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* [PATCH 0/2] tcg/riscv: Use BEXTI for single-bit extractions
@ 2025-01-02 18:15 Richard Henderson
  2025-01-02 18:16 ` [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs Richard Henderson
  2025-01-02 18:16 ` [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
  0 siblings, 2 replies; 8+ messages in thread
From: Richard Henderson @ 2025-01-02 18:15 UTC (permalink / raw)
  To: qemu-devel; +Cc: qemu-riscv, palmer, Alistair.Francis

Based-on: 20250102180654.1420056-1-richard.henderson@linaro.org
("[PATCH 00/73] tcg: Merge *_i32 and *_i64 opcodes")

While riscv does not yet have a completely general extract,
the Zbs extension added a single-bit extract.

Tested on cfarm95, a Banana Pi BPI-F3.


r~


Richard Henderson (2):
  util/cpuinfo-riscv: Detect Zbs
  tcg/riscv: Use BEXTI for single-bit extractions

 host/include/riscv/host/cpuinfo.h |  5 +++--
 tcg/riscv/tcg-target-has.h        |  8 +++++++-
 util/cpuinfo-riscv.c              | 18 ++++++++++++++++--
 tcg/riscv/tcg-target.c.inc        | 13 +++++++++++--
 4 files changed, 37 insertions(+), 7 deletions(-)

-- 
2.43.0



^ permalink raw reply	[flat|nested] 8+ messages in thread

* [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs
  2025-01-02 18:15 [PATCH 0/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
@ 2025-01-02 18:16 ` Richard Henderson
  2025-01-06  0:44   ` Alistair Francis
  2025-01-07  9:05   ` Philippe Mathieu-Daudé
  2025-01-02 18:16 ` [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
  1 sibling, 2 replies; 8+ messages in thread
From: Richard Henderson @ 2025-01-02 18:16 UTC (permalink / raw)
  To: qemu-devel; +Cc: qemu-riscv, palmer, Alistair.Francis

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 host/include/riscv/host/cpuinfo.h |  5 +++--
 util/cpuinfo-riscv.c              | 18 ++++++++++++++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/host/include/riscv/host/cpuinfo.h b/host/include/riscv/host/cpuinfo.h
index cdc784e7b6..b2b53dbf62 100644
--- a/host/include/riscv/host/cpuinfo.h
+++ b/host/include/riscv/host/cpuinfo.h
@@ -9,8 +9,9 @@
 #define CPUINFO_ALWAYS          (1u << 0)  /* so cpuinfo is nonzero */
 #define CPUINFO_ZBA             (1u << 1)
 #define CPUINFO_ZBB             (1u << 2)
-#define CPUINFO_ZICOND          (1u << 3)
-#define CPUINFO_ZVE64X          (1u << 4)
+#define CPUINFO_ZBS             (1u << 3)
+#define CPUINFO_ZICOND          (1u << 4)
+#define CPUINFO_ZVE64X          (1u << 5)
 
 /* Initialized with a constructor. */
 extern unsigned cpuinfo;
diff --git a/util/cpuinfo-riscv.c b/util/cpuinfo-riscv.c
index 971c924012..0291b7218a 100644
--- a/util/cpuinfo-riscv.c
+++ b/util/cpuinfo-riscv.c
@@ -36,7 +36,8 @@ static void sigill_handler(int signo, siginfo_t *si, void *data)
 /* Called both as constructor and (possibly) via other constructors. */
 unsigned __attribute__((constructor)) cpuinfo_init(void)
 {
-    unsigned left = CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZICOND | CPUINFO_ZVE64X;
+    unsigned left = CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS
+                  | CPUINFO_ZICOND | CPUINFO_ZVE64X;
     unsigned info = cpuinfo;
 
     if (info) {
@@ -50,6 +51,9 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
 #if defined(__riscv_arch_test) && defined(__riscv_zbb)
     info |= CPUINFO_ZBB;
 #endif
+#if defined(__riscv_arch_test) && defined(__riscv_zbs)
+    info |= CPUINFO_ZBS;
+#endif
 #if defined(__riscv_arch_test) && defined(__riscv_zicond)
     info |= CPUINFO_ZICOND;
 #endif
@@ -71,7 +75,8 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
             && pair.key >= 0) {
             info |= pair.value & RISCV_HWPROBE_EXT_ZBA ? CPUINFO_ZBA : 0;
             info |= pair.value & RISCV_HWPROBE_EXT_ZBB ? CPUINFO_ZBB : 0;
-            left &= ~(CPUINFO_ZBA | CPUINFO_ZBB);
+            info |= pair.value & RISCV_HWPROBE_EXT_ZBS ? CPUINFO_ZBS : 0;
+            left &= ~(CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS);
 #ifdef RISCV_HWPROBE_EXT_ZICOND
             info |= pair.value & RISCV_HWPROBE_EXT_ZICOND ? CPUINFO_ZICOND : 0;
             left &= ~CPUINFO_ZICOND;
@@ -117,6 +122,15 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
             left &= ~CPUINFO_ZBB;
         }
 
+        if (left & CPUINFO_ZBS) {
+            /* Probe for Zbs: bext zero,zero,zero. */
+            got_sigill = 0;
+            asm volatile(".insn r 0x33, 5, 0x24, zero, zero, zero"
+                         : : : "memory");
+            info |= got_sigill ? 0 : CPUINFO_ZBS;
+            left &= ~CPUINFO_ZBS;
+        }
+
         if (left & CPUINFO_ZICOND) {
             /* Probe for Zicond: czero.eqz zero,zero,zero. */
             got_sigill = 0;
-- 
2.43.0



^ permalink raw reply related	[flat|nested] 8+ messages in thread

* [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions
  2025-01-02 18:15 [PATCH 0/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
  2025-01-02 18:16 ` [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs Richard Henderson
@ 2025-01-02 18:16 ` Richard Henderson
  2025-01-06  0:45   ` Alistair Francis
  2025-01-07 10:29   ` Philippe Mathieu-Daudé
  1 sibling, 2 replies; 8+ messages in thread
From: Richard Henderson @ 2025-01-02 18:16 UTC (permalink / raw)
  To: qemu-devel; +Cc: qemu-riscv, palmer, Alistair.Francis

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/riscv/tcg-target-has.h |  8 +++++++-
 tcg/riscv/tcg-target.c.inc | 13 +++++++++++--
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/tcg/riscv/tcg-target-has.h b/tcg/riscv/tcg-target-has.h
index 10e61edc45..ea38ee5cbb 100644
--- a/tcg/riscv/tcg-target-has.h
+++ b/tcg/riscv/tcg-target-has.h
@@ -64,7 +64,13 @@ tcg_target_extract_valid(TCGType type, unsigned ofs, unsigned len)
         /* ofs > 0 uses SRLIW; ofs == 0 uses add.uw. */
         return ofs || (cpuinfo & CPUINFO_ZBA);
     }
-    return (cpuinfo & CPUINFO_ZBB) && ofs == 0 && len == 16;
+    switch (len) {
+    case 1:
+        return (cpuinfo & CPUINFO_ZBS) && ofs != 0;
+    case 16:
+        return (cpuinfo & CPUINFO_ZBB) && ofs == 0;
+    }
+    return false;
 }
 #define TCG_TARGET_extract_valid  tcg_target_extract_valid
 
diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
index 12c3cffcc0..83ec7cd980 100644
--- a/tcg/riscv/tcg-target.c.inc
+++ b/tcg/riscv/tcg-target.c.inc
@@ -162,6 +162,7 @@ typedef enum {
     OPC_ANDI = 0x7013,
     OPC_AUIPC = 0x17,
     OPC_BEQ = 0x63,
+    OPC_BEXTI = 0x48005013,
     OPC_BGE = 0x5063,
     OPC_BGEU = 0x7063,
     OPC_BLT = 0x4063,
@@ -2307,9 +2308,17 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, TCGType type,
             } else {
                 tcg_out_opc_imm(s, OPC_SRLIW, a0, a1, a2);
             }
-        } else if (a2 == 0 && args[3] == 16) {
+            break;
+        }
+        switch (args[3]) {
+        case 1:
+            tcg_out_opc_imm(s, OPC_BEXTI, a0, a1, a2);
+            break;
+        case 16:
+            tcg_debug_assert(a2 == 0);
             tcg_out_ext16u(s, a0, a1);
-        } else {
+            break;
+        default:
             g_assert_not_reached();
         }
         break;
-- 
2.43.0



^ permalink raw reply related	[flat|nested] 8+ messages in thread

* Re: [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs
  2025-01-02 18:16 ` [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs Richard Henderson
@ 2025-01-06  0:44   ` Alistair Francis
  2025-01-07  9:05   ` Philippe Mathieu-Daudé
  1 sibling, 0 replies; 8+ messages in thread
From: Alistair Francis @ 2025-01-06  0:44 UTC (permalink / raw)
  To: Richard Henderson; +Cc: qemu-devel, qemu-riscv, palmer, Alistair.Francis

On Fri, Jan 3, 2025 at 4:28 AM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  host/include/riscv/host/cpuinfo.h |  5 +++--
>  util/cpuinfo-riscv.c              | 18 ++++++++++++++++--
>  2 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/host/include/riscv/host/cpuinfo.h b/host/include/riscv/host/cpuinfo.h
> index cdc784e7b6..b2b53dbf62 100644
> --- a/host/include/riscv/host/cpuinfo.h
> +++ b/host/include/riscv/host/cpuinfo.h
> @@ -9,8 +9,9 @@
>  #define CPUINFO_ALWAYS          (1u << 0)  /* so cpuinfo is nonzero */
>  #define CPUINFO_ZBA             (1u << 1)
>  #define CPUINFO_ZBB             (1u << 2)
> -#define CPUINFO_ZICOND          (1u << 3)
> -#define CPUINFO_ZVE64X          (1u << 4)
> +#define CPUINFO_ZBS             (1u << 3)
> +#define CPUINFO_ZICOND          (1u << 4)
> +#define CPUINFO_ZVE64X          (1u << 5)
>
>  /* Initialized with a constructor. */
>  extern unsigned cpuinfo;
> diff --git a/util/cpuinfo-riscv.c b/util/cpuinfo-riscv.c
> index 971c924012..0291b7218a 100644
> --- a/util/cpuinfo-riscv.c
> +++ b/util/cpuinfo-riscv.c
> @@ -36,7 +36,8 @@ static void sigill_handler(int signo, siginfo_t *si, void *data)
>  /* Called both as constructor and (possibly) via other constructors. */
>  unsigned __attribute__((constructor)) cpuinfo_init(void)
>  {
> -    unsigned left = CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZICOND | CPUINFO_ZVE64X;
> +    unsigned left = CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS
> +                  | CPUINFO_ZICOND | CPUINFO_ZVE64X;
>      unsigned info = cpuinfo;
>
>      if (info) {
> @@ -50,6 +51,9 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>  #if defined(__riscv_arch_test) && defined(__riscv_zbb)
>      info |= CPUINFO_ZBB;
>  #endif
> +#if defined(__riscv_arch_test) && defined(__riscv_zbs)
> +    info |= CPUINFO_ZBS;
> +#endif
>  #if defined(__riscv_arch_test) && defined(__riscv_zicond)
>      info |= CPUINFO_ZICOND;
>  #endif
> @@ -71,7 +75,8 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>              && pair.key >= 0) {
>              info |= pair.value & RISCV_HWPROBE_EXT_ZBA ? CPUINFO_ZBA : 0;
>              info |= pair.value & RISCV_HWPROBE_EXT_ZBB ? CPUINFO_ZBB : 0;
> -            left &= ~(CPUINFO_ZBA | CPUINFO_ZBB);
> +            info |= pair.value & RISCV_HWPROBE_EXT_ZBS ? CPUINFO_ZBS : 0;
> +            left &= ~(CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS);
>  #ifdef RISCV_HWPROBE_EXT_ZICOND
>              info |= pair.value & RISCV_HWPROBE_EXT_ZICOND ? CPUINFO_ZICOND : 0;
>              left &= ~CPUINFO_ZICOND;
> @@ -117,6 +122,15 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>              left &= ~CPUINFO_ZBB;
>          }
>
> +        if (left & CPUINFO_ZBS) {
> +            /* Probe for Zbs: bext zero,zero,zero. */
> +            got_sigill = 0;
> +            asm volatile(".insn r 0x33, 5, 0x24, zero, zero, zero"
> +                         : : : "memory");
> +            info |= got_sigill ? 0 : CPUINFO_ZBS;
> +            left &= ~CPUINFO_ZBS;
> +        }
> +
>          if (left & CPUINFO_ZICOND) {
>              /* Probe for Zicond: czero.eqz zero,zero,zero. */
>              got_sigill = 0;
> --
> 2.43.0
>
>


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions
  2025-01-02 18:16 ` [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
@ 2025-01-06  0:45   ` Alistair Francis
  2025-01-07 10:29   ` Philippe Mathieu-Daudé
  1 sibling, 0 replies; 8+ messages in thread
From: Alistair Francis @ 2025-01-06  0:45 UTC (permalink / raw)
  To: Richard Henderson; +Cc: qemu-devel, qemu-riscv, palmer, Alistair.Francis

On Fri, Jan 3, 2025 at 4:21 AM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  tcg/riscv/tcg-target-has.h |  8 +++++++-
>  tcg/riscv/tcg-target.c.inc | 13 +++++++++++--
>  2 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/tcg/riscv/tcg-target-has.h b/tcg/riscv/tcg-target-has.h
> index 10e61edc45..ea38ee5cbb 100644
> --- a/tcg/riscv/tcg-target-has.h
> +++ b/tcg/riscv/tcg-target-has.h
> @@ -64,7 +64,13 @@ tcg_target_extract_valid(TCGType type, unsigned ofs, unsigned len)
>          /* ofs > 0 uses SRLIW; ofs == 0 uses add.uw. */
>          return ofs || (cpuinfo & CPUINFO_ZBA);
>      }
> -    return (cpuinfo & CPUINFO_ZBB) && ofs == 0 && len == 16;
> +    switch (len) {
> +    case 1:
> +        return (cpuinfo & CPUINFO_ZBS) && ofs != 0;
> +    case 16:
> +        return (cpuinfo & CPUINFO_ZBB) && ofs == 0;
> +    }
> +    return false;
>  }
>  #define TCG_TARGET_extract_valid  tcg_target_extract_valid
>
> diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
> index 12c3cffcc0..83ec7cd980 100644
> --- a/tcg/riscv/tcg-target.c.inc
> +++ b/tcg/riscv/tcg-target.c.inc
> @@ -162,6 +162,7 @@ typedef enum {
>      OPC_ANDI = 0x7013,
>      OPC_AUIPC = 0x17,
>      OPC_BEQ = 0x63,
> +    OPC_BEXTI = 0x48005013,
>      OPC_BGE = 0x5063,
>      OPC_BGEU = 0x7063,
>      OPC_BLT = 0x4063,
> @@ -2307,9 +2308,17 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, TCGType type,
>              } else {
>                  tcg_out_opc_imm(s, OPC_SRLIW, a0, a1, a2);
>              }
> -        } else if (a2 == 0 && args[3] == 16) {
> +            break;
> +        }
> +        switch (args[3]) {
> +        case 1:
> +            tcg_out_opc_imm(s, OPC_BEXTI, a0, a1, a2);
> +            break;
> +        case 16:
> +            tcg_debug_assert(a2 == 0);
>              tcg_out_ext16u(s, a0, a1);
> -        } else {
> +            break;
> +        default:
>              g_assert_not_reached();
>          }
>          break;
> --
> 2.43.0
>
>


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs
  2025-01-02 18:16 ` [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs Richard Henderson
  2025-01-06  0:44   ` Alistair Francis
@ 2025-01-07  9:05   ` Philippe Mathieu-Daudé
  1 sibling, 0 replies; 8+ messages in thread
From: Philippe Mathieu-Daudé @ 2025-01-07  9:05 UTC (permalink / raw)
  To: Richard Henderson, qemu-devel; +Cc: qemu-riscv, palmer, Alistair.Francis

On 2/1/25 19:16, Richard Henderson wrote:
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   host/include/riscv/host/cpuinfo.h |  5 +++--
>   util/cpuinfo-riscv.c              | 18 ++++++++++++++++--
>   2 files changed, 19 insertions(+), 4 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>



^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions
  2025-01-02 18:16 ` [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
  2025-01-06  0:45   ` Alistair Francis
@ 2025-01-07 10:29   ` Philippe Mathieu-Daudé
  2025-01-07 15:27     ` Richard Henderson
  1 sibling, 1 reply; 8+ messages in thread
From: Philippe Mathieu-Daudé @ 2025-01-07 10:29 UTC (permalink / raw)
  To: Richard Henderson, qemu-devel; +Cc: qemu-riscv, palmer, Alistair.Francis

Hi Richard,

On 2/1/25 19:16, Richard Henderson wrote:
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   tcg/riscv/tcg-target-has.h |  8 +++++++-
>   tcg/riscv/tcg-target.c.inc | 13 +++++++++++--
>   2 files changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/tcg/riscv/tcg-target-has.h b/tcg/riscv/tcg-target-has.h
> index 10e61edc45..ea38ee5cbb 100644
> --- a/tcg/riscv/tcg-target-has.h
> +++ b/tcg/riscv/tcg-target-has.h
> @@ -64,7 +64,13 @@ tcg_target_extract_valid(TCGType type, unsigned ofs, unsigned len)
>           /* ofs > 0 uses SRLIW; ofs == 0 uses add.uw. */
>           return ofs || (cpuinfo & CPUINFO_ZBA);
>       }
> -    return (cpuinfo & CPUINFO_ZBB) && ofs == 0 && len == 16;
> +    switch (len) {
> +    case 1:
> +        return (cpuinfo & CPUINFO_ZBS) && ofs != 0;

Why can't we have ofs=0?

> +    case 16:
> +        return (cpuinfo & CPUINFO_ZBB) && ofs == 0;
> +    }
> +    return false;
>   }
>   #define TCG_TARGET_extract_valid  tcg_target_extract_valid
>   
> diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
> index 12c3cffcc0..83ec7cd980 100644
> --- a/tcg/riscv/tcg-target.c.inc
> +++ b/tcg/riscv/tcg-target.c.inc
> @@ -162,6 +162,7 @@ typedef enum {
>       OPC_ANDI = 0x7013,
>       OPC_AUIPC = 0x17,
>       OPC_BEQ = 0x63,
> +    OPC_BEXTI = 0x48005013,
>       OPC_BGE = 0x5063,
>       OPC_BGEU = 0x7063,
>       OPC_BLT = 0x4063,
> @@ -2307,9 +2308,17 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, TCGType type,
>               } else {
>                   tcg_out_opc_imm(s, OPC_SRLIW, a0, a1, a2);
>               }
> -        } else if (a2 == 0 && args[3] == 16) {
> +            break;
> +        }
> +        switch (args[3]) {
> +        case 1:
> +            tcg_out_opc_imm(s, OPC_BEXTI, a0, a1, a2);
> +            break;
> +        case 16:
> +            tcg_debug_assert(a2 == 0);
>               tcg_out_ext16u(s, a0, a1);
> -        } else {
> +            break;
> +        default:
>               g_assert_not_reached();
>           }
>           break;



^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions
  2025-01-07 10:29   ` Philippe Mathieu-Daudé
@ 2025-01-07 15:27     ` Richard Henderson
  0 siblings, 0 replies; 8+ messages in thread
From: Richard Henderson @ 2025-01-07 15:27 UTC (permalink / raw)
  To: Philippe Mathieu-Daudé, qemu-devel
  Cc: qemu-riscv, palmer, Alistair.Francis

On 1/7/25 02:29, Philippe Mathieu-Daudé wrote:
> Hi Richard,
> 
> On 2/1/25 19:16, Richard Henderson wrote:
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   tcg/riscv/tcg-target-has.h |  8 +++++++-
>>   tcg/riscv/tcg-target.c.inc | 13 +++++++++++--
>>   2 files changed, 18 insertions(+), 3 deletions(-)
>>
>> diff --git a/tcg/riscv/tcg-target-has.h b/tcg/riscv/tcg-target-has.h
>> index 10e61edc45..ea38ee5cbb 100644
>> --- a/tcg/riscv/tcg-target-has.h
>> +++ b/tcg/riscv/tcg-target-has.h
>> @@ -64,7 +64,13 @@ tcg_target_extract_valid(TCGType type, unsigned ofs, unsigned len)
>>           /* ofs > 0 uses SRLIW; ofs == 0 uses add.uw. */
>>           return ofs || (cpuinfo & CPUINFO_ZBA);
>>       }
>> -    return (cpuinfo & CPUINFO_ZBB) && ofs == 0 && len == 16;
>> +    switch (len) {
>> +    case 1:
>> +        return (cpuinfo & CPUINFO_ZBS) && ofs != 0;
> 
> Why can't we have ofs=0?

To prefer ANDI.


r~


^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2025-01-07 15:27 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-01-02 18:15 [PATCH 0/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
2025-01-02 18:16 ` [PATCH 1/2] util/cpuinfo-riscv: Detect Zbs Richard Henderson
2025-01-06  0:44   ` Alistair Francis
2025-01-07  9:05   ` Philippe Mathieu-Daudé
2025-01-02 18:16 ` [PATCH 2/2] tcg/riscv: Use BEXTI for single-bit extractions Richard Henderson
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2025-01-07 15:27     ` Richard Henderson

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