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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/100464] [11/12 Regression] emitted binary
 code changes when -g is enabled at -O3
Date: Fri, 07 May 2021 07:51:09 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100464

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
So the difference is that 'b' is TREE_ADDRESSABLE with -g but not without.

in forwprop2 we do

-  # DEBUG j$40 =3D> MEM <int *> [(int *[33] *)&*.LC0{&} + 40B]
+  # DEBUG j$40 =3D> &b{&}

and that makes b TREE_ADDRESSABLE which happens in

tree
canonicalize_constructor_val (tree cval, tree from_decl)
{
...
      if (VAR_P (base))
        TREE_ADDRESSABLE (base) =3D 1;

which was added in r181197 as to fix "Java early folding".  I'll test remov=
ing
that (it should assert the addressable flag is set, but _not_ when we're
ultimatively coming from a debug stmt which means it'll be awkward to keep)=
.=