Re: [PATCH] Fix RTL DSE compile time hog (PR rtl-optimization/48141)

[Richard Guenther <richard dot guenther at gmail dot com>]

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
>