Hi,
for incremental linking of LTO objects we need to copy debug sections from
source object files into destination without renaming them from .gnu.debuglto
into the standard debug section (because they will again be LTO debug section
in the resulting object file).
I have discussed this with Richard on IRC and I hope it is fine to change the
API here becuase lto-wrapper is the only user of this function. I will send
lto-wrapper support in separate patch.
I have lto-bootstrapped/regtested the whole incremental linking patchet on
x86-64-linux with libbackend being incrementaly linked and also experimented
with extra testcases and tested that debugging works on resulting cc1 binary.
OK?
Honza
* simple-object.h (simple_object_copy_lto_debug_sections): Add rename
parameter.
* simple-object.c (handle_lto_debug_sections): Add rename parameter.
(handle_lto_debug_sections_rename): New function.
(handle_lto_debug_sections_norename): New function.
(simple_object_copy_lto_debug_sections): Add rename parameter.
Index: include/simple-object.h
===================================================================
--- include/simple-object.h (revision 260042)
+++ include/simple-object.h (working copy)
@@ -198,12 +198,15 @@
simple_object_release_write (simple_object_write *);
/* Copy LTO debug sections from SRC_OBJECT to DEST.
+ If RENAME is true, rename LTO debug section into debug section (i.e.
+ when producing final binary) and if it is false, keep the sections with
+ original names (when incrementally linking).
If an error occurs, return the errno value in ERR and an error string. */
extern const char *
simple_object_copy_lto_debug_sections (simple_object_read *src_object,
const char *dest,
- int *err);
+ int *err, int rename);
#ifdef __cplusplus
}
Index: libiberty/simple-object.c
===================================================================
--- libiberty/simple-object.c (revision 260042)
+++ libiberty/simple-object.c (working copy)
@@ -251,12 +251,15 @@
}
/* Callback to identify and rename LTO debug sections by name.
- Returns 1 if NAME is a LTO debug section, 0 if not. */
+ Returns non-NULL if NAME is a LTO debug section, NULL if not.
+ If RENAME is true it will rename LTO debug sections to non-LTO
+ ones. */
static char *
-handle_lto_debug_sections (const char *name)
+handle_lto_debug_sections (const char *name, int rename)
{
- char *newname = XCNEWVEC (char, strlen (name) + 1);
+ char *newname = rename ? XCNEWVEC (char, strlen (name) + 1)
+ : xstrdup (name);
/* ??? So we can't use .gnu.lto_ prefixed sections as the assembler
complains about bogus section flags. Which means we need to arrange
@@ -265,12 +268,14 @@
/* Also include corresponding reloc sections. */
if (strncmp (name, ".rela", sizeof (".rela") - 1) == 0)
{
- strncpy (newname, name, sizeof (".rela") - 1);
+ if (rename)
+ strncpy (newname, name, sizeof (".rela") - 1);
name += sizeof (".rela") - 1;
}
else if (strncmp (name, ".rel", sizeof (".rel") - 1) == 0)
{
- strncpy (newname, name, sizeof (".rel") - 1);
+ if (rename)
+ strncpy (newname, name, sizeof (".rel") - 1);
name += sizeof (".rel") - 1;
}
/* ??? For now this handles both .gnu.lto_ and .gnu.debuglto_ prefixed
@@ -277,10 +282,10 @@
sections. */
/* Copy LTO debug sections and rename them to their non-LTO name. */
if (strncmp (name, ".gnu.debuglto_", sizeof (".gnu.debuglto_") - 1) == 0)
- return strcat (newname, name + sizeof (".gnu.debuglto_") - 1);
+ return rename ? strcat (newname, name + sizeof (".gnu.debuglto_") - 1) :
newname;
else if (strncmp (name, ".gnu.lto_.debug_",
sizeof (".gnu.lto_.debug_") -1) == 0)
- return strcat (newname, name + sizeof (".gnu.lto_") - 1);
+ return rename ? strcat (newname, name + sizeof (".gnu.lto_") - 1) :
newname;
/* Copy over .note.GNU-stack section under the same name if present. */
else if (strcmp (name, ".note.GNU-stack") == 0)
return strcpy (newname, name);
@@ -289,14 +294,31 @@
COMDAT sections in objects produced by GCC. */
else if (strcmp (name, ".comment") == 0)
return strcpy (newname, name);
+ free (newname);
return NULL;
}
+/* Wrapper for handle_lto_debug_sections. */
+
+static char *
+handle_lto_debug_sections_rename (const char *name)
+{
+ return handle_lto_debug_sections (name, 1);
+}
+
+/* Wrapper for handle_lto_debug_sections. */
+
+static char *
+handle_lto_debug_sections_norename (const char *name)
+{
+ return handle_lto_debug_sections (name, 0);
+}
+
/* Copy LTO debug sections. */
const char *
simple_object_copy_lto_debug_sections (simple_object_read *sobj,
- const char *dest, int *err)
+ const char *dest, int *err, int rename)
{
const char *errmsg;
simple_object_write *dest_sobj;
@@ -317,9 +339,10 @@
if (! dest_sobj)
return errmsg;
- errmsg = sobj->functions->copy_lto_debug_sections (sobj, dest_sobj,
- handle_lto_debug_sections,
- err);
+ errmsg = sobj->functions->copy_lto_debug_sections
+ (sobj, dest_sobj,
+ rename ? handle_lto_debug_sections_rename
+ : handle_lto_debug_sections_norename, err);
if (errmsg)
{
simple_object_release_write (dest_sobj);
