[Bug target/77527] [7 Regression] ICE: in make_decl_rtl, at varasm.c:1311 with -mstringop-strategy=libcall

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77527

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, what I see happening is that lim2 creates a v_lsm.5 VAR_DECL here, and it
is is_gimple_reg and only used in SSA_NAMEs.  As it is a wide vector, it is
BLKmode in the end, and during expansion emit_block_move called because of an
assignment to it calls mark_decl_addressable on the VAR_DECL (which queues
TREE_ADDRESSABLE set for after expansion).  The v_lsm.5 VAR_DECL then appears
in MEM_EXPRs of various MEMs, but because the VAR_DECL has been originally
gimple register, it doesn't have DECL_RTL set during expansion (each SSA_NAME
for it has its own I bet).  Then when nonoverlapping_memrefs_p is called on it
during DSE, it sees  the MEM_EXPR is not is_gimple_reg and uses DECL_RTL, which
ICEs, because it doesn't have the rtl and is not meant to get rtl created that
way.

I wonder if the queued addressable decls set to TREE_ADDRESSABLE after it
shouldn't have DECL_RTL set at that point (but to which one), or alternatively
if nonoverlapping_memrefs_p should use DECL_RTL_IF_SET instead and somehow deal
with the fact when that returns NULL_RTX (dunno if it should handle that
conservatively, by giving up, or if there are cases which it could still
handle).