toolchain: gcc: backport inline subword atomic support for riscv

RISC-V has no support for subword atomic operations; code currently
generates libatomic library calls.

This patch changes the default behavior to fast inline subword atomic
calls that do not require libatomic.

Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>
(cherry picked from commit 7b4a966de88aa0e1f9b7faa62a4d6cb7b01e9f8f)

toolchain/gcc/patches-11.x/701-riscv-linux-Don-t-add-latomic-with-pthread.patch

@@ -0,0 +1,36 @@
+From 203f3060dd363361b172f7295f42bb6bf5ac0b3b Mon Sep 17 00:00:00 2001
+From: Andreas Schwab <schwab@suse.de>
+Date: Sat, 23 Apr 2022 15:48:42 +0200
+Subject: [PATCH] riscv/linux: Don't add -latomic with -pthread
+
+Now that we have support for inline subword atomic operations, it is no
+longer necessary to link against libatomic.  This also fixes testsuite
+failures because the framework does not properly set up the linker flags
+for finding libatomic.
+The use of atomic operations is also independent of the use of libpthread.
+
+gcc/
+	* config/riscv/linux.h (LIB_SPEC): Don't redefine.
+---
+ gcc/config/riscv/linux.h | 10 ----------
+ 1 file changed, 10 deletions(-)
+
+--- a/gcc/config/riscv/linux.h
++++ b/gcc/config/riscv/linux.h
+@@ -35,16 +35,6 @@ along with GCC; see the file COPYING3.
+ #undef MUSL_DYNAMIC_LINKER
+ #define MUSL_DYNAMIC_LINKER "/lib/ld-musl-riscv" XLEN_SPEC MUSL_ABI_SUFFIX ".so.1"
+ 
+-/* Because RISC-V only has word-sized atomics, it requries libatomic where
+-   others do not.  So link libatomic by default, as needed.  */
+-#undef LIB_SPEC
+-#ifdef LD_AS_NEEDED_OPTION
+-#define LIB_SPEC GNU_USER_TARGET_LIB_SPEC \
+-  " %{pthread:" LD_AS_NEEDED_OPTION " -latomic " LD_NO_AS_NEEDED_OPTION "}"
+-#else
+-#define LIB_SPEC GNU_USER_TARGET_LIB_SPEC " -latomic "
+-#endif
+-
+ #define ICACHE_FLUSH_FUNC "__riscv_flush_icache"
+ 
+ #define CPP_SPEC "%{pthread:-D_REENTRANT}"

toolchain/gcc/patches-11.x/910-mbsd_multi.patch

@@ -114,7 +114,7 @@ Date:   Tue Jul 31 00:52:27 2007 +0000
  ; On SVR4 targets, it also controls whether or not to emit a
 --- a/gcc/doc/invoke.texi
 +++ b/gcc/doc/invoke.texi
-@@ -9058,6 +9058,17 @@ This option is only supported for C and
+@@ -9059,6 +9059,17 @@ This option is only supported for C and
  @option{-Wall} and by @option{-Wpedantic}, which can be disabled with
  @option{-Wno-pointer-sign}.
  

toolchain/gcc/patches-12.x/701-riscv-linux-Don-t-add-latomic-with-pthread.patch

@@ -0,0 +1,36 @@
+From 203f3060dd363361b172f7295f42bb6bf5ac0b3b Mon Sep 17 00:00:00 2001
+From: Andreas Schwab <schwab@suse.de>
+Date: Sat, 23 Apr 2022 15:48:42 +0200
+Subject: [PATCH] riscv/linux: Don't add -latomic with -pthread
+
+Now that we have support for inline subword atomic operations, it is no
+longer necessary to link against libatomic.  This also fixes testsuite
+failures because the framework does not properly set up the linker flags
+for finding libatomic.
+The use of atomic operations is also independent of the use of libpthread.
+
+gcc/
+	* config/riscv/linux.h (LIB_SPEC): Don't redefine.
+---
+ gcc/config/riscv/linux.h | 10 ----------
+ 1 file changed, 10 deletions(-)
+
+--- a/gcc/config/riscv/linux.h
++++ b/gcc/config/riscv/linux.h
+@@ -35,16 +35,6 @@ along with GCC; see the file COPYING3.
+ #undef MUSL_DYNAMIC_LINKER
+ #define MUSL_DYNAMIC_LINKER "/lib/ld-musl-riscv" XLEN_SPEC MUSL_ABI_SUFFIX ".so.1"
+ 
+-/* Because RISC-V only has word-sized atomics, it requries libatomic where
+-   others do not.  So link libatomic by default, as needed.  */
+-#undef LIB_SPEC
+-#ifdef LD_AS_NEEDED_OPTION
+-#define LIB_SPEC GNU_USER_TARGET_LIB_SPEC \
+-  " %{pthread:" LD_AS_NEEDED_OPTION " -latomic " LD_NO_AS_NEEDED_OPTION "}"
+-#else
+-#define LIB_SPEC GNU_USER_TARGET_LIB_SPEC " -latomic "
+-#endif
+-
+ #define ICACHE_FLUSH_FUNC "__riscv_flush_icache"
+ 
+ #define CPP_SPEC "%{pthread:-D_REENTRANT}"

toolchain/gcc/patches-12.x/910-mbsd_multi.patch

@@ -114,7 +114,7 @@ Date:   Tue Jul 31 00:52:27 2007 +0000
  ; On SVR4 targets, it also controls whether or not to emit a
 --- a/gcc/doc/invoke.texi
 +++ b/gcc/doc/invoke.texi
-@@ -9596,6 +9596,17 @@ This option is only supported for C and
+@@ -9597,6 +9597,17 @@ This option is only supported for C and
  @option{-Wall} and by @option{-Wpedantic}, which can be disabled with
  @option{-Wno-pointer-sign}.
  

toolchain/gcc/patches-13.x/701-riscv-linux-Don-t-add-latomic-with-pthread.patch

@@ -0,0 +1,36 @@
+From 203f3060dd363361b172f7295f42bb6bf5ac0b3b Mon Sep 17 00:00:00 2001
+From: Andreas Schwab <schwab@suse.de>
+Date: Sat, 23 Apr 2022 15:48:42 +0200
+Subject: [PATCH] riscv/linux: Don't add -latomic with -pthread
+
+Now that we have support for inline subword atomic operations, it is no
+longer necessary to link against libatomic.  This also fixes testsuite
+failures because the framework does not properly set up the linker flags
+for finding libatomic.
+The use of atomic operations is also independent of the use of libpthread.
+
+gcc/
+	* config/riscv/linux.h (LIB_SPEC): Don't redefine.
+---
+ gcc/config/riscv/linux.h | 10 ----------
+ 1 file changed, 10 deletions(-)
+
+--- a/gcc/config/riscv/linux.h
++++ b/gcc/config/riscv/linux.h
+@@ -35,16 +35,6 @@ along with GCC; see the file COPYING3.
+ #undef MUSL_DYNAMIC_LINKER
+ #define MUSL_DYNAMIC_LINKER "/lib/ld-musl-riscv" XLEN_SPEC MUSL_ABI_SUFFIX ".so.1"
+ 
+-/* Because RISC-V only has word-sized atomics, it requries libatomic where
+-   others do not.  So link libatomic by default, as needed.  */
+-#undef LIB_SPEC
+-#ifdef LD_AS_NEEDED_OPTION
+-#define LIB_SPEC GNU_USER_TARGET_LIB_SPEC \
+-  " %{pthread:" LD_AS_NEEDED_OPTION " -latomic " LD_NO_AS_NEEDED_OPTION "}"
+-#else
+-#define LIB_SPEC GNU_USER_TARGET_LIB_SPEC " -latomic "
+-#endif
+-
+ #define ICACHE_FLUSH_FUNC "__riscv_flush_icache"
+ 
+ #define CPP_SPEC "%{pthread:-D_REENTRANT}"

toolchain/gcc/patches-13.x/910-mbsd_multi.patch

@@ -114,7 +114,7 @@ Date:   Tue Jul 31 00:52:27 2007 +0000
  ; On SVR4 targets, it also controls whether or not to emit a
 --- a/gcc/doc/invoke.texi
 +++ b/gcc/doc/invoke.texi
-@@ -10061,6 +10061,17 @@ This option is only supported for C and
+@@ -10062,6 +10062,17 @@ This option is only supported for C and
  @option{-Wall} and by @option{-Wpedantic}, which can be disabled with
  @option{-Wno-pointer-sign}.