG_G0);
         hi = arg >> 32;
-        tcg_out_movi(s, TCG_TYPE_I32, ret, hi);
-        tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_T2, lo);
+        tcg_out_movi_int(s, TCG_TYPE_I32, ret, hi, in_prologue, scratch);
+        tcg_out_movi_int(s, TCG_TYPE_I32, scratch, lo, in_prologue, TCG_REG_G0);
         tcg_out_arithi(s, ret, ret, 32, SHIFT_SLLX);
-        tcg_out_arith(s, ret, ret, TCG_REG_T2, ARITH_OR);
+        tcg_out_arith(s, ret, ret, scratch, ARITH_OR);
     }
 }
 
 static void tcg_out_movi(TCGContext *s, TCGType type,
                          TCGReg ret, tcg_target_long arg)
 {
-    tcg_out_movi_int(s, type, ret, arg, false);
+    /* When outputting to T2, we have no scratch available. */
+    TCGReg scratch = ret != TCG_REG_T2 ? TCG_REG_T2 : TCG_REG_G0;
+    tcg_out_movi_int(s, type, ret, arg, false, scratch);
 }
 
 static void tcg_out_ldst_rr(TCGContext *s, TCGReg data, TCGReg a1,
@@ -837,7 +841,7 @@ static void tcg_out_call_nodelay(TCGContext *s, const tcg_insn_unit *dest,
     } else {
         uintptr_t desti = (uintptr_t)dest;
         tcg_out_movi_int(s, TCG_TYPE_PTR, TCG_REG_T1,
-                         desti & ~0xfff, in_prologue);
+                         desti & ~0xfff, in_prologue, TCG_REG_O7);
         tcg_out_arithi(s, TCG_REG_O7, TCG_REG_T1, desti & 0xfff, JMPL);
     }
 }
@@ -1013,7 +1017,8 @@ static void tcg_target_qemu_prologue(TCGContext *s)
 
 #ifndef CONFIG_SOFTMMU
     if (guest_base != 0) {
-        tcg_out_movi_int(s, TCG_TYPE_PTR, TCG_GUEST_BASE_REG, guest_base, true);
+        tcg_out_movi_int(s, TCG_TYPE_PTR, TCG_GUEST_BASE_REG, guest_base,
+                         true, TCG_REG_T1);
         tcg_regset_set_reg(s->reserved_regs, TCG_GUEST_BASE_REG);
     }
 #endif
-- 
2.25.1
Re: [PATCH v5 1/6] tcg/sparc: Add scratch argument to tcg_out_movi_int
Posted by Peter Maydell 4 years ago 
On Sun, 6 Feb 2022 at 10:31, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> This will allow us to control exactly what scratch register is
> used for loading the constant.  Also, fix a theoretical problem
> in recursing through tcg_out_movi, which may provide a different
> value for in_prologue.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  tcg/sparc/tcg-target.c.inc | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/tcg/sparc/tcg-target.c.inc b/tcg/sparc/tcg-target.c.inc
> index 0c062c60eb..8c3671f56a 100644
> --- a/tcg/sparc/tcg-target.c.inc
> +++ b/tcg/sparc/tcg-target.c.inc
> @@ -414,7 +414,8 @@ static void tcg_out_movi_imm13(TCGContext *s, TCGReg ret, int32_t arg)
>  }
>
>  static void tcg_out_movi_int(TCGContext *s, TCGType type, TCGReg ret,
> -                             tcg_target_long arg, bool in_prologue)
> +                             tcg_target_long arg, bool in_prologue,
> +                             TCGReg scratch)
>  {
>      tcg_target_long hi, lo = (int32_t)arg;
>      tcg_target_long test, lsb;
> @@ -471,22 +472,25 @@ static void tcg_out_movi_int(TCGContext *s, TCGType type, TCGReg ret,
>      /* A 64-bit constant decomposed into 2 32-bit pieces.  */
>      if (check_fit_i32(lo, 13)) {
>          hi = (arg - lo) >> 32;
> -        tcg_out_movi(s, TCG_TYPE_I32, ret, hi);
> +        tcg_out_movi_int(s, TCG_TYPE_I32, ret, hi, in_prologue, scratch);
>          tcg_out_arithi(s, ret, ret, 32, SHIFT_SLLX);
>          tcg_out_arithi(s, ret, ret, lo, ARITH_ADD);
>      } else {
> +        tcg_debug_assert(scratch != TCG_REG_G0);
>          hi = arg >> 32;
> -        tcg_out_movi(s, TCG_TYPE_I32, ret, hi);
> -        tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_T2, lo);
> +        tcg_out_movi_int(s, TCG_TYPE_I32, ret, hi, in_prologue, scratch);
> +        tcg_out_movi_int(s, TCG_TYPE_I32, scratch, lo, in_prologue, TCG_REG_G0);
>          tcg_out_arithi(s, ret, ret, 32, SHIFT_SLLX);
> -        tcg_out_arith(s, ret, ret, TCG_REG_T2, ARITH_OR);
> +        tcg_out_arith(s, ret, ret, scratch, ARITH_OR);
>      }
>  }
>
>  static void tcg_out_movi(TCGContext *s, TCGType type,
>                           TCGReg ret, tcg_target_long arg)
>  {
> -    tcg_out_movi_int(s, type, ret, arg, false);
> +    /* When outputting to T2, we have no scratch available. */
> +    TCGReg scratch = ret != TCG_REG_T2 ? TCG_REG_T2 : TCG_REG_G0;

Why won't using G0 trip the assertion above that scratch != TCG_REG_G0 ?

> +    tcg_out_movi_int(s, type, ret, arg, false, scratch);
>  }
>

-- PMM
Re: [PATCH v5 1/6] tcg/sparc: Add scratch argument to tcg_out_movi_int
Posted by Richard Henderson 4 years ago 
On 2/8/22 04:59, Peter Maydell wrote:
> On Sun, 6 Feb 2022 at 10:31, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> This will allow us to control exactly what scratch register is
>> used for loading the constant.  Also, fix a theoretical problem
>> in recursing through tcg_out_movi, which may provide a different
>> value for in_prologue.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   tcg/sparc/tcg-target.c.inc | 21 +++++++++++++--------
>>   1 file changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/tcg/sparc/tcg-target.c.inc b/tcg/sparc/tcg-target.c.inc
>> index 0c062c60eb..8c3671f56a 100644
>> --- a/tcg/sparc/tcg-target.c.inc
>> +++ b/tcg/sparc/tcg-target.c.inc
>> @@ -414,7 +414,8 @@ static void tcg_out_movi_imm13(TCGContext *s, TCGReg ret, int32_t arg)
>>   }
>>
>>   static void tcg_out_movi_int(TCGContext *s, TCGType type, TCGReg ret,
>> -                             tcg_target_long arg, bool in_prologue)
>> +                             tcg_target_long arg, bool in_prologue,
>> +                             TCGReg scratch)
>>   {
>>       tcg_target_long hi, lo = (int32_t)arg;
>>       tcg_target_long test, lsb;
>> @@ -471,22 +472,25 @@ static void tcg_out_movi_int(TCGContext *s, TCGType type, TCGReg ret,
>>       /* A 64-bit constant decomposed into 2 32-bit pieces.  */
>>       if (check_fit_i32(lo, 13)) {
>>           hi = (arg - lo) >> 32;
>> -        tcg_out_movi(s, TCG_TYPE_I32, ret, hi);
>> +        tcg_out_movi_int(s, TCG_TYPE_I32, ret, hi, in_prologue, scratch);
>>           tcg_out_arithi(s, ret, ret, 32, SHIFT_SLLX);
>>           tcg_out_arithi(s, ret, ret, lo, ARITH_ADD);
>>       } else {
>> +        tcg_debug_assert(scratch != TCG_REG_G0);
>>           hi = arg >> 32;
>> -        tcg_out_movi(s, TCG_TYPE_I32, ret, hi);
>> -        tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_T2, lo);
>> +        tcg_out_movi_int(s, TCG_TYPE_I32, ret, hi, in_prologue, scratch);
>> +        tcg_out_movi_int(s, TCG_TYPE_I32, scratch, lo, in_prologue, TCG_REG_G0);
>>           tcg_out_arithi(s, ret, ret, 32, SHIFT_SLLX);
>> -        tcg_out_arith(s, ret, ret, TCG_REG_T2, ARITH_OR);
>> +        tcg_out_arith(s, ret, ret, scratch, ARITH_OR);
>>       }
>>   }
>>
>>   static void tcg_out_movi(TCGContext *s, TCGType type,
>>                            TCGReg ret, tcg_target_long arg)
>>   {
>> -    tcg_out_movi_int(s, type, ret, arg, false);
>> +    /* When outputting to T2, we have no scratch available. */
>> +    TCGReg scratch = ret != TCG_REG_T2 ? TCG_REG_T2 : TCG_REG_G0;
> 
> Why won't using G0 trip the assertion above that scratch != TCG_REG_G0 ?

It would only do so for full 64-bit constants, where the scratch is needed.  For the case 
in which we use T2 explicitly, the value is constrained to J (a 13-bit constant).

I suppose I could have also changed addsub2 to use tcg_out_movi_imm13 directly...


r~

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