vulkan: fail the build when a shader fails to compile (#24450)

* vulkan-shaders-gen: fail the build when a shader fails to compile

vulkan-shaders-gen did not detect shader-compile subprocess failures, so a
broken libggml-vulkan could be produced while the build reported success and
the breakage only surfaced at run time. execute_command() discarded the child
exit code (POSIX waitpid passed nullptr for status; the Windows branch never
called GetExitCodeProcess) and string_to_spv decided success only from whether
stderr was empty, so a non-zero exit with empty stderr, or a subprocess that
failed to launch, was treated as success.

Return the child exit code from execute_command() (WEXITSTATUS on POSIX,
GetExitCodeProcess on Windows), treat a non-zero exit or non-empty stderr or a
launch exception as a failure, and record it in an atomic flag. main() checks
the flag after process_shaders() and returns EXIT_FAILURE before writing the
output files, so the build stops instead of emitting a broken backend.

Fixes #24393

Signed-off-by: liminfei-amd <91481003+liminfei-amd@users.noreply.github.com>

* vulkan-shaders-gen: simplify compile_failed access and drop unreachable return

Address review feedback on #24450:
- Access the std::atomic<bool> compile_failed directly (= / implicit bool)
  instead of .store()/.load(); the flag stays atomic because the worker
  threads in process_shaders() set it concurrently.
- Remove the unreachable trailing return -1 in execute_command(): on POSIX the
  child _exit()s after execvp and the parent returns (fork()<0 throws); on
  Windows the block returns the exit code.

Signed-off-by: liminfei-amd <91481003+liminfei-amd@users.noreply.github.com>

---------

Signed-off-by: liminfei-amd <91481003+liminfei-amd@users.noreply.github.com>

ggml/src/ggml-vulkan/vulkan-shaders/vulkan-shaders-gen.cpp

@@ -11,6 +11,7 @@
 #include <future>
 #include <queue>
 #include <condition_variable>
+#include <atomic>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
@@ -34,6 +35,9 @@
 
 std::mutex lock;
 std::vector<std::pair<std::string, std::string>> shader_fnames;
+// Set when any shader subprocess fails (non-zero exit / stderr / launch failure) so the
+// build is stopped instead of silently producing a broken libggml-vulkan. (issue #24393)
+static std::atomic<bool> compile_failed{false};
 std::locale c_locale("C");
 
 std::string GLSLC = "glslc";
@@ -78,7 +82,7 @@ enum MatMulIdType {
 
 namespace {
 
-void execute_command(std::vector<std::string>& command, std::string& stdout_str, std::string& stderr_str) {
+int execute_command(std::vector<std::string>& command, std::string& stdout_str, std::string& stderr_str) {
 #ifdef _WIN32
     HANDLE stdout_read, stdout_write;
     HANDLE stderr_read, stderr_write;
@@ -127,8 +131,11 @@ void execute_command(std::vector<std::string>& command, std::string& stdout_str,
     CloseHandle(stdout_read);
     CloseHandle(stderr_read);
     WaitForSingleObject(pi.hProcess, INFINITE);
+    DWORD exit_code = 1;
+    GetExitCodeProcess(pi.hProcess, &exit_code);
     CloseHandle(pi.hProcess);
     CloseHandle(pi.hThread);
+    return (int)exit_code;
 #else
     int stdout_pipe[2];
     int stderr_pipe[2];
@@ -175,7 +182,9 @@ void execute_command(std::vector<std::string>& command, std::string& stdout_str,
 
         close(stdout_pipe[0]);
         close(stderr_pipe[0]);
-        waitpid(pid, nullptr, 0);
+        int status = 0;
+        waitpid(pid, &status, 0);
+        return WIFEXITED(status) ? WEXITSTATUS(status) : -1;
     }
 #endif
 }
@@ -372,13 +381,14 @@ void string_to_spv_func(std::string name, std::string in_path, std::string out_p
         // }
         // std::cout << std::endl;
 
-        execute_command(cmd, stdout_str, stderr_str);
-        if (!stderr_str.empty()) {
-            std::cerr << "cannot compile " << name << "\n\n";
+        int exit_code = execute_command(cmd, stdout_str, stderr_str);
+        if (exit_code != 0 || !stderr_str.empty()) {
+            std::cerr << "cannot compile " << name << " (exit code " << exit_code << ")\n\n";
             for (const auto& part : cmd) {
                 std::cerr << part << " ";
             }
             std::cerr << "\n\n" << stderr_str << std::endl;
+            compile_failed = true;
             return;
         }
 
@@ -398,6 +408,7 @@ void string_to_spv_func(std::string name, std::string in_path, std::string out_p
         shader_fnames.push_back(std::make_pair(name, out_path));
     } catch (const std::exception& e) {
         std::cerr << "Error executing command for " << name << ": " << e.what() << std::endl;
+        compile_failed = true;
     }
 }
 
@@ -1271,6 +1282,11 @@ int main(int argc, char** argv) {
 
     process_shaders();
 
+    if (compile_failed) {
+        std::cerr << "vulkan-shaders-gen: one or more shaders failed to compile" << std::endl;
+        return EXIT_FAILURE;
+    }
+
     write_output_files();
 
     return EXIT_SUCCESS;