[build, c++, lto] Support COMDAT group with Sun as (PR target/40483)
Rainer Orth
ro@CeBiTec.Uni-Bielefeld.DE
Mon Jun 7 18:49:00 GMT 2010
Jason Merrill <jason@redhat.com> writes:
>> ** The C++ frontend generates an artificial identifier as group
>> signature in cp/optimize.c (cdtor_comdat_group), which isn't ever
>> defined (and doesn't demangle at all). To solve that problem, I've
>> decided to set a flag on that identifier which config/sol2.c
>> (solaris_elf_asm_comdat_section) can use to decide if it needs to
>> define the symbol. I've chosen IDENTIFIER_CTOR_OR_DTOR_P since it
>> seemed to make most sense and the obvious DECL_ARTIFICIAL cannot be
>> set on an IDENTIFIER_NODE. The complication is that I cannot simply
>> include cp/cp-tree.h in sol2.c since all non-C++ compilers fail to
>> link. So I've cheated and use the underlying TREE_LANG_FLAG_3
>> instead. This is clearly a hack, but worked for me.
>
> Yeah, we clearly can't use TREE_LANG_FLAG in general. There are still
> plenty of unused language-independent flags on IDENTIFIER_NODE, though it
> seems undesirable to use one for a corner case like this.
>
> How about having sparc.c remember the names of comdat groups and then at
> EOF emit dummy definitions for any that don't have TREE_SYMBOL_REFERENCED
> set?
That was an excellent suggestion: works nicely for the C++ case and also
fixes the LTO failures I had.
Here's the patch I've tested, although it took quite some time fighting
with hashtab.[ch]. With maybe two exceptions, it only touches code I
can approve myself:
* The i386/i386.c changes, although they are done in a way which only
affects Solaris.
* The sparc/sparc.c change, though again it is inside a Solaris-specific
function.
Apart from the new way to detect undefined signature symbols, there's
one other change prompted by SPARC testing: the two architectures
differ in that SPARC as needs double-quoted section names, while x86 as
does not. I had to deal with this difference already for
PUSHSECTION_FORMAT, but instead of defining yet another macro, I've
generalized this to introduce and use a new SECTION_NAME_FORMAT_INSTEAD.
Bootstrapped without regressions on i386-pc-solaris2.11,
sparc-sun-solaris2.11 bootstrap to follow.
I won't commit this yet, though, since due to a Sun assembler bug on
both architectures I get some link failures, both building libstdc++.so
and during the testsuite run. This can be worked around for the moment
by building with LD_OPTIONS='-z relaxreloc', but I've agreed with the
Sun linker maintainers that this isn't desirable. As soon as I've got
fixed assemblers, I'll add a configure test to detect that.
As I've said, I could probably commit this patch without further
approval, but would like others to look over it to check if I might have
missed something.
Rainer
--
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University
2010-03-07 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
PR target/40483
* configure.ac (gcc_cv_as_comdat_group_group): Check for Sun as
COMDAT group syntax, both SPARC and x86 variants.
(HAVE_COMDAT_GROUP): Also define if gcc_cv_as_comdat_group_group.
* configure: Regenerate.
* config/sol2.h (TARGET_SOLARIS): Define.
(PUSHSECTION_FORMAT): Remove.
(SECTION_NAME_FORMAT): Define.
* config/sol2.c: Include target.h, hashtab.h.
(solaris_output_init_fini): Replace PUSHSECTION_FORMAT by its
expansion, using SECTION_NAME_FORMAT.
(solaris_comdat_htab): New variable.
(struct comdat_entry): Define.
(comdat_hash): New function.
(comdat_eq): New function.
(solaris_elf_asm_comdat_section): New function.
(solaris_define_comdat_signature): New function.
(solaris_code_end): New function.
* config/sol2-protos.h (solaris_elf_asm_comdat_section): Declare.
(solaris_code_end): Declare.
* config/t-sol2 (sol2.o): Add target.h, $HASHTAB_H dependencies.
* config/i386/i386.c (ix86_code_end) [TARGET_SOLARIS]: Call
solaris_code_end.
(i386_solaris_elf_named_section) [!USE_GAS]: Call
solaris_elf_asm_comdat_section for SECTION_LINKONCE sections if
HAVE_COMDAT_GROUP.
* config/sparc/sparc.c (sparc_solaris_elf_asm_named_section):
Likewise.
* config/i386/sol2-10.h (TARGET_ASM_NAMED_SECTION): Moved ...
* config/i386/sol2.h (TARGET_ASM_NAMED_SECTION): ... here.
* config/sparc/sol2.h (TARGET_ASM_CODE_END): Redefine.
(PUSHSECTION_FORMAT): Remove.
(SECTION_NAME_FORMAT): Redefine.
diff -r 279b577e5bf6 gcc/config/i386/i386.c
--- a/gcc/config/i386/i386.c Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/i386/i386.c Mon Jun 07 13:23:57 2010 +0200
@@ -7720,6 +7720,10 @@
rtx xops[2];
int regno;
+#ifdef TARGET_SOLARIS
+ solaris_code_end ();
+#endif
+
for (regno = 0; regno < 8; ++regno)
{
char name[32];
@@ -28609,6 +28613,15 @@
flags & SECTION_WRITE ? "aw" : "a");
return;
}
+
+#ifndef USE_GAS
+ if (HAVE_COMDAT_GROUP && flags & SECTION_LINKONCE)
+ {
+ solaris_elf_asm_comdat_section (name, flags, decl);
+ return;
+ }
+#endif
+
default_elf_asm_named_section (name, flags, decl);
}
diff -r 279b577e5bf6 gcc/config/i386/sol2-10.h
--- a/gcc/config/i386/sol2-10.h Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/i386/sol2-10.h Mon Jun 07 13:23:57 2010 +0200
@@ -143,9 +143,6 @@
/* We do not need to search a special directory for startup files. */
#undef MD_STARTFILE_PREFIX
-#undef TARGET_ASM_NAMED_SECTION
-#define TARGET_ASM_NAMED_SECTION i386_solaris_elf_named_section
-
#undef SUBTARGET_RETURN_IN_MEMORY
#define SUBTARGET_RETURN_IN_MEMORY(TYPE, FNTYPE) \
ix86_sol10_return_in_memory (TYPE, FNTYPE)
diff -r 279b577e5bf6 gcc/config/i386/sol2.h
--- a/gcc/config/i386/sol2.h Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/i386/sol2.h Mon Jun 07 13:23:57 2010 +0200
@@ -150,6 +150,9 @@
} \
while (0)
+#undef TARGET_ASM_NAMED_SECTION
+#define TARGET_ASM_NAMED_SECTION i386_solaris_elf_named_section
+
/* We do not need NT_VERSION notes. */
#undef X86_FILE_START_VERSION_DIRECTIVE
#define X86_FILE_START_VERSION_DIRECTIVE false
diff -r 279b577e5bf6 gcc/config/sol2-protos.h
--- a/gcc/config/sol2-protos.h Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/sol2-protos.h Mon Jun 07 13:23:57 2010 +0200
@@ -22,3 +22,5 @@
extern void solaris_register_pragmas (void);
extern void solaris_output_init_fini (FILE *, tree);
extern void solaris_assemble_visibility (tree, int);
+extern void solaris_elf_asm_comdat_section (const char *, unsigned int, tree);
+extern void solaris_code_end (void);
diff -r 279b577e5bf6 gcc/config/sol2.c
--- a/gcc/config/sol2.c Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/sol2.c Mon Jun 07 13:23:57 2010 +0200
@@ -25,9 +25,11 @@
#include "output.h"
#include "tm.h"
#include "rtl.h"
+#include "target.h"
#include "tm_p.h"
#include "toplev.h"
#include "ggc.h"
+#include "hashtab.h"
tree solaris_pending_aligns, solaris_pending_inits, solaris_pending_finis;
@@ -105,14 +107,14 @@
{
if (lookup_attribute ("init", DECL_ATTRIBUTES (decl)))
{
- fprintf (file, PUSHSECTION_FORMAT, ".init");
+ fprintf (file, "\t.pushsection\t" SECTION_NAME_FORMAT "\n", ".init");
ASM_OUTPUT_CALL (file, decl);
fprintf (file, "\t.popsection\n");
}
if (lookup_attribute ("fini", DECL_ATTRIBUTES (decl)))
{
- fprintf (file, PUSHSECTION_FORMAT, ".fini");
+ fprintf (file, "\t.pushsection\t" SECTION_NAME_FORMAT "\n", ".fini");
ASM_OUTPUT_CALL (file, decl);
fprintf (file, "\t.popsection\n");
}
@@ -156,3 +158,130 @@
"in this configuration; ignored");
#endif
}
+
+/* Hash table of group signature symbols. */
+
+static htab_t solaris_comdat_htab;
+
+/* Group section information entry stored in solaris_comdat_htab. */
+
+typedef struct comdat_entry
+{
+ const char *name;
+ unsigned int flags;
+ tree decl;
+ const char *sig;
+} comdat_entry;
+
+/* Helper routines for maintaining solaris_comdat_htab. */
+
+static hashval_t
+comdat_hash (const void *p)
+{
+ const comdat_entry *entry = (const comdat_entry *) p;
+
+ return htab_hash_string (entry->sig);
+}
+
+static int
+comdat_eq (const void *p1, const void *p2)
+{
+ const comdat_entry *entry1 = (const comdat_entry *) p1;
+ const comdat_entry *entry2 = (const comdat_entry *) p2;
+
+ return strcmp (entry1->sig, entry2->sig) == 0;
+}
+
+/* Output assembly to switch to COMDAT group section NAME with attributes
+ FLAGS and group signature symbol DECL, using Sun as syntax. */
+
+void
+solaris_elf_asm_comdat_section (const char *name, unsigned int flags, tree decl)
+{
+ const char *signature;
+ char *section;
+ comdat_entry entry, **slot;
+
+ if (TREE_CODE (decl) == IDENTIFIER_NODE)
+ signature = IDENTIFIER_POINTER (decl);
+ else
+ signature = IDENTIFIER_POINTER (DECL_COMDAT_GROUP (decl));
+
+ /* Sun as requires group sections to be fragmented, i.e. to have names of
+ the form <section>%<fragment>. Strictly speaking this is only
+ necessary to support cc -xF, but is enforced globally in violation of
+ the ELF gABI. We keep the section names generated by GCC (generally
+ of the form .text.<signature>) and append %<signature> to pacify as,
+ despite the redundancy. */
+ section = concat (name, "%", signature, NULL);
+
+ /* Clear SECTION_LINKONCE flag so targetm.asm_out.named_section only
+ emits this as a regular section. Emit section before .group
+ directive since Sun as treats undeclared sections as @progbits,
+ which conflicts with .bss* sections which are @nobits. */
+ targetm.asm_out.named_section (section, flags & ~SECTION_LINKONCE, decl);
+
+ /* Sun as separates declaration of a group section and of the group
+ itself, using the .group directive and the #comdat flag. */
+ fprintf (asm_out_file, "\t.group\t%s," SECTION_NAME_FORMAT ",#comdat\n",
+ signature, section);
+
+ /* Unlike GNU as, group signature symbols need to be defined explicitly
+ for Sun as. With a few exceptions, this is already the case. To
+ identify the missing ones without changing the affected frontents,
+ remember the signature symbols and emit those not marked
+ TREE_SYMBOL_REFERENCED in solaris_code_end. */
+ if (solaris_comdat_htab == NULL)
+ solaris_comdat_htab = htab_create (37, comdat_hash, comdat_eq, NULL);
+
+ entry.sig = signature;
+ slot = (comdat_entry **) htab_find_slot (solaris_comdat_htab, &entry, INSERT);
+
+ if (slot != NULL && *slot == NULL)
+ {
+ *slot = XCNEW (comdat_entry);
+ /* Remember fragmented section name. */
+ (*slot)->name = section;
+ /* Emit as regular section, .group declaration has already been done. */
+ (*slot)->flags = flags & ~SECTION_LINKONCE;
+ (*slot)->decl = decl;
+ (*slot)->sig = signature;
+ }
+}
+
+/* Define unreferenced COMDAT group signature symbol corresponding to SLOT. */
+
+static int
+solaris_define_comdat_signature (void **slot, void *aux ATTRIBUTE_UNUSED)
+{
+ comdat_entry *entry = *(comdat_entry **) slot;
+ tree decl = entry->decl;
+
+ if (TREE_CODE (decl) != IDENTIFIER_NODE)
+ decl = DECL_COMDAT_GROUP (decl);
+
+ if (!TREE_SYMBOL_REFERENCED (decl))
+ {
+ /* Switch to group section, otherwise Sun as complains
+ `Group Id symbol defined outside of group'. */
+ switch_to_section (get_section (entry->name, entry->flags, entry->decl));
+
+ targetm.asm_out.globalize_label (asm_out_file, entry->sig);
+ ASM_OUTPUT_LABEL (asm_out_file, entry->sig);
+ TREE_SYMBOL_REFERENCED (decl) = 1;
+ }
+
+ /* Continue with scan. */
+ return 1;
+}
+
+/* Emit unreferenced COMDAT group signature symbols for Sun as. */
+
+void
+solaris_code_end (void)
+{
+ if (solaris_comdat_htab == NULL)
+ return;
+
+ htab_traverse (solaris_comdat_htab, solaris_define_comdat_signature, NULL);
+}
diff -r 279b577e5bf6 gcc/config/sol2.h
--- a/gcc/config/sol2.h Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/sol2.h Mon Jun 07 13:23:57 2010 +0200
@@ -19,6 +19,9 @@
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
+/* We are compiling for Solaris 2 now. */
+#define TARGET_SOLARIS 1
+
/* We use stabs-in-elf for debugging, because that is what the native
toolchain uses. */
#undef PREFERRED_DEBUGGING_TYPE
@@ -259,9 +262,8 @@
{ "init", 0, 0, true, false, false, NULL }, \
{ "fini", 0, 0, true, false, false, NULL }
-/* Solaris/x86 as and gas support the common ELF .section/.pushsection
- syntax. */
-#define PUSHSECTION_FORMAT "\t.pushsection\t%s\n"
+/* Solaris/x86 as and gas support unquoted section names. */
+#define SECTION_NAME_FORMAT "%s"
/* This is how to declare the size of a function. For Solaris, we output
any .init or .fini entries here. */
diff -r 279b577e5bf6 gcc/config/sparc/sol2.h
--- a/gcc/config/sparc/sol2.h Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/sparc/sol2.h Mon Jun 07 13:23:57 2010 +0200
@@ -181,11 +181,15 @@
#undef TARGET_ASM_NAMED_SECTION
#define TARGET_ASM_NAMED_SECTION sparc_solaris_elf_asm_named_section
-/* Solaris/SPARC as uses a non-standard .section/.pushsection syntax.
- While gas supports it, too, we prefer the standard variant. */
+/* Emit COMDAT group signature symbols for Sun as. */
+#undef TARGET_ASM_CODE_END
+#define TARGET_ASM_CODE_END solaris_code_end
+
+/* Solaris/SPARC as requires doublequoted section names. While gas
+ supports that, too, we prefer the standard variant. */
#ifndef USE_GAS
-#undef PUSHSECTION_FORMAT
-#define PUSHSECTION_FORMAT "\t.pushsection\t\"%s\"\n"
+#undef SECTION_NAME_FORMAT
+#define SECTION_NAME_FORMAT "\"%s\""
#endif
#define MD_UNWIND_SUPPORT "config/sparc/sol2-unwind.h"
diff -r 279b577e5bf6 gcc/config/sparc/sparc.c
--- a/gcc/config/sparc/sparc.c Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/sparc/sparc.c Mon Jun 07 13:23:57 2010 +0200
@@ -8070,6 +8070,12 @@
sparc_solaris_elf_asm_named_section (const char *name, unsigned int flags,
tree decl ATTRIBUTE_UNUSED)
{
+ if (HAVE_COMDAT_GROUP && flags & SECTION_LINKONCE)
+ {
+ solaris_elf_asm_comdat_section (name, flags, decl);
+ return;
+ }
+
fprintf (asm_out_file, "\t.section\t\"%s\"", name);
if (!(flags & SECTION_DEBUG))
diff -r 279b577e5bf6 gcc/config/t-sol2
--- a/gcc/config/t-sol2 Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/config/t-sol2 Mon Jun 07 13:23:57 2010 +0200
@@ -25,6 +25,6 @@
# Solaris-specific attributes
sol2.o: $(srcdir)/config/sol2.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
- tree.h output.h $(TM_H) $(TM_P_H) toplev.h $(GGC_H)
+ tree.h output.h $(TM_H) target.h $(TM_P_H) toplev.h $(GGC_H) $(HASHTAB_H)
$(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
$(srcdir)/config/sol2.c
diff -r 279b577e5bf6 gcc/configure.ac
--- a/gcc/configure.ac Mon Jun 07 13:23:04 2010 +0200
+++ b/gcc/configure.ac Mon Jun 07 13:23:57 2010 +0200
@@ -2524,10 +2524,36 @@
[.section .text,"axG",@progbits,.foo,comdat])
if test $gcc_cv_as_comdat_group = yes; then
gcc_cv_as_comdat_group_percent=no
+ gcc_cv_as_comdat_group_group=no
else
gcc_GAS_CHECK_FEATURE(COMDAT group support, gcc_cv_as_comdat_group_percent,
[elf,2,16,0], [--fatal-warnings],
[.section .text,"axG",%progbits,.foo,comdat])
+ if test $gcc_cv_as_comdat_group_percent = yes; then
+ gcc_cv_as_comdat_group_group=no
+ else
+ # Sun as uses a completely different syntax.
+ case "${target}" in
+ sparc*-*-solaris2*)
+ gcc_GAS_CHECK_FEATURE(COMDAT group support,
+ gcc_cv_as_comdat_group_group,
+ ,,
+ [.group foo,".text%foo",#comdat
+ .section ".text%foo", #alloc,#execinstr,#progbits
+ .globl foo
+ foo:])
+ ;;
+ i?86-*-solaris2*)
+ gcc_GAS_CHECK_FEATURE(COMDAT group support,
+ gcc_cv_as_comdat_group_group,
+ ,,
+ [.group foo,.text%foo,#comdat
+ .section .text%foo, "ax", @progbits
+ .globl foo
+ foo:])
+ ;;
+ esac
+ fi
fi
if test x"$ld_is_gold" = xyes; then
comdat_group=yes
@@ -2579,9 +2605,12 @@
if test $comdat_group = no; then
gcc_cv_as_comdat_group=no
gcc_cv_as_comdat_group_percent=no
+ gcc_cv_as_comdat_group_group=no
fi
AC_DEFINE_UNQUOTED(HAVE_COMDAT_GROUP,
- [`if test $gcc_cv_as_comdat_group = yes || test $gcc_cv_as_comdat_group_percent = yes; then echo 1; else echo 0; fi`],
+ [`if test $gcc_cv_as_comdat_group = yes \
+ || test $gcc_cv_as_comdat_group_percent = yes \
+ || test $gcc_cv_as_comdat_group_group = yes; then echo 1; else echo 0; fi`],
[Define 0/1 if your assembler and linker support COMDAT groups.])
gcc_GAS_CHECK_FEATURE([line table discriminator support],
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