On Thu, Mar 17, 2011 at 9:41 AM, Richard Guenther
<richard.guent...@gmail.com> wrote:
> On Thu, Mar 17, 2011 at 12:32 AM, Jakub Jelinek <ja...@redhat.com> wrote:
>> Hi!
>>
>> Currently expand_debug_expr doesn't always guarantee canonical
>> MEM_EXPRs, if MEM_EXPR isn't canonical, sometimes aliasing code ICEs on it
>> (since recent Richard's change fortunately only if --enable-checking=yes).
>>
>> The following patch canonicalizes those using fold and if canonicalization
>> isn't successful, just clears the MEM_EXPR.
>>
>> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk and
>> 4.6.1?
>>
>> 2011-03-17 Jakub Jelinek <ja...@redhat.com>
>>
>> PR debug/48134
>> * cfgexpand.c (expand_debug_expr) <component_ref>: Use fold to
>> canonicalize MEM_EXPR, if it still isn't canonical afterwards, just
>> clear MEM_EXPR.
>>
>> * gcc.dg/pr48134.c: New test.
>>
>> --- gcc/cfgexpand.c.jj 2011-03-16 18:30:12.000000000 +0100
>> +++ gcc/cfgexpand.c 2011-03-16 22:05:13.000000000 +0100
>> @@ -2712,6 +2712,8 @@ expand_debug_expr (tree exp)
>>
>> if (MEM_P (op0))
>> {
>> + tree mem_exp;
>> +
>> if (mode1 == VOIDmode)
>> /* Bitfield. */
>> mode1 = smallest_mode_for_size (bitsize, MODE_INT);
>> @@ -2736,6 +2738,12 @@ expand_debug_expr (tree exp)
>> if (op0 == orig_op0)
>> op0 = shallow_copy_rtx (op0);
>> set_mem_attributes (op0, exp, 0);
>> + mem_exp = fold (exp);
>> + if (!SSA_VAR_P (mem_exp)
>> + && TREE_CODE (mem_exp) != MEM_REF
>> + && TREE_CODE (mem_exp) != TARGET_MEM_REF)
>> + mem_exp = NULL_TREE;
>> + set_mem_expr (op0, mem_exp);
>
> That will, for the testcase drop the MEM[&t.s].w completely, right?
> I think you eventually want to use maybe_fold_reference which does
> canonicalize mem-refs after propagation (but also watch for bogus
> debug information due to constant folding of initializers I
> ran into because of setting DECL_INITIAL to error_mark_node for
> unused globals - I'll try to dig up the patch I had to fix that).I am testing the following. Richard.
fix-pr48134
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