diff mbox series

[09/12] gdbsupport: add gdb::string_view_hash

Message ID 20221206135729.3937767-10-simon.marchi@efficios.com
State Committed
Commit 1a8605a8c79b0c4ebc71f5691e36a1338d407837
Headers
Series Initial support for ROCm platform (AMDGPU) debugging |

Commit Message

Simon Marchi Dec. 6, 2022, 1:57 p.m. UTC 
  Add the string_view_hash type, which will be useful to be able to use
gdb::string_view as std::unordered_map keys.

Use it in gdb/symtab.c, to exercise it.

Change-Id: Id69a466ab19a9f6620b5df8a2dd29b5cddd94c00
---
 gdb/symtab.c              |  2 +-
 gdbsupport/common-utils.h | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

Comments

Andrew Burgess Dec. 6, 2022, 5:19 p.m. UTC | #1 
Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

> Add the string_view_hash type, which will be useful to be able to use
> gdb::string_view as std::unordered_map keys.
>
> Use it in gdb/symtab.c, to exercise it.

LGTM.

Thanks,
Andrew

>
> Change-Id: Id69a466ab19a9f6620b5df8a2dd29b5cddd94c00
> ---
>  gdb/symtab.c              |  2 +-
>  gdbsupport/common-utils.h | 17 +++++++++++++++++
>  2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/symtab.c b/gdb/symtab.c
> index 0d342f765f2..f6ddd8e3c41 100644
> --- a/gdb/symtab.c
> +++ b/gdb/symtab.c
> @@ -812,7 +812,7 @@ hash_demangled_name_entry (const void *data)
>    const struct demangled_name_entry *e
>      = (const struct demangled_name_entry *) data;
>  
> -  return fast_hash (e->mangled.data (), e->mangled.length ());
> +  return gdb::string_view_hash () (e->mangled);
>  }
>  
>  /* Equality function for the demangled name hash.  */
> diff --git a/gdbsupport/common-utils.h b/gdbsupport/common-utils.h
> index fae77640666..2525d287c87 100644
> --- a/gdbsupport/common-utils.h
> +++ b/gdbsupport/common-utils.h
> @@ -193,4 +193,21 @@ fast_hash (const void *ptr, size_t len, unsigned int start_value = 0)
>  #endif
>  }
>  
> +namespace gdb
> +{
> +
> +/* Hash type for gdb::string_view.
> +
> +   Even after we switch to C++17 and dump our string_view implementation, we
> +   might want to keep this hash implementation if it's faster than std::hash
> +   for std::string_view.  */
> +
> +struct string_view_hash
> +{
> +  std::size_t operator() (gdb::string_view view) const
> +  {  return fast_hash (view.data (), view.length ()); }
> +};
> +
> +} /* namespace gdb */
> +
>  #endif /* COMMON_COMMON_UTILS_H */
> -- 
> 2.38.1
diff mbox series

Patch

diff --git a/gdb/symtab.c b/gdb/symtab.c
index 0d342f765f2..f6ddd8e3c41 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -812,7 +812,7 @@  hash_demangled_name_entry (const void *data)
   const struct demangled_name_entry *e
     = (const struct demangled_name_entry *) data;
 
-  return fast_hash (e->mangled.data (), e->mangled.length ());
+  return gdb::string_view_hash () (e->mangled);
 }
 
 /* Equality function for the demangled name hash.  */
diff --git a/gdbsupport/common-utils.h b/gdbsupport/common-utils.h
index fae77640666..2525d287c87 100644
--- a/gdbsupport/common-utils.h
+++ b/gdbsupport/common-utils.h
@@ -193,4 +193,21 @@  fast_hash (const void *ptr, size_t len, unsigned int start_value = 0)
 #endif
 }
 
+namespace gdb
+{
+
+/* Hash type for gdb::string_view.
+
+   Even after we switch to C++17 and dump our string_view implementation, we
+   might want to keep this hash implementation if it's faster than std::hash
+   for std::string_view.  */
+
+struct string_view_hash
+{
+  std::size_t operator() (gdb::string_view view) const
+  {  return fast_hash (view.data (), view.length ()); }
+};
+
+} /* namespace gdb */
+
 #endif /* COMMON_COMMON_UTILS_H */