On Thu, Oct 31, 2013 at 6:41 AM, Jeff Law <l...@redhat.com> wrote: > On 10/28/13 23:02, Jeff Law wrote: >> >> >> Based on a suggestion from Marc, I want to use infer_nonnull_range in >> the erroneous path isolation optimization. >> >> In the process of doing that, I found a few deficiencies in >> infer_nonnull_range that need to be addressed. >> >> >> First, infer_nonnull_range_p doesn't infer ranges from a GIMPLE_RETURN >> if the current function is marked as returns_nonnull. That's fixed in >> the relatively obvious way. >> >> Second, infer_nonnull_range_p, when presented with an arglist where the >> non-null attribute applies to all pointer arguments, it won't bother to >> determine if OP is actually one of the arguments :( It just assumes >> that OP is in the argument list. Opps. >> >> Third, I want to be able to call infer_nonnull_range with OP being 0B. >> That lets me use infer_nonnull_range to look for explicit null pointer >> dereferences, explicit uses of null in a return statement in functions >> that can't return non-null and explicit uses of null arguments when >> those arguments can't be null. Sadly, to make that work we need to use >> operand_equal_p rather than simple pointer comparisons to see if OP >> shows up in STMT. >> >> Finally, for detecting explicit null pointers, infer_nonnull_range calls >> count_ptr_derefs. count_ptr_derefs counts things in two ways. One with >> a FOR_EACH_SSA_TREE_OPERAND, then again with simple walks of the tree >> structures. Not surprisingly if we're looking for an explicit 0B, then >> the loop over the operands finds nothing, but walking the tree >> structures does. And the checking assert triggers. This change removes >> the assert and instead sets *num_uses_p to a sane value. >> >> I don't have testcases for this stuff that are independent of the >> erroneous path isolation optimization. However, each is triggered by >> tests I'll include in the the erroneous path isolation patch. >> >> Bootstrapped and regression tested on x86_64-unknown-linux-gnu. OK for >> the trunk? > > I'm withdrawing this patch. While everything works exactly how I wanted, I > think it's best to rework things a bit and totally eliminate > count_ptr_derefs entirely.
Yes! And count_uses_and_derefs, too. See walk_stmt_load_store_addr_ops. Richard. > That change makes it significantly easier to move infer_nonnull_range out of > tree-vrp.c and into gimple.c (or wherever Andrew wants it) without a > significant modularity break. > Jeff >
