propagating NEW into ORIG, consolidate aliasing information so that
they both share the same memory tags. */
-static void
+void
merge_alias_info (tree orig, tree new)
{
tree new_sym = SSA_NAME_VAR (new);
#endif
/* Synchronize the type tags. If both pointers had a tag and they
- are different, then something has gone wrong. */
+ are different, then something has gone wrong. Type tags can
+ always be merged because they are flow insensitive, all the SSA
+ names of the same base DECL share the same type tag. */
if (new_ann->type_mem_tag == NULL_TREE)
new_ann->type_mem_tag = orig_ann->type_mem_tag;
else if (orig_ann->type_mem_tag == NULL_TREE)
else
gcc_assert (new_ann->type_mem_tag == orig_ann->type_mem_tag);
- /* Synchronize the name tags. If NEW did not have a name tag, get
- it from ORIG. This happens when NEW is a compiler generated
- temporary which still hasn't had its points-to information filled
- in. */
- if (SSA_NAME_PTR_INFO (orig))
+ /* Check that flow-sensitive information is compatible. Notice that
+ we may not merge flow-sensitive information here. This function
+ is called when propagating equivalences dictated by the IL, like
+ a copy operation P_i = Q_j, and from equivalences dictated by
+ control-flow, like if (P_i == Q_j).
+
+ In the former case, P_i and Q_j are equivalent in every block
+ dominated by the assignment, so their flow-sensitive information
+ is always the same. However, in the latter case, the pointers
+ P_i and Q_j are only equivalent in one of the sub-graphs out of
+ the predicate, so their flow-sensitive information is not the
+ same in every block dominated by the predicate.
+
+ Since we cannot distinguish one case from another in this
+ function, we can only make sure that if P_i and Q_j have
+ flow-sensitive information, they should be compatible. */
+ if (SSA_NAME_PTR_INFO (orig) && SSA_NAME_PTR_INFO (new))
{
struct ptr_info_def *orig_ptr_info = SSA_NAME_PTR_INFO (orig);
struct ptr_info_def *new_ptr_info = SSA_NAME_PTR_INFO (new);
- if (new_ptr_info == NULL)
- duplicate_ssa_name_ptr_info (new, orig_ptr_info);
- else if (orig_ptr_info->name_mem_tag
- && new_ptr_info->name_mem_tag
- && orig_ptr_info->pt_vars
- && new_ptr_info->pt_vars)
- {
- /* Note that pointer NEW may actually have a different set
- of pointed-to variables. However, since NEW is being
- copy-propagated into ORIG, it must always be true that
- the pointed-to set for pointer NEW is the same, or a
- subset, of the pointed-to set for pointer ORIG. If this
- isn't the case, we shouldn't have been able to do the
- propagation of NEW into ORIG. */
- gcc_assert (bitmap_intersect_p (new_ptr_info->pt_vars,
- orig_ptr_info->pt_vars));
- }
+ /* Note that pointer NEW and ORIG may actually have different
+ pointed-to variables (e.g., PR 18291 represented in
+ testsuite/gcc.c-torture/compile/pr18291.c). However, since
+ NEW is being copy-propagated into ORIG, it must always be
+ true that the pointed-to set for pointer NEW is the same, or
+ a subset, of the pointed-to set for pointer ORIG. If this
+ isn't the case, we shouldn't have been able to do the
+ propagation of NEW into ORIG. */
+ if (orig_ptr_info->name_mem_tag
+ && new_ptr_info->name_mem_tag
+ && orig_ptr_info->pt_vars
+ && new_ptr_info->pt_vars)
+ gcc_assert (bitmap_intersect_p (new_ptr_info->pt_vars,
+ orig_ptr_info->pt_vars));
}
}
/* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
- into the operand pointed by OP_P.
+ into the operand pointed to by OP_P.
Use this version for const/copy propagation as it will perform additional
checks to ensure validity of the const/copy propagation. */
/* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
- into the tree pointed by OP_P.
+ into the tree pointed to by OP_P.
Use this version for const/copy propagation when SSA operands are not
available. It will perform the additional checks to ensure validity of
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