configure.ac (gcc_cv_ld_mips_personality_relaxation): New feature check.

gcc/
	* configure.ac (gcc_cv_ld_mips_personality_relaxation): New
	feature check.
	(HAVE_LD_PERSONALITY_RELAXATION): New macro definition.
	* configure, config.in: Regenerate.
	* dwarf2asm.c (eh_data_format_name): Handle DW_EH_PE_indirect |
	DW_EH_PE_absptr.
	* config/mips/mips.h (TARGET_WRITABLE_EH_FRAME): New macro.
	(ASM_PREFERRED_EH_DATA_FORMAT): Define.  Use MIPS_EH_INDIRECT
	for global data if the output could be used in a shared library.
	* config/mips/mips.c (mips_override_options): Set flag_dwarf2_cfi_asm
	to 0 if TARGET_WRITABLE_EH_FRAME.

From-SVN: r151896

1 files changed, 35 insertions, 0 deletions

diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 71b9b1b..defcd6e 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -230,6 +230,14 @@ enum mips_code_readable_setting {
    && !TARGET_ABSOLUTE_ABICALLS			\
    && !(mips_abi == ABI_64 && TARGET_IRIX))
 
+/* True if the output must have a writable .eh_frame.
+   See ASM_PREFERRED_EH_DATA_FORMAT for details.  */
+#ifdef HAVE_LD_PERSONALITY_RELAXATION
+#define TARGET_WRITABLE_EH_FRAME 0
+#else
+#define TARGET_WRITABLE_EH_FRAME (flag_pic && TARGET_SHARED)
+#endif
+
 /* Generate mips16 code */
 #define TARGET_MIPS16		((target_flags & MASK_MIPS16) != 0)
 /* Generate mips16e code. Default 16bit ASE for mips32* and mips64* */
@@ -3182,3 +3190,30 @@ extern enum mips_code_readable_setting mips_code_readable;
 /* This is necessary to avoid a warning about comparing different enum
    types.  */
 #define mips_tune_attr ((enum attr_cpu) mips_tune)
+
+/* As on most targets, we want the .eh_frame section to be read-only where
+   possible.  And as on most targets, this means two things:
+
+     (a) Non-locally-binding pointers must have an indirect encoding,
+	 so that the addresses in the .eh_frame section itself become
+	 locally-binding.
+
+     (b) A shared library's .eh_frame section must encode locally-binding
+	 pointers in a relative (relocation-free) form.
+
+   However, MIPS has traditionally not allowed directives like:
+
+	.long	x-.
+
+   in cases where "x" is in a different section, or is not defined in the
+   same assembly file.  We are therefore unable to emit the PC-relative
+   form required by (b) at assembly time.
+
+   Fortunately, the linker is able to convert absolute addresses into
+   PC-relative addresses on our behalf.  Unfortunately, only certain
+   versions of the linker know how to do this for indirect pointers,
+   and for personality data.  We must fall back on using writable
+   .eh_frame sections for shared libraries if the linker does not
+   support this feature.  */
+#define ASM_PREFERRED_EH_DATA_FORMAT(CODE,GLOBAL) \
+  (((GLOBAL) ? DW_EH_PE_indirect : 0) | DW_EH_PE_absptr)