fixup

src/CMakeLists.txt

@@ -264,6 +264,15 @@ set_property(TARGET vm_static vm_shared APPEND PROPERTY
   COMPILE_FLAGS "${TARGET_VM_FLAGS}"
 )
 
+add_library(stack_collector OBJECT EXCLUDE_FROM_ALL lj_stack_collector.c)
+set_property(TARGET stack_collector APPEND PROPERTY
+  COMPILE_FLAGS "${TARGET_C_FLAGS}"
+)
+set_property(TARGET stack_collector APPEND PROPERTY
+  POSITION_INDEPENDENT_CODE ON
+)
+target_link_libraries(stack_collector PRIVATE ${LIBUNWIND_LIBRARIES})
+
 # Platform core.
 add_library(core_static OBJECT EXCLUDE_FROM_ALL ${SOURCES_CORE})
 add_library(core_shared OBJECT EXCLUDE_FROM_ALL ${SOURCES_CORE})
@@ -284,10 +293,6 @@ add_dependencies(core_shared buildvm_output)
 
 list(APPEND TARGET_LIBS m)
 
-if(NOT LUAJIT_DISABLE_SYSPROF)
-  list(APPEND TARGET_LIBS ${LIBUNWIND_LIBRARIES})
-endif()
-
 set(LIB_OBJECTS_STATIC
   $<TARGET_OBJECTS:vm_static>
   $<TARGET_OBJECTS:core_static>
@@ -316,6 +321,9 @@ set_target_properties(libluajit_shared PROPERTIES
 )
 target_link_libraries(libluajit_shared ${TARGET_LIBS})
 
+target_link_libraries(libluajit_shared stack_collector)
+target_link_libraries(libluajit_static stack_collector)
+
 # Compiling and linking CLIs.
 
 # XXX: Order of the branches below matters, since when BUILDMODE

src/lj_stack_collector.c

@@ -0,0 +1,41 @@
+/*
+** Libunwind-based stack collector.
+*/
+#include "lj_stack_collector.h"
+
+/*
+** We only need local unwinding, then a special implementation
+** can be selected which may run much faster than the generic
+** implementation which supports both kinds of unwinding, local
+** and remote.
+*/
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+
+ssize_t collect_stack(void **buffer, int size)
+{
+  int frame_no = 0;
+  unw_context_t unw_ctx;
+  unw_cursor_t unw_cur;
+
+  int rc = unw_getcontext(&unw_ctx);
+  if (rc != 0)
+    return -1;
+
+  rc = unw_init_local(&unw_cur, &unw_ctx);
+  if (rc != 0)
+    return -1;
+
+  for (; frame_no < size; ++frame_no) {
+    unw_word_t ip;
+    rc = unw_get_reg(&unw_cur, UNW_REG_IP, &ip);
+    if (rc != 0)
+      return -1;
+
+    buffer[frame_no] = (void *)ip;
+    rc = unw_step(&unw_cur);
+    if (rc <= 0)
+      break;
+  }
+  return frame_no;
+}

src/lj_stack_collector.h

@@ -0,0 +1,18 @@
+/*
+** Libunwind-based stack collector.
+**
+** XXX: This module must be compiled and linked separately from
+** other LuaJIT sources. Otherwise, the definitions from
+** libunwind and libgcc can collide, leading to unwinding working
+** improperly. Compiling this module separately ensures that the
+** only place where libunwind is used is here.
+*/
+
+#ifndef _LJ_STACK_COLLECTOR_H
+#define _LJ_STACK_COLLECTOR_H
+
+#include <sys/types.h>
+
+ssize_t collect_stack(void **buffer, int size);
+
+#endif

src/lj_sysprof.c

@@ -20,24 +20,17 @@
 #include "lj_trace.h"
 #endif
 
+#ifndef LUAJIT_EXTERNAL_SYSPROF_BACKTRACER
+#include "lj_stack_collector.h"
+#endif
+
 #include "lj_wbuf.h"
 #include "lj_profile_timer.h"
 #include "lj_symtab.h"
 
 #include <pthread.h>
 #include <errno.h>
 
-#ifndef LUAJIT_EXTERNAL_SYSPROF_BACKTRACER
-/*
-** We only need local unwinding, then a special implementation
-** can be selected which may run much faster than the generic
-** implementation which supports both kinds of unwinding, local
-** and remote.
-*/
-#define UNW_LOCAL_ONLY
-#include <libunwind.h>
-#endif
-
 /*
 ** Number of profiler frames we need to omit during stack
 ** unwinding.
@@ -97,34 +90,6 @@ static struct sysprof sysprof = {0};
 
 #ifndef LUAJIT_EXTERNAL_SYSPROF_BACKTRACER
 
-static ssize_t collect_stack(void **buffer, int size)
-{
-  int frame_no = 0;
-  unw_context_t unw_ctx;
-  unw_cursor_t unw_cur;
-
-  int rc = unw_getcontext(&unw_ctx);
-  if (rc != 0)
-    return -1;
-
-  rc = unw_init_local(&unw_cur, &unw_ctx);
-  if (rc != 0)
-    return -1;
-
-  for (; frame_no < size; ++frame_no) {
-    unw_word_t ip;
-    rc = unw_get_reg(&unw_cur, UNW_REG_IP, &ip);
-    if (rc != 0)
-      return -1;
-
-    buffer[frame_no] = (void *)ip;
-    rc = unw_step(&unw_cur);
-    if (rc <= 0)
-      break;
-  }
-  return frame_no;
-}
-
 static void default_backtrace_host(void *(writer)(int frame_no, void *addr))
 {
   static void *backtrace_buf[SYSPROF_BACKTRACE_FRAME_MAX] = {};