re PR tree-optimization/78821 (GCC7: Copying whole 32 bits structure field by field not optimised into copying whole 32 bits at once)
PR tree-optimization/78821
* gimple-ssa-store-merging.c (find_bswap_or_nop_load): Give up
if base is TARGET_MEM_REF. If base is not MEM_REF, set base_addr
to the address of the base rather than the base itself.
(find_bswap_or_nop_1): Just use pointer comparison for vuse check.
(find_bswap_or_nop_finalize): New function.
(find_bswap_or_nop): Use it.
(bswap_replace): Return a tree rather than bool, change first
argument from gimple * to gimple_stmt_iterator, allow inserting
into an empty sequence, allow ins_stmt to be NULL - then emit
all stmts into gsi. Fix up MEM_REF address gimplification.
(pass_optimize_bswap::execute): Adjust bswap_replace caller.
(struct store_immediate_info): Add N and INS_STMT non-static
data members.
(store_immediate_info::store_immediate_info): Initialize them
from newly added ctor args.
(merged_store_group::apply_stores): Formatting fixes. Sort by
bitpos at the end.
(stmts_may_clobber_ref_p): For stores call also
refs_anti_dependent_p.
(gather_bswap_load_refs): New function.
(imm_store_chain_info::try_coalesce_bswap): New method.
(imm_store_chain_info::coalesce_immediate_stores): Use it.
(split_group): Handle LROTATE_EXPR and NOP_EXPR rhs_code specially.
(imm_store_chain_info::output_merged_store): Fail if number of
new estimated stmts is bigger or equal than old. Handle LROTATE_EXPR
and NOP_EXPR rhs_code.
(pass_store_merging::process_store): Compute n and ins_stmt, if
ins_stmt is non-NULL and the store rhs is otherwise invalid, use
LROTATE_EXPR rhs_code. Pass n and ins_stmt to store_immediate_info
ctor.
(pass_store_merging::execute): Calculate dominators.
* gcc.dg/store_merging_16.c: New test.
From-SVN: r254948
