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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug rtl-optimization/49169] ARM: optimisations strip the Thumb/ARM mode bit off function pointers
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49169

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-05-26 08:20:22 UTC ---
There are several places in the compiler where we assume DECL_ALIGN
constraints the lower bits of the address of the DECL.

See several similar bugs in the past (PR47239 comes to my mind).

fold-const.c:get_pointer_modulus_and_residue looks suspicious to me here,
so you might want to try

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    (revision 174266)
+++ gcc/fold-const.c    (working copy)
@@ -9219,7 +9219,8 @@ get_pointer_modulus_and_residue (tree ex
   *residue = 0;

   code = TREE_CODE (expr);
-  if (code == ADDR_EXPR)
+  if (code == ADDR_EXPR
+      && TREE_CODE (TREE_OPERAND (expr, 0)) != FUNCTION_DECL)
     {
       unsigned int bitalign;
       bitalign = get_object_alignment_1 (TREE_OPERAND (expr, 0), residue);