[PATCH] Implement redundant store elimination, fix PR38513
Richard Guenther
rguenther@suse.de
Tue Dec 30 21:18:00 GMT 2008
On Tue, 30 Dec 2008, Richard Guenther wrote:
>
> This implements redundant store elimination (just like postreload CSE
> does) from within FRE. It triggers quite some time for C++ code and
> also breaks the following testcases for now
>
> FAIL: g++.dg/warn/Warray-bounds.C (test for warnings, line 32)
> FAIL: g++.dg/warn/Warray-bounds.C (test for warnings, line 43)
> FAIL: g++.dg/warn/Warray-bounds.C (test for warnings, line 54)
>
> FAIL: gcc.dg/Warray-bounds.c (test for warnings, line 32)
> FAIL: gcc.dg/Warray-bounds.c (test for warnings, line 43)
> FAIL: gcc.dg/Warray-bounds.c (test for warnings, line 54)
> FAIL: gcc.dg/vect/vect-35.c scan-tree-dump-times vect "vectorized 1 loops" 1
> FAIL: gcc.dg/vect/vect-multitypes-16.c scan-tree-dump-times vect
> "vectorized 1 loops" 1
> FAIL: gcc.dg/vect/vect-multitypes-17.c scan-tree-dump-times vect
> "vectorized 1 loops" 1
> FAIL: gcc.dg/vect/vect-reduc-dot-u8b.c scan-tree-dump-times vect
> "vectorized 1 loops" 1
> FAIL: gcc.dg/vect/slp-widen-mult-u8.c scan-tree-dump-times vect
> "vectorized 1 loops" 1
> FAIL: gcc.dg/vect/wrapv-vect-reduc-dot-s8b.c scan-tree-dump-times vect
> "vectorized 1 loops" 1
>
> because all of them test for something on redundant stores that are
> now removed. Before applying the patch I need to sort them out, but
> I am just posting the patch now as it works and do that work later.
>
> Otherwise bootstrapped and tested on x86_64-unknown-linux-gnu.
Oops. Old patch. This is the current one.
Richard.
2008-12-29 Richard Guenther <rguenther@suse.de>
PR tree-optimization/38513
* tree-ssa-pre.c (eliminate): Remove redundant stores.
* gcc.dg/tree-ssa/ssa-fre-18.c: New testcase.
* gcc.dg/tree-ssa/ssa-dse-11.c: Adjust.
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-18.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-18.c (revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-18.c (revision 0)
***************
*** 0 ****
--- 1,26 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O -fdump-tree-fre" } */
+
+ struct f {
+ float a;
+ float b;
+ float c;
+ float d;
+ };
+
+ struct f a;
+
+ void h(float, float, float, float);
+
+ void g(void)
+ {
+ float a1 = a.a, b = a.b, c = a.c, d = a.d;
+ a.a = a1;
+ a.b = b;
+ a.c = c;
+ a.d = d;
+ h(a1, b, c, d);
+ }
+
+ /* { dg-final { scan-tree-dump-not "a\\\.? = " "fre" } } */
+ /* { dg-final { cleanup-tree-dump "fre" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-11.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-11.c (revision 142949)
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-11.c (working copy)
*************** void foo(int *p)
*** 6,18 ****
{
while (1)
{
! *p = 0;
*p = 0;
}
}
void bar(int *p)
{
! *p = 0;
*p = 0;
abort ();
}
--- 6,18 ----
{
while (1)
{
! *p = 1;
*p = 0;
}
}
void bar(int *p)
{
! *p = 1;
*p = 0;
abort ();
}
Index: gcc/tree-ssa-pre.c
===================================================================
*** gcc/tree-ssa-pre.c (revision 142960)
--- gcc/tree-ssa-pre.c (working copy)
*************** eliminate (void)
*** 3848,3854 ****
{
gimple_stmt_iterator i;
! for (i = gsi_start_bb (b); !gsi_end_p (i); gsi_next (&i))
{
gimple stmt = gsi_stmt (i);
--- 3848,3854 ----
{
gimple_stmt_iterator i;
! for (i = gsi_start_bb (b); !gsi_end_p (i);)
{
gimple stmt = gsi_stmt (i);
*************** eliminate (void)
*** 3906,3911 ****
--- 3906,3912 ----
propagate_tree_value_into_stmt (&i, sprime);
stmt = gsi_stmt (i);
update_stmt (stmt);
+ gsi_next (&i);
continue;
}
*************** eliminate (void)
*** 3966,3971 ****
--- 3967,4024 ----
}
}
}
+ /* If the statement is a scalar store, see if the expression
+ has the same value number as its rhs. If so, the store is
+ dead. */
+ else if (gimple_assign_single_p (stmt)
+ && !is_gimple_reg (gimple_assign_lhs (stmt))
+ && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
+ || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
+ {
+ tree rhs = gimple_assign_rhs1 (stmt);
+ tree val;
+ val = vn_reference_lookup (gimple_assign_lhs (stmt),
+ shared_vuses_from_stmt (stmt),
+ true, NULL);
+ if (TREE_CODE (rhs) == SSA_NAME)
+ rhs = VN_INFO (rhs)->valnum;
+ if (val
+ && operand_equal_p (val, rhs, 0))
+ {
+ def_operand_p def;
+ use_operand_p use;
+ vuse_vec_p usevec;
+ ssa_op_iter oi;
+ imm_use_iterator ui;
+ gimple use_stmt;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Deleted dead store ");
+ print_gimple_stmt (dump_file, stmt, 0, 0);
+ }
+
+ /* Propagate all may-uses to the uses of their defs. */
+ FOR_EACH_SSA_VDEF_OPERAND (def, usevec, stmt, oi)
+ {
+ tree vuse = VUSE_ELEMENT_VAR (*usevec, 0);
+ tree vdef = DEF_FROM_PTR (def);
+
+ /* If the vdef is used in an abnormal PHI node we
+ have to propagate that flag to the vuse as well. */
+ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vdef))
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vuse) = 1;
+
+ FOR_EACH_IMM_USE_STMT (use_stmt, ui, vdef)
+ FOR_EACH_IMM_USE_ON_STMT (use, ui)
+ SET_USE (use, vuse);
+ }
+
+ gsi_remove (&i, true);
+ release_defs (stmt);
+ continue;
+ }
+ }
/* Visit COND_EXPRs and fold the comparison with the
available value-numbers. */
else if (gimple_code (stmt) == GIMPLE_COND)
*************** eliminate (void)
*** 3990,3995 ****
--- 4043,4050 ----
todo = TODO_cleanup_cfg;
}
}
+
+ gsi_next (&i);
}
}
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