[PATCH] gdb/arm: Simplify logic for updating addresses

[PATCH] gdb/arm: Simplify logic for updating addresses

[Yvan Roux]

Hi,

Small performance improvment by fetching the previous SP value only
once before the loop and reuse it to avoid fetching at every
iteration.

Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@st.com>
Signed-off-by: Yvan Roux <yvan.roux@foss.st.com>
---
 gdb/arm-tdep.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 50ec41a66b1..23e3ad4a072 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -2177,7 +2177,7 @@ arm_make_prologue_cache (struct frame_info *this_frame)
 {
   int reg;
   struct arm_prologue_cache *cache;
-  CORE_ADDR unwound_fp;
+  CORE_ADDR unwound_fp, prev_sp;
 
   cache = FRAME_OBSTACK_ZALLOC (struct arm_prologue_cache);
   arm_cache_init (cache, this_frame);
@@ -2191,14 +2191,15 @@ arm_make_prologue_cache (struct frame_info *this_frame)
   arm_gdbarch_tdep *tdep =
     (arm_gdbarch_tdep *) gdbarch_tdep (get_frame_arch (this_frame));
 
-  arm_cache_set_active_sp_value (cache, tdep, unwound_fp + cache->framesize);
+  prev_sp = unwound_fp + cache->framesize;
+  arm_cache_set_active_sp_value (cache, tdep, prev_sp);
 
   /* Calculate actual addresses of saved registers using offsets
      determined by arm_scan_prologue.  */
   for (reg = 0; reg < gdbarch_num_regs (get_frame_arch (this_frame)); reg++)
     if (cache->saved_regs[reg].is_addr ())
-      cache->saved_regs[reg].set_addr (cache->saved_regs[reg].addr ()
-				       + arm_cache_get_prev_sp_value (cache, tdep));
+      cache->saved_regs[reg].set_addr (cache->saved_regs[reg].addr () +
+				       prev_sp);
 
   return cache;
 }
-- 
2.17.1

Re: [PATCH] gdb/arm: Simplify logic for updating addresses

[Luis Machado]

On 6/2/22 15:21, Yvan Roux wrote:
> Hi,
> 
> Small performance improvment by fetching the previous SP value only

improvment -> improvement

> once before the loop and reuse it to avoid fetching at every
> iteration.
> 
> Signed-off-by: Torbj�rn SVENSSON <torbjorn.svensson@st.com>
> Signed-off-by: Yvan Roux <yvan.roux@foss.st.com>
> ---
>   gdb/arm-tdep.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
> index 50ec41a66b1..23e3ad4a072 100644
> --- a/gdb/arm-tdep.c
> +++ b/gdb/arm-tdep.c
> @@ -2177,7 +2177,7 @@ arm_make_prologue_cache (struct frame_info *this_frame)
>   {
>     int reg;
>     struct arm_prologue_cache *cache;
> -  CORE_ADDR unwound_fp;
> +  CORE_ADDR unwound_fp, prev_sp;
>   
>     cache = FRAME_OBSTACK_ZALLOC (struct arm_prologue_cache);
>     arm_cache_init (cache, this_frame);
> @@ -2191,14 +2191,15 @@ arm_make_prologue_cache (struct frame_info *this_frame)
>     arm_gdbarch_tdep *tdep =
>       (arm_gdbarch_tdep *) gdbarch_tdep (get_frame_arch (this_frame));
>   
> -  arm_cache_set_active_sp_value (cache, tdep, unwound_fp + cache->framesize);
> +  prev_sp = unwound_fp + cache->framesize;
> +  arm_cache_set_active_sp_value (cache, tdep, prev_sp);
>   
>     /* Calculate actual addresses of saved registers using offsets
>        determined by arm_scan_prologue.  */
>     for (reg = 0; reg < gdbarch_num_regs (get_frame_arch (this_frame)); reg++)
>       if (cache->saved_regs[reg].is_addr ())
> -      cache->saved_regs[reg].set_addr (cache->saved_regs[reg].addr ()
> -				       + arm_cache_get_prev_sp_value (cache, tdep));
> +      cache->saved_regs[reg].set_addr (cache->saved_regs[reg].addr () +
> +				       prev_sp);
>   
>     return cache;
>   }

Thanks. This is OK.