Re: Support Dwarf3 DW_CFA_val_* expressions

[Alexandre Oliva <aoliva at redhat dot com>]

On Mar 11, 2006, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:

> Anyway, feel free to commit the code that adds support for the new
> DWARF3 expressions (the origional one, not the "corrected" one ;).

Thanks, and sorry about the delay.  I'm finally checking this in.

for gdb/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	* dwarf2-frame.h (enum dwarf2_frame_reg_rule): Add
	DWARF2_FRAME_REG_SAVED_VAL_OFFSET and
	DWARF2_FRAME_REG_SAVED_VAL_EXP.
	* dwarf2-frame.c (execute_cfa_program): Handle val_offset,
	val_offset_sf and val_expression.
	(dwarf2_frame_prev_register): Handle the new reg rules.
	(dwarf2_frame_this_id): Use pc instead of function entry point.

Index: gdb/dwarf2-frame.c
===================================================================
--- gdb/dwarf2-frame.c.orig	2006-05-28 02:44:41.000000000 -0300
+++ gdb/dwarf2-frame.c	2006-05-28 02:44:47.000000000 -0300
@@ -481,6 +481,34 @@ bad CFI data; mismatched DW_CFA_restore_
 	      fs->regs.reg[reg].loc.offset = offset;
 	      break;
 
+	    case DW_CFA_val_offset:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	      offset = utmp * fs->data_align;
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
+	      fs->regs.reg[reg].loc.offset = offset;
+	      break;
+
+	    case DW_CFA_val_offset_sf:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
+	      offset *= fs->data_align;
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
+	      fs->regs.reg[reg].loc.offset = offset;
+	      break;
+
+	    case DW_CFA_val_expression:
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
+	      dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+	      fs->regs.reg[reg].loc.exp = insn_ptr;
+	      fs->regs.reg[reg].exp_len = utmp;
+	      fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP;
+	      insn_ptr += utmp;
+	      break;
+
 	    case DW_CFA_def_cfa_sf:
 	      insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
 	      if (eh_frame_p)
@@ -965,6 +993,28 @@ dwarf2_frame_prev_register (struct frame
 	}
       break;
 
+    case DWARF2_FRAME_REG_SAVED_VAL_OFFSET:
+      *optimizedp = 0;
+      *lvalp = not_lval;
+      *addrp = 0;
+      *realnump = -1;
+      if (valuep)
+	store_unsigned_integer (valuep, register_size (gdbarch, regnum),
+				cache->cfa + cache->reg[regnum].loc.offset);
+      break;
+
+    case DWARF2_FRAME_REG_SAVED_VAL_EXP:
+      *optimizedp = 0;
+      *lvalp = not_lval;
+      *addrp = 0;
+      *realnump = -1;
+      if (valuep)
+	store_unsigned_integer (valuep, register_size (gdbarch, regnum),
+				execute_stack_op (cache->reg[regnum].loc.exp,
+						  cache->reg[regnum].exp_len,
+						  next_frame, cache->cfa));
+      break;
+
     case DWARF2_FRAME_REG_UNSPECIFIED:
       /* GCC, in its infinite wisdom decided to not provide unwind
 	 information for registers that are "same value".  Since
Index: gdb/dwarf2-frame.h
===================================================================
--- gdb/dwarf2-frame.h.orig	2006-05-28 02:00:31.000000000 -0300
+++ gdb/dwarf2-frame.h	2006-05-28 02:44:47.000000000 -0300
@@ -51,6 +51,10 @@ enum dwarf2_frame_reg_rule
   DWARF2_FRAME_REG_SAVED_EXP,
   DWARF2_FRAME_REG_SAME_VALUE,
 
+  /* These are defined in Dwarf3.  */
+  DWARF2_FRAME_REG_SAVED_VAL_OFFSET,
+  DWARF2_FRAME_REG_SAVED_VAL_EXP,
+
   /* These aren't defined by the DWARF2 CFI specification, but are
      used internally by GDB.  */
   DWARF2_FRAME_REG_RA,		/* Return Address.  */

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
Secretary for FSF Latin America        http://www.fsfla.org/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}