Richard Biener <rguent...@suse.de> writes:
> The following rectifies a change during hash-map intruction which
> changed the uncprop operand_equal_p based hash to a pointer-based
> hash_map. That assumes pointer equality between constants which
> does not hold since different (but compatible) typed constants
> can appear in the IL. For SSA names the equivalence holds, of course.
>
> Fixing this should increase the number of eliminated const-copies
> on edges during out-of-SSA. It also happens to fix the LTO
> bootstrap miscompare of cc1 and friends, but I can't really
> explain that.
>
> [LTO] bootstrapped and tested on x86_64-unknown-linux-gnu, applied
> to trunk.
>
> Richard.
>
> 2019-01-03 Jan Hubicka <hubi...@ucw.cz>
>
> PR tree-optimization/85574
> * tree-ssa-uncprop.c (struct equiv_hash_elt): Remove unused
> structure.
> (struct ssa_equip_hash_traits): Declare.
> (val_ssa_equiv): Use custom hash traits using operand_equal_p.
>
> Index: gcc/tree-ssa-uncprop.c
> ===================================================================
> --- gcc/tree-ssa-uncprop.c (revision 267549)
> +++ gcc/tree-ssa-uncprop.c (working copy)
> @@ -268,21 +268,24 @@ associate_equivalences_with_edges (void)
> so with each value we have a list of SSA_NAMEs that have the
> same value. */
>
> -
> -/* Main structure for recording equivalences into our hash table. */
> -struct equiv_hash_elt
> -{
> - /* The value/key of this entry. */
> - tree value;
> -
> - /* List of SSA_NAMEs which have the same value/key. */
> - vec<tree> equivalences;
> +/* Traits for the hash_map to record the value to SSA name equivalences
> + mapping. */
> +struct ssa_equip_hash_traits : default_hash_traits <tree>
> +{
> + static inline hashval_t hash (value_type value)
> + { return iterative_hash_expr (value, 0); }
> + static inline bool equal (value_type existing, value_type candidate)
> + { return operand_equal_p (existing, candidate, 0); }
> };
FWIW, this is a dup of tree_operand_hash.
Thanks,
Richard
> +typedef hash_map<tree, auto_vec<tree>,
> + simple_hashmap_traits <ssa_equip_hash_traits,
> + auto_vec <tree> > > val_ssa_equiv_t;
> +
> /* Global hash table implementing a mapping from invariant values
> to a list of SSA_NAMEs which have the same value. We might be
> able to reuse tree-vn for this code. */
> -static hash_map<tree, auto_vec<tree> > *val_ssa_equiv;
> +val_ssa_equiv_t *val_ssa_equiv;
>
> static void uncprop_into_successor_phis (basic_block);
>
> @@ -476,7 +479,7 @@ pass_uncprop::execute (function *fun)
> associate_equivalences_with_edges ();
>
> /* Create our global data structures. */
> - val_ssa_equiv = new hash_map<tree, auto_vec<tree> > (1024);
> + val_ssa_equiv = new val_ssa_equiv_t (1024);
>
> /* We're going to do a dominator walk, so ensure that we have
> dominance information. */
