build: fix detection of USDT support on macOS and generate probes.h

- Partially revert bitcoin#22238 as after the macOS USDT support, just checking
for the `sys/sdt.h` header is enough.
- Generate `util/probes.h` during build time when supported.

.gitignore

@@ -40,6 +40,7 @@ libtool
 src/config/bitcoin-config.h
 src/config/bitcoin-config.h.in
 src/config/stamp-h1
+src/util/probes.h
 src/obj
 share/setup.nsi
 share/qt/Info.plist

configure.ac

@@ -1385,14 +1385,28 @@ fi
 
 if test "$use_usdt" != "no"; then
   AC_MSG_CHECKING([whether Userspace, Statically Defined Tracing tracepoints are supported])
-  AC_COMPILE_IFELSE([
-    AC_LANG_PROGRAM(
-      [#include <sys/sdt.h>],
-      [DTRACE_PROBE("context", "event");]
-    )],
-    [AC_MSG_RESULT([yes]); AC_DEFINE([ENABLE_TRACING], [1], [Define to 1 to enable tracepoints for Userspace, Statically Defined Tracing])],
-    [AC_MSG_RESULT([no]); use_usdt=no;]
-  )
+  AC_CHECK_HEADER([sys/sdt.h], [use_usdt=yes], [use_usdt=no])
+else
+  use_usdt=no
+fi
+
+dnl Check for dtrace(1)
+if test x$use_usdt = xyes; then
+  AC_PATH_PROG([DTRACE], [dtrace])
+  if test "$TARGET_OS" = "darwin"; then
+      dnl USDT is only supported on darwin if dtrace exists
+      if test -n "$DTRACE"; then
+        AM_CONDITIONAL([HAVE_DTRACE], [test -n "$DTRACE"])
+      else
+        use_usdt=no
+      fi
+  else
+    AM_CONDITIONAL([HAVE_DTRACE], [test -n "$DTRACE"])
+  fi
+fi
+
+if test x$use_usdt = xyes; then
+  AC_DEFINE([ENABLE_TRACING], [1], [Define to 1 to enable tracepoints for Userspace, Statically Defined Tracing])
 fi
 AM_CONDITIONAL([ENABLE_USDT_TRACEPOINTS], [test "$use_usdt" = "yes"])
 

src/Makefile.am

@@ -328,6 +328,13 @@ BITCOIN_CORE_H = \
   zmq/zmqrpc.h \
   zmq/zmqutil.h
 
+if HAVE_DTRACE
+util/probes.h: util/probes.d
+	$(AM_V_GEN) $(DTRACE) -h -s $< -o $@
+
+BUILT_SOURCES = util/probes.h
+BITCOIN_CORE_H += util/probes.h
+endif
 
 obj/build.h: FORCE
 	@$(MKDIR_P) $(builddir)/obj
@@ -979,6 +986,7 @@ CLEANFILES += wallet/*.gcda wallet/*.gcno
 CLEANFILES += wallet/test/*.gcda wallet/test/*.gcno
 CLEANFILES += zmq/*.gcda zmq/*.gcno
 CLEANFILES += obj/build.h
+CLEANFILES += util/probes.h
 
 EXTRA_DIST = $(CTAES_DIST)