===================================================================
@@ -692,16 +692,16 @@ get_value_range (const_tree var)
/* Defer allocating the equivalence set. */
vr->equiv = NULL;
- /* If VAR is a default definition, the variable can take any value
- in VAR's type. */
+ /* If VAR is a default definition of a parameter, the variable can
+ take any value in VAR's type. */
sym = SSA_NAME_VAR (var);
- if (SSA_NAME_IS_DEFAULT_DEF (var))
+ if (SSA_NAME_IS_DEFAULT_DEF (var)
+ && TREE_CODE (sym) == PARM_DECL)
{
/* Try to use the "nonnull" attribute to create ~[0, 0]
anti-ranges for pointers. Note that this is only valid with
default definitions of PARM_DECLs. */
- if (TREE_CODE (sym) == PARM_DECL
- && POINTER_TYPE_P (TREE_TYPE (sym))
+ if (POINTER_TYPE_P (TREE_TYPE (sym))
&& nonnull_arg_p (sym))
set_value_range_to_nonnull (vr, TREE_TYPE (sym));
else
@@ -2225,12 +2225,20 @@ extract_range_from_binary_expr (value_ra
else
set_value_range_to_varying (&vr1);
- /* If either range is UNDEFINED, so is the result. */
- if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
+ /* If both ranges are UNDEFINED, so is the result. */
+ if (vr0.type == VR_UNDEFINED && vr1.type == VR_UNDEFINED)
{
set_value_range_to_undefined (vr);
return;
}
+ /* If one of the ranges is UNDEFINED drop it to VARYING for the following
+ code. At some point we may want to special-case operations that
+ have UNDEFINED result for all or some value-ranges of the not UNDEFINED
+ operand. */
+ else if (vr0.type == VR_UNDEFINED)
+ set_value_range_to_varying (&vr0);
+ else if (vr1.type == VR_UNDEFINED)
+ set_value_range_to_varying (&vr1);
/* The type of the resulting value range defaults to VR0.TYPE. */
type = vr0.type;
@@ -6642,6 +6650,8 @@ vrp_visit_phi_node (gimple phi)
if (vr_result.type == VR_VARYING)
goto varying;
+ else if (vr_result.type == VR_UNDEFINED)
+ goto update_range;
old_edges = vr_phi_edge_counts[SSA_NAME_VERSION (lhs)];
vr_phi_edge_counts[SSA_NAME_VERSION (lhs)] = edges;
@@ -6713,6 +6723,7 @@ vrp_visit_phi_node (gimple phi)
/* If the new range is different than the previous value, keep
iterating. */
+update_range:
if (update_value_range (lhs, &vr_result))
{
if (dump_file && (dump_flags & TDF_DETAILS))
I noticed that for binary expressions VRP contains the same bugs that CCP once did (it treats UNDEFINED * 0 as UNDEFINED). Then I noticed we never hit this bug because we never end up with any range being UNDEFINED - which is bad, because this way we miss value-ranges for all conditionally initialized variables. Thus, the following patch fixes this and conservatively handles the binary expression case (which is only of academic interest anyway - the important part is to handle UNDEFINED in PHIs). Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk. Richard. 2011-07-29 Richard Guenther <rguenther@suse.de> * tree-vrp.c (get_value_range): Only set parameter default definitions to varying, leave others at undefined. (extract_range_from_binary_expr): Fix undefined handling. (vrp_visit_phi_node): Handle merged undefined state. * gcc.dg/uninit-suppress.c: Also disable VRP. * gcc.dg/uninit-suppress_2.c: Likewise. Index: gcc/testsuite/gcc.dg/uninit-suppress.c =================================================================== *** gcc/testsuite/gcc.dg/uninit-suppress.c (revision 176869) --- gcc/testsuite/gcc.dg/uninit-suppress.c (working copy) *************** *** 1,5 **** /* { dg-do compile } */ ! /* { dg-options "-fno-tree-ccp -O2 -Wuninitialized -Wno-maybe-uninitialized" } */ void blah(); int gflag; --- 1,5 ---- /* { dg-do compile } */ ! /* { dg-options "-fno-tree-ccp -fno-tree-vrp -O2 -Wuninitialized -Wno-maybe-uninitialized" } */ void blah(); int gflag; Index: gcc/testsuite/gcc.dg/uninit-suppress_2.c =================================================================== *** gcc/testsuite/gcc.dg/uninit-suppress_2.c (revision 176869) --- gcc/testsuite/gcc.dg/uninit-suppress_2.c (working copy) *************** *** 1,5 **** /* { dg-do compile } */ ! /* { dg-options "-fno-tree-ccp -O2 -Wuninitialized -Werror=uninitialized -Wno-error=maybe-uninitialized" } */ void blah(); int gflag; --- 1,5 ---- /* { dg-do compile } */ ! /* { dg-options "-fno-tree-ccp -fno-tree-vrp -O2 -Wuninitialized -Werror=uninitialized -Wno-error=maybe-uninitialized" } */ void blah(); int gflag;