Hi,
for some reasons the FAIL of pass49-frag now annoyed me enough to look
into it, where it didn't do so for the last 50 years it's failing (give or
take a few). mudflap has a mean to mark some expressions as not
interesting to generate checks for, which is used to disable this for the
indirect refs that are generated for the varargs accesses (naturally these
can't be checked because nobody registers these stack slots). That is
done via build_va_arg_indirect_ref calling mf_mark on the generated
indirect_ref.
Now, our gimplifier changes this indirect_ref into a mem_ref, making the
marking (via a hash-table marked_trees in tree-mudflap.c) obsolete.
Instead of amending the gimplifier to copy the mark whenever changing a
marked tree, I chose to instead simply generate a memref right from the
start, which isn't gimplified further, hence the mark stays okay.
Yes, that's somewhat fragile, but so is the whole mudflap code generation.
And in the abstract it seems better to generate more natural gimple code
to begin with (of course the operand still is gimplified when necessary,
but that doesn't destroy the mark as it's done in place).
Why pass49-frag also failed before mem-ref I don't know. I don't want to
know. I'd speculate that it's similar reasons. Or maybe it wasn't
failing and I confuse it with some other pass4x-frag that was failing for
years where nobody cared.
In any case, patch fixes this mudflap testcase and for x86_64-linux that
was the last failing one. Regstrapping on x86_64-linux in progress. Okay
for trunk?
Ciao,
Michael.
PS: Btw, that varargs at least for x86_64 didn't work with mudflap makes
me somewhat suspicious about the existence of people using -fmudflap.
Perhaps we should just remove the whole mudflap code for 4.7.
--
* builtins.c (build_va_arg_indirect_ref): Use
build_simple_mem_ref_loc.
Index: builtins.c
===================================================================
--- builtins.c (revision 171675)
+++ builtins.c (working copy)
@@ -4748,7 +4748,7 @@ std_gimplify_va_arg_expr (tree valist, t
tree
build_va_arg_indirect_ref (tree addr)
{
- addr = build_fold_indirect_ref_loc (EXPR_LOCATION (addr), addr);
+ addr = build_simple_mem_ref_loc (EXPR_LOCATION (addr), addr);
if (flag_mudflap) /* Don't instrument va_arg INDIRECT_REF. */
mf_mark (addr);
