tm.texi (DWARF_FRAME_REGISTERS): Add documentation.

        * doc/tm.texi (DWARF_FRAME_REGISTERS): Add documentation.
        (PRE_GCC3_DWARF_FRAME_REGISTERS): Same.

        * unwind-dw2.c (__frame_state_for): Change DWARF_FRAME_REGISTERS
        to PRE_GCC3_DWARF_FRAME_REGISTERS.
        (frame_state): Same.
        (PRE_GCC3_DWARF_FRAME_REGISTERS): Define if not already defined.

Co-Authored-By: Richard Henderson <rth@redhat.com>

From-SVN: r47730

gcc/ChangeLog

+2001-12-06  Aldy Hernandez  <aldyh@redhat.com>
+            Richard Henderson  <rth@redhat.com>
+
+	* doc/tm.texi (DWARF_FRAME_REGISTERS): Add documentation.
+        (PRE_GCC3_DWARF_FRAME_REGISTERS): Same.
+
+        * unwind-dw2.c (__frame_state_for): Change DWARF_FRAME_REGISTERS
+        to PRE_GCC3_DWARF_FRAME_REGISTERS.
+        (frame_state): Same.
+	(PRE_GCC3_DWARF_FRAME_REGISTERS): Define if not already defined.
+
 2001-12-06  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* langhooks.c (lhd_staticp): Mark parameter with

gcc/doc/tm.texi

@@ -3011,6 +3011,33 @@ macros and should be used to refer to those items.
 
 If the static chain is passed in a register, the two previous macros should
 be defined instead.
+
+@findex DWARF_FRAME_REGISTERS
+@item DWARF_FRAME_REGISTERS
+This macro specifies the maximum number of hard registers that can be
+saved in a call frame.  This is used to size data structures used in
+DWARF2 exception handling.
+
+Prior to GCC 3.0, this macro was needed in order to establish a stable
+exception handling ABI in the face of adding new hard registers for ISA
+extensions.  In GCC 3.0 and later, the EH ABI is insulated from changes
+in the number of hard registers.  Nevertheless, this macro can still be
+used to reduce the runtime memory requirements of the exception handling
+routines, which can be substantial if the ISA contains a lot of
+registers that are not call-saved.
+
+If this macro is not defined, it defaults to
+@code{FIRST_PSEUDO_REGISTER}.
+
+@findex PRE_GCC3_DWARF_FRAME_REGISTERS
+@item PRE_GCC3_DWARF_FRAME_REGISTERS
+
+This macro is similar to @code{DWARF_FRAME_REGISTERS}, but is provided
+for backward compatibility in pre GCC 3.0 compiled code.
+
+If this macro is not defined, it defaults to
+@code{DWARF_FRAME_REGISTERS}.
+
 @end table
 
 @node Elimination

gcc/unwind-dw2.c

@@ -42,6 +42,11 @@
 #define DWARF_FRAME_REGISTERS FIRST_PSEUDO_REGISTER
 #endif
 
+/* Dwarf frame registers used for pre gcc 3.0 compiled glibc.  */
+#ifndef PRE_GCC3_DWARF_FRAME_REGISTERS
+#define PRE_GCC3_DWARF_FRAME_REGISTERS DWARF_FRAME_REGISTERS
+#endif
+
 /* This is the register and unwind state for a particular frame.  */
 struct _Unwind_Context
 {
@@ -944,10 +949,10 @@ typedef struct frame_state
   void *eh_ptr;
   long cfa_offset;
   long args_size;
-  long reg_or_offset[DWARF_FRAME_REGISTERS+1];
+  long reg_or_offset[PRE_GCC3_DWARF_FRAME_REGISTERS+1];
   unsigned short cfa_reg;
   unsigned short retaddr_column;
-  char saved[DWARF_FRAME_REGISTERS+1];
+  char saved[PRE_GCC3_DWARF_FRAME_REGISTERS+1];
 } frame_state;
 
 struct frame_state * __frame_state_for (void *, struct frame_state *);
@@ -974,7 +979,7 @@ __frame_state_for (void *pc_target, struct frame_state *state_in)
   if (fs.cfa_how == CFA_EXP)
     return 0;
 
-  for (reg = 0; reg < DWARF_FRAME_REGISTERS + 1; reg++)
+  for (reg = 0; reg < PRE_GCC3_DWARF_FRAME_REGISTERS + 1; reg++)
     {
       state_in->saved[reg] = fs.regs.reg[reg].how;
       switch (state_in->saved[reg])