Introduce cosmocc flags -mdbg -mtiny -moptlinux

The cosmocc.zip toolchain will now include four builds of the libcosmo.a
runtime libraries. You can pass the -mdbg flag if you want to debug your
cosmopolitan runtime. You can pass the -moptlinux flag if you don't want
windows code lurking in your binary. See tool/cosmocc/README.md for more
details on how these flags may be used and their important implications.

libc/calls/tcflush.c

@@ -17,7 +17,6 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/internal.h"
-#include "libc/intrin/fds.h"
 #include "libc/calls/syscall-nt.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/calls/syscall_support-nt.internal.h"
@@ -25,6 +24,7 @@
 #include "libc/dce.h"
 #include "libc/errno.h"
 #include "libc/fmt/itoa.h"
+#include "libc/intrin/fds.h"
 #include "libc/intrin/strace.h"
 #include "libc/mem/alloca.h"
 #include "libc/nt/comms.h"
@@ -52,6 +52,7 @@ static const char *DescribeFlush(char buf[12], int action) {
 }
 
 static dontinline textwindows int sys_tcflush_nt(int fd, int queue) {
+#ifdef __x86_64__
   if (!sys_isatty(fd)) {
     return -1;  // ebadf, enotty
   }
@@ -59,6 +60,9 @@ static dontinline textwindows int sys_tcflush_nt(int fd, int queue) {
     return 0;  // windows console output is never buffered
   }
   return FlushConsoleInputBytes();
+#else
+  return enosys();
+#endif
 }
 
 /**

libc/dlopen/dlopen.c

@@ -557,7 +557,9 @@ static void *foreign_thunk_nt(void *func) {
   // movabs $tramp,%r10
   code[14] = 0x49;
   code[15] = 0xba;
+#ifdef __x86_64__
   WRITE64LE(code + 16, (uintptr_t)__sysv2nt14);
+#endif
   // jmp *%r10
   code[24] = 0x41;
   code[25] = 0xff;

libc/intrin/cp.c

@@ -18,6 +18,9 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/blockcancel.internal.h"
 #include "libc/calls/cp.internal.h"
+#include "libc/intrin/describebacktrace.h"
+#include "libc/intrin/kprintf.h"
+#include "libc/nexgen32e/stackframe.h"
 #include "libc/runtime/internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/thread/posixthread.internal.h"
@@ -46,7 +49,11 @@ void end_cancelation_point(int state) {
   }
 }
 
-void report_cancelation_point(void) {
+void report_cancelation_point(int sysv_ordinal, int xnu_ordinal) {
+  char bt[160];
+  struct StackFrame *bp = __builtin_frame_address(0);
+  kprintf("error: report_cancelation_point(%#x, %#x) %s\n", sysv_ordinal,
+          xnu_ordinal, (DescribeBacktrace)(bt, bp));
   __builtin_trap();
 }
 

libc/log/oncrash_arm64.c

@@ -266,7 +266,8 @@ static relegated void __oncrash_impl(int sig, siginfo_t *si, ucontext_t *ctx) {
         if (j)
           Append(b, " ");
         Append(b, "%s%016lx%s x%d%s", ColorRegister(r),
-               ctx->uc_mcontext.regs[r], reset, r, r == 8 || r == 9 ? " " : "");
+               ((uint64_t *)ctx->uc_mcontext.regs)[r], reset, r,
+               r == 8 || r == 9 ? " " : "");
       }
       Append(b, "\n");
     }

libc/nexgen32e/nt2sysv.h

@@ -7,6 +7,10 @@
  *
  * This macro should be used when specifying callbacks in the WIN32 API.
  */
+#ifdef __x86_64__
 #define NT2SYSV(FUNCTION) TRAMPOLINE(FUNCTION, __nt2sysv)
+#else
+#define NT2SYSV(FUNCTION) FUNCTION
+#endif
 
 #endif /* COSMOPOLITAN_LIBC_NEXGEN32E_NT2SYSV_H_ */

libc/proc/posix_spawn.c

@@ -22,7 +22,6 @@
 #include "libc/calls/calls.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/state.internal.h"
-#include "libc/intrin/fds.h"
 #include "libc/calls/struct/rlimit.h"
 #include "libc/calls/struct/rlimit.internal.h"
 #include "libc/calls/struct/rusage.internal.h"
@@ -39,6 +38,7 @@
 #include "libc/intrin/bsf.h"
 #include "libc/intrin/describeflags.h"
 #include "libc/intrin/dll.h"
+#include "libc/intrin/fds.h"
 #include "libc/intrin/strace.h"
 #include "libc/intrin/weaken.h"
 #include "libc/mem/alloca.h"
@@ -95,6 +95,10 @@
 
 #define CLOSER_CONTAINER(e) DLL_CONTAINER(struct Closer, elem, e)
 
+static atomic_bool has_vfork;  // i.e. not qemu/wsl/xnu/openbsd
+
+#ifdef __x86_64__
+
 struct Closer {
   int64_t handle;
   struct Dll elem;
@@ -106,8 +110,6 @@ struct SpawnFds {
   struct Dll *closers;
 };
 
-static atomic_bool has_vfork;  // i.e. not qemu/wsl/xnu/openbsd
-
 static textwindows int64_t spawnfds_handle(struct SpawnFds *fds, int fd) {
   if (__is_cloexec(fds->p + fd))
     return -1;
@@ -429,6 +431,8 @@ static textwindows dontinline errno_t posix_spawn_nt(
   return err;
 }
 
+#endif  // __x86_64__
+
 /**
  * Spawns process, the POSIX way, e.g.
  *
@@ -482,8 +486,10 @@ errno_t posix_spawn(int *pid, const char *path,
                     const posix_spawn_file_actions_t *file_actions,
                     const posix_spawnattr_t *attrp, char *const argv[],
                     char *const envp[]) {
+#ifdef __x86_64__
   if (IsWindows())
     return posix_spawn_nt(pid, path, file_actions, attrp, argv, envp);
+#endif
   int pfds[2];
   bool use_pipe;
   volatile int status = 0;

libc/runtime/clone.c

@@ -589,7 +589,9 @@ int sys_clone_linux(int flags,         // rdi
 
 static int LinuxThreadEntry(void *arg, int tid) {
   struct LinuxCloneArgs *wt = arg;
+#if defined(__x86_64__)
   sys_set_tls(ARCH_SET_GS, wt->tls);
+#endif
   return wt->func(wt->arg, tid);
 }
 

libc/runtime/stack.h

@@ -6,7 +6,11 @@
 /**
  * Returns preferred size and alignment of thread stack.
  */
+#ifndef MODE_DBG
 #define GetStackSize() 81920
+#else
+#define GetStackSize() 163840
+#endif
 
 /**
  * Returns preferred stack guard size.

libc/sysv/BUILD.mk

@@ -88,7 +88,7 @@ o/$(MODE)/libc/sysv/sysret.o: private			\
 
 ifeq ($(ARCH),aarch64)
 o/$(MODE)/libc/sysv/sysv.o: private			\
-		CFLAGS +=				\
+		OVERRIDE_CFLAGS +=			\
 			-ffixed-x0			\
 			-ffixed-x1			\
 			-ffixed-x2			\

libc/sysv/sysv.c

@@ -37,7 +37,7 @@ register long freebsd_ordinal asm("x9");
 register long xnu_ordinal asm("x16");
 register long cosmo_tls_register asm("x28");
 
-void report_cancelation_point(void);
+void report_cancelation_point(int, int);
 
 dontinline long systemfive_cancel(void) {
   return _weaken(_pthread_cancel_ack)();
@@ -58,9 +58,9 @@ dontinline long systemfive_cancellable(void) {
       return systemfive_cancel();
     }
 #if IsModeDbg()
-    if (!(pth->pt_flags & PT_INCANCEL)) {
+    if (!(pth->pt_flags & PT_INCANCEL) && !(pth->pt_flags & PT_NOCANCEL)) {
       if (_weaken(report_cancelation_point)) {
-        _weaken(report_cancelation_point)();
+        _weaken(report_cancelation_point)(sysv_ordinal, xnu_ordinal);
       }
       __builtin_trap();
     }

libc/tinymath/powl.c

@@ -930,7 +930,7 @@ powl(long double x, long double y)
   z = one - (r - z);
   o.value = z;
   j = o.parts32.mswhi;
-  j += (n << 16);
+  j += (int32_t)((uint32_t)n << 16); // TODO(jart): why ubsan
   if ((j >> 16) <= 0)
     z = scalbnl (z, n);	/* subnormal output */
   else