xcoff.h (EH_FRAME_IN_DATA_SECTION): New.

        * config/rs6000/xcoff.h (EH_FRAME_IN_DATA_SECTION): New.
        * defaults.h (EH_FRAME_SECTION_NAME): Respect it.
        * doc/tm.texi (Exception Region Output): Document it.

From-SVN: r44869

gcc/ChangeLog

+2001-08-13  Richard Henderson  <rth@redhat.com>
+
+	* config/rs6000/xcoff.h (EH_FRAME_IN_DATA_SECTION): New.
+	* defaults.h (EH_FRAME_SECTION_NAME): Respect it.
+	* doc/tm.texi (Exception Region Output): Document it.
+
 2001-08-13  Geoffrey Keating  <geoffk@redhat.com>
 
 	* config/rs6000/sysv4.h (PREFERRED_DEBUGGING_TYPE): Use

gcc/config/rs6000/xcoff.h

@@ -492,8 +492,11 @@ toc_section ()						\
 /* Switch into a generic section.  */
 #define TARGET_ASM_NAMED_SECTION  xcoff_asm_named_section
 
-/* Define the name of the section to use for the exception tables.
-   TODO: test and see if we can use read_only_data_section, if so,
-   remove this.  */
-
+/* Define the name of the section to use for the EH language specific
+   data areas (.gcc_except_table on most other systems).  */
 #define EXCEPTION_SECTION data_section
+
+/* Define to prevent DWARF2 unwind info in the data section rather
+   than in the .eh_frame section.  We do this because the AIX linker
+   would otherwise garbage collect these sections.  */
+#define EH_FRAME_IN_DATA_SECTION 1

gcc/defaults.h

@@ -211,7 +211,7 @@ do { ASM_OUTPUT_LABEL(FILE,LABEL_ALTERNATE_NAME (INSN)); } while (0)
 
 /* If we have named sections, and we're using crtstuff to run ctors,
    use them for registering eh frame information.  */
-#if defined (TARGET_ASM_NAMED_SECTION)
+#if defined (TARGET_ASM_NAMED_SECTION) && !defined(EH_FRAME_IN_DATA_SECTION)
 #ifndef EH_FRAME_SECTION_NAME
 #define EH_FRAME_SECTION_NAME ".eh_frame"
 #endif

gcc/doc/tm.texi

@@ -7068,6 +7068,16 @@ provide a default definition if the target supports named sections.
 You should define this symbol if your target supports DWARF 2 frame
 unwind information and the default definition does not work.
 
+@findex EH_FRAME_IN_DATA_SECTION
+@item EH_FRAME_IN_DATA_SECTION
+If defined, DWARF 2 frame unwind information will be placed in the
+data section even though the target supports named sections.  This
+might be necessary, for instance, if the system linker does garbage
+collection and sections cannot be marked as not to be collected.
+
+Do not define this macro unless @code{TARGET_ASM_NAMED_SECTION} is
+also defined.
+
 @findex OMIT_EH_TABLE
 @item OMIT_EH_TABLE ()
 A C expression that is nonzero if the normal exception table output