Patchwork PR 50686: dwarf2cfi fix for IRIX

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Submitter Bernd Schmidt
Date April 24, 2013, 9:39 a.m.
Message ID <5177A86E.5000107@codesourcery.com>
Download mbox | patch
Permalink /patch/239115/
State New
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Comments

Bernd Schmidt - April 24, 2013, 9:39 a.m.
Before the target was removed, IRIX defined DWARF_FRAME_RETURN_COLUMN to
be reg 64, which is something other than INCOMING_RETURN_ADDR_RTX (reg
31).  This means that when we see a save of reg 31, we discover that
this is really a save of reg 64 and produce dwarf information
accordingly.  However, there is nothing that handles a restore of reg 31
specially, which means that reg 64 is unaffected by it. This is a
problem when shrink-wrapping, if we end up merging two paths where one
can arrive directly from the function start, and another where we've
gone through a save/restore of reg 31. The paths will disagree on where
reg 64 is saved.

The following patch fixes it by handling restores of
INCOMING_RETURN_ADDR_RTX specially if it is different from
DWARF_FRAME_RETURN_COLUMN.  Bootstrapped and tested on x86_64-linux, and
also bootstrapped by Rainer Orth on IRIX with 4.7.3. Ok?


Bernd

Patch

	* dwarf2cfi.c (dwarf2out_frame_debug_cfa_restore): When restoring
	INCOMING_RETURN_ADDR_RTX, and it is different from
	DWARF_FRAME_RETURN_COLUMN, mark the latter as saved in the former.

Index: gcc/dwarf2cfi.c
===================================================================
--- gcc/dwarf2cfi.c	(revision 189425)
+++ gcc/dwarf2cfi.c	(working copy)
@@ -1240,6 +1240,10 @@  dwarf2out_frame_debug_cfa_restore (rtx r
 
   add_cfi_restore (regno);
   update_row_reg_save (cur_row, regno, NULL);
+  if (REG_P (INCOMING_RETURN_ADDR_RTX)
+      && regno == dwf_regno (INCOMING_RETURN_ADDR_RTX)
+      && regno != DWARF_FRAME_RETURN_COLUMN)
+    reg_save (DWARF_FRAME_RETURN_COLUMN, regno, 0);
 }
 
 /* A subroutine of dwarf2out_frame_debug, process a REG_CFA_WINDOW_SAVE.