Re: Incorrect DWARF-2 register numbers on PPC64?

[Alan Modra <amodra@bigpond.net.au>]

On Wed, Jan 07, 2004 at 09:01:31PM -0800, Geoff Keating wrote:
> That will also mean that executables built with a new version of GCC won't
> run on operating systems with an old libgcc.  For Darwin, because of
> historical mistakes involving non-shared libgcc, it will make life
> very difficult.

I hadn't thought of that.  This means we are stuck with the current
.eh_frame register numbering.  It should be possible to fix .debug_frame
with something like the following totally untested patch.  I'm throwing
it out to the list now for comment.

With a little more work, I can get rid of DWARF_REG_TO_UNWIND_COLUMN
by having the SPE hack generate a number suitable for .eh_frame, and
mapping up to 1200 in DBX_REGISTER_NUMBER and the new
DWARF2_FRAME_REG_OUT.  So the final patch won't increasing the number of
macros littering gcc.  :)

	  * config/rs6000/sysv4.h (DWARF2_FRAME_REG_OUT): Define.
	  * dwraf2out.c (output_cfi): Map regs using DWARF2_FRAME_REG_OUT.

Index: gcc/config/rs6000/sysv4.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/sysv4.h,v
retrieving revision 1.144
diff -u -p -r1.144 sysv4.h
--- gcc/config/rs6000/sysv4.h	7 Jan 2004 01:21:28 -0000	1.144
+++ gcc/config/rs6000/sysv4.h	9 Jan 2004 02:24:39 -0000
@@ -744,6 +744,18 @@ extern int fixuplabelno;
 
 #define DBX_REGISTER_NUMBER(REGNO) rs6000_dbx_register_number (REGNO)
 
+/* Map register numbers held in the call frame info that gcc has
+   collected using DWARF_FRAME_REGNUM to those that should be output in
+   .debug_frame and .eh_frame.  We continue to use gcc hard reg numbers
+   for .eh_frame, but use the numbers mandated by the various ABIs for
+   .debug_frame.  rs6000_emit_prologue has translated any combination of
+   CR2, CR3, CR4 saves to a save of CR2.  The actual code emitted saves
+   the whole of CR, so we map CR2_REGNO to the DWARF reg for CR.  */
+#define DWARF2_FRAME_REG_OUT(REGNO, FOR_EH)	\
+  ((FOR_EH) ? (REGNO)				\
+   : (REGNO) == CR2_REGNO ? 64			\
+   : DBX_REGISTER_NUMBER (REGNO))
+
 #define TARGET_ENCODE_SECTION_INFO  rs6000_elf_encode_section_info
 #define TARGET_IN_SMALL_DATA_P  rs6000_elf_in_small_data_p
 #define TARGET_SECTION_TYPE_FLAGS  rs6000_elf_section_type_flags
Index: gcc/dwarf2out.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/dwarf2out.c,v
retrieving revision 1.471
diff -u -p -r1.471 dwarf2out.c
--- gcc/dwarf2out.c	8 Jan 2004 07:54:11 -0000	1.471
+++ gcc/dwarf2out.c	9 Jan 2004 02:24:32 -0000
@@ -1783,11 +1783,21 @@ dw_cfi_oprnd2_desc (enum dwarf_call_fram
 
 #if defined (DWARF2_DEBUGGING_INFO) || defined (DWARF2_UNWIND_INFO)
 
+/* Map register numbers held in the call frame info that gcc has
+   collected using DWARF_FRAME_REGNUM to those that should be output in
+   .debug_frame and .eh_frame.  */
+#ifndef DWARF2_FRAME_REG_OUT
+#define DWARF2_FRAME_REG_OUT(REGNO, FOR_EH) (REGNO)
+#endif
+
 /* Output a Call Frame Information opcode and its operand(s).  */
 
 static void
 output_cfi (dw_cfi_ref cfi, dw_fde_ref fde, int for_eh)
 {
+  unsigned long op1_reg;
+  op1_reg = DWARF2_FRAME_REG_OUT (cfi->dw_cfi_oprnd1.dw_cfi_reg_num, for_eh);
+
   if (cfi->dw_cfi_opc == DW_CFA_advance_loc)
     dw2_asm_output_data (1, (cfi->dw_cfi_opc
 			     | (cfi->dw_cfi_oprnd1.dw_cfi_offset & 0x3f)),
@@ -1795,17 +1805,15 @@ output_cfi (dw_cfi_ref cfi, dw_fde_ref f
 			 cfi->dw_cfi_oprnd1.dw_cfi_offset);
   else if (cfi->dw_cfi_opc == DW_CFA_offset)
     {
-      dw2_asm_output_data (1, (cfi->dw_cfi_opc
-			       | (cfi->dw_cfi_oprnd1.dw_cfi_reg_num & 0x3f)),
+      dw2_asm_output_data (1, (cfi->dw_cfi_opc | (op1_reg & 0x3f)),
 			   "DW_CFA_offset, column 0x%lx",
-			   cfi->dw_cfi_oprnd1.dw_cfi_reg_num);
+			   op1_reg);
       dw2_asm_output_data_uleb128 (cfi->dw_cfi_oprnd2.dw_cfi_offset, NULL);
     }
   else if (cfi->dw_cfi_opc == DW_CFA_restore)
-    dw2_asm_output_data (1, (cfi->dw_cfi_opc
-			     | (cfi->dw_cfi_oprnd1.dw_cfi_reg_num & 0x3f)),
+    dw2_asm_output_data (1, (cfi->dw_cfi_opc | (op1_reg & 0x3f)),
 			 "DW_CFA_restore, column 0x%lx",
-			 cfi->dw_cfi_oprnd1.dw_cfi_reg_num);
+			 op1_reg);
   else
     {
       dw2_asm_output_data (1, cfi->dw_cfi_opc,
@@ -1850,15 +1858,13 @@ output_cfi (dw_cfi_ref cfi, dw_fde_ref f
 
 	case DW_CFA_offset_extended:
 	case DW_CFA_def_cfa:
-	  dw2_asm_output_data_uleb128 (cfi->dw_cfi_oprnd1.dw_cfi_reg_num,
-				       NULL);
+	  dw2_asm_output_data_uleb128 (op1_reg, NULL);
 	  dw2_asm_output_data_uleb128 (cfi->dw_cfi_oprnd2.dw_cfi_offset, NULL);
 	  break;
 
 	case DW_CFA_offset_extended_sf:
 	case DW_CFA_def_cfa_sf:
-	  dw2_asm_output_data_uleb128 (cfi->dw_cfi_oprnd1.dw_cfi_reg_num,
-				       NULL);
+	  dw2_asm_output_data_uleb128 (op1_reg, NULL);
 	  dw2_asm_output_data_sleb128 (cfi->dw_cfi_oprnd2.dw_cfi_offset, NULL);
 	  break;
 
@@ -1866,15 +1872,14 @@ output_cfi (dw_cfi_ref cfi, dw_fde_ref f
 	case DW_CFA_undefined:
 	case DW_CFA_same_value:
 	case DW_CFA_def_cfa_register:
-	  dw2_asm_output_data_uleb128 (cfi->dw_cfi_oprnd1.dw_cfi_reg_num,
-				       NULL);
+	  dw2_asm_output_data_uleb128 (op1_reg, NULL);
 	  break;
 
 	case DW_CFA_register:
-	  dw2_asm_output_data_uleb128 (cfi->dw_cfi_oprnd1.dw_cfi_reg_num,
-				       NULL);
-	  dw2_asm_output_data_uleb128 (cfi->dw_cfi_oprnd2.dw_cfi_reg_num,
-				       NULL);
+	  dw2_asm_output_data_uleb128 (op1_reg, NULL);
+	  dw2_asm_output_data_uleb128
+	    (DWARF2_FRAME_REG_OUT (cfi->dw_cfi_oprnd2.dw_cfi_reg_num, for_eh),
+	     NULL);
 	  break;
 
 	case DW_CFA_def_cfa_offset:
@@ -1904,7 +1909,7 @@ output_cfi (dw_cfi_ref cfi, dw_fde_ref f
     }
 }
 
-/* Output the call frame information used to used to record information
+/* Output the call frame information used to record information
    that relates to calculating the frame pointer, and records the
    location of saved registers.  */
 

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre