re PR debug/41276 (Segmentation fault in lookup_page_table_entry)

PR debug/41276
PR debug/41307
* cselib.c (cselib_expand_value_rtx_cb): Document callback
interface.
(cselib_expand_value_rtx_1): Use callback for SUBREGs.  Adjust
for VALUEs, to implement the documented interface.
* var-tracking.c (vt_expand_loc_callback): Handle SUBREGs.
Adjust for VALUEs and anything else, to implement the
documented interface.

From-SVN: r151628

1 files changed, 37 insertions, 6 deletions

diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index 475ba57..0e665b9 100644
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -6243,7 +6243,8 @@ check_wrap_constant (enum machine_mode mode, rtx result)
 }
 
 /* Callback for cselib_expand_value, that looks for expressions
-   holding the value in the var-tracking hash tables.  */
+   holding the value in the var-tracking hash tables.  Return X for
+   standard processing, anything else is to be used as-is.  */
 
 static rtx
 vt_expand_loc_callback (rtx x, bitmap regs, int max_depth, void *data)
@@ -6254,19 +6255,46 @@ vt_expand_loc_callback (rtx x, bitmap regs, int max_depth, void *data)
   location_chain loc;
   rtx result;
 
-  gcc_assert (GET_CODE (x) == VALUE);
+  if (GET_CODE (x) == SUBREG)
+    {
+      rtx subreg = SUBREG_REG (x);
+
+      if (GET_CODE (SUBREG_REG (x)) != VALUE)
+	return x;
+
+      subreg = cselib_expand_value_rtx_cb (SUBREG_REG (x), regs,
+					   max_depth - 1,
+					   vt_expand_loc_callback, data);
+
+      if (!subreg)
+	return NULL;
+
+      result = simplify_gen_subreg (GET_MODE (x), subreg,
+				    GET_MODE (SUBREG_REG (x)),
+				    SUBREG_BYTE (x));
+
+      /* Invalid SUBREGs are ok in debug info.  ??? We could try
+	 alternate expansions for the VALUE as well.  */
+      if (!result && (REG_P (subreg) || MEM_P (subreg)))
+	result = gen_rtx_raw_SUBREG (GET_MODE (x), subreg, SUBREG_BYTE (x));
+
+      return result;
+    }
+
+  if (GET_CODE (x) != VALUE)
+    return x;
 
   if (VALUE_RECURSED_INTO (x))
-    return NULL;
+    return x;
 
   dv = dv_from_value (x);
   var = (variable) htab_find_with_hash (vars, dv, dv_htab_hash (dv));
 
   if (!var)
-    return NULL;
+    return x;
 
   if (var->n_var_parts == 0)
-    return NULL;
+    return x;
 
   gcc_assert (var->n_var_parts == 1);
 
@@ -6283,7 +6311,10 @@ vt_expand_loc_callback (rtx x, bitmap regs, int max_depth, void *data)
     }
 
   VALUE_RECURSED_INTO (x) = false;
-  return result;
+  if (result)
+    return result;
+  else
+    return x;
 }
 
 /* Expand VALUEs in LOC, using VARS as well as cselib's equivalence