Build and run all tests as shared libraries (#780)

This PR is derived from #779 to build and run dynamically-linked tests
in wasi-libc to help exercise shared-library-related support. This
requires the fix from #779, for example, to get tests passing. This
takes a different approach to testing, however, to build and run all
tests as dynamically linked instead of only some particular tests. This
avoids the need for a one-off test and additionally helps reuse all
existing infrastructure for tests. This expands the test coverage more
and documents a few cases where dynamic libraries don't work (long-float
intrinsics and setjmp)

---------

Co-authored-by: Joel Dice <joel.dice@akamai.com>

Author: alexcrichton

libc-bottom-half/CMakeLists.txt

@@ -179,6 +179,13 @@ if (WASI STREQUAL "p3")
   )
 endif()
 
+# Don't export symbols of generated code in shared libraries, so specifically
+# pass `-fvisibility=hidden`.
+set_source_files_properties(sources/wasip2.c PROPERTIES
+  COMPILE_OPTIONS -fvisibility=hidden)
+set_source_files_properties(sources/wasip3.c PROPERTIES
+  COMPILE_OPTIONS -fvisibility=hidden)
+
 add_object_library(bottom-half ${bottom_half_sources})
 foreach(obj bottom-half-shared bottom-half-static)
   target_link_libraries(${obj} PUBLIC musl-top-half-interface)

libc-bottom-half/clocks/clock.c

@@ -1,20 +1,17 @@
 #define _WASI_EMULATED_PROCESS_CLOCKS
 #include <common/time.h>
 #include <time.h>
-#include <wasi/api.h>
 
 _Static_assert(CLOCKS_PER_SEC == NSEC_PER_SEC,
                "This implementation assumes that `clock` is in nanoseconds");
 
-#if defined(__wasip1__)
-
 // Snapshot of the monotonic clock at the start of the program.
-static __wasi_timestamp_t start;
+static struct timespec start;
 
 // Use a priority of 10 to run fairly early in the implementation-reserved
 // constructor priority range.
 __attribute__((constructor(10))) static void init(void) {
-  (void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &start);
+  clock_gettime(CLOCK_MONOTONIC, &start);
 }
 
 // Define the libc symbol as `__clock` so that we can reliably call it
@@ -24,36 +21,10 @@ clock_t __clock(void) {
   // an inherent concept of a process. Note that this means we'll incorrectly
   // include time from other processes, so this function is only declared by
   // the headers if `_WASI_EMULATED_PROCESS_CLOCKS` is defined.
-  __wasi_timestamp_t now = 0;
-  (void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &now);
-  return now - start;
-}
-
-#elif defined(__wasip2__) || defined(__wasip3__)
-
-// Snapshot of the monotonic clock at the start of the program.
-static monotonic_clock_instant_t start;
-
-// Use a priority of 10 to run fairly early in the implementation-reserved
-// constructor priority range.
-__attribute__((constructor(10))) static void init(void) {
-  start = monotonic_clock_now();
+  struct timespec now;
+  clock_gettime(CLOCK_MONOTONIC, &now);
+  return (now.tv_sec - start.tv_sec) * 1E9 - start.tv_nsec + now.tv_nsec;
 }
 
-// Define the libc symbol as `__clock` so that we can reliably call it
-// from elsewhere in libc.
-clock_t __clock(void) {
-  // Use `MONOTONIC` instead of `PROCESS_CPUTIME_ID` since WASI doesn't have
-  // an inherent concept of a process. Note that this means we'll incorrectly
-  // include time from other processes, so this function is only declared by
-  // the headers if `_WASI_EMULATED_PROCESS_CLOCKS` is defined.
-  monotonic_clock_instant_t now = monotonic_clock_now();
-  return now - start;
-}
-
-#else
-#error "Unknown WASI version"
-#endif
-
 // Define a user-visible alias as a weak symbol.
 __attribute__((__weak__, __alias__("__clock"))) clock_t clock(void);

libc-bottom-half/clocks/times.c

@@ -2,7 +2,6 @@
 #include <common/time.h>
 #include <sys/times.h>
 #include <time.h>
-#include <wasi/api.h>
 
 _Static_assert(CLOCKS_PER_SEC == NSEC_PER_SEC,
                "This implementation assumes that `clock` is in nanoseconds");
@@ -12,25 +11,13 @@ _Static_assert(CLOCKS_PER_SEC == NSEC_PER_SEC,
 clock_t __clock(void);
 
 clock_t times(struct tms *buffer) {
-#if defined(__wasip1__)
-  __wasi_timestamp_t user = __clock();
-  *buffer = (struct tms){
-      .tms_utime = user,
-      // WASI doesn't provide a way to spawn a new process, so always 0.
-      .tms_cutime = 0};
-
-  __wasi_timestamp_t realtime = 0;
-  (void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &realtime);
-#elif defined(__wasip2__) || defined(__wasip3__)
   clock_t user = __clock();
   *buffer = (struct tms){
       .tms_utime = user,
       // WASI doesn't provide a way to spawn a new process, so always 0.
       .tms_cutime = 0};
 
-  monotonic_clock_instant_t realtime = monotonic_clock_now();
-#else
-#error "Unsupported WASI version"
-#endif
-  return realtime;
+  struct timespec now;
+  clock_gettime(CLOCK_MONOTONIC, &now);
+  return now.tv_sec * 1E9 + now.tv_nsec;
 }

libc-bottom-half/headers/public/__macro_PAGESIZE.h

@@ -14,7 +14,9 @@
  * consideration. POSIX has deprecated `getpagesize` in favor of
  * `sysconf(_SC_PAGESIZE)` which does not have this problem.
  */
-#if __clang_major__ >= 22
+// FIXME(#778): `__wasm_first_page_end` is broken for PIC as of this writing and
+// will likely require `wasm-ld` changes, at which point we can re-enable it.
+#if __clang_major__ >= 22 && !defined __pic__
 extern char __wasm_first_page_end;
 #define PAGESIZE ((unsigned long)&__wasm_first_page_end)
 #else