[Bug tree-optimization/19853] [4.0 Regression] ICE with address in struct assignment

["uweigand at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From uweigand at gcc dot gnu dot org  2005-02-10 14:03 -------
Some more information about the problem.

The __builtin_memset call gets as V_MAY_DEF operands all global variables
(using the call_clobbered_vars mechanism).  Initially, this does *not*
include global_int, because it is not referenced in the function.  When
transforming the function into SSA form, all such V_MAY_DEF operands get
annotated with an SSA_NAME.

During SRA, the intializer &global_int is copied into a statement, thus
exposing global_int as referenced variable.  The generate_element_init
function calls find_new_referenced_vars, which notices that fact, and
adds global_int to call_clobbered_vars.  After SRA is done, another SSA
rename pass renames all existing uses of this new variable.  Note,
however, that at this point the V_MAY_DEF list of the __builtin_memset
call does *not* (yet) contain global_int, and so it is not renamed.

During a later optimzation pass (redphi), the operand list of the
__builtin_memset call is recomputed (for unrelated reasons).  At this
point, the full contents of the call_clobbered_vars list, now including
global_int, is added as V_MAY_DEF operands.  All such operands that were
already in that list before will keep their SSA_NAME numbers.  However,
global_int was not in that list before and thus gets entered as pure DECL
into the V_MAY_DEF list.  Also, the redphi pass does not mark this variable
as to-be-renamed (it doesn't actually know anything about the variable),
and thus it remains unrenamed.

At the end of the redphi pass, verify_ssa goes through all operands of
all statements, and aborts because it finds a DECL as V_MAY_DEF.




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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19853