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[review] Add a fast_hash function in common-utils

Message ID 20191016130855.53CB020AF7@gnutoolchain-gerrit.osci.io
State New
Headers show

Commit Message

Simon Marchi (Code Review) Oct. 16, 2019, 1:08 p.m. UTC
Christian Biesinger has uploaded a new patch set version (#2).

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/38
......................................................................

Add a fast_hash function in common-utils

Also updates a caller in symtab.c. For now this just calls htab_hash_string
but the next patch will change it to xxhash, if available.

gdb/ChangeLog:

2019-09-27  Christian Biesinger  <cbiesinger@google.com>

	* utils.c (fast_hash): New function.
	* utils.h (fast_hash): New function.
	* symtab.c (hash_demangled_name_entry): Call new function
	fast_hash.

Change-Id: I77cac0d9aa78fc65316a2af449f52edcae72dc9b
---
M gdb/symtab.c
M gdb/utils.c
M gdb/utils.h
3 files changed, 16 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/gdb/symtab.c b/gdb/symtab.c
index 0724110..2577f39 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -70,6 +70,7 @@ 
 #include <algorithm>
 #include "gdbsupport/gdb_string_view.h"
 #include "gdbsupport/pathstuff.h"
+#include "gdbsupport/common-utils.h"
 
 /* Forward declarations for local functions.  */
 
@@ -727,7 +728,7 @@ 
   const struct demangled_name_entry *e
     = (const struct demangled_name_entry *) data;
 
-  return iterative_hash (e->mangled.data (), e->mangled.length (), 0);
+  return fast_hash (e->mangled.data (), e->mangled.length ());
 }
 
 /* Equality function for the demangled name hash.  */
diff --git a/gdb/utils.c b/gdb/utils.c
index e685cc2..127ff43 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -3436,6 +3436,14 @@ 
     }
 }
 
+/* See utils.h.  */
+
+unsigned int
+fast_hash (const char* str, size_t len)
+{
+  return iterative_hash (str, len, 0);
+}
+
 void
 _initialize_utils (void)
 {
diff --git a/gdb/utils.h b/gdb/utils.h
index 76f0da6..83dc57e 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -569,4 +569,10 @@ 
 			  const gdb_byte *source, ULONGEST source_offset,
 			  ULONGEST nbits, int bits_big_endian);
 
+/* A fast hashing function.  This can be used to hash strings in a fast way
+   when the length is known.  If no fast hashing library is available, falls
+   back to iterative_hash from libiberty.  */
+
+extern unsigned int fast_hash (const char* str, size_t len);
+
 #endif /* UTILS_H */