[glibc/azanella/clang] elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=fef612a18315ff9bf1598c4b768e3d382418e37e

commit fef612a18315ff9bf1598c4b768e3d382418e37e
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Mar 30 09:23:35 2022 -0300

    elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support
    
    Besides the option being gcc specific, this approach is still fragile
    and not future proof since we do not if this will be the only
    optimization option gcc will add that transform loops to memset
    (or any libcall).
    
    This patch add a new header dl-symbol-hacks.h that can be used to
    redirect the compiler generated libcalls to port specific string
    implementatation if required (defined by dl-ifunc-generic.h).
    
    Checked on x86_64-linux-gnu and aarch64-linux-gnu.

Diff:
---
 elf/Makefile                                       |  5 ---
 elf/dl-support.c                                   |  1 +
 elf/dl-symbol-hacks.h                              | 31 ++++++++++++++++++
 sysdeps/aarch64/multiarch/dl-ifunc-generic.h       | 24 ++++++++++++++
 sysdeps/generic/dl-ifunc-generic.h                 | 37 ++++++++++++++++++++++
 sysdeps/i386/i686/multiarch/dl-ifunc-generic.h     | 24 ++++++++++++++
 .../powerpc64/le/multiarch/dl-ifunc-generic.h      | 24 ++++++++++++++
 sysdeps/s390/multiarch/dl-ifunc-generic.h          | 29 +++++++++++++++++
 .../sparc32/sparcv9/multiarch/dl-ifunc-generic.h   | 24 ++++++++++++++
 sysdeps/sparc/sparc64/multiarch/dl-ifunc-generic.h | 24 ++++++++++++++
 sysdeps/x86_64/multiarch/dl-ifunc-generic.h        | 32 +++++++++++++++++++
 11 files changed, 250 insertions(+), 5 deletions(-)

diff --git a/elf/Makefile b/elf/Makefile
index 008770bfaf..b915ea8f02 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -162,11 +162,6 @@ ifeq (yes,$(have-loop-to-function))
 CFLAGS-rtld.c += -fno-tree-loop-distribute-patterns
 endif
 
-ifeq (yes,$(have-loop-to-function))
-# Likewise, during static library startup, memset is not yet available.
-CFLAGS-dl-support.c = -fno-tree-loop-distribute-patterns
-endif
-
 # Compile rtld itself without stack protection.
 # Also compile all routines in the static library that are elided from
 # the shared libc because they are in libc.a in the same way.
diff --git a/elf/dl-support.c b/elf/dl-support.c
index 4af0b5b2ce..6d1996ae6e 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -44,6 +44,7 @@
 #include <dl-auxv.h>
 #include <dl-find_object.h>
 #include <array_length.h>
+#include <dl-symbol-hacks.h>
 
 extern char *__progname;
 char **_dl_argv = &__progname;	/* This is checked for some error messages.  */
diff --git a/elf/dl-symbol-hacks.h b/elf/dl-symbol-hacks.h
new file mode 100644
index 0000000000..1b83b284dd
--- /dev/null
+++ b/elf/dl-symbol-hacks.h
@@ -0,0 +1,31 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_SYMBOL_HACKS_H
+#define _DL_SYMBOL_HACKS_H
+
+#include <dl-ifunc-generic.h>
+
+/* Some compiler optimizations may transform loops into memset/memmove
+   calls and without proper redirection it might call PLT throught
+   ifunc without relocations being processed.  */
+#ifdef HAVE_MEMSET_IFUNC_GENERIC
+asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC);
+#endif
+
+#endif
diff --git a/sysdeps/aarch64/multiarch/dl-ifunc-generic.h b/sysdeps/aarch64/multiarch/dl-ifunc-generic.h
new file mode 100644
index 0000000000..1278a06ff0
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/dl-ifunc-generic.h
@@ -0,0 +1,24 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+#define HAVE_MEMSET_IFUNC_GENERIC "__memset_generic"
+
+#endif
diff --git a/sysdeps/generic/dl-ifunc-generic.h b/sysdeps/generic/dl-ifunc-generic.h
new file mode 100644
index 0000000000..5e1d5c1fd8
--- /dev/null
+++ b/sysdeps/generic/dl-ifunc-generic.h
@@ -0,0 +1,37 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+/* The compiler might optimize loops or other constructs to library calls even
+   in freestanding mode.  Although it is safe in most scenarios, on program
+   loading and static startup, iFUNC resolution might require other dynamic
+   relocation that are not yet done.
+
+   Instead of adding per-file compiler flags to avoid the libcall generation,
+   this header defines generic symbols that will be routed instead of the
+   default symbols name.
+
+   Each port can then define the following macro to the expected generic
+   implementation if the symbol is provided as iFUNC:
+
+   HAVE_MEMSET_IFUNC_GENERIC - the generic memset call.
+ */
+
+#endif
diff --git a/sysdeps/i386/i686/multiarch/dl-ifunc-generic.h b/sysdeps/i386/i686/multiarch/dl-ifunc-generic.h
new file mode 100644
index 0000000000..a538931c03
--- /dev/null
+++ b/sysdeps/i386/i686/multiarch/dl-ifunc-generic.h
@@ -0,0 +1,24 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+#define HAVE_MEMSET_IFUNC_GENERIC "__memset_ia32"
+
+#endif
diff --git a/sysdeps/powerpc/powerpc64/le/multiarch/dl-ifunc-generic.h b/sysdeps/powerpc/powerpc64/le/multiarch/dl-ifunc-generic.h
new file mode 100644
index 0000000000..1bf516494d
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/le/multiarch/dl-ifunc-generic.h
@@ -0,0 +1,24 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+#define HAVE_MEMSET_IFUNC_GENERIC "__memset_power8"
+
+#endif
diff --git a/sysdeps/s390/multiarch/dl-ifunc-generic.h b/sysdeps/s390/multiarch/dl-ifunc-generic.h
new file mode 100644
index 0000000000..b0e5ed23aa
--- /dev/null
+++ b/sysdeps/s390/multiarch/dl-ifunc-generic.h
@@ -0,0 +1,29 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+#include <ifunc-memset.h>
+
+#define IFUNC_SYMBOL_STR1(s)	#s
+#define IFUNC_SYMBOL_STR(s)	IFUNC_SYMBOL_STR1(s)
+
+#define HAVE_MEMSET_IFUNC_GENERIC IFUNC_SYMBOL_STR(MEMSET_DEFAULT)
+
+#endif
diff --git a/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-ifunc-generic.h b/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-ifunc-generic.h
new file mode 100644
index 0000000000..417b24d2c1
--- /dev/null
+++ b/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-ifunc-generic.h
@@ -0,0 +1,24 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+#define HAVE_MEMSET_IFUNC_GENERIC "__memset_ultra1"
+
+#endif
diff --git a/sysdeps/sparc/sparc64/multiarch/dl-ifunc-generic.h b/sysdeps/sparc/sparc64/multiarch/dl-ifunc-generic.h
new file mode 100644
index 0000000000..417b24d2c1
--- /dev/null
+++ b/sysdeps/sparc/sparc64/multiarch/dl-ifunc-generic.h
@@ -0,0 +1,24 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+#define HAVE_MEMSET_IFUNC_GENERIC "__memset_ultra1"
+
+#endif
diff --git a/sysdeps/x86_64/multiarch/dl-ifunc-generic.h b/sysdeps/x86_64/multiarch/dl-ifunc-generic.h
new file mode 100644
index 0000000000..7b7cf1c3d6
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/dl-ifunc-generic.h
@@ -0,0 +1,32 @@
+/* Symbol rediretion for loader/static initialization code.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_IFUNC_GENERIC_H
+#define _DL_IFUNC_GENERIC_H
+
+#include <isa-level.h>
+
+#if MINIMUM_X86_ISA_LEVEL >= 4
+# define HAVE_MEMSET_IFUNC_GENERIC "__memset_evex_unaligned"
+#elif MINIMUM_X86_ISA_LEVEL == 3
+# define HAVE_MEMSET_IFUNC_GENERIC "__memset_avx2_unaligned"
+#else
+# define HAVE_MEMSET_IFUNC_GENERIC "__memset_sse2_unaligned"
+#endif
+
+#endif