trace: Workaround GCC bug compiling with old systemtap

Author: luke-jr

cmake/module/FindUSDT.cmake

@@ -36,6 +36,10 @@ if(USDT_INCLUDE_DIR)
   include(CheckCXXSourceCompiles)
   set(CMAKE_REQUIRED_INCLUDES ${USDT_INCLUDE_DIR})
   check_cxx_source_compiles("
+    #if defined(__arm__)
+    #  define STAP_SDT_ARG_CONSTRAINT g
+    #endif
+
     // Setting SDT_USE_VARIADIC lets systemtap (sys/sdt.h) know that we want to use
     // the optional variadic macros to define tracepoints.
     #define SDT_USE_VARIADIC 1

src/util/trace.h

@@ -9,6 +9,13 @@
 
 #ifdef ENABLE_TRACING
 
+// Workaround for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103395
+// systemtap 4.6 on 32-bit ARM triggers internal compiler error
+// (this workaround is included in systemtap 4.7+)
+#if defined(__arm__)
+#  define STAP_SDT_ARG_CONSTRAINT g
+#endif
+
 // Setting SDT_USE_VARIADIC lets systemtap (sys/sdt.h) know that we want to use
 // the optional variadic macros to define tracepoints.
 #define SDT_USE_VARIADIC 1