Re: musl-cross-make / litecross improvements

[Patrick Oppenlander <pattyo.lists@gmail.com>]

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On 06/05/16 12:44, Rich Felker wrote:
> It looks like there's a useless dependency on kernel headers in stuff
> for the target libs. I suspect you might have omitted the recommended
> --enable-languages=c,c++ and let it build all langs; IIRC boehm-gc is
> not built at all for a c/c++ only build. Other langs are completely
> untested and probably don't work, but it would be nice to find out why
> and fix the ones that are practical to fix.
>
> I should probably also add COMMON_CONFIG += --enable-languages=c,c++
> _before_ config.mak inclusion so that, by default, you get the working
> configuration. Having this before config.mak should make it so any
> --enable-languages option you manually add with += takes precedence.

I think that's a good idea.

README.md says that the only mandatory variable is TARGET. I assumed 
c,c++ only was default.

>
>> Are you planning on supporting GCC 5.3? I may be able to contribute
>> some patches.
> I suspect the same patches for 5.2 apply just fine, but I haven't
> taken the time to test yet. If you can confirm they work or tweak them
> so they work I'd be happy to add 5.3 support. Other versions I'd like
> to support are 4.7.4 (last C-only, also last before some sketchy
> optimizations were added) and 6.1.0, but in order to add a version it
> should have proper support (at least the main musl patch with dynamic
> linker names, include paths, etc. fully ported) rather than just being
> enough to compile.

I had a quick look. Patches apply with two very minor adjustments, I've 
attached the edited patches. I rebuilt arm-linux-musleabi but haven't 
used it in anger yet. Is there a way to easily check all targets?

Also, is there a way to get linux headers installed with the toolchain 
(like crosstool does)?

I use 4.9.3 for building old arm 2.6 kernels and haven't had a problem 
with it yet.

         Patrick

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--- a/gcc/config/sh/sh.md (revision 233324)
+++ b/gcc/config/sh/sh.md (working copy)
@@ -10476,7 +10476,7 @@
        (call (mem:SI (match_operand:SI 1 "symbol_ref_operand" ""))
              (match_operand 2 "" "")))
    (use (reg:SI FPSCR_MODES_REG))
-   (clobber (match_scratch:SI 3 "=&k"))
+   (clobber (reg:SI R1_REG))
    (return)]
   "TARGET_SH2 && !TARGET_FDPIC"
   "#"
@@ -10491,6 +10495,8 @@
   rtx lab = PATTERN (gen_call_site ());
   rtx call_insn;

+  operands[3] =  gen_rtx_REG (SImode, R1_REG);
+
   sh_expand_sym_label2reg (operands[3], operands[1], lab, true);
   call_insn = emit_call_insn (gen_sibcall_valuei_pcrel (operands[0],
                                                        operands[3],
@@ -10511,7 +10519,7 @@
              (match_operand 2)))
    (use (reg:SI FPSCR_MODES_REG))
    (use (reg:SI PIC_REG))
-   (clobber (match_scratch:SI 3 "=k"))
+   (clobber (reg:SI R1_REG))
    (return)]
   "TARGET_SH2 && TARGET_FDPIC"
   "#"
@@ -10520,6 +10528,8 @@
 {
   rtx lab = PATTERN (gen_call_site ());

+  operands[3] =  gen_rtx_REG (SImode, R1_REG);
+
   sh_expand_sym_label2reg (operands[3], operands[1], lab, true);
   rtx i = emit_call_insn (gen_sibcall_valuei_pcrel_fdpic (operands[0],
                                                          operands[3],


[-- Attachment #3: 0001-musl.diff --]
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diff --git a/fixincludes/mkfixinc.sh b/fixincludes/mkfixinc.sh
index 6653fed..0d96c8c 100755
--- a/fixincludes/mkfixinc.sh
+++ b/fixincludes/mkfixinc.sh
@@ -19,7 +19,8 @@ case $machine in
     powerpc-*-eabi*    | \
     powerpc-*-rtems*   | \
     powerpcle-*-eabisim* | \
-    powerpcle-*-eabi* )
+    powerpcle-*-eabi* | \
+    *-musl* )
 	#  IF there is no include fixing,
 	#  THEN create a no-op fixer and exit
 	(echo "#! /bin/sh" ; echo "exit 0" ) > ${target}
diff --git a/gcc/config.gcc b/gcc/config.gcc
index 3ede69b..d9eb8cf 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -575,7 +575,7 @@ case ${target} in
 esac
 
 # Common C libraries.
-tm_defines="$tm_defines LIBC_GLIBC=1 LIBC_UCLIBC=2 LIBC_BIONIC=3"
+tm_defines="$tm_defines LIBC_GLIBC=1 LIBC_UCLIBC=2 LIBC_BIONIC=3 LIBC_MUSL=4"
 
 # 32-bit x86 processors supported by --with-arch=.  Each processor
 # MUST be separated by exactly one space.
@@ -720,6 +720,9 @@ case ${target} in
     *-*-*uclibc*)
       tm_defines="$tm_defines DEFAULT_LIBC=LIBC_UCLIBC"
       ;;
+    *-*-*musl*)
+      tm_defines="$tm_defines DEFAULT_LIBC=LIBC_MUSL"
+      ;;
     *)
       tm_defines="$tm_defines DEFAULT_LIBC=LIBC_GLIBC"
       ;;
diff --git a/gcc/config/aarch64/aarch64-linux.h b/gcc/config/aarch64/aarch64-linux.h
index ba7fc3b..1600a32 100644
--- a/gcc/config/aarch64/aarch64-linux.h
+++ b/gcc/config/aarch64/aarch64-linux.h
@@ -23,6 +23,9 @@
 
 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux-aarch64%{mbig-endian:_be}%{mabi=ilp32:_ilp32}.so.1"
 
+#undef MUSL_DYNAMIC_LINKER
+#define MUSL_DYNAMIC_LINKER "/lib/ld-musl-aarch64%{mbig-endian:_be}%{mabi=ilp32:_ilp32}.so.1"
+
 #undef  ASAN_CC1_SPEC
 #define ASAN_CC1_SPEC "%{%:sanitize(address):-funwind-tables}"
 
diff --git a/gcc/config/alpha/linux.h b/gcc/config/alpha/linux.h
index c567f43..475ea06 100644
--- a/gcc/config/alpha/linux.h
+++ b/gcc/config/alpha/linux.h
@@ -61,10 +61,14 @@ along with GCC; see the file COPYING3.  If not see
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 /* Determine what functions are present at the runtime;
diff --git a/gcc/config/arm/linux-eabi.h b/gcc/config/arm/linux-eabi.h
index e9d65dc..f12e6bd 100644
--- a/gcc/config/arm/linux-eabi.h
+++ b/gcc/config/arm/linux-eabi.h
@@ -77,6 +77,23 @@
     %{mfloat-abi=soft*:" GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "} \
     %{!mfloat-abi=*:" GLIBC_DYNAMIC_LINKER_DEFAULT "}"
 
+/* For ARM musl currently supports four dynamic linkers:
+   - ld-musl-arm.so.1 - for the EABI-derived soft-float ABI
+   - ld-musl-armhf.so.1 - for the EABI-derived hard-float ABI
+   - ld-musl-armeb.so.1 - for the EABI-derived soft-float ABI, EB
+   - ld-musl-armebhf.so.1 - for the EABI-derived hard-float ABI, EB
+   musl does not support the legacy OABI mode.
+   All the dynamic linkers live in /lib.
+   We default to soft-float, EL. */
+#undef  MUSL_DYNAMIC_LINKER
+#if TARGET_BIG_ENDIAN_DEFAULT
+#define MUSL_DYNAMIC_LINKER_E "%{mlittle-endian:;:eb}"
+#else
+#define MUSL_DYNAMIC_LINKER_E "%{mbig-endian:eb}"
+#endif
+#define MUSL_DYNAMIC_LINKER \
+  "/lib/ld-musl-arm" MUSL_DYNAMIC_LINKER_E "%{mfloat-abi=hard:hf}.so.1"
+
 /* At this point, bpabi.h will have clobbered LINK_SPEC.  We want to
    use the GNU/Linux version, not the generic BPABI version.  */
 #undef  LINK_SPEC
diff --git a/gcc/config/glibc-stdint.h b/gcc/config/glibc-stdint.h
index 3fc67dc..98f4f04 100644
--- a/gcc/config/glibc-stdint.h
+++ b/gcc/config/glibc-stdint.h
@@ -22,6 +22,12 @@ a copy of the GCC Runtime Library Exception along with this program;
 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 <http://www.gnu.org/licenses/>.  */
 
+/* Systems using musl libc should use this header and make sure
+   OPTION_MUSL is defined correctly before using the TYPE macros. */
+#ifndef OPTION_MUSL
+#define OPTION_MUSL 0
+#endif
+
 #define SIG_ATOMIC_TYPE "int"
 
 #define INT8_TYPE "signed char"
@@ -43,12 +49,12 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define UINT_LEAST64_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "long long unsigned int")
 
 #define INT_FAST8_TYPE "signed char"
-#define INT_FAST16_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "int")
-#define INT_FAST32_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "int")
+#define INT_FAST16_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long int" : "int")
+#define INT_FAST32_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long int" : "int")
 #define INT_FAST64_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "long long int")
 #define UINT_FAST8_TYPE "unsigned char"
-#define UINT_FAST16_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "unsigned int")
-#define UINT_FAST32_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "unsigned int")
+#define UINT_FAST16_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long unsigned int" : "unsigned int")
+#define UINT_FAST32_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long unsigned int" : "unsigned int")
 #define UINT_FAST64_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "long long unsigned int")
 
 #define INTPTR_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "int")
diff --git a/gcc/config/i386/linux.h b/gcc/config/i386/linux.h
index a100963..385aefd 100644
--- a/gcc/config/i386/linux.h
+++ b/gcc/config/i386/linux.h
@@ -21,3 +21,6 @@ along with GCC; see the file COPYING3.  If not see
 
 #define GNU_USER_LINK_EMULATION "elf_i386"
 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.2"
+
+#undef MUSL_DYNAMIC_LINKER
+#define MUSL_DYNAMIC_LINKER "/lib/ld-musl-i386.so.1"
diff --git a/gcc/config/i386/linux64.h b/gcc/config/i386/linux64.h
index a27d3be..e300480 100644
--- a/gcc/config/i386/linux64.h
+++ b/gcc/config/i386/linux64.h
@@ -30,3 +30,10 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define GLIBC_DYNAMIC_LINKER32 "/lib/ld-linux.so.2"
 #define GLIBC_DYNAMIC_LINKER64 "/lib64/ld-linux-x86-64.so.2"
 #define GLIBC_DYNAMIC_LINKERX32 "/libx32/ld-linux-x32.so.2"
+
+#undef MUSL_DYNAMIC_LINKER32
+#define MUSL_DYNAMIC_LINKER32 "/lib/ld-musl-i386.so.1"
+#undef MUSL_DYNAMIC_LINKER64
+#define MUSL_DYNAMIC_LINKER64 "/lib/ld-musl-x86_64.so.1"
+#undef MUSL_DYNAMIC_LINKERX32
+#define MUSL_DYNAMIC_LINKERX32 "/lib/ld-musl-x32.so.1"
diff --git a/gcc/config/linux.h b/gcc/config/linux.h
index 857389a..7bc87ab 100644
--- a/gcc/config/linux.h
+++ b/gcc/config/linux.h
@@ -32,10 +32,14 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 #define GNU_USER_TARGET_OS_CPP_BUILTINS()			\
@@ -50,21 +54,25 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     } while (0)
 
 /* Determine which dynamic linker to use depending on whether GLIBC or
-   uClibc or Bionic is the default C library and whether
-   -muclibc or -mglibc or -mbionic has been passed to change the default.  */
+   uClibc or Bionic or musl is the default C library and whether
+   -muclibc or -mglibc or -mbionic or -mmusl has been passed to change
+   the default.  */
 
-#define CHOOSE_DYNAMIC_LINKER1(LIBC1, LIBC2, LIBC3, LD1, LD2, LD3)	\
-  "%{" LIBC2 ":" LD2 ";:%{" LIBC3 ":" LD3 ";:" LD1 "}}"
+#define CHOOSE_DYNAMIC_LINKER1(LIBC1, LIBC2, LIBC3, LIBC4, LD1, LD2, LD3, LD4)	\
+  "%{" LIBC2 ":" LD2 ";:%{" LIBC3 ":" LD3 ";:%{" LIBC4 ":" LD4 ";:" LD1 "}}}"
 
 #if DEFAULT_LIBC == LIBC_GLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
-  CHOOSE_DYNAMIC_LINKER1 ("mglibc", "muclibc", "mbionic", G, U, B)
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("mglibc", "muclibc", "mbionic", "mmusl", G, U, B, M)
 #elif DEFAULT_LIBC == LIBC_UCLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
-  CHOOSE_DYNAMIC_LINKER1 ("muclibc", "mglibc", "mbionic", U, G, B)
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("muclibc", "mglibc", "mbionic", "mmusl", U, G, B, M)
 #elif DEFAULT_LIBC == LIBC_BIONIC
-#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
-  CHOOSE_DYNAMIC_LINKER1 ("mbionic", "mglibc", "muclibc", B, G, U)
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("mbionic", "mglibc", "muclibc", "mmusl", B, G, U, M)
+#elif DEFAULT_LIBC == LIBC_MUSL
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("mmusl", "mglibc", "muclibc", "mbionic", M, G, U, B)
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif /* DEFAULT_LIBC */
@@ -81,24 +89,100 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define BIONIC_DYNAMIC_LINKER32 "/system/bin/linker"
 #define BIONIC_DYNAMIC_LINKER64 "/system/bin/linker64"
 #define BIONIC_DYNAMIC_LINKERX32 "/system/bin/linkerx32"
+/* Should be redefined for each target that supports musl.  */
+#define MUSL_DYNAMIC_LINKER "/dev/null"
+#define MUSL_DYNAMIC_LINKER32 "/dev/null"
+#define MUSL_DYNAMIC_LINKER64 "/dev/null"
+#define MUSL_DYNAMIC_LINKERX32 "/dev/null"
 
 #define GNU_USER_DYNAMIC_LINKER						\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER,	\
-			 BIONIC_DYNAMIC_LINKER)
+			 BIONIC_DYNAMIC_LINKER, MUSL_DYNAMIC_LINKER)
 #define GNU_USER_DYNAMIC_LINKER32					\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32, \
-			 BIONIC_DYNAMIC_LINKER32)
+			 BIONIC_DYNAMIC_LINKER32, MUSL_DYNAMIC_LINKER32)
 #define GNU_USER_DYNAMIC_LINKER64					\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64, \
-			 BIONIC_DYNAMIC_LINKER64)
+			 BIONIC_DYNAMIC_LINKER64, MUSL_DYNAMIC_LINKER64)
 #define GNU_USER_DYNAMIC_LINKERX32					\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKERX32, UCLIBC_DYNAMIC_LINKERX32, \
-			 BIONIC_DYNAMIC_LINKERX32)
+			 BIONIC_DYNAMIC_LINKERX32, MUSL_DYNAMIC_LINKERX32)
 
 /* Whether we have Bionic libc runtime */
 #undef TARGET_HAS_BIONIC
 #define TARGET_HAS_BIONIC (OPTION_BIONIC)
 
+/* musl avoids problematic includes by rearranging the include directories.
+ * Unfortunately, this is mostly duplicated from cppdefault.c */
+#if DEFAULT_LIBC == LIBC_MUSL
+#define INCLUDE_DEFAULTS_MUSL_GPP			\
+    { GPLUSPLUS_INCLUDE_DIR, "G++", 1, 1,		\
+      GPLUSPLUS_INCLUDE_DIR_ADD_SYSROOT, 0 },		\
+    { GPLUSPLUS_TOOL_INCLUDE_DIR, "G++", 1, 1,		\
+      GPLUSPLUS_INCLUDE_DIR_ADD_SYSROOT, 1 },		\
+    { GPLUSPLUS_BACKWARD_INCLUDE_DIR, "G++", 1, 1,	\
+      GPLUSPLUS_INCLUDE_DIR_ADD_SYSROOT, 0 },
+
+#ifdef LOCAL_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_LOCAL			\
+    { LOCAL_INCLUDE_DIR, 0, 0, 1, 1, 2 },		\
+    { LOCAL_INCLUDE_DIR, 0, 0, 1, 1, 0 },
+#else
+#define INCLUDE_DEFAULTS_MUSL_LOCAL
+#endif
+
+#ifdef PREFIX_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_PREFIX			\
+    { PREFIX_INCLUDE_DIR, 0, 0, 1, 0, 0},
+#else
+#define INCLUDE_DEFAULTS_MUSL_PREFIX
+#endif
+
+#ifdef CROSS_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_CROSS			\
+    { CROSS_INCLUDE_DIR, "GCC", 0, 0, 0, 0},
+#else
+#define INCLUDE_DEFAULTS_MUSL_CROSS
+#endif
+
+#ifdef TOOL_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_TOOL			\
+    { TOOL_INCLUDE_DIR, "BINUTILS", 0, 1, 0, 0},
+#else
+#define INCLUDE_DEFAULTS_MUSL_TOOL
+#endif
+
+#ifdef NATIVE_SYSTEM_HEADER_DIR
+#define INCLUDE_DEFAULTS_MUSL_NATIVE			\
+    { NATIVE_SYSTEM_HEADER_DIR, 0, 0, 0, 1, 2 },	\
+    { NATIVE_SYSTEM_HEADER_DIR, 0, 0, 0, 1, 0 },
+#else
+#define INCLUDE_DEFAULTS_MUSL_NATIVE
+#endif
+
+#if defined (CROSS_DIRECTORY_STRUCTURE) && !defined (TARGET_SYSTEM_ROOT)
+# undef INCLUDE_DEFAULTS_MUSL_LOCAL
+# define INCLUDE_DEFAULTS_MUSL_LOCAL
+# undef INCLUDE_DEFAULTS_MUSL_NATIVE
+# define INCLUDE_DEFAULTS_MUSL_NATIVE
+#else
+# undef INCLUDE_DEFAULTS_MUSL_CROSS
+# define INCLUDE_DEFAULTS_MUSL_CROSS
+#endif
+
+#undef INCLUDE_DEFAULTS
+#define INCLUDE_DEFAULTS				\
+  {							\
+    INCLUDE_DEFAULTS_MUSL_GPP				\
+    INCLUDE_DEFAULTS_MUSL_PREFIX			\
+    INCLUDE_DEFAULTS_MUSL_CROSS				\
+    INCLUDE_DEFAULTS_MUSL_TOOL				\
+    INCLUDE_DEFAULTS_MUSL_NATIVE			\
+    { GCC_INCLUDE_DIR, "GCC", 0, 1, 0, 0 },		\
+    { 0, 0, 0, 0, 0, 0 }				\
+  }
+#endif
+
 #if (DEFAULT_LIBC == LIBC_UCLIBC) && defined (SINGLE_LIBC) /* uClinux */
 /* This is a *uclinux* target.  We don't define below macros to normal linux
    versions, because doing so would require *uclinux* targets to include
diff --git a/gcc/config/linux.opt b/gcc/config/linux.opt
index c054338..ef055a7 100644
--- a/gcc/config/linux.opt
+++ b/gcc/config/linux.opt
@@ -28,5 +28,9 @@ Target Report RejectNegative Var(linux_libc,LIBC_GLIBC) Negative(muclibc)
 Use GNU C library
 
 muclibc
-Target Report RejectNegative Var(linux_libc,LIBC_UCLIBC) Negative(mbionic)
+Target Report RejectNegative Var(linux_libc,LIBC_UCLIBC) Negative(mmusl)
 Use uClibc C library
+
+mmusl
+Target Report RejectNegative Var(linux_libc,LIBC_MUSL) Negative(mbionic)
+Use musl C library
diff --git a/gcc/config/microblaze/linux.h b/gcc/config/microblaze/linux.h
index 655a70f..a8a3f3e 100644
--- a/gcc/config/microblaze/linux.h
+++ b/gcc/config/microblaze/linux.h
@@ -28,10 +28,20 @@
 #undef TLS_NEEDS_GOT
 #define TLS_NEEDS_GOT 1
 
-#define DYNAMIC_LINKER "/lib/ld.so.1"
+#define GLIBC_DYNAMIC_LINKER "/lib/ld.so.1"
+
+#if TARGET_BIG_ENDIAN_DEFAULT == 0 /* LE */
+#define MUSL_DYNAMIC_LINKER_E "%{mbig-endian:;:el}"
+#else
+#define MUSL_DYNAMIC_LINKER_E "%{mlittle-endian:el}"
+#endif
+
+#undef MUSL_DYNAMIC_LINKER
+#define MUSL_DYNAMIC_LINKER "/lib/ld-musl-microblaze" MUSL_DYNAMIC_LINKER_E ".so.1"
+
 #undef  SUBTARGET_EXTRA_SPECS
 #define SUBTARGET_EXTRA_SPECS \
-  { "dynamic_linker", DYNAMIC_LINKER }
+  { "dynamic_linker", GNU_USER_DYNAMIC_LINKER }
 
 #undef LINK_SPEC
 #define LINK_SPEC "%{shared:-shared} \
diff --git a/gcc/config/mips/linux.h b/gcc/config/mips/linux.h
index 91df261..fb358e2 100644
--- a/gcc/config/mips/linux.h
+++ b/gcc/config/mips/linux.h
@@ -37,7 +37,13 @@ along with GCC; see the file COPYING3.  If not see
 #define UCLIBC_DYNAMIC_LINKERN32 \
   "%{mnan=2008:/lib32/ld-uClibc-mipsn8.so.0;:/lib32/ld-uClibc.so.0}"
 
+#undef MUSL_DYNAMIC_LINKER32
+#define MUSL_DYNAMIC_LINKER32 "/lib/ld-musl-mips%{EL:el}%{msoft-float:-sf}.so.1"
+#undef MUSL_DYNAMIC_LINKER64
+#define MUSL_DYNAMIC_LINKER64 "/lib/ld-musl-mips64%{EL:el}%{msoft-float:-sf}.so.1"
+#define MUSL_DYNAMIC_LINKERN32 "/lib/ld-musl-mipsn32%{EL:el}%{msoft-float:-sf}.so.1"
+
 #define BIONIC_DYNAMIC_LINKERN32 "/system/bin/linker32"
 #define GNU_USER_DYNAMIC_LINKERN32 \
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKERN32, UCLIBC_DYNAMIC_LINKERN32, \
-                         BIONIC_DYNAMIC_LINKERN32)
+                         BIONIC_DYNAMIC_LINKERN32, MUSL_DYNAMIC_LINKERN32)
diff --git a/gcc/config/rs6000/linux.h b/gcc/config/rs6000/linux.h
index fe0ebd6..a68ff69 100644
--- a/gcc/config/rs6000/linux.h
+++ b/gcc/config/rs6000/linux.h
@@ -30,10 +30,14 @@
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 /* Determine what functions are present at the runtime;
diff --git a/gcc/config/rs6000/linux64.h b/gcc/config/rs6000/linux64.h
index 0879e7e..6a7d435 100644
--- a/gcc/config/rs6000/linux64.h
+++ b/gcc/config/rs6000/linux64.h
@@ -299,10 +299,14 @@ extern int dot_symbols;
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 /* Determine what functions are present at the runtime;
@@ -365,17 +369,23 @@ extern int dot_symbols;
 #endif
 #define UCLIBC_DYNAMIC_LINKER32 "/lib/ld-uClibc.so.0"
 #define UCLIBC_DYNAMIC_LINKER64 "/lib/ld64-uClibc.so.0"
+#define MUSL_DYNAMIC_LINKER32 \
+  "/lib/ld-musl-powerpc" MUSL_DYNAMIC_LINKER_E "%{msoft-float:-sf}.so.1"
+#define MUSL_DYNAMIC_LINKER64 \
+  "/lib/ld-musl-powerpc64" MUSL_DYNAMIC_LINKER_E "%{msoft-float:-sf}.so.1"
 #if DEFAULT_LIBC == LIBC_UCLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{mglibc:" G ";:" U "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{mmusl:" M ";:" U "}}"
 #elif DEFAULT_LIBC == LIBC_GLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{muclibc:" U ";:" G "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{muclibc:" U ";:%{mmusl:" M ";:" G "}}"
+#elif DEFAULT_LIBC == LIBC_MUSL
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{muclibc:" U ";:" M "}}"
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif
 #define GNU_USER_DYNAMIC_LINKER32 \
-  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32)
+  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32, MUSL_DYNAMIC_LINKER32)
 #define GNU_USER_DYNAMIC_LINKER64 \
-  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64)
+  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64, MUSL_DYNAMIC_LINKER64)
 
 #undef  DEFAULT_ASM_ENDIAN
 #if (TARGET_DEFAULT & MASK_LITTLE_ENDIAN)
diff --git a/gcc/config/rs6000/secureplt.h b/gcc/config/rs6000/secureplt.h
index b463463..77edf2a 100644
--- a/gcc/config/rs6000/secureplt.h
+++ b/gcc/config/rs6000/secureplt.h
@@ -18,3 +18,4 @@ along with GCC; see the file COPYING3.  If not see
 <http://www.gnu.org/licenses/>.  */
 
 #define CC1_SECURE_PLT_DEFAULT_SPEC "-msecure-plt"
+#define LINK_SECURE_PLT_DEFAULT_SPEC "--secure-plt"
diff --git a/gcc/config/rs6000/sysv4.h b/gcc/config/rs6000/sysv4.h
index 9917c2f..68365de 100644
--- a/gcc/config/rs6000/sysv4.h
+++ b/gcc/config/rs6000/sysv4.h
@@ -537,6 +537,9 @@ ENDIAN_SELECT(" -mbig", " -mlittle", DEFAULT_ASM_ENDIAN)
 #ifndef CC1_SECURE_PLT_DEFAULT_SPEC
 #define CC1_SECURE_PLT_DEFAULT_SPEC ""
 #endif
+#ifndef LINK_SECURE_PLT_DEFAULT_SPEC
+#define LINK_SECURE_PLT_DEFAULT_SPEC ""
+#endif
 
 /* Pass -G xxx to the compiler.  */
 #undef CC1_SPEC
@@ -574,7 +577,8 @@
 %{R*} \
 %(link_shlib) \
 %{!T*: %(link_start) } \
-%(link_os)"
+%(link_os)" \
+"%{!mbss-plt: %{!msecure-plt: %(link_secure_plt_default)}}"
 
 /* Shared libraries are not default.  */
 #define LINK_SHLIB_SPEC "\
@@ -762,17 +766,23 @@ ENDIAN_SELECT(" -mbig", " -mlittle", DEFAULT_ASM_ENDIAN)
 
 #define LINK_START_LINUX_SPEC ""
 
+#define MUSL_DYNAMIC_LINKER_E ENDIAN_SELECT("","le","")
+
 #define GLIBC_DYNAMIC_LINKER "/lib/ld.so.1"
 #define UCLIBC_DYNAMIC_LINKER "/lib/ld-uClibc.so.0"
+#define MUSL_DYNAMIC_LINKER \
+  "/lib/ld-musl-powerpc" MUSL_DYNAMIC_LINKER_E "%{msoft-float:-sf}.so.1"
 #if DEFAULT_LIBC == LIBC_UCLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{mglibc:" G ";:" U "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{mmusl:" M ";:" U "}}"
+#elif DEFAULT_LIBC == LIBC_MUSL
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{muclibc:" U ";:" M "}}"
 #elif !defined (DEFAULT_LIBC) || DEFAULT_LIBC == LIBC_GLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{muclibc:" U ";:" G "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{muclibc:" U ";:%{mmusl:" M ";:" G "}}"
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif
 #define GNU_USER_DYNAMIC_LINKER \
-  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER)
+  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER, MUSL_DYNAMIC_LINKER)
 
 #define LINK_OS_LINUX_SPEC "-m elf32ppclinux %{!shared: %{!static: \
   %{rdynamic:-export-dynamic} \
@@ -895,6 +905,7 @@ ncrtn.o%s"
   { "link_os_openbsd",		LINK_OS_OPENBSD_SPEC },			\
   { "link_os_default",		LINK_OS_DEFAULT_SPEC },			\
   { "cc1_secure_plt_default",	CC1_SECURE_PLT_DEFAULT_SPEC },		\
+  { "link_secure_plt_default",	LINK_SECURE_PLT_DEFAULT_SPEC },		\
   { "cpp_os_ads",		CPP_OS_ADS_SPEC },			\
   { "cpp_os_yellowknife",	CPP_OS_YELLOWKNIFE_SPEC },		\
   { "cpp_os_mvme",		CPP_OS_MVME_SPEC },			\
@@ -949,3 +960,72 @@ ncrtn.o%s"
 /* This target uses the sysv4.opt file.  */
 #define TARGET_USES_SYSV4_OPT 1
 
+/* Include order changes for musl, same as in generic linux.h.  */
+#if DEFAULT_LIBC == LIBC_MUSL
+#define INCLUDE_DEFAULTS_MUSL_GPP			\
+    { GPLUSPLUS_INCLUDE_DIR, "G++", 1, 1,		\
+      GPLUSPLUS_INCLUDE_DIR_ADD_SYSROOT, 0 },		\
+    { GPLUSPLUS_TOOL_INCLUDE_DIR, "G++", 1, 1,		\
+      GPLUSPLUS_INCLUDE_DIR_ADD_SYSROOT, 1 },		\
+    { GPLUSPLUS_BACKWARD_INCLUDE_DIR, "G++", 1, 1,	\
+      GPLUSPLUS_INCLUDE_DIR_ADD_SYSROOT, 0 },
+
+#ifdef LOCAL_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_LOCAL			\
+    { LOCAL_INCLUDE_DIR, 0, 0, 1, 1, 2 },		\
+    { LOCAL_INCLUDE_DIR, 0, 0, 1, 1, 0 },
+#else
+#define INCLUDE_DEFAULTS_MUSL_LOCAL
+#endif
+
+#ifdef PREFIX_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_PREFIX			\
+    { PREFIX_INCLUDE_DIR, 0, 0, 1, 0, 0},
+#else
+#define INCLUDE_DEFAULTS_MUSL_PREFIX
+#endif
+
+#ifdef CROSS_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_CROSS			\
+    { CROSS_INCLUDE_DIR, "GCC", 0, 0, 0, 0},
+#else
+#define INCLUDE_DEFAULTS_MUSL_CROSS
+#endif
+
+#ifdef TOOL_INCLUDE_DIR
+#define INCLUDE_DEFAULTS_MUSL_TOOL			\
+    { TOOL_INCLUDE_DIR, "BINUTILS", 0, 1, 0, 0},
+#else
+#define INCLUDE_DEFAULTS_MUSL_TOOL
+#endif
+
+#ifdef NATIVE_SYSTEM_HEADER_DIR
+#define INCLUDE_DEFAULTS_MUSL_NATIVE			\
+    { NATIVE_SYSTEM_HEADER_DIR, 0, 0, 0, 1, 2 },	\
+    { NATIVE_SYSTEM_HEADER_DIR, 0, 0, 0, 1, 0 },
+#else
+#define INCLUDE_DEFAULTS_MUSL_NATIVE
+#endif
+
+#if defined (CROSS_DIRECTORY_STRUCTURE) && !defined (TARGET_SYSTEM_ROOT)
+# undef INCLUDE_DEFAULTS_MUSL_LOCAL
+# define INCLUDE_DEFAULTS_MUSL_LOCAL
+# undef INCLUDE_DEFAULTS_MUSL_NATIVE
+# define INCLUDE_DEFAULTS_MUSL_NATIVE
+#else
+# undef INCLUDE_DEFAULTS_MUSL_CROSS
+# define INCLUDE_DEFAULTS_MUSL_CROSS
+#endif
+
+#undef INCLUDE_DEFAULTS
+#define INCLUDE_DEFAULTS				\
+  {							\
+    INCLUDE_DEFAULTS_MUSL_GPP				\
+    INCLUDE_DEFAULTS_MUSL_PREFIX			\
+    INCLUDE_DEFAULTS_MUSL_CROSS				\
+    INCLUDE_DEFAULTS_MUSL_TOOL				\
+    INCLUDE_DEFAULTS_MUSL_NATIVE			\
+    { GCC_INCLUDE_DIR, "GCC", 0, 1, 0, 0 },		\
+    { 0, 0, 0, 0, 0, 0 }				\
+  }
+#endif
diff --git a/gcc/config/rs6000/sysv4le.h b/gcc/config/rs6000/sysv4le.h
index 7b1d6a1..064323c 100644
--- a/gcc/config/rs6000/sysv4le.h
+++ b/gcc/config/rs6000/sysv4le.h
@@ -35,3 +35,5 @@
 /* Little-endian PowerPC64 Linux uses the ELF v2 ABI by default.  */
 #define LINUX64_DEFAULT_ABI_ELFv2
 
+#undef MUSL_DYNAMIC_LINKER_E
+#define MUSL_DYNAMIC_LINKER_E ENDIAN_SELECT("","le","le")
diff --git a/gcc/config/sh/linux.h b/gcc/config/sh/linux.h
index 0f5d614..4c167c6 100644
--- a/gcc/config/sh/linux.h
+++ b/gcc/config/sh/linux.h
@@ -43,6 +43,29 @@ along with GCC; see the file COPYING3.  If not see
 
 #define TARGET_ASM_FILE_END file_end_indicate_exec_stack
 
+#if TARGET_ENDIAN_DEFAULT == MASK_LITTLE_ENDIAN
+#define MUSL_DYNAMIC_LINKER_E "%{mb:eb}"
+#else
+#define MUSL_DYNAMIC_LINKER_E "%{!ml:eb}"
+#endif
+
+#if TARGET_CPU_DEFAULT & ( MASK_HARD_SH2A_DOUBLE | MASK_SH4 )
+/* "-nofpu" if any nofpu option is specified */
+#define MUSL_DYNAMIC_LINKER_FP \
+  "%{m1|m2|m2a-nofpu|m3|m4-nofpu|m4-100-nofpu|m4-200-nofpu|m4-300-nofpu|" \
+  "m4-340|m4-400|m4-500|m4al|m5-32media-nofpu|m5-64media-nofpu|" \
+  "m5-compact-nofpu:-nofpu}"
+#else
+/* "-nofpu" if none of the hard fpu options are specified */
+#define MUSL_DYNAMIC_LINKER_FP \
+  "%{m2a|m4|m4-100|m4-200|m4-300|m4a|m5-32media|m5-64media|m5-compact:;:-nofpu}"
+#endif
+
+#undef MUSL_DYNAMIC_LINKER
+#define MUSL_DYNAMIC_LINKER \
+  "/lib/ld-musl-sh" MUSL_DYNAMIC_LINKER_E MUSL_DYNAMIC_LINKER_FP \
+  "%{mfdpic:-fdpic}.so.1"
+
 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.2"
 
 #undef SUBTARGET_LINK_EMUL_SUFFIX
diff --git a/gcc/configure b/gcc/configure
index 0037240..66aab9f 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -27742,6 +27742,9 @@ if test "${gcc_cv_libc_provides_ssp+set}" = set; then :
 else
   gcc_cv_libc_provides_ssp=no
     case "$target" in
+       *-*-musl*)
+	 # All versions of musl provide stack protector
+	 gcc_cv_libc_provides_ssp=yes;;
        *-*-linux* | *-*-kfreebsd*-gnu | *-*-knetbsd*-gnu)
       # glibc 2.4 and later provides __stack_chk_fail and
       # either __stack_chk_guard, or TLS access to stack guard canary.
@@ -27774,6 +27777,7 @@ fi
 	 # <http://gcc.gnu.org/ml/gcc/2008-10/msg00130.html>) and for now
 	 # simply assert that glibc does provide this, which is true for all
 	 # realistically usable GNU/Hurd configurations.
+	 # All supported versions of musl provide it as well
 	 gcc_cv_libc_provides_ssp=yes;;
        *-*-darwin* | *-*-freebsd*)
 	 ac_fn_c_check_func "$LINENO" "__stack_chk_fail" "ac_cv_func___stack_chk_fail"
@@ -27870,6 +27874,9 @@ case "$target" in
       gcc_cv_target_dl_iterate_phdr=no
     fi
     ;;
+  *-linux-musl*)
+    gcc_cv_target_dl_iterate_phdr=yes
+    ;;
 esac
 
 if test x$gcc_cv_target_dl_iterate_phdr = xyes; then
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 6f38ba1..b81960c 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -5229,6 +5229,9 @@ AC_CACHE_CHECK(__stack_chk_fail in target C library,
       gcc_cv_libc_provides_ssp,
       [gcc_cv_libc_provides_ssp=no
     case "$target" in
+       *-*-musl*)
+	 # All versions of musl provide stack protector
+	 gcc_cv_libc_provides_ssp=yes;;
        *-*-linux* | *-*-kfreebsd*-gnu | *-*-knetbsd*-gnu)
       # glibc 2.4 and later provides __stack_chk_fail and
       # either __stack_chk_guard, or TLS access to stack guard canary.
@@ -5255,6 +5258,7 @@ AC_CACHE_CHECK(__stack_chk_fail in target C library,
 	 # <http://gcc.gnu.org/ml/gcc/2008-10/msg00130.html>) and for now
 	 # simply assert that glibc does provide this, which is true for all
 	 # realistically usable GNU/Hurd configurations.
+	 # All supported versions of musl provide it as well
 	 gcc_cv_libc_provides_ssp=yes;;
        *-*-darwin* | *-*-freebsd*)
 	 AC_CHECK_FUNC(__stack_chk_fail,[gcc_cv_libc_provides_ssp=yes],
@@ -5328,6 +5332,9 @@ case "$target" in
       gcc_cv_target_dl_iterate_phdr=no
     fi
     ;;
+  *-linux-musl*)
+    gcc_cv_target_dl_iterate_phdr=yes
+    ;;
 esac
 GCC_TARGET_TEMPLATE([TARGET_DL_ITERATE_PHDR])
 if test x$gcc_cv_target_dl_iterate_phdr = xyes; then
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index f84a199..ee9765b 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -667,7 +667,7 @@ Objective-C and Objective-C++ Dialects}.
 -mcpu=@var{cpu}}
 
 @emph{GNU/Linux Options}
-@gccoptlist{-mglibc -muclibc -mbionic -mandroid @gol
+@gccoptlist{-mglibc -muclibc -mmusl -mbionic -mandroid @gol
 -tno-android-cc -tno-android-ld}
 
 @emph{H8/300 Options}
@@ -15324,13 +15324,19 @@ These @samp{-m} options are defined for GNU/Linux targets:
 @item -mglibc
 @opindex mglibc
 Use the GNU C library.  This is the default except
-on @samp{*-*-linux-*uclibc*} and @samp{*-*-linux-*android*} targets.
+on @samp{*-*-linux-*uclibc*}, @samp{*-*-linux-*musl*} and
+@samp{*-*-linux-*android*} targets.
 
 @item -muclibc
 @opindex muclibc
 Use uClibc C library.  This is the default on
 @samp{*-*-linux-*uclibc*} targets.
 
+@item -mmusl
+@opindex mmusl
+Use the musl C library.  This is the default on
+@samp{*-*-linux-*musl*} targets.
+
 @item -mbionic
 @opindex mbionic
 Use Bionic C library.  This is the default on
diff --git a/libcilkrts/runtime/os-unix.c b/libcilkrts/runtime/os-unix.c
index cb582dd..e43d7d5 100644
--- a/libcilkrts/runtime/os-unix.c
+++ b/libcilkrts/runtime/os-unix.c
@@ -51,6 +51,7 @@
 #if defined __linux__
 #   include <sys/sysinfo.h>
 #   include <sys/syscall.h>
+#   include <sched.h>
 #elif defined __APPLE__
 #   include <sys/sysctl.h>
     // Uses sysconf(_SC_NPROCESSORS_ONLN) in verbose output
@@ -400,28 +401,19 @@ COMMON_SYSDEP void __cilkrts_sleep(void)
 
 COMMON_SYSDEP void __cilkrts_yield(void)
 {
-#if __APPLE__ || __FreeBSD__ || __VXWORKS__
-    // On MacOS, call sched_yield to yield quantum.  I'm not sure why we
-    // don't do this on Linux also.
-    sched_yield();
-#elif defined(__DragonFly__)
-    // On DragonFly BSD, call sched_yield to yield quantum.
-    sched_yield();
-#elif defined(__MIC__)
+#if defined(__MIC__)
     // On MIC, pthread_yield() really trashes things.  Arch's measurements
     // showed that calling _mm_delay_32() (or doing nothing) was a better
     // option.  Delaying 1024 clock cycles is a reasonable compromise between
     // giving up the processor and latency starting up when work becomes
     // available
     _mm_delay_32(1024);
-#elif defined(__ANDROID__) || (defined(__sun__) && defined(__svr4__))
-    // On Android and Solaris, call sched_yield to yield quantum.  I'm not
-    // sure why we don't do this on Linux also.
-    sched_yield();
-#else
-    // On Linux, call pthread_yield (which in turn will call sched_yield)
-    // to yield quantum.
+#elif defined(__sun__) && !defined(__svr4__)
+    // On old SunOS call pthread_yield to yield a quantum.
     pthread_yield();
+#else
+    // On other platforms call sched_yield to yield a quantum.
+    sched_yield();
 #endif
 }
 
diff --git a/libgcc/unwind-dw2-fde-dip.c b/libgcc/unwind-dw2-fde-dip.c
index e1e566b..137dced 100644
--- a/libgcc/unwind-dw2-fde-dip.c
+++ b/libgcc/unwind-dw2-fde-dip.c
@@ -59,6 +59,12 @@
 
 #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
     && defined(TARGET_DL_ITERATE_PHDR) \
+    && defined(__linux__)
+# define USE_PT_GNU_EH_FRAME
+#endif
+
+#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
+    && defined(TARGET_DL_ITERATE_PHDR) \
     && (defined(__DragonFly__) || defined(__FreeBSD__))
 # define ElfW __ElfN
 # define USE_PT_GNU_EH_FRAME
diff --git a/libgfortran/acinclude.m4 b/libgfortran/acinclude.m4
index ba890f9..30b8b1a6 100644
--- a/libgfortran/acinclude.m4
+++ b/libgfortran/acinclude.m4
@@ -100,7 +100,7 @@ void foo (void);
 	      [Define to 1 if the target supports #pragma weak])
   fi
   case "$host" in
-    *-*-darwin* | *-*-hpux* | *-*-cygwin* | *-*-mingw* )
+    *-*-darwin* | *-*-hpux* | *-*-cygwin* | *-*-mingw* | *-*-musl* )
       AC_DEFINE(GTHREAD_USE_WEAK, 0,
 		[Define to 0 if the target shouldn't use #pragma weak])
       ;;
diff --git a/libgfortran/configure b/libgfortran/configure
index e1592f7..07542e1 100755
--- a/libgfortran/configure
+++ b/libgfortran/configure
@@ -26447,7 +26447,7 @@ $as_echo "#define SUPPORTS_WEAK 1" >>confdefs.h
 
   fi
   case "$host" in
-    *-*-darwin* | *-*-hpux* | *-*-cygwin* | *-*-mingw* )
+    *-*-darwin* | *-*-hpux* | *-*-cygwin* | *-*-mingw* | *-*-musl* )
 
 $as_echo "#define GTHREAD_USE_WEAK 0" >>confdefs.h
 
diff --git a/libitm/config/arm/hwcap.cc b/libitm/config/arm/hwcap.cc
index a1c2cfd..ea8f023 100644
--- a/libitm/config/arm/hwcap.cc
+++ b/libitm/config/arm/hwcap.cc
@@ -40,7 +40,7 @@ int GTM_hwcap HIDDEN = 0
 
 #ifdef __linux__
 #include <unistd.h>
-#include <sys/fcntl.h>
+#include <fcntl.h>
 #include <elf.h>
 
 static void __attribute__((constructor))
diff --git a/libitm/config/linux/x86/tls.h b/libitm/config/linux/x86/tls.h
index e731ab7..54ad8b6 100644
--- a/libitm/config/linux/x86/tls.h
+++ b/libitm/config/linux/x86/tls.h
@@ -25,16 +25,19 @@
 #ifndef LIBITM_X86_TLS_H
 #define LIBITM_X86_TLS_H 1
 
-#if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 10)
+#if defined(__GLIBC_PREREQ)
+#if __GLIBC_PREREQ(2, 10)
 /* Use slots in the TCB head rather than __thread lookups.
    GLIBC has reserved words 10 through 13 for TM.  */
 #define HAVE_ARCH_GTM_THREAD 1
 #define HAVE_ARCH_GTM_THREAD_DISP 1
 #endif
+#endif
 
 #include "config/generic/tls.h"
 
-#if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 10)
+#if defined(__GLIBC_PREREQ)
+#if __GLIBC_PREREQ(2, 10)
 namespace GTM HIDDEN {
 
 #ifdef __x86_64__
@@ -101,5 +104,6 @@ static inline void set_abi_disp(struct abi_dispatch *x)
 
 } // namespace GTM
 #endif /* >= GLIBC 2.10 */
+#endif
 
 #endif // LIBITM_X86_TLS_H
diff --git a/libstdc++-v3/config/os/generic/os_defines.h b/libstdc++-v3/config/os/generic/os_defines.h
index 45bf52a..103ec0e 100644
--- a/libstdc++-v3/config/os/generic/os_defines.h
+++ b/libstdc++-v3/config/os/generic/os_defines.h
@@ -33,4 +33,9 @@
 // System-specific #define, typedefs, corrections, etc, go here.  This
 // file will come before all others.
 
+// Disable the weak reference logic in gthr.h for os/generic because it
+// is broken on every platform unless there is implementation specific
+// workaround in gthr-posix.h and at link-time for static linking.
+#define _GLIBCXX_GTHREAD_USE_WEAK 0
+
 #endif
diff --git a/libstdc++-v3/configure.host b/libstdc++-v3/configure.host
index 640199c..106134e 100644
--- a/libstdc++-v3/configure.host
+++ b/libstdc++-v3/configure.host
@@ -273,6 +273,9 @@ case "${host_os}" in
   freebsd*)
     os_include_dir="os/bsd/freebsd"
     ;;
+  linux-musl*)
+    os_include_dir="os/generic"
+    ;;
   gnu* | linux* | kfreebsd*-gnu | knetbsd*-gnu)
     if [ "$uclibc" = "yes" ]; then
       os_include_dir="os/uclibc"