Merge pull request #10143 from nuald/single-threaded-cpp1

Normalized C++ compilation options for single-threaded targets

2 files changed, 31 insertions, 6 deletions

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 9126289804..5e4ab0ec12 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -1180,6 +1180,15 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
         if (must_single_thread and !single_threaded) {
             return error.TargetRequiresSingleThreaded;
         }
+        if (!single_threaded and options.link_libcpp) {
+            if (options.target.cpu.arch.isARM()) {
+                log.warn(
+                    \\libc++ does not work on multi-threaded ARM yet.
+                    \\For more details: https://github.com/ziglang/zig/issues/6573
+                , .{});
+                return error.TargetRequiresSingleThreaded;
+            }
+        }
 
         const llvm_cpu_features: ?[*:0]const u8 = if (build_options.have_llvm and use_llvm) blk: {
             var buf = std.ArrayList(u8).init(arena);
@@ -3803,6 +3812,10 @@ pub fn addCCArgs(
         try argv.append("-D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS");
         try argv.append("-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS");
         try argv.append("-D_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS");
+
+        if (comp.bin_file.options.single_threaded) {
+            try argv.append("-D_LIBCPP_HAS_NO_THREADS");
+        }
     }
 
     if (comp.bin_file.options.link_libunwind) {
diff --git a/src/libcxx.zig b/src/libcxx.zig
index b2974e24c9..a5ab242339 100644
--- a/src/libcxx.zig
+++ b/src/libcxx.zig
@@ -128,6 +128,12 @@ pub fn buildLibCXX(comp: *Compilation) !void {
             continue;
         if (std.mem.startsWith(u8, cxx_src, "src/support/ibm/") and target.os.tag != .zos)
             continue;
+        if (comp.bin_file.options.single_threaded) {
+            if (std.mem.startsWith(u8, cxx_src, "src/support/win32/thread_win32.cpp")) {
+                continue;
+            }
+            try cflags.append("-D_LIBCPP_HAS_NO_THREADS");
+        }
 
         try cflags.append("-DNDEBUG");
         try cflags.append("-D_LIBCPP_BUILDING_LIBRARY");
@@ -145,8 +151,7 @@ pub fn buildLibCXX(comp: *Compilation) !void {
         }
 
         if (target.os.tag == .wasi) {
-            // WASI doesn't support thread and exception yet.
-            try cflags.append("-D_LIBCPP_HAS_NO_THREADS");
+            // WASI doesn't support exceptions yet.
             try cflags.append("-fno-exceptions");
         }
 
@@ -264,13 +269,20 @@ pub fn buildLibCXXABI(comp: *Compilation) !void {
         var cflags = std.ArrayList([]const u8).init(arena);
 
         if (target.os.tag == .wasi) {
-            // WASI doesn't support thread and exception yet.
-            if (std.mem.startsWith(u8, cxxabi_src, "src/cxa_thread_atexit.cpp") or
-                std.mem.startsWith(u8, cxxabi_src, "src/cxa_exception.cpp") or
+            // WASI doesn't support exceptions yet.
+            if (std.mem.startsWith(u8, cxxabi_src, "src/cxa_exception.cpp") or
                 std.mem.startsWith(u8, cxxabi_src, "src/cxa_personality.cpp"))
                 continue;
-            try cflags.append("-D_LIBCXXABI_HAS_NO_THREADS");
             try cflags.append("-fno-exceptions");
+        }
+
+        // WASM targets are single threaded.
+        if (comp.bin_file.options.single_threaded) {
+            if (std.mem.startsWith(u8, cxxabi_src, "src/cxa_thread_atexit.cpp")) {
+                continue;
+            }
+            try cflags.append("-D_LIBCXXABI_HAS_NO_THREADS");
+            try cflags.append("-D_LIBCPP_HAS_NO_THREADS");
         } else {
             try cflags.append("-DHAVE___CXA_THREAD_ATEXIT_IMPL");
         }