On Sat, 7 May 2022, Giuliano Belinassi wrote:
> When -fpatchable-function-entry= is enabled, certain C++ codes fails to
> link because of generated references to discarded sections in
> __patchable_function_entry section. This commit fixes this problem by
> puting those references in a COMDAT section.
>
> On the previous patch, GCC fails to compile with --enable-vtable-verify
> enabled. This version compiles fine with it.
OK for trunk.
Thanks,
Richard.
> 2022-05-06 Giuliano Belinassi <gbelina...@suse.de>
>
> PR c++/105169
> * targhooks.cc (default_print_patchable_function_entry_1): Handle
> COMDAT case.
> * varasm.cc (switch_to_comdat_section): New
> (handle_vtv_comdat_section): Call switch_to_comdat_section.
> * varasm.h: Declare switch_to_comdat_section.
>
> gcc/testsuite/ChangeLog
> 2022-05-06 Giuliano Belinassi <gbelina...@suse.de>
>
> PR c++/105169
> * g++.dg/modules/pr105169.h: New file.
> * g++.dg/modules/pr105169_a.C: New test.
> * g++.dg/modules/pr105169_b.C: New file.
> ---
> gcc/targhooks.cc | 8 ++++--
> gcc/testsuite/g++.dg/modules/pr105169.h | 22 +++++++++++++++
> gcc/testsuite/g++.dg/modules/pr105169_a.C | 25 +++++++++++++++++
> gcc/testsuite/g++.dg/modules/pr105169_b.C | 12 +++++++++
> gcc/varasm.cc | 33 ++++++++++++++---------
> gcc/varasm.h | 2 ++
> 6 files changed, 87 insertions(+), 15 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/modules/pr105169.h
> create mode 100644 gcc/testsuite/g++.dg/modules/pr105169_a.C
> create mode 100644 gcc/testsuite/g++.dg/modules/pr105169_b.C
>
> diff --git a/gcc/targhooks.cc b/gcc/targhooks.cc
> index 399d6f874dc..b15ae19bcb6 100644
> --- a/gcc/targhooks.cc
> +++ b/gcc/targhooks.cc
> @@ -2009,8 +2009,12 @@ default_print_patchable_function_entry_1 (FILE *file,
> patch_area_number++;
> ASM_GENERATE_INTERNAL_LABEL (buf, "LPFE", patch_area_number);
>
> - switch_to_section (get_section ("__patchable_function_entries",
> - flags, current_function_decl));
> + section *sect = get_section ("__patchable_function_entries",
> + flags, current_function_decl);
> + if (HAVE_COMDAT_GROUP && DECL_COMDAT_GROUP (current_function_decl))
> + switch_to_comdat_section (sect, current_function_decl);
> + else
> + switch_to_section (sect);
> assemble_align (POINTER_SIZE);
> fputs (asm_op, file);
> assemble_name_raw (file, buf);
> diff --git a/gcc/testsuite/g++.dg/modules/pr105169.h
> b/gcc/testsuite/g++.dg/modules/pr105169.h
> new file mode 100644
> index 00000000000..a7e76270531
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr105169.h
> @@ -0,0 +1,22 @@
> +class IPXAddressClass
> +{
> +public:
> + IPXAddressClass(void);
> +};
> +
> +class WinsockInterfaceClass
> +{
> +
> +public:
> + WinsockInterfaceClass(void);
> +
> + virtual void Set_Broadcast_Address(void*){};
> +
> + virtual int Get_Protocol(void)
> + {
> + return 0;
> + };
> +
> +protected:
> +};
> +
> diff --git a/gcc/testsuite/g++.dg/modules/pr105169_a.C
> b/gcc/testsuite/g++.dg/modules/pr105169_a.C
> new file mode 100644
> index 00000000000..66dc4b7901f
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr105169_a.C
> @@ -0,0 +1,25 @@
> +/* { dg-module-do link } */
> +/* { dg-options "-std=c++11 -fpatchable-function-entry=1 -O2" } */
> +/* { dg-additional-options "-std=c++11 -fpatchable-function-entry=1 -O2" } */
> +
> +/* This test is in the "modules" package because it supports multiple files
> + linkage. */
> +
> +#include "pr105169.h"
> +
> +WinsockInterfaceClass* PacketTransport;
> +
> +IPXAddressClass::IPXAddressClass(void)
> +{
> +}
> +
> +int function()
> +{
> + return PacketTransport->Get_Protocol();
> +}
> +
> +int main()
> +{
> + IPXAddressClass ipxaddr;
> + return 0;
> +}
> diff --git a/gcc/testsuite/g++.dg/modules/pr105169_b.C
> b/gcc/testsuite/g++.dg/modules/pr105169_b.C
> new file mode 100644
> index 00000000000..5f8b00dfe51
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr105169_b.C
> @@ -0,0 +1,12 @@
> +/* { dg-module-do link } */
> +/* { dg-options "-std=c++11 -fpatchable-function-entry=1 -O2" } */
> +/* { dg-additional-options "-std=c++11 -fpatchable-function-entry=1 -O2" } */
> +
> +/* This test is in the "modules" package because it supports multiple files
> + linkage. */
> +
> +#include "pr105169.h"
> +
> +WinsockInterfaceClass::WinsockInterfaceClass(void)
> +{
> +}
> diff --git a/gcc/varasm.cc b/gcc/varasm.cc
> index c41f17d64f7..6454f1ce519 100644
> --- a/gcc/varasm.cc
> +++ b/gcc/varasm.cc
> @@ -8457,25 +8457,21 @@ default_asm_output_ident_directive (const char
> *ident_str)
> fprintf (asm_out_file, "%s\"%s\"\n", ident_asm_op, ident_str);
> }
>
> -
> -/* This function ensures that vtable_map variables are not only
> - in the comdat section, but that each variable has its own unique
> - comdat name. Without this the variables end up in the same section
> - with a single comdat name.
> -
> +/* Switch to a COMDAT section with COMDAT name of decl.
> +
> FIXME: resolve_unique_section needs to deal better with
> decls with both DECL_SECTION_NAME and DECL_ONE_ONLY. Once
> that is fixed, this if-else statement can be replaced with
> a single call to "switch_to_section (sect)". */
>
> -static void
> -handle_vtv_comdat_section (section *sect, const_tree decl ATTRIBUTE_UNUSED)
> +void
> +switch_to_comdat_section (section *sect, tree decl)
> {
> #if defined (OBJECT_FORMAT_ELF)
> targetm.asm_out.named_section (sect->named.name,
> sect->named.common.flags
> | SECTION_LINKONCE,
> - DECL_NAME (decl));
> + decl);
> in_section = sect;
> #else
> /* Neither OBJECT_FORMAT_PE, nor OBJECT_FORMAT_COFF is set here.
> @@ -8490,18 +8486,18 @@ handle_vtv_comdat_section (section *sect, const_tree
> decl ATTRIBUTE_UNUSED)
> {
> char *name;
>
> - if (TREE_CODE (DECL_NAME (decl)) == IDENTIFIER_NODE)
> + if (TREE_CODE (decl) == IDENTIFIER_NODE)
> name = ACONCAT ((sect->named.name, "$",
> - IDENTIFIER_POINTER (DECL_NAME (decl)), NULL));
> + IDENTIFIER_POINTER (decl), NULL));
> else
> name = ACONCAT ((sect->named.name, "$",
> - IDENTIFIER_POINTER (DECL_COMDAT_GROUP (DECL_NAME
> (decl))),
> + IDENTIFIER_POINTER (DECL_COMDAT_GROUP (decl)),
> NULL));
>
> targetm.asm_out.named_section (name,
> sect->named.common.flags
> | SECTION_LINKONCE,
> - DECL_NAME (decl));
> + decl);
> in_section = sect;
> }
> else
> @@ -8509,4 +8505,15 @@ handle_vtv_comdat_section (section *sect, const_tree
> decl ATTRIBUTE_UNUSED)
> #endif
> }
>
> +/* This function ensures that vtable_map variables are not only
> + in the comdat section, but that each variable has its own unique
> + comdat name. Without this the variables end up in the same section
> + with a single comdat name. */
> +
> +static void
> +handle_vtv_comdat_section (section *sect, const_tree decl ATTRIBUTE_UNUSED)
> +{
> + switch_to_comdat_section(sect, DECL_NAME (decl));
> +}
> +
> #include "gt-varasm.h"
> diff --git a/gcc/varasm.h b/gcc/varasm.h
> index d5d8c4e5578..8ba8374e779 100644
> --- a/gcc/varasm.h
> +++ b/gcc/varasm.h
> @@ -79,4 +79,6 @@ extern rtx assemble_static_space (unsigned HOST_WIDE_INT);
>
> extern rtx assemble_trampoline_template (void);
>
> +extern void switch_to_comdat_section (section *, tree);
> +
> #endif // GCC_VARASM_H
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
