[review] Store the mangled name as a string_view

[review] Store the mangled name as a string_view

[Christian Biesinger (Code Review)]

Christian Biesinger has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................


Uploaded patch set 2: Patch Set 1 was rebased.

[review v3] Store the mangled name as a string_view

[Christian Biesinger (Code Review)]

Christian Biesinger has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................


Patch Set 3:

Ping

[review v3] Store the mangled name as a string_view

[Simon Marchi (Code Review)]

Simon Marchi has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................


Patch Set 3:

(1 comment)

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/3/gdb/symtab.c 
File gdb/symtab.c:

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/3/gdb/symtab.c@891 
PS3, Line 891: 			      + demangled_len + 1));
Pedantically, since demangled_name_entry is now a non-POD, we should run the constructor here and the destructor when we release them.  Running the constructor here would not be too complicated, but running the destructor might be a bit more (and maybe it's not really necessary), I guess we'd need a "delete" function on the htab.

[review v4] Store the mangled name as a string_view

[Christian Biesinger (Code Review)]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................

Store the mangled name as a string_view

This should be a bit faster (because we can compare the size first),
but it is also a dependency for the next patch.

(3.47% of gdb startup time is spent in eq_demangled_name_entry when
attaching to Chrome's content_shell binary)

gdb/ChangeLog:

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

	* symtab.c (struct demangled_name_entry): Change type of mangled
	to gdb::string_view.
	(hash_demangled_name_entry): Update.
	(eq_demangled_name_entry): Update.
	(symbol_set_names): Update.

Change-Id: I24711ae2bcaa9e79ca89a6f8fda385d400419175
---
M gdb/symtab.c
1 file changed, 18 insertions(+), 7 deletions(-)



diff --git a/gdb/symtab.c b/gdb/symtab.c
index fc736fd..f4d35a2 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -68,6 +68,7 @@
 #include "filename-seen-cache.h"
 #include "arch-utils.h"
 #include <algorithm>
+#include "gdbsupport/gdb_string_view.h"
 #include "gdbsupport/pathstuff.h"
 
 /* Forward declarations for local functions.  */
@@ -713,7 +714,7 @@
 /* Objects of this type are stored in the demangled name hash table.  */
 struct demangled_name_entry
 {
-  const char *mangled;
+  gdb::string_view mangled;
   ENUM_BITFIELD(language) language : LANGUAGE_BITS;
   char demangled[1];
 };
@@ -726,7 +727,7 @@
   const struct demangled_name_entry *e
     = (const struct demangled_name_entry *) data;
 
-  return htab_hash_string (e->mangled);
+  return iterative_hash (e->mangled.data (), e->mangled.length (), 0);
 }
 
 /* Equality function for the demangled name hash.  */
@@ -739,7 +740,16 @@
   const struct demangled_name_entry *db
     = (const struct demangled_name_entry *) b;
 
-  return strcmp (da->mangled, db->mangled) == 0;
+  return da->mangled == db->mangled;
+}
+
+static void
+free_demangled_name_entry (void *data)
+{
+  struct demangled_name_entry *e
+    = (struct demangled_name_entry *) data;
+
+  e->~demangled_name_entry();
 }
 
 /* Create the hash table used for demangled names.  Each hash entry is
@@ -855,7 +865,7 @@
   else
     linkage_name_copy = linkage_name;
 
-  entry.mangled = linkage_name_copy;
+  entry.mangled = gdb::string_view (linkage_name_copy, len);
   slot = ((struct demangled_name_entry **)
 	  htab_find_slot (per_bfd->demangled_names_hash.get (),
 			  &entry, INSERT));
@@ -888,7 +898,8 @@
 	       obstack_alloc (&per_bfd->storage_obstack,
 			      offsetof (struct demangled_name_entry, demangled)
 			      + demangled_len + 1));
-	  (*slot)->mangled = linkage_name;
+	  new (*slot) demangled_name_entry();
+	  (*slot)->mangled = gdb::string_view (linkage_name, len);
 	}
       else
 	{
@@ -904,7 +915,7 @@
 			      + len + demangled_len + 2));
 	  mangled_ptr = &((*slot)->demangled[demangled_len + 1]);
 	  strcpy (mangled_ptr, linkage_name_copy);
-	  (*slot)->mangled = mangled_ptr;
+	  (*slot)->mangled = gdb::string_view (mangled_ptr, len);
 	}
       (*slot)->language = gsymbol->language;
 
@@ -917,7 +928,7 @@
 	   || gsymbol->language == language_auto)
     gsymbol->language = (*slot)->language;
 
-  gsymbol->name = (*slot)->mangled;
+  gsymbol->name = (*slot)->mangled.data ();
   if ((*slot)->demangled[0] != '\0')
     symbol_set_demangled_name (gsymbol, (*slot)->demangled,
 			       &per_bfd->storage_obstack);

[review v5] Store the mangled name as a string_view

[Christian Biesinger (Code Review)]

Christian Biesinger has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................


Patch Set 5:

(1 comment)

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/3/gdb/symtab.c 
File gdb/symtab.c:

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/3/gdb/symtab.c@891 
PS3, Line 891: 			      + demangled_len + 1));
> Pedantically, since demangled_name_entry is now a non-POD, we should run the constructor here and th […]
Sure, happy to add a delete function -- I have another pending patch that also needs one (https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/132).

Done.

[review v5] Store the mangled name as a string_view

[Christian Biesinger (Code Review)]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................

Store the mangled name as a string_view

This should be a bit faster (because we can compare the size first),
but it is also a dependency for the next patch.

(3.47% of gdb startup time is spent in eq_demangled_name_entry when
attaching to Chrome's content_shell binary)

gdb/ChangeLog:

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

	* symtab.c (struct demangled_name_entry): Change type of mangled
	to gdb::string_view.
	(hash_demangled_name_entry): Update.
	(eq_demangled_name_entry): Update.
	(symbol_set_names): Update.

Change-Id: I24711ae2bcaa9e79ca89a6f8fda385d400419175
---
M gdb/symtab.c
1 file changed, 23 insertions(+), 9 deletions(-)



diff --git a/gdb/symtab.c b/gdb/symtab.c
index fc736fd..06c0d03 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -68,6 +68,7 @@
 #include "filename-seen-cache.h"
 #include "arch-utils.h"
 #include <algorithm>
+#include "gdbsupport/gdb_string_view.h"
 #include "gdbsupport/pathstuff.h"
 
 /* Forward declarations for local functions.  */
@@ -713,7 +714,10 @@
 /* Objects of this type are stored in the demangled name hash table.  */
 struct demangled_name_entry
 {
-  const char *mangled;
+  demangled_name_entry (gdb::string_view mangled_name)
+    : mangled (mangled_name) {}
+
+  gdb::string_view mangled;
   ENUM_BITFIELD(language) language : LANGUAGE_BITS;
   char demangled[1];
 };
@@ -726,7 +730,7 @@
   const struct demangled_name_entry *e
     = (const struct demangled_name_entry *) data;
 
-  return htab_hash_string (e->mangled);
+  return iterative_hash (e->mangled.data (), e->mangled.length (), 0);
 }
 
 /* Equality function for the demangled name hash.  */
@@ -739,7 +743,16 @@
   const struct demangled_name_entry *db
     = (const struct demangled_name_entry *) b;
 
-  return strcmp (da->mangled, db->mangled) == 0;
+  return da->mangled == db->mangled;
+}
+
+static void
+free_demangled_name_entry (void *data)
+{
+  struct demangled_name_entry *e
+    = (struct demangled_name_entry *) data;
+
+  e->~demangled_name_entry();
 }
 
 /* Create the hash table used for demangled names.  Each hash entry is
@@ -756,7 +769,7 @@
 
   per_bfd->demangled_names_hash.reset (htab_create_alloc
     (256, hash_demangled_name_entry, eq_demangled_name_entry,
-     NULL, xcalloc, xfree));
+     free_demangled_name_entry, xcalloc, xfree));
 }
 
 /* Try to determine the demangled name for a symbol, based on the
@@ -817,7 +830,6 @@
   struct demangled_name_entry **slot;
   /* A 0-terminated copy of the linkage name.  */
   const char *linkage_name_copy;
-  struct demangled_name_entry entry;
 
   if (gsymbol->language == language_ada)
     {
@@ -855,7 +867,7 @@
   else
     linkage_name_copy = linkage_name;
 
-  entry.mangled = linkage_name_copy;
+  struct demangled_name_entry entry (gdb::string_view (linkage_name_copy, len));
   slot = ((struct demangled_name_entry **)
 	  htab_find_slot (per_bfd->demangled_names_hash.get (),
 			  &entry, INSERT));
@@ -888,7 +900,8 @@
 	       obstack_alloc (&per_bfd->storage_obstack,
 			      offsetof (struct demangled_name_entry, demangled)
 			      + demangled_len + 1));
-	  (*slot)->mangled = linkage_name;
+	  new (*slot) demangled_name_entry
+	    (gdb::string_view (linkage_name, len));
 	}
       else
 	{
@@ -904,7 +917,8 @@
 			      + len + demangled_len + 2));
 	  mangled_ptr = &((*slot)->demangled[demangled_len + 1]);
 	  strcpy (mangled_ptr, linkage_name_copy);
-	  (*slot)->mangled = mangled_ptr;
+	  new (*slot) demangled_name_entry
+	    (gdb::string_view (mangled_ptr, len));
 	}
       (*slot)->language = gsymbol->language;
 
@@ -917,7 +931,7 @@
 	   || gsymbol->language == language_auto)
     gsymbol->language = (*slot)->language;
 
-  gsymbol->name = (*slot)->mangled;
+  gsymbol->name = (*slot)->mangled.data ();
   if ((*slot)->demangled[0] != '\0')
     symbol_set_demangled_name (gsymbol, (*slot)->demangled,
 			       &per_bfd->storage_obstack);

[review v5] Store the mangled name as a string_view

[Simon Marchi (Code Review)]

Simon Marchi has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................


Patch Set 5: Code-Review+2

Thanks, this LGTM.  Just make sure to update the ChangeLog entry.

[review v5] Store the mangled name as a string_view

[Tom Tromey (Code Review)]

Tom Tromey has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................


Patch Set 5:

(1 comment)

I had a comment on this one, but I agree with Simon that this is fine as-is.

Thanks for doing this.

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/5/gdb/symtab.c 
File gdb/symtab.c:

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/5/gdb/symtab.c@903 
PS5, Line 903: 	  new (*slot) demangled_name_entry
FWIW I don't think there's a deep reason these objects have to
be stored on an obstack.  We could just use plain new and make
`free_demangled_name_entry` a wrapper for `delete`.  Or maybe
it's finally time to import some version of the gcc hash table.

[review v5] Store the mangled name as a string_view

[Christian Biesinger (Code Review)]

Christian Biesinger has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................


Patch Set 5:

(1 comment)

Thanks for the reviews! Will push once I update the rest of this patch series per your comments.

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/5/gdb/symtab.c 
File gdb/symtab.c:

https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37/5/gdb/symtab.c@903 
PS5, Line 903: 	  new (*slot) demangled_name_entry
> FWIW I don't think there's a deep reason these objects have to […]
OK, I'll keep that in mind.

[review v6] Store the mangled name as a string_view

[Christian Biesinger (Code Review)]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................

Store the mangled name as a string_view

This should be a bit faster (because we can compare the size first),
but it is also a dependency for the next patch.

(3.47% of gdb startup time is spent in eq_demangled_name_entry when
attaching to Chrome's content_shell binary)

gdb/ChangeLog:

2019-10-22  Christian Biesinger  <cbiesinger@google.com>

	* symtab.c (struct demangled_name_entry): Change type of mangled
	to gdb::string_view. Also adds a constructor that takes the
	mangled name.
	(hash_demangled_name_entry): Update.
	(eq_demangled_name_entry): Update.
	(free_demangled_name_entry): New function to call the destructor
	now that this is not a POD anymore.
	(create_demangled_names_hash): Pass free_demangled_name_entry to
	htab_create_alloc.
	(symbol_set_names): Update.

Change-Id: I24711ae2bcaa9e79ca89a6f8fda385d400419175
---
M gdb/ChangeLog
M gdb/symtab.c
2 files changed, 21 insertions(+), 7 deletions(-)



diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a70f3e1..d271330 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,16 @@
+2019-10-22  Christian Biesinger  <cbiesinger@google.com>
+
+	* symtab.c (struct demangled_name_entry): Change type of mangled
+	to gdb::string_view. Also adds a constructor that takes the
+	mangled name.
+	(hash_demangled_name_entry): Update.
+	(eq_demangled_name_entry): Update.
+	(free_demangled_name_entry): New function to call the destructor
+	now that this is not a POD anymore.
+	(create_demangled_names_hash): Pass free_demangled_name_entry to
+	htab_create_alloc.
+	(symbol_set_names): Update.
+
 2019-10-21  Ali Tamur  <tamu@google.com>
 
 	* dwarf2read.c (dir_index): Change type.
diff --git a/gdb/symtab.c b/gdb/symtab.c
index fc736fd..567d09d 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -68,6 +68,7 @@
 #include "filename-seen-cache.h"
 #include "arch-utils.h"
 #include <algorithm>
+#include "gdbsupport/gdb_string_view.h"
 #include "gdbsupport/pathstuff.h"
 
 /* Forward declarations for local functions.  */
@@ -713,7 +714,7 @@
 /* Objects of this type are stored in the demangled name hash table.  */
 struct demangled_name_entry
 {
-  const char *mangled;
+  gdb::string_view mangled;
   ENUM_BITFIELD(language) language : LANGUAGE_BITS;
   char demangled[1];
 };
@@ -726,7 +727,7 @@
   const struct demangled_name_entry *e
     = (const struct demangled_name_entry *) data;
 
-  return htab_hash_string (e->mangled);
+  return iterative_hash (e->mangled.data (), e->mangled.length (), 0);
 }
 
 /* Equality function for the demangled name hash.  */
@@ -739,7 +740,7 @@
   const struct demangled_name_entry *db
     = (const struct demangled_name_entry *) b;
 
-  return strcmp (da->mangled, db->mangled) == 0;
+  return da->mangled == db->mangled;
 }
 
 /* Create the hash table used for demangled names.  Each hash entry is
@@ -855,7 +856,7 @@
   else
     linkage_name_copy = linkage_name;
 
-  entry.mangled = linkage_name_copy;
+  entry.mangled = gdb::string_view (linkage_name_copy, len);
   slot = ((struct demangled_name_entry **)
 	  htab_find_slot (per_bfd->demangled_names_hash.get (),
 			  &entry, INSERT));
@@ -888,7 +889,7 @@
 	       obstack_alloc (&per_bfd->storage_obstack,
 			      offsetof (struct demangled_name_entry, demangled)
 			      + demangled_len + 1));
-	  (*slot)->mangled = linkage_name;
+	  (*slot)->mangled = gdb::string_view (linkage_name, len);
 	}
       else
 	{
@@ -904,7 +905,7 @@
 			      + len + demangled_len + 2));
 	  mangled_ptr = &((*slot)->demangled[demangled_len + 1]);
 	  strcpy (mangled_ptr, linkage_name_copy);
-	  (*slot)->mangled = mangled_ptr;
+	  (*slot)->mangled = gdb::string_view (mangled_ptr, len);
 	}
       (*slot)->language = gsymbol->language;
 
@@ -917,7 +918,7 @@
 	   || gsymbol->language == language_auto)
     gsymbol->language = (*slot)->language;
 
-  gsymbol->name = (*slot)->mangled;
+  gsymbol->name = (*slot)->mangled.data ();
   if ((*slot)->demangled[0] != '\0')
     symbol_set_demangled_name (gsymbol, (*slot)->demangled,
 			       &per_bfd->storage_obstack);

[pushed] Store the mangled name as a string_view

[Sourceware to Gerrit sync (Code Review)]

Sourceware to Gerrit sync has submitted this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/37
......................................................................

Store the mangled name as a string_view

This should be a bit faster (because we can compare the size first),
but it is also a dependency for the next patch.

(3.47% of gdb startup time is spent in eq_demangled_name_entry when
attaching to Chrome's content_shell binary)

gdb/ChangeLog:

2019-10-22  Christian Biesinger  <cbiesinger@google.com>

	* symtab.c (struct demangled_name_entry): Change type of mangled
	to gdb::string_view. Also adds a constructor that takes the
	mangled name.
	(hash_demangled_name_entry): Update.
	(eq_demangled_name_entry): Update.
	(free_demangled_name_entry): New function to call the destructor
	now that this is not a POD anymore.
	(create_demangled_names_hash): Pass free_demangled_name_entry to
	htab_create_alloc.
	(symbol_set_names): Update.

Change-Id: I24711ae2bcaa9e79ca89a6f8fda385d400419175
---
M gdb/ChangeLog
M gdb/symtab.c
2 files changed, 21 insertions(+), 7 deletions(-)


diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a70f3e1..d271330 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,16 @@
+2019-10-22  Christian Biesinger  <cbiesinger@google.com>
+
+	* symtab.c (struct demangled_name_entry): Change type of mangled
+	to gdb::string_view. Also adds a constructor that takes the
+	mangled name.
+	(hash_demangled_name_entry): Update.
+	(eq_demangled_name_entry): Update.
+	(free_demangled_name_entry): New function to call the destructor
+	now that this is not a POD anymore.
+	(create_demangled_names_hash): Pass free_demangled_name_entry to
+	htab_create_alloc.
+	(symbol_set_names): Update.
+
 2019-10-21  Ali Tamur  <tamu@google.com>
 
 	* dwarf2read.c (dir_index): Change type.
diff --git a/gdb/symtab.c b/gdb/symtab.c
index fc736fd..567d09d 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -68,6 +68,7 @@
 #include "filename-seen-cache.h"
 #include "arch-utils.h"
 #include <algorithm>
+#include "gdbsupport/gdb_string_view.h"
 #include "gdbsupport/pathstuff.h"
 
 /* Forward declarations for local functions.  */
@@ -713,7 +714,7 @@
 /* Objects of this type are stored in the demangled name hash table.  */
 struct demangled_name_entry
 {
-  const char *mangled;
+  gdb::string_view mangled;
   ENUM_BITFIELD(language) language : LANGUAGE_BITS;
   char demangled[1];
 };
@@ -726,7 +727,7 @@
   const struct demangled_name_entry *e
     = (const struct demangled_name_entry *) data;
 
-  return htab_hash_string (e->mangled);
+  return iterative_hash (e->mangled.data (), e->mangled.length (), 0);
 }
 
 /* Equality function for the demangled name hash.  */
@@ -739,7 +740,7 @@
   const struct demangled_name_entry *db
     = (const struct demangled_name_entry *) b;
 
-  return strcmp (da->mangled, db->mangled) == 0;
+  return da->mangled == db->mangled;
 }
 
 /* Create the hash table used for demangled names.  Each hash entry is
@@ -855,7 +856,7 @@
   else
     linkage_name_copy = linkage_name;
 
-  entry.mangled = linkage_name_copy;
+  entry.mangled = gdb::string_view (linkage_name_copy, len);
   slot = ((struct demangled_name_entry **)
 	  htab_find_slot (per_bfd->demangled_names_hash.get (),
 			  &entry, INSERT));
@@ -888,7 +889,7 @@
 	       obstack_alloc (&per_bfd->storage_obstack,
 			      offsetof (struct demangled_name_entry, demangled)
 			      + demangled_len + 1));
-	  (*slot)->mangled = linkage_name;
+	  (*slot)->mangled = gdb::string_view (linkage_name, len);
 	}
       else
 	{
@@ -904,7 +905,7 @@
 			      + len + demangled_len + 2));
 	  mangled_ptr = &((*slot)->demangled[demangled_len + 1]);
 	  strcpy (mangled_ptr, linkage_name_copy);
-	  (*slot)->mangled = mangled_ptr;
+	  (*slot)->mangled = gdb::string_view (mangled_ptr, len);
 	}
       (*slot)->language = gsymbol->language;
 
@@ -917,7 +918,7 @@
 	   || gsymbol->language == language_auto)
     gsymbol->language = (*slot)->language;
 
-  gsymbol->name = (*slot)->mangled;
+  gsymbol->name = (*slot)->mangled.data ();
   if ((*slot)->demangled[0] != '\0')
     symbol_set_demangled_name (gsymbol, (*slot)->demangled,
 			       &per_bfd->storage_obstack);