Stack traces for x86_64

[Andrew Haley]

Stack traces don't work on x86_64.  With some programming languages
that's just a minor annoyance but with Java it means we can't
implement the API.

It turns out that the reason for the non-functionality is very simple:
programs are compiled with -fomit-frame-pointer by default, unlike our
other platforms.  The fix is similarly simple, and seems to work well:

java.lang.Throwable
   at bloop.foo() (/home/aph/gcc/build/bloop.java:5)
   at baz.foo() (/home/aph/gcc/build/baz.java:11)
   at foo.bar() (/home/aph/gcc/build/foo.java:13)
   at foo.main(java.lang.String[]) (/home/aph/gcc/build/foo.java:19)

It might be that one day we'll use the DWARF unwinder machinery to get
stack traces, and then we won't need to do this.

In a related note: sibling calls also break stack traces, so we might
have to disable them too when we need compliance with the Java
security sandbox model.

Andrew.

2003-01-28  Andrew Haley  <aph@redhat.com>

        * libgcj.spec.in (jc1): Add BACKTRACESPEC.
        * configure.host (x86_64): Default to -fno-omit-frame-pointer.
        * configure.in (BACKTRACESPEC): New.
        * configure: Regenerate.

Index: configure.host
===================================================================
RCS file: /cvs/gcc/gcc/libjava/configure.host,v
retrieving revision 1.44
diff -u -r1.44 configure.host
--- configure.host      22 Jan 2003 17:50:38 -0000      1.44
+++ configure.host      28 Jan 2003 18:38:43 -0000
@@ -98,12 +98,12 @@
   x86_64-*)
        CHECKREFSPEC="%{m32:-fcheck-references}"
        sysdeps_dir=x86-64
-       libgcj_flags="${libgcj_flags} -ffloat-store"
+       libgcj_flags="${libgcj_flags} -ffloat-store -fno-omit-frame-pointer"
        libgcj_cxxflags="-D__NO_MATH_INLINES"
        libgcj_cflags="-D__NO_MATH_INLINES"
        enable_hash_synchronization_default=yes
        slow_pthread_self=yes
        ;;
   alpha*-*)
        sysdeps_dir=alpha
Index: configure.in
===================================================================
RCS file: /cvs/gcc/gcc/libjava/configure.in,v
retrieving revision 1.144
diff -u -r1.144 configure.in
--- configure.in        14 Jan 2003 13:51:13 -0000      1.144
+++ configure.in        28 Jan 2003 18:38:44 -0000
@@ -937,6 +937,15 @@
    SIGNAL_HANDLER=include/default-signal.h
 fi
 
+# Define here any compiler flags that you need in order to make backtrace() work.
+BACKTRACESPEC=
+case "${host}" in
+ x86_64*-*-linux*)
+    BACKTRACESPEC=-fno-omit-frame-pointer
+    ;;
+esac
+AC_SUBST(BACKTRACESPEC)
+
 AC_SUBST(SYSDEP_SOURCES)
 
 AC_LINK_FILES($SIGNAL_HANDLER, include/java-signal.h)
Index: libgcj.spec.in
===================================================================
RCS file: /cvs/gcc/gcc/libjava/libgcj.spec.in,v
retrieving revision 1.23
diff -u -r1.23 libgcj.spec.in
--- libgcj.spec.in      31 Mar 2002 18:24:59 -0000      1.23
+++ libgcj.spec.in      28 Jan 2003 18:38:44 -0000
@@ -6,4 +6,4 @@
 %rename lib liborig
 *lib: -lgcj -lm @LIBICONV@ @GCSPEC@ @THREADSPEC@ @ZLIBSPEC@ @SYSTEMSPEC@ %(libgcc) %(liborig)
 
-*jc1: @HASH_SYNC_SPEC@ @DIVIDESPEC@ @CHECKREFSPEC@ @JC1GCSPEC@ @EXCEPTIONSPEC@ -fkeep-inline-functions
+*jc1: @HASH_SYNC_SPEC@ @DIVIDESPEC@ @CHECKREFSPEC@ @JC1GCSPEC@ @EXCEPTIONSPEC@ @BACKTRACESPEC@ -fkeep-inline-functions