This is split off from PR38474 for clarity, see steven's comment #35 in that PR. Compiling the testcase of that PR (http://gcc.gnu.org/bugzilla/attachment.cgi?id=16873) should be illuminating
Created attachment 17024 [details] Add address -> temp slot map Instead of huge list walks, just look up the address in the hash table and use the mapped temp slot of the address maps to a temp slot.
Ok. Thanks.
Subject: Bug 38586 Author: steven Date: Sun Jan 4 00:15:58 2009 New Revision: 143041 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=143041 Log: PR middle-end/38586 * function.c (struct temp_slot): Move to the section of the file that deals with temp slots. Remove field 'address'. (temp_slot_address_table): New hash table of address -> temp slot. (struct temp_slot_address_entry): New struct, items for the table. (temp_slot_address_compute_hash, temp_slot_address_hash, temp_slot_address_eq, insert_temp_slot_address): Support functions for the new table. (find_temp_slot_from_address): Rewrite to use the new hash table. (remove_unused_temp_slot_addresses): Remove addresses of temp slots that have been made available. (remove_unused_temp_slot_addresses_1): Call-back for htab_traverse, worker function for remove_unused_temp_slot_addresses. (assign_stack_temp_for_type): Don't clear the temp slot address list. Add the temp slot address to the address -> temp slot map. (update_temp_slot_address): Update via insert_temp_slot_address. (free_temp_slots): Call remove_unused_temp_slot_addresses. (pop_temp_slots): Likewise. (init_temp_slots): Allocate the address -> temp slot map, or empty the map if it is already allocated. (prepare_function_start): Initialize temp slot processing. Modified: trunk/gcc/ChangeLog trunk/gcc/function.c
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