tm.texi (Exception Region Output): Document DWARF_CIE_DATA_ALIGNMENT.

	* tm.texi (Exception Region Output): Document
	DWARF_CIE_DATA_ALIGNMENT.
	* dwarf2out.c (DWARF_CIE_DATA_ALIGNMENT): Wrap definition in
	#ifndef.
	[ENABLE_CHECKING] (reg_save): Abort if offset is not a multiple of
	DWARF_CIE_DATA_ALIGNMENT.

From-SVN: r36935

gcc/ChangeLog

+2000-10-18  Hans-Peter Nilsson  <hp@axis.com>
+
+	* tm.texi (Exception Region Output): Document
+	DWARF_CIE_DATA_ALIGNMENT.
+	* dwarf2out.c (DWARF_CIE_DATA_ALIGNMENT): Wrap definition in
+	#ifndef.
+	[ENABLE_CHECKING] (reg_save): Abort if offset is not a multiple of
+	DWARF_CIE_DATA_ALIGNMENT.
+
 2000-10-18  Michael Hayes  <mhayes@cygnus.com>
 
 	* basic-block.h (struct loop): Delete fields pre_header_root

gcc/dwarf2out.c

@@ -169,11 +169,13 @@ dw_fde_node;
   ((((SIZE) + (BOUNDARY) - 1) / (BOUNDARY)) * (BOUNDARY))
 
 /* Offsets recorded in opcodes are a multiple of this alignment factor.  */
+#ifndef DWARF_CIE_DATA_ALIGNMENT
 #ifdef STACK_GROWS_DOWNWARD
 #define DWARF_CIE_DATA_ALIGNMENT (-((int) UNITS_PER_WORD))
 #else
 #define DWARF_CIE_DATA_ALIGNMENT ((int) UNITS_PER_WORD)
 #endif
+#endif /* not DWARF_CIE_DATA_ALIGNMENT */
 
 /* A pointer to the base of a table that contains frame description
    information for each routine.  */
@@ -940,6 +942,18 @@ reg_save (label, reg, sreg, offset)
       else
 	cfi->dw_cfi_opc = DW_CFA_offset;
 
+#ifdef ENABLE_CHECKING
+      {
+	/* If we get an offset that is not a multiple of
+	   DWARF_CIE_DATA_ALIGNMENT, there is either a bug in the
+	   definition of DWARF_CIE_DATA_ALIGNMENT, or a bug in the machine
+	   description.  */
+	long check_offset = offset / DWARF_CIE_DATA_ALIGNMENT;
+
+	if (check_offset * DWARF_CIE_DATA_ALIGNMENT != offset)
+	  abort ();
+      }
+#endif
       offset /= DWARF_CIE_DATA_ALIGNMENT;
       if (offset < 0)
 	{

gcc/tm.texi

@@ -6682,6 +6682,15 @@ default.
 If this macro is defined to anything, the DWARF 2 unwinder will be used
 instead of inline unwinders and __unwind_function in the non-setjmp case.
 
+@findex DWARF_CIE_DATA_ALIGNMENT
+@item DWARF_CIE_DATA_ALIGNMENT
+This macro need only be defined if the target might save registers in the
+function prologue at an offset to the stack pointer that is not aligned to
+@code{UNITS_PER_WORD}.  The definition should be the negative minimum
+alignment if @code{STACK_GROWS_DOWNWARD} is defined, and the positive
+minimum alignment otherwise.  @xref{SDB and DWARF}.  Only applicable if
+the target supports DWARF 2 frame unwind information.
+
 @end table
 
 @node Alignment Output