emscripten-core · aheejin · Jul 24, 2025 · Jul 21, 2025 · Jul 21, 2025 · Jul 22, 2025
diff --git a/ChangeLog.md b/ChangeLog.md
@@ -20,6 +20,8 @@ See docs/process.md for more on how version tagging works.
 
 4.0.12 (in development)
 -----------------------
+- libcxx, libcxxabi, libunwind, and compiler-rt were updated to LLVM 20.1.8.
+  (#24757)
 - The `fsblkcnt_t` and `fsfilcnt_t` types used by `statfs`/`statvfs` were
   changed from 32-bit to 64-bit. (#24769)
 - Support for `-sTEXT_DECODER=0` was removed, due to widespread support for

diff --git a/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_ioctl.inc b/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_ioctl.inc
@@ -338,17 +338,9 @@ static void ioctl_table_fill() {
   _(SOUND_PCM_WRITE_CHANNELS, WRITE, sizeof(int));
   _(SOUND_PCM_WRITE_FILTER, WRITE, sizeof(int));
   _(TCFLSH, NONE, 0);
-#if SANITIZER_GLIBC
-  _(TCGETA, WRITE, struct_termio_sz);
-#endif
   _(TCGETS, WRITE, struct_termios_sz);
   _(TCSBRK, NONE, 0);
   _(TCSBRKP, NONE, 0);
-#if SANITIZER_GLIBC
-  _(TCSETA, READ, struct_termio_sz);
-  _(TCSETAF, READ, struct_termio_sz);
-  _(TCSETAW, READ, struct_termio_sz);
-#endif
   _(TCSETS, READ, struct_termios_sz);
   _(TCSETSF, READ, struct_termios_sz);
   _(TCSETSW, READ, struct_termios_sz);

diff --git a/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -86,6 +86,10 @@
 #    include <sys/sysmacros.h>
 #  endif
 
+#  if SANITIZER_LINUX && defined(__powerpc64__)
+#    include <asm/ptrace.h>
+#  endif
+
 #  if SANITIZER_FREEBSD
 #    include <machine/atomic.h>
 #    include <sys/exec.h>

diff --git a/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp b/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
@@ -619,21 +619,22 @@ static void GetTls(uptr *addr, uptr *size) {
   *addr = tp - RoundUpTo(*size, align);
   *size = tp - *addr + ThreadDescriptorSize();
 #      else
-  if (SANITIZER_GLIBC)
-    *size += 1664;
-  else if (SANITIZER_FREEBSD)
-    *size += 128;  // RTLD_STATIC_TLS_EXTRA
-#        if defined(__mips__) || defined(__powerpc64__) || SANITIZER_RISCV64
+#        if SANITIZER_GLIBC
+  *size += 1664;
+#        elif SANITIZER_FREEBSD
+  *size += 128;  // RTLD_STATIC_TLS_EXTRA
+#          if defined(__mips__) || defined(__powerpc64__) || SANITIZER_RISCV64
   const uptr pre_tcb_size = TlsPreTcbSize();
   *addr -= pre_tcb_size;
   *size += pre_tcb_size;
-#        else
+#          else
   // arm and aarch64 reserve two words at TP, so this underestimates the range.
   // However, this is sufficient for the purpose of finding the pointers to
   // thread-specific data keys.
   const uptr tcb_size = ThreadDescriptorSize();
   *addr -= tcb_size;
   *size += tcb_size;
+#          endif
 #        endif
 #      endif
 #    elif SANITIZER_NETBSD

diff --git a/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.cpp b/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.cpp
@@ -96,7 +96,7 @@
 # include <sys/ptrace.h>
 #    if defined(__mips64) || defined(__aarch64__) || defined(__arm__) ||       \
         defined(__hexagon__) || defined(__loongarch__) || SANITIZER_RISCV64 || \
-        defined(__sparc__)
+        defined(__sparc__) || defined(__powerpc64__)
 #      include <asm/ptrace.h>
 #      ifdef __arm__
 typedef struct user_fpregs elf_fpregset_t;
@@ -488,9 +488,6 @@ unsigned struct_ElfW_Phdr_sz = sizeof(Elf_Phdr);
   unsigned struct_input_id_sz = sizeof(struct input_id);
   unsigned struct_mtpos_sz = sizeof(struct mtpos);
   unsigned struct_rtentry_sz = sizeof(struct rtentry);
-#if SANITIZER_GLIBC || SANITIZER_ANDROID
-  unsigned struct_termio_sz = sizeof(struct termio);
-#endif
   unsigned struct_vt_consize_sz = sizeof(struct vt_consize);
   unsigned struct_vt_sizes_sz = sizeof(struct vt_sizes);
   unsigned struct_vt_stat_sz = sizeof(struct vt_stat);

diff --git a/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h b/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_posix.h
@@ -1059,7 +1059,6 @@ extern unsigned struct_hd_geometry_sz;
 extern unsigned struct_input_absinfo_sz;
 extern unsigned struct_input_id_sz;
 extern unsigned struct_mtpos_sz;
-extern unsigned struct_termio_sz;
 extern unsigned struct_vt_consize_sz;
 extern unsigned struct_vt_sizes_sz;
 extern unsigned struct_vt_stat_sz;

diff --git a/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp b/system/lib/compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp
@@ -31,7 +31,8 @@
 #include <sys/types.h> // for pid_t
 #include <sys/uio.h> // for iovec
 #include <elf.h> // for NT_PRSTATUS
-#if (defined(__aarch64__) || SANITIZER_RISCV64 || SANITIZER_LOONGARCH64) && \
+#if (defined(__aarch64__) || defined(__powerpc64__) || \
+     SANITIZER_RISCV64 || SANITIZER_LOONGARCH64) &&    \
      !SANITIZER_ANDROID
 // GLIBC 2.20+ sys/user does not include asm/ptrace.h
 # include <asm/ptrace.h>

diff --git a/system/lib/compiler-rt/readme.txt b/system/lib/compiler-rt/readme.txt
@@ -1,7 +1,7 @@
 llvm's compiler-rt
 ------------------
 
-These files are from the llvm-project based on release 20.1.4.
+These files are from the llvm-project based on release 20.1.8.
 
 We maintain a local fork of llvm-project that contains any emscripten
 specific patches:
@@ -20,4 +20,4 @@ Modifications
 
 For a list of changes from upstream see the compiler-rt files that are part of:
 
-https://github.com/llvm/llvm-project/compare/llvmorg-20.1.4...emscripten-core:emscripten-libs-20
+https://github.com/llvm/llvm-project/compare/llvmorg-20.1.8...emscripten-core:emscripten-libs-20
diff --git a/system/lib/libcxx/include/__configuration/availability.h b/system/lib/libcxx/include/__configuration/availability.h
@@ -69,7 +69,13 @@
 
 // Availability markup is disabled when building the library, or when a non-Clang
 // compiler is used because only Clang supports the necessary attributes.
-#if defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCXXABI_BUILDING_LIBRARY) || !defined(_LIBCPP_COMPILER_CLANG_BASED)
+//
+// We also allow users to force-disable availability markup via the `_LIBCPP_DISABLE_AVAILABILITY`
+// macro because that is the only way to work around a Clang bug related to availability
+// attributes: https://github.com/llvm/llvm-project/issues/134151.
+// Once that bug has been fixed, we should remove the macro.
+#if defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCXXABI_BUILDING_LIBRARY) ||                                       \
+    !defined(_LIBCPP_COMPILER_CLANG_BASED) || defined(_LIBCPP_DISABLE_AVAILABILITY)
 #  undef _LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS
 #  define _LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS 0
 #endif

diff --git a/system/lib/libcxx/include/__flat_map/flat_map.h b/system/lib/libcxx/include/__flat_map/flat_map.h
@@ -113,7 +113,7 @@ class flat_map {
 
   class value_compare {
   private:
-    key_compare __comp_;
+    _LIBCPP_NO_UNIQUE_ADDRESS key_compare __comp_;
     _LIBCPP_HIDE_FROM_ABI value_compare(key_compare __c) : __comp_(__c) {}
     friend flat_map;
 

diff --git a/system/lib/libcxx/include/__flat_map/flat_multimap.h b/system/lib/libcxx/include/__flat_map/flat_multimap.h
@@ -115,7 +115,7 @@ class flat_multimap {
 
   class value_compare {
   private:
-    key_compare __comp_;
+    _LIBCPP_NO_UNIQUE_ADDRESS key_compare __comp_;
     _LIBCPP_HIDE_FROM_ABI value_compare(key_compare __c) : __comp_(__c) {}
     friend flat_multimap;
 

diff --git a/system/lib/libcxx/readme.txt b/system/lib/libcxx/readme.txt
@@ -1,7 +1,7 @@
 llvm's libcxx
 -------------
 
-These files are from the llvm-project based on release 20.1.4.
+These files are from the llvm-project based on release 20.1.8.
 
 We maintain a local fork of llvm-project that contains any emscripten
 specific patches:
@@ -20,4 +20,4 @@ Modifications
 
 For a list of changes from upstream see the libcxx files that are part of:
 
-https://github.com/llvm/llvm-project/compare/llvmorg-20.1.4...emscripten-core:emscripten-libs-20
+https://github.com/llvm/llvm-project/compare/llvmorg-20.1.8...emscripten-core:emscripten-libs-20
diff --git a/system/lib/libcxxabi/readme.txt b/system/lib/libcxxabi/readme.txt
@@ -1,7 +1,7 @@
 llvm's libcxxabi
 ----------------
 
-These files are from the llvm-project based on release 20.1.4.
+These files are from the llvm-project based on release 20.1.8.
 
 We maintain a local fork of llvm-project that contains any emscripten
 specific patches:
@@ -20,4 +20,4 @@ Modifications
 
 For a list of changes from upstream see the libcxxabi files that are part of:
 
-https://github.com/llvm/llvm-project/compare/llvmorg-20.1.4...emscripten-core:emscripten-libs-20
+https://github.com/llvm/llvm-project/compare/llvmorg-20.1.8...emscripten-core:emscripten-libs-20
diff --git a/system/lib/libunwind/readme.txt b/system/lib/libunwind/readme.txt
@@ -1,7 +1,7 @@
 llvm's libunwind
 ----------------
 
-These files are from the llvm-project based on release 20.1.4.
+These files are from the llvm-project based on release 20.1.8.
 
 We maintain a local fork of llvm-project that contains any emscripten
 specific patches:
@@ -20,4 +20,4 @@ Modifications
 
 For a list of changes from upstream see the libunwind files that are part of:
 
-https://github.com/llvm/llvm-project/compare/llvmorg-20.1.4...emscripten-core:emscripten-libs-20
+https://github.com/llvm/llvm-project/compare/llvmorg-20.1.8...emscripten-core:emscripten-libs-20