reassoc: Fix reassociation on 32-bit hosts with > 32767 bbs [PR98514]

Hi!

Apparently reassoc ICEs on large functions (more than 32767 basic blocks
with something to reassociate in those).
The problem is that the pass uses long type to store the ranks, and
the bb ranks are (number of SSA_NAMEs with default defs + 2 + bb->index) << 16,
so with many basic blocks we overflow the ranks and we then have assertions
rank is not negative.

The following patch just uses HOST_WIDE_INT instead of long in the pass,
yes, it means slightly higher memory consumption (one array indexed by
bb->index is twice as large, and one hash_map from trees to the ranks
will grow by 50%, but I think it is better than punting on large functions
the reassociation on 32-bit hosts and making it inconsistent e.g. when
cross-compiling.  Given vec.h uses unsigned for vect element counts,
we don't really support more than 4G of SSA_NAMEs or more than 2G of basic
blocks in a function, so even with the << 16 we can't really overflow the
HOST_WIDE_INT rank counters.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2021-01-05  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/98514
	* tree-ssa-reassoc.c (bb_rank): Change type from long * to
	HOST_WIDE_INT *.
	(operand_rank): Change type from hash_map<tree, long> to
	hash_map<tree, HOST_WIDE_INT>.
	(phi_rank): Change return type from long to HOST_WIDE_INT.
	(loop_carried_phi): Change block_rank variable type from long to
	HOST_WIDE_INT.
	(propagate_rank): Change return type, rank parameter type and
	op_rank variable type from long to HOST_WIDE_INT.
	(find_operand_rank): Change return type from long to HOST_WIDE_INT
	and change slot variable type from long * to HOST_WIDE_INT *.
	(insert_operand_rank): Change rank parameter type from long to
	HOST_WIDE_INT.
	(get_rank): Change return type and rank variable type from long to
	HOST_WIDE_INT.  Use HOST_WIDE_INT_PRINT_DEC instead of %ld to print
	the rank.
	(init_reassoc): Change rank variable type from long to HOST_WIDE_INT
	and adjust correspondingly bb_rank and operand_rank initialization.


	Jakub

On Tue, 5 Jan 2021, Jakub Jelinek wrote:

> Hi!
> 
> Apparently reassoc ICEs on large functions (more than 32767 basic blocks
> with something to reassociate in those).
> The problem is that the pass uses long type to store the ranks, and
> the bb ranks are (number of SSA_NAMEs with default defs + 2 + bb->index) << 16,
> so with many basic blocks we overflow the ranks and we then have assertions
> rank is not negative.
> 
> The following patch just uses HOST_WIDE_INT instead of long in the pass,
> yes, it means slightly higher memory consumption (one array indexed by
> bb->index is twice as large, and one hash_map from trees to the ranks
> will grow by 50%, but I think it is better than punting on large functions
> the reassociation on 32-bit hosts and making it inconsistent e.g. when
> cross-compiling.  Given vec.h uses unsigned for vect element counts,
> we don't really support more than 4G of SSA_NAMEs or more than 2G of basic
> blocks in a function, so even with the << 16 we can't really overflow the
> HOST_WIDE_INT rank counters.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK (can you use int64_t instead?)

Thanks,
Richard.

> 2021-01-05  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR tree-optimization/98514
> 	* tree-ssa-reassoc.c (bb_rank): Change type from long * to
> 	HOST_WIDE_INT *.
> 	(operand_rank): Change type from hash_map<tree, long> to
> 	hash_map<tree, HOST_WIDE_INT>.
> 	(phi_rank): Change return type from long to HOST_WIDE_INT.
> 	(loop_carried_phi): Change block_rank variable type from long to
> 	HOST_WIDE_INT.
> 	(propagate_rank): Change return type, rank parameter type and
> 	op_rank variable type from long to HOST_WIDE_INT.
> 	(find_operand_rank): Change return type from long to HOST_WIDE_INT
> 	and change slot variable type from long * to HOST_WIDE_INT *.
> 	(insert_operand_rank): Change rank parameter type from long to
> 	HOST_WIDE_INT.
> 	(get_rank): Change return type and rank variable type from long to
> 	HOST_WIDE_INT.  Use HOST_WIDE_INT_PRINT_DEC instead of %ld to print
> 	the rank.
> 	(init_reassoc): Change rank variable type from long to HOST_WIDE_INT
> 	and adjust correspondingly bb_rank and operand_rank initialization.
> 
> --- gcc/tree-ssa-reassoc.c.jj	2021-01-04 10:25:37.153252851 +0100
> +++ gcc/tree-ssa-reassoc.c	2021-01-04 17:01:15.211112328 +0100
> @@ -200,10 +200,10 @@ static unsigned int next_operand_entry_i
>  /* Starting rank number for a given basic block, so that we can rank
>     operations using unmovable instructions in that BB based on the bb
>     depth.  */
> -static long *bb_rank;
> +static HOST_WIDE_INT *bb_rank;
>  
>  /* Operand->rank hashtable.  */
> -static hash_map<tree, long> *operand_rank;
> +static hash_map<tree, HOST_WIDE_INT> *operand_rank;
>  
>  /* Vector of SSA_NAMEs on which after reassociate_bb is done with
>     all basic blocks the CFG should be adjusted - basic blocks
> @@ -212,7 +212,7 @@ static hash_map<tree, long> *operand_ran
>  static vec<tree> reassoc_branch_fixups;
>  
>  /* Forward decls.  */
> -static long get_rank (tree);
> +static HOST_WIDE_INT get_rank (tree);
>  static bool reassoc_stmt_dominates_stmt_p (gimple *, gimple *);
>  
>  /* Wrapper around gsi_remove, which adjusts gimple_uid of debug stmts
> @@ -257,7 +257,7 @@ reassoc_remove_stmt (gimple_stmt_iterato
>     calculated into an accumulator variable to be independent for each
>     iteration of the loop.  If STMT is some other phi, the rank is the
>     block rank of its containing block.  */
> -static long
> +static HOST_WIDE_INT
>  phi_rank (gimple *stmt)
>  {
>    basic_block bb = gimple_bb (stmt);
> @@ -311,7 +311,7 @@ static bool
>  loop_carried_phi (tree exp)
>  {
>    gimple *phi_stmt;
> -  long block_rank;
> +  HOST_WIDE_INT block_rank;
>  
>    if (TREE_CODE (exp) != SSA_NAME
>        || SSA_NAME_IS_DEFAULT_DEF (exp))
> @@ -337,10 +337,10 @@ loop_carried_phi (tree exp)
>     from expression OP.  For most operands, this is just the rank of OP.
>     For loop-carried phis, the value is zero to avoid undoing the bias
>     in favor of the phi.  */
> -static long
> -propagate_rank (long rank, tree op)
> +static HOST_WIDE_INT
> +propagate_rank (HOST_WIDE_INT rank, tree op)
>  {
> -  long op_rank;
> +  HOST_WIDE_INT op_rank;
>  
>    if (loop_carried_phi (op))
>      return rank;
> @@ -352,17 +352,17 @@ propagate_rank (long rank, tree op)
>  
>  /* Look up the operand rank structure for expression E.  */
>  
> -static inline long
> +static inline HOST_WIDE_INT
>  find_operand_rank (tree e)
>  {
> -  long *slot = operand_rank->get (e);
> +  HOST_WIDE_INT *slot = operand_rank->get (e);
>    return slot ? *slot : -1;
>  }
>  
>  /* Insert {E,RANK} into the operand rank hashtable.  */
>  
>  static inline void
> -insert_operand_rank (tree e, long rank)
> +insert_operand_rank (tree e, HOST_WIDE_INT rank)
>  {
>    gcc_assert (rank > 0);
>    gcc_assert (!operand_rank->put (e, rank));
> @@ -370,7 +370,7 @@ insert_operand_rank (tree e, long rank)
>  
>  /* Given an expression E, return the rank of the expression.  */
>  
> -static long
> +static HOST_WIDE_INT
>  get_rank (tree e)
>  {
>    /* SSA_NAME's have the rank of the expression they are the result
> @@ -414,7 +414,7 @@ get_rank (tree e)
>      {
>        ssa_op_iter iter;
>        gimple *stmt;
> -      long rank;
> +      HOST_WIDE_INT rank;
>        tree op;
>  
>        /* If we already have a rank for this expression, use that.  */
> @@ -448,7 +448,7 @@ get_rank (tree e)
>  	{
>  	  fprintf (dump_file, "Rank for ");
>  	  print_generic_expr (dump_file, e);
> -	  fprintf (dump_file, " is %ld\n", rank);
> +	  fprintf (dump_file, " is " HOST_WIDE_INT_PRINT_DEC "\n", rank);
>  	}
>  
>        /* Note the rank in the hashtable so we don't recompute it.  */
> @@ -6774,7 +6774,7 @@ static void
>  init_reassoc (void)
>  {
>    int i;
> -  long rank = 2;
> +  HOST_WIDE_INT rank = 2;
>    int *bbs = XNEWVEC (int, n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS);
>  
>    /* Find the loops, so that we can prevent moving calculations in
> @@ -6788,8 +6788,8 @@ init_reassoc (void)
>    /* Reverse RPO (Reverse Post Order) will give us something where
>       deeper loops come later.  */
>    pre_and_rev_post_order_compute (NULL, bbs, false);
> -  bb_rank = XCNEWVEC (long, last_basic_block_for_fn (cfun));
> -  operand_rank = new hash_map<tree, long>;
> +  bb_rank = XCNEWVEC (HOST_WIDE_INT, last_basic_block_for_fn (cfun));
> +  operand_rank = new hash_map<tree, HOST_WIDE_INT>;
>  
>    /* Give each default definition a distinct rank.  This includes
>       parameters and the static chain.  Walk backwards over all
> 
> 	Jakub
> 
>