tree-predcom.c: Add general comment on Store-Store chains.
* tree-predcom.c: Add general comment on Store-Store chains. (split_data_refs_to_components): Postpone clearing eliminate_store_p flag in component. (get_chain_last_ref_at): Rename into... (get_chain_last_write_at): ...this. (get_chain_last_write_before_load): New function. (add_ref_to_chain): Promote type of chain from CT_STORE_LOAD to CT_STORE_STORE when write reference is added. (determine_roots_comp): Support load ref in CT_STORE_STORE chains. (is_inv_store_elimination_chain): Update get_chain_last_write_at call. (initialize_root_vars_store_elim_1): Ditto. (initialize_root_vars_store_elim_2): Ditto. Replace rhs once default definition is created. (execute_pred_commoning_chain): Support load ref in CT_STORE_STORE chain by replacing it with dominant stored value. gcc/testsuite * gcc.dg/tree-ssa/predcom-dse-12.c: New test. From-SVN: r254956
This commit is contained in:
Bin Cheng
Bin Cheng
parent
90ef577378
commit
9cdcebf971
4 changed files with 177 additions and 23 deletions
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@ -1,3 +1,21 @@
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2017-11-20 Bin Cheng <bin.cheng@arm.com>
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* tree-predcom.c: Add general comment on Store-Store chains.
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(split_data_refs_to_components): Postpone clearing eliminate_store_p
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flag in component.
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(get_chain_last_ref_at): Rename into...
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(get_chain_last_write_at): ...this.
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(get_chain_last_write_before_load): New function.
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(add_ref_to_chain): Promote type of chain from CT_STORE_LOAD to
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CT_STORE_STORE when write reference is added.
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(determine_roots_comp): Support load ref in CT_STORE_STORE chains.
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(is_inv_store_elimination_chain): Update get_chain_last_write_at call.
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(initialize_root_vars_store_elim_1): Ditto.
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(initialize_root_vars_store_elim_2): Ditto. Replace rhs once default
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definition is created.
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(execute_pred_commoning_chain): Support load ref in CT_STORE_STORE
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chain by replacing it with dominant stored value.
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2017-11-20 Bin Cheng <bin.cheng@arm.com>
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* tree-predcom.c (add_ref_to_chain): Remove check on distance.
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@ -1,3 +1,7 @@
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2017-11-20 Bin Cheng <bin.cheng@arm.com>
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* gcc.dg/tree-ssa/predcom-dse-12.c: New test.
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2017-11-20 Marc Glisse <marc.glisse@inria.fr>
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PR testsuite/82951
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67
gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-12.c
Normal file
67
gcc/testsuite/gcc.dg/tree-ssa/predcom-dse-12.c
Normal file
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@ -0,0 +1,67 @@
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/* { dg-do run } */
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/* { dg-options "-O2 -fno-inline -fpredictive-commoning -fdump-tree-pcom-details" } */
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int arr[105] = {2, 3, 5, 7, 11};
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int result0[10] = {2, 3, 5, 7, 11};
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int result1[10] = {0, -1, 5, -2, 11, 0};
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int result2[10] = {0, 0, -1, -2, -2, 0};
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int result3[10] = {0, 0, 0, -1, -2, -2, 0};
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int result4[10] = {0, 0, 0, 0, -1, -2, -2, 0};
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int result100[105] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -2, 0};
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extern void abort (void);
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int sum;
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void __attribute__((noinline)) foo (int * restrict a, int len, int t1, int t2)
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{
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int i;
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for (i = 0; i < len; i++)
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{
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a[i] = t1;
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a[i + 3] = t2;
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a[i + 1] = -1;
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sum = sum + a[i] + a[i + 3];
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}
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}
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void check (int *a, int *res, int len, int sval)
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{
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int i;
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if (sum != sval)
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abort ();
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for (i = 0; i < len; i++)
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if (a[i] != res[i])
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abort ();
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}
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int main (void)
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{
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foo (arr, 0, 0, -2);
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check (arr, result0, 10, 0);
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foo (arr, 1, 0, -2);
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check (arr, result1, 10, -2);
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foo (arr, 2, 0, -2);
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check (arr, result2, 10, -6);
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foo (arr, 3, 0, -2);
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check (arr, result3, 10, -12);
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foo (arr, 4, 0, -2);
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check (arr, result4, 10, -20);
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foo (arr, 100, 0, -2);
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check (arr, result100, 105, -220);
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return 0;
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}
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/* { dg-final { scan-tree-dump "Store-stores chain" "pcom"} } */
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@ -192,6 +192,10 @@ along with GCC; see the file COPYING3. If not see
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The interesting part is this can be viewed either as general store motion
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or general dead store elimination in either intra/inter-iterations way.
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With trivial effort, we also support load inside Store-Store chains if the
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load is dominated by a store statement in the same iteration of loop. You
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can see this as a restricted Store-Mixed-Load-Store chain.
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TODO: For now, we don't support store-store chains in multi-exit loops. We
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force to not unroll in case of store-store chain even if other chains might
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ask for unroll.
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@ -902,8 +906,6 @@ split_data_refs_to_components (struct loop *loop,
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gimple_bb (dataref->stmt));
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dataref->pos = comp->refs.length ();
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comp->refs.quick_push (dataref);
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if (DR_IS_READ (dr))
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comp->eliminate_store_p = false;
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}
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for (i = 0; i < n; i++)
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@ -1039,19 +1041,36 @@ get_chain_root (chain_p chain)
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return chain->refs[0];
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}
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/* Given CHAIN, returns the last ref at DISTANCE, or NULL if it doesn't
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/* Given CHAIN, returns the last write ref at DISTANCE, or NULL if it doesn't
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exist. */
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static inline dref
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get_chain_last_ref_at (chain_p chain, unsigned distance)
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get_chain_last_write_at (chain_p chain, unsigned distance)
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{
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unsigned i;
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for (unsigned i = chain->refs.length (); i > 0; i--)
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if (DR_IS_WRITE (chain->refs[i - 1]->ref)
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&& distance == chain->refs[i - 1]->distance)
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return chain->refs[i - 1];
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for (i = chain->refs.length (); i > 0; i--)
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if (distance == chain->refs[i - 1]->distance)
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break;
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return NULL;
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}
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return (i > 0) ? chain->refs[i - 1] : NULL;
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/* Given CHAIN, returns the last write ref with the same distance before load
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at index LOAD_IDX, or NULL if it doesn't exist. */
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static inline dref
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get_chain_last_write_before_load (chain_p chain, unsigned load_idx)
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{
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gcc_assert (load_idx < chain->refs.length ());
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unsigned distance = chain->refs[load_idx]->distance;
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for (unsigned i = load_idx; i > 0; i--)
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if (DR_IS_WRITE (chain->refs[i - 1]->ref)
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&& distance == chain->refs[i - 1]->distance)
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return chain->refs[i - 1];
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return NULL;
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}
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/* Adds REF to the chain CHAIN. */
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@ -1075,6 +1094,10 @@ add_ref_to_chain (chain_p chain, dref ref)
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chain->has_max_use_after = false;
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}
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/* Promote this chain to CT_STORE_STORE if it has multiple stores. */
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if (DR_IS_WRITE (ref->ref))
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chain->type = CT_STORE_STORE;
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/* Don't set the flag for store-store chain since there is no use. */
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if (chain->type != CT_STORE_STORE
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&& ref->distance == chain->length
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@ -1347,9 +1370,29 @@ determine_roots_comp (struct loop *loop,
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}
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comp->refs.qsort (order_drefs);
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/* For Store-Store chain, we only support load if it is dominated by a
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store statement in the same iteration of loop. */
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if (comp->eliminate_store_p)
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for (a = NULL, i = 0; i < comp->refs.length (); i++)
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{
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if (DR_IS_WRITE (comp->refs[i]->ref))
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a = comp->refs[i];
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else if (a == NULL || a->offset != comp->refs[i]->offset)
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{
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/* If there is load that is not dominated by a store in the
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same iteration of loop, clear the flag so no Store-Store
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chain is generated for this component. */
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comp->eliminate_store_p = false;
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break;
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}
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}
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/* Determine roots and create chains for components. */
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FOR_EACH_VEC_ELT (comp->refs, i, a)
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{
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if (!chain
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|| (chain->type == CT_LOAD && DR_IS_WRITE (a->ref))
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|| (!comp->eliminate_store_p && DR_IS_WRITE (a->ref))
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|| wi::leu_p (MAX_DISTANCE, a->offset - last_ofs))
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{
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@ -1361,11 +1404,11 @@ determine_roots_comp (struct loop *loop,
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else
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release_chain (chain);
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if (DR_IS_READ (a->ref))
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type = CT_LOAD;
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else
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type = comp->eliminate_store_p ? CT_STORE_STORE : CT_STORE_LOAD;
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/* Determine type of the chain. If the root reference is a load,
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this can only be a CT_LOAD chain; other chains are intialized
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to CT_STORE_LOAD and might be promoted to CT_STORE_STORE when
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new reference is added. */
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type = DR_IS_READ (a->ref) ? CT_LOAD : CT_STORE_LOAD;
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chain = make_rooted_chain (a, type);
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last_ofs = a->offset;
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continue;
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@ -1676,7 +1719,7 @@ is_inv_store_elimination_chain (struct loop *loop, chain_p chain)
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values. */
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for (unsigned i = 0; i < chain->length; i++)
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{
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dref a = get_chain_last_ref_at (chain, i);
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dref a = get_chain_last_write_at (chain, i);
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if (a == NULL)
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continue;
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@ -1720,7 +1763,7 @@ initialize_root_vars_store_elim_1 (chain_p chain)
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/* Initialize root value for eliminated stores at each distance. */
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for (i = 0; i < n; i++)
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{
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dref a = get_chain_last_ref_at (chain, i);
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dref a = get_chain_last_write_at (chain, i);
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if (a == NULL)
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continue;
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@ -1783,10 +1826,13 @@ initialize_root_vars_store_elim_2 (struct loop *loop,
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{
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/* Root value is rhs operand of the store to be eliminated if
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it isn't loaded from memory before loop. */
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dref a = get_chain_last_ref_at (chain, i);
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dref a = get_chain_last_write_at (chain, i);
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val = gimple_assign_rhs1 (a->stmt);
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if (TREE_CLOBBER_P (val))
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val = get_or_create_ssa_default_def (cfun, SSA_NAME_VAR (var));
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{
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val = get_or_create_ssa_default_def (cfun, SSA_NAME_VAR (var));
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gimple_assign_set_rhs1 (a->stmt, val);
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}
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vtemps[n - i - 1] = val;
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}
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@ -2054,7 +2100,7 @@ static void
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execute_pred_commoning_chain (struct loop *loop, chain_p chain,
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bitmap tmp_vars)
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{
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unsigned i, n;
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unsigned i;
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dref a;
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tree var;
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bool in_lhs;
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@ -2091,10 +2137,29 @@ execute_pred_commoning_chain (struct loop *loop, chain_p chain,
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finalize_eliminated_stores (loop, chain);
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}
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/* Eliminate the stores killed by following store. */
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n = chain->refs.length ();
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for (i = 0; i < n - 1; i++)
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remove_stmt (chain->refs[i]->stmt);
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bool last_store_p = true;
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for (i = chain->refs.length (); i > 0; i--)
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{
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a = chain->refs[i - 1];
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/* Preserve the last store of the chain. Eliminate other stores
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which are killed by the last one. */
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if (DR_IS_WRITE (a->ref))
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{
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if (last_store_p)
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last_store_p = false;
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else
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remove_stmt (a->stmt);
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continue;
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}
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/* Any load in Store-Store chain must be dominated by a previous
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store, we replace the load reference with rhs of the store. */
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dref b = get_chain_last_write_before_load (chain, i - 1);
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gcc_assert (b != NULL);
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var = gimple_assign_rhs1 (b->stmt);
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replace_ref_with (a->stmt, var, false, false);
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}
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}
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else
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{
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