[PATCH] Fix RTL DSE compile time hog (PR rtl-optimization/48141)
Kenneth Zadeck
zadeck@naturalbridge.com
Wed Mar 16 13:28:00 GMT 2011
i think that i sympathize with richard's "do we really need another
parm?" whine. I would have just nailed it in without the parm. I
think that it is unreasonable to expect that a program with basic blocks
this big needs the full range of optimizations performed.
It is perfectly reasonable to have the quality of the optimization
degrade as a function of size.
If you want to tie the trigger to something, then leave out the parm and
tie it -O3.
On 03/16/2011 07:59 AM, Richard Guenther wrote:
> On Wed, Mar 16, 2011 at 12:52 PM, Jakub Jelinek<jakub@redhat.com> wrote:
>> On Wed, Mar 16, 2011 at 09:46:20AM +0100, Paolo Bonzini wrote:
>>> On 03/16/2011 12:12 AM, Kenneth Zadeck wrote:
>>>> so how much time does this save?
>>>>
>>>> I agree that this is a useful simplification, but it seems unlikely to
>>>> be that important in real code.
>>>> it seems like the 5000 store test would in general provide a better
>>>> safety valve.
>>> I think having both is a good idea.
>> Here is the second patch, ok for both to trunk if this one passes
>> bootstrap/regtest?
>>
>> With just this patch alone on the testcase with the default
>> --param=max-dse-active-local-stores=5000 cc1 spends 18.9 seconds
>> in DSE1+DSE2, with =1000 just 4 seconds and with =10 0.4 seconds.
>> With the earlier patch in addition to this one the time in DSE1+DSE2
>> is 0.3 seconds no matter what the parameter is.
> That suggests we can avoid the new param? (btw, we should start
> thinking of emitting a diagnostic if we run into such artificial limits)
>
> The earlier patch is ok for all branches.
>
> Thanks,
> Richard.
>
>> 2011-03-16 Jakub Jelinek<jakub@redhat.com>
>>
>> PR rtl-optimization/48141
>> * params.def (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES): New.
>> * dse.c: Include params.h.
>> (active_local_stores_len): New variable.
>> (add_wild_read, dse_step1): Clear it when setting active_local_stores
>> to NULL.
>> (record_store, check_mem_read_rtx): Decrease it when removing
>> from the chain.
>> (scan_insn): Likewise. Increase it when adding to chain, if it
>> reaches PARAM_MAX_DSE_ACTIVE_LOCAL_STORES limit, set to 1 and
>> set active_local_stores to NULL before the addition.
>> * Makefile.in (dse.o): Depend on $(PARAMS_H).
>>
>> --- gcc/params.def.jj 2011-02-15 15:42:27.000000000 +0100
>> +++ gcc/params.def 2011-03-16 12:20:16.000000000 +0100
>> @@ -698,6 +698,12 @@ DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
>> "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
>> 100, 0, 0)
>>
>> +/* This is the maximum number of active local stores RTL DSE will consider. */
>> +DEFPARAM (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES,
>> + "max-dse-active-local-stores",
>> + "Maximum number of active local stores in RTL dead store elimination",
>> + 5000, 0, 0)
>> +
>> /* Prefetching and cache-optimizations related parameters. Default values are
>> usually set by machine description. */
>>
>> --- gcc/dse.c.jj 2011-02-15 15:42:26.000000000 +0100
>> +++ gcc/dse.c 2011-03-16 12:34:18.000000000 +0100
>> @@ -47,6 +47,7 @@ along with GCC; see the file COPYING3.
>> #include "optabs.h"
>> #include "dbgcnt.h"
>> #include "target.h"
>> +#include "params.h"
>>
>> /* This file contains three techniques for performing Dead Store
>> Elimination (dse).
>> @@ -387,6 +388,7 @@ static alloc_pool insn_info_pool;
>> /* The linked list of stores that are under consideration in this
>> basic block. */
>> static insn_info_t active_local_stores;
>> +static int active_local_stores_len;
>>
>> struct bb_info
>> {
>> @@ -947,6 +949,7 @@ add_wild_read (bb_info_t bb_info)
>> }
>> insn_info->wild_read = true;
>> active_local_stores = NULL;
>> + active_local_stores_len = 0;
>> }
>>
>>
>> @@ -1538,6 +1541,7 @@ record_store (rtx body, bb_info_t bb_inf
>> {
>> insn_info_t insn_to_delete = ptr;
>>
>> + active_local_stores_len--;
>> if (last)
>> last->next_local_store = ptr->next_local_store;
>> else
>> @@ -2074,6 +2078,7 @@ check_mem_read_rtx (rtx *loc, void *data
>> if (dump_file)
>> dump_insn_info ("removing from active", i_ptr);
>>
>> + active_local_stores_len--;
>> if (last)
>> last->next_local_store = i_ptr->next_local_store;
>> else
>> @@ -2163,6 +2168,7 @@ check_mem_read_rtx (rtx *loc, void *data
>> if (dump_file)
>> dump_insn_info ("removing from active", i_ptr);
>>
>> + active_local_stores_len--;
>> if (last)
>> last->next_local_store = i_ptr->next_local_store;
>> else
>> @@ -2222,6 +2228,7 @@ check_mem_read_rtx (rtx *loc, void *data
>> if (dump_file)
>> dump_insn_info ("removing from active", i_ptr);
>>
>> + active_local_stores_len--;
>> if (last)
>> last->next_local_store = i_ptr->next_local_store;
>> else
>> @@ -2426,6 +2433,7 @@ scan_insn (bb_info_t bb_info, rtx insn)
>> if (dump_file)
>> dump_insn_info ("removing from active", i_ptr);
>>
>> + active_local_stores_len--;
>> if (last)
>> last->next_local_store = i_ptr->next_local_store;
>> else
>> @@ -2453,6 +2461,12 @@ scan_insn (bb_info_t bb_info, rtx insn)
>> fprintf (dump_file, "handling memset as BLKmode store\n");
>> if (mems_found == 1)
>> {
>> + if (active_local_stores_len++
>> +>= PARAM_VALUE (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES))
>> + {
>> + active_local_stores_len = 1;
>> + active_local_stores = NULL;
>> + }
>> insn_info->next_local_store = active_local_stores;
>> active_local_stores = insn_info;
>> }
>> @@ -2496,6 +2510,12 @@ scan_insn (bb_info_t bb_info, rtx insn)
>> it as cannot delete. This simplifies the processing later. */
>> if (mems_found == 1)
>> {
>> + if (active_local_stores_len++
>> +>= PARAM_VALUE (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES))
>> + {
>> + active_local_stores_len = 1;
>> + active_local_stores = NULL;
>> + }
>> insn_info->next_local_store = active_local_stores;
>> active_local_stores = insn_info;
>> }
>> @@ -2534,6 +2554,7 @@ remove_useless_values (cselib_val *base)
>>
>> if (del)
>> {
>> + active_local_stores_len--;
>> if (last)
>> last->next_local_store = insn_info->next_local_store;
>> else
>> @@ -2584,6 +2605,7 @@ dse_step1 (void)
>> = create_alloc_pool ("cse_store_info_pool",
>> sizeof (struct store_info), 100);
>> active_local_stores = NULL;
>> + active_local_stores_len = 0;
>> cselib_clear_table ();
>>
>> /* Scan the insns. */
>> --- gcc/Makefile.in.jj 2011-02-02 16:30:50.000000000 +0100
>> +++ gcc/Makefile.in 2011-03-16 12:26:12.000000000 +0100
>> @@ -3070,7 +3070,7 @@ dse.o : dse.c $(CONFIG_H) $(SYSTEM_H) co
>> $(TREE_H) $(TM_P_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) insn-config.h \
>> $(RECOG_H) $(EXPR_H) $(DF_H) cselib.h $(DBGCNT_H) $(TIMEVAR_H) \
>> $(TREE_PASS_H) alloc-pool.h $(ALIAS_H) dse.h $(OPTABS_H) $(TARGET_H) \
>> - $(BITMAP_H)
>> + $(BITMAP_H) $(PARAMS_H)
>> fwprop.o : fwprop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
>> $(DIAGNOSTIC_CORE_H) insn-config.h $(RECOG_H) $(FLAGS_H) $(OBSTACK_H) $(BASIC_BLOCK_H) \
>> output.h $(DF_H) alloc-pool.h $(TIMEVAR_H) $(TREE_PASS_H) $(TARGET_H) \
>>
>>
>> Jakub
>>
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