Add a compilation flag that adds unwind info to all files that are present in the stack starting from MPI_Init.

This is so when a debugger attaches using MPIR, it can step out of this stack back into main.
This cannot be done with certain aggressive optimisations and missing debug information.

Signed-off-by: James Clark <james.clark@arm.com>

Author: James-A-Clark

config/orte_setup_debugger_flags.m4

@@ -53,4 +53,26 @@ AC_DEFUN([ORTE_SETUP_DEBUGGER_FLAGS],[
 
     AC_SUBST(CFLAGS_WITHOUT_OPTFLAGS)
     AC_SUBST(DEBUGGER_CFLAGS)
+
+    # Check for compiler specific flag to add in unwind information.
+    # This is needed when attaching using MPIR to unwind back to the
+    # user's main function. Certain optimisations can prevent GDB from
+    # producing a stack when explicit unwind information is unavailable.
+    # This is implied by -g, but we want to save space and don't need
+    # full debug symbols.
+    if test "x$opal_cv_c_compiler_vendor" = "xibm"; then
+        MPIR_UNWIND_CFLAGS="-g"
+    elif test "x$opal_cv_c_compiler_vendor" = "xgnu"; then
+        MPIR_UNWIND_CFLAGS="-fasynchronous-unwind-tables"
+    elif test "x$opal_cv_c_compiler_vendor" = "xintel"; then
+        MPIR_UNWIND_CFLAGS="-fasynchronous-unwind-tables"
+    elif test "x$opal_cv_c_compiler_vendor" = "xportland group"; then
+        MPIR_UNWIND_CFLAGS="-Meh_frame -Mframe"
+    else
+        MPIR_UNWIND_CFLAGS=
+    fi
+
+    AC_MSG_CHECKING([for MPIR unwind info flags])
+    AC_MSG_RESULT([$MPIR_UNWIND_CFLAGS])
+    AC_SUBST(MPIR_UNWIND_CFLAGS)
 ])

ompi/runtime/Makefile.am

@@ -32,9 +32,18 @@ headers += \
 lib@OMPI_LIBMPI_NAME@_la_SOURCES += \
         runtime/ompi_mpi_abort.c \
         runtime/ompi_mpi_dynamics.c \
-        runtime/ompi_mpi_init.c \
         runtime/ompi_mpi_finalize.c \
         runtime/ompi_mpi_params.c \
         runtime/ompi_mpi_preconnect.c \
 	runtime/ompi_cr.c \
 	runtime/ompi_info_support.c
+
+# The MPIR portion of the library must be built with flags to
+# enable stepping out of MPI_INIT into main.
+# Use an intermediate library to isolate the debug object.
+noinst_LTLIBRARIES += libompi_mpir.la
+libompi_mpir_la_SOURCES = \
+	runtime/ompi_mpi_init.c
+libompi_mpir_la_CFLAGS = $(MPIR_UNWIND_CFLAGS)
+
+lib@OMPI_LIBMPI_NAME@_la_LIBADD += libompi_mpir.la

orte/mca/ess/Makefile.am

@@ -17,7 +17,9 @@
 # $HEADER$
 #
 
-AM_CPPFLAGS = $(LTDLINCL)
+# Add unwind flags because all of the files in this tree are
+# involved in startup.
+AM_CPPFLAGS = $(LTDLINCL) $(MPIR_UNWIND_CFLAGS)
 
 # main library setup
 noinst_LTLIBRARIES = libmca_ess.la

orte/mca/ess/pmi/Makefile.am

@@ -11,7 +11,7 @@
 # $HEADER$
 #
 
-AM_CPPFLAGS = $(ess_pmi_CPPFLAGS)
+AM_CPPFLAGS = $(ess_pmi_CPPFLAGS) $(MPIR_UNWIND_CFLAGS)
 
 sources = \
         ess_pmi.h \

orte/runtime/Makefile.am

@@ -38,7 +38,6 @@ headers += \
 
 lib@ORTE_LIB_PREFIX@open_rte_la_SOURCES += \
         runtime/orte_finalize.c \
-        runtime/orte_init.c \
         runtime/orte_locks.c \
         runtime/orte_globals.c \
         runtime/orte_quit.c \
@@ -52,3 +51,12 @@ lib@ORTE_LIB_PREFIX@open_rte_la_SOURCES += \
         runtime/orte_cr.c \
         runtime/orte_data_server.c \
         runtime/orte_info_support.c
+
+# The MPIR portion of the library must be built with flags to
+# enable stepping out of MPI_INIT into main.
+# Use an intermediate library to isolate the debug object.
+noinst_LTLIBRARIES += libruntime_mpir.la
+libruntime_mpir_la_SOURCES = \
+        runtime/orte_init.c
+libruntime_mpir_la_CFLAGS = $(MPIR_UNWIND_CFLAGS)
+lib@ORTE_LIB_PREFIX@open_rte_la_LIBADD += libruntime_mpir.la