Add WASI platform support.

This includes the following significant changes:
  * Patching ezsat and minisat to disable resource limiting code
    on WASM/WASI, since the POSIX functions they use are unavailable.
  * Adding a new definition, YOSYS_DISABLE_SPAWN, present if platform
    does not support spawning subprocesses (i.e. Emscripten or WASI).
    This definition hides the definition of `run_command()`.
  * Adding a new Makefile flag, DISABLE_SPAWN, present in the same
    condition. This flag disables all passes that require spawning
    subprocesses for their function.

4 files changed, 40 insertions, 10 deletions

diff --git a/kernel/driver.cc b/kernel/driver.cc
index 5f0959776..57ed7b8b4 100644
--- a/kernel/driver.cc
+++ b/kernel/driver.cc
@@ -155,6 +155,19 @@ int yosys_history_offset = 0;
 std::string yosys_history_file;
 #endif
 
+#if defined(__wasm)
+extern "C" {
+	// FIXME: WASI does not currently support exceptions.
+	void* __cxa_allocate_exception(size_t thrown_size) throw() {
+		return malloc(thrown_size);
+	}
+	bool __cxa_uncaught_exception() throw();
+	void __cxa_throw(void* thrown_exception, struct std::type_info * tinfo, void (*dest)(void*)) {
+		std::terminate();
+	}
+}
+#endif
+
 void yosys_atexit()
 {
 #if defined(YOSYS_ENABLE_READLINE) || defined(YOSYS_ENABLE_EDITLINE)
@@ -587,9 +600,11 @@ int main(int argc, char **argv)
 			ru_buffer.ru_utime.tv_usec += ru_buffer_children.ru_utime.tv_usec;
 			ru_buffer.ru_stime.tv_sec += ru_buffer_children.ru_stime.tv_sec;
 			ru_buffer.ru_stime.tv_usec += ru_buffer_children.ru_stime.tv_usec;
+#if defined(__linux__) || defined(__FreeBSD__)
 			ru_buffer.ru_maxrss = std::max(ru_buffer.ru_maxrss, ru_buffer_children.ru_maxrss);
+#endif
 		}
-#  if defined(__linux__) || defined(__FreeBSD__)
+#if defined(__linux__) || defined(__FreeBSD__)
 		meminfo = stringf(", MEM: %.2f MB peak",
 				ru_buffer.ru_maxrss / 1024.0);
 #endif
diff --git a/kernel/register.cc b/kernel/register.cc
index 925d0d776..02974e534 100644
--- a/kernel/register.cc
+++ b/kernel/register.cc
@@ -238,6 +238,7 @@ void Pass::call(RTLIL::Design *design, std::string command)
 		return;
 
 	if (tok[0] == '!') {
+#if !defined(YOSYS_DISABLE_SPAWN)
 		cmd_buf = command.substr(command.find('!') + 1);
 		while (!cmd_buf.empty() && (cmd_buf.back() == ' ' || cmd_buf.back() == '\t' ||
 				cmd_buf.back() == '\r' || cmd_buf.back() == '\n'))
@@ -247,6 +248,9 @@ void Pass::call(RTLIL::Design *design, std::string command)
 		if (retCode != 0)
 			log_cmd_error("Shell command returned error code %d.\n", retCode);
 		return;
+#else
+		log_cmd_error("Shell is not available.\n");
+#endif
 	}
 
 	while (!tok.empty()) {
diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index 01131601f..2ec3dca0c 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -45,8 +45,10 @@
 #  include <unistd.h>
 #  include <dirent.h>
 #  include <sys/types.h>
-#  include <sys/wait.h>
 #  include <sys/stat.h>
+#  if !defined(YOSYS_DISABLE_SPAWN)
+#    include <sys/wait.h>
+#  endif
 #endif
 
 #if !defined(_WIN32) && defined(YOSYS_ENABLE_GLOB)
@@ -336,16 +338,13 @@ bool patmatch(const char *pattern, const char *string)
 	return false;
 }
 
+#if !defined(YOSYS_DISABLE_SPAWN)
 int run_command(const std::string &command, std::function<void(const std::string&)> process_line)
 {
 	if (!process_line)
 		return system(command.c_str());
 
-#ifdef EMSCRIPTEN
-	FILE *f = nullptr;
-#else
 	FILE *f = popen(command.c_str(), "r");
-#endif
 	if (f == nullptr)
 		return -1;
 
@@ -368,10 +367,16 @@ int run_command(const std::string &command, std::function<void(const std::string
 	return WEXITSTATUS(ret);
 #endif
 }
+#endif
 
 std::string make_temp_file(std::string template_str)
 {
-#ifdef _WIN32
+#if defined(__wasm)
+	size_t pos = template_str.rfind("XXXXXX");
+	log_assert(pos != std::string::npos);
+	static size_t index = 0;
+	template_str.replace(pos, 6, stringf("%06zu", index++));
+#elif defined(_WIN32)
 	if (template_str.rfind("/tmp/", 0) == 0) {
 #  ifdef __MINGW32__
 		char longpath[MAX_PATH + 1];
@@ -420,10 +425,14 @@ std::string make_temp_file(std::string template_str)
 
 std::string make_temp_dir(std::string template_str)
 {
-#ifdef _WIN32
+#if defined(_WIN32)
 	template_str = make_temp_file(template_str);
 	mkdir(template_str.c_str());
 	return template_str;
+#elif defined(__wasm)
+	template_str = make_temp_file(template_str);
+	mkdir(template_str.c_str(), 0777);
+	return template_str;
 #else
 #  ifndef NDEBUG
 	size_t pos = template_str.rfind("XXXXXX");
@@ -806,7 +815,7 @@ std::string proc_self_dirname()
 		path += char(shortpath[i]);
 	return path;
 }
-#elif defined(EMSCRIPTEN)
+#elif defined(EMSCRIPTEN) || defined(__wasm)
 std::string proc_self_dirname()
 {
 	return "/";
@@ -815,7 +824,7 @@ std::string proc_self_dirname()
 	#error "Don't know how to determine process executable base path!"
 #endif
 
-#ifdef EMSCRIPTEN
+#if defined(EMSCRIPTEN) || defined(__wasm)
 std::string proc_share_dirname()
 {
 	return "/share/";
diff --git a/kernel/yosys.h b/kernel/yosys.h
index ed48eec09..af1e376b1 100644
--- a/kernel/yosys.h
+++ b/kernel/yosys.h
@@ -264,7 +264,9 @@ int readsome(std::istream &f, char *s, int n);
 std::string next_token(std::string &text, const char *sep = " \t\r\n", bool long_strings = false);
 std::vector<std::string> split_tokens(const std::string &text, const char *sep = " \t\r\n");
 bool patmatch(const char *pattern, const char *string);
+#if !defined(YOSYS_DISABLE_SPAWN)
 int run_command(const std::string &command, std::function<void(const std::string&)> process_line = std::function<void(const std::string&)>());
+#endif
 std::string make_temp_file(std::string template_str = "/tmp/yosys_XXXXXX");
 std::string make_temp_dir(std::string template_str = "/tmp/yosys_XXXXXX");
 bool check_file_exists(std::string filename, bool is_exec = false);