[Bug rtl-optimization/59890] var-tracking.c:val_reset segfaults

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59890

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Even with the obvious fix to val_reset

Index: gcc/var-tracking.c
===================================================================
--- gcc/var-tracking.c  (revision 206808)
+++ gcc/var-tracking.c  (working copy)
@@ -2501,7 +2501,8 @@ val_reset (dataflow_set *set, decl_or_va

   gcc_assert (var->n_var_parts == 1);

-  if (var->onepart == ONEPART_VALUE)
+  if (var->onepart == ONEPART_VALUE
+      && local_get_addr_cache != NULL)
     {     
       rtx x = dv_as_value (dv);
       void **slot;


I get during -m32 multilib x86_64 libjava build

Program received signal SIGSEGV, Segmentation fault.
vt_get_canonicalize_base (loc=0x0)
    at /space/rguenther/src/svn/trunk/gcc/var-tracking.c:1985
1985              || GET_CODE (loc) == AND)
(gdb) bt
#0  vt_get_canonicalize_base (loc=0x0)
    at /space/rguenther/src/svn/trunk/gcc/var-tracking.c:1985
#1  0x0000000000ba7db0 in local_get_addr_clear_given_value (v=<optimized out>, 
    slot=0x1ab8c28, x=0x1a6bdc8)
    at /space/rguenther/src/svn/trunk/gcc/var-tracking.c:2484
#2  0x00000000008bfeec in pointer_map_traverse (pmap=0x0, fn=0x1ab8c28, 
    data=0x1a6bdc8) at /space/rguenther/src/svn/trunk/gcc/pointer-set.c:269
#3  0x0000000000bb6612 in val_reset (set=set@entry=0x1ab74b8, 
    dv=dv@entry=0x1a6bdc8)
    at /space/rguenther/src/svn/trunk/gcc/var-tracking.c:2522
#4  0x0000000000bba55c in val_resolve (set=set@entry=0x1ab74b8, val=0x1a6bdc8, 
    loc=0x7ffff60b6b20, insn=insn@entry=0x7ffff4c07dc8)
    at /space/rguenther/src/svn/trunk/gcc/var-tracking.c:2597
#5  0x0000000000bbac6f in compute_bb_dataflow (
    bb=<error reading variable: Unhandled dwarf expression opcode 0xfa>)
    at /space/rguenther/src/svn/trunk/gcc/var-tracking.c:6695
#6  0x0000000000bbbfa9 in vt_find_locations ()
    at /space/rguenther/src/svn/trunk/gcc/var-tracking.c:7047

Btw, this all is with

Index: gcc/var-tracking.c
===================================================================
--- gcc/var-tracking.c  (revision 206808)
+++ gcc/var-tracking.c  (working copy)
@@ -6934,12 +6935,12 @@ vt_find_locations (void)
   bool success = true;

   timevar_push (TV_VAR_TRACKING_DATAFLOW);
-  /* Compute reverse completion order of depth first search of the CFG
+  /* Compute reverse top sord order of the inverted CFG
      so that the data-flow runs faster.  */
-  rc_order = XNEWVEC (int, n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS);
+  rc_order = XNEWVEC (int, n_basic_blocks_for_fn (cfun));
   bb_order = XNEWVEC (int, last_basic_block_for_fn (cfun));
-  pre_and_rev_post_order_compute (NULL, rc_order, false);
-  for (i = 0; i < n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS; i++)
+  int num = inverted_post_order_compute (rc_order);
+  for (i = 0; i < num; i++)
     bb_order[rc_order[i]] = i;
   free (rc_order);


which provides a nice speedup for some testcases (inverted post-order
is the correct order for a forward dataflow problem).

static bool
local_get_addr_clear_given_value (const void *v ATTRIBUTE_UNUSED,
                                  void **slot, void *x)
{
  if (vt_get_canonicalize_base ((rtx)*slot) == x)
    *slot = NULL;
  return true;
}

if you do that again you have to guard against a cleared valued!
(pointer-map does not allow removal)

Index: gcc/var-tracking.c
===================================================================
--- gcc/var-tracking.c  (revision 206808)
+++ gcc/var-tracking.c  (working copy)
@@ -2481,7 +2481,8 @@ static bool
 local_get_addr_clear_given_value (const void *v ATTRIBUTE_UNUSED,
                                  void **slot, void *x)
 {
-  if (vt_get_canonicalize_base ((rtx)*slot) == x)
+  if (*slot != NULL
+      && vt_get_canonicalize_base ((rtx)*slot) == x)
     *slot = NULL;
   return true;
 }