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Remove recursion in simplify_control_stmt_condition_1 [PR114855].

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Remove some ad-hoc simplification code in the forward threader, as the
call into the ranger in m_simplifier->simplify() will handle anything we
can do manually in simplify_control_stmt_condition_1.

In PR114855, DOM time is reduced from 120s to 92s (-23%) and overall
compilation time from 235s to 205s (-12%).  The total thread count at -O1 is
unchanged for the testcase.

In our bootstrap .ii benchmark suite, I see we thread 3 threads less
over all files at -O1.  At -O2, the backward threader picks up one more,
for no difference over all.

	PR tree-optimization/114855

gcc/ChangeLog:

	* tree-ssa-threadedge.cc: Remove unneeded recursion.
This commit is contained in:
Aldy Hernandez 2024-08-26 07:33:38 +02:00 committed by Richard Biener
parent 63a598deb0
commit 9b76263838
1 changed files with 0 additions and 118 deletions
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118
gcc/tree-ssa-threadedge.cc
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@ -496,124 +496,6 @@ jump_threader::simplify_control_stmt_condition_1
std::swap (op0, op1);
}
/* If the condition has the form (A & B) CMP 0 or (A | B) CMP 0 then
recurse into the LHS to see if there is a simplification that
makes this condition always true or always false along the edge
E. */
if ((cond_code == EQ_EXPR || cond_code == NE_EXPR)
&& TREE_CODE (op0) == SSA_NAME
&& integer_zerop (op1))
{
gimple *def_stmt = SSA_NAME_DEF_STMT (op0);
if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
;
else if (gimple_assign_rhs_code (def_stmt) == BIT_AND_EXPR
|| gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR)
{
enum tree_code rhs_code = gimple_assign_rhs_code (def_stmt);
const tree rhs1 = gimple_assign_rhs1 (def_stmt);
const tree rhs2 = gimple_assign_rhs2 (def_stmt);
/* Is A != 0 ? */
const tree res1
= simplify_control_stmt_condition_1 (e, def_stmt,
rhs1, NE_EXPR, op1,
limit - 1);
if (res1 == NULL_TREE)
;
else if (rhs_code == BIT_AND_EXPR && integer_zerop (res1))
{
/* If A == 0 then (A & B) != 0 is always false. */
if (cond_code == NE_EXPR)
return boolean_false_node;
/* If A == 0 then (A & B) == 0 is always true. */
if (cond_code == EQ_EXPR)
return boolean_true_node;
}
else if (rhs_code == BIT_IOR_EXPR && integer_nonzerop (res1))
{
/* If A != 0 then (A | B) != 0 is always true. */
if (cond_code == NE_EXPR)
return boolean_true_node;
/* If A != 0 then (A | B) == 0 is always false. */
if (cond_code == EQ_EXPR)
return boolean_false_node;
}
/* Is B != 0 ? */
const tree res2
= simplify_control_stmt_condition_1 (e, def_stmt,
rhs2, NE_EXPR, op1,
limit - 1);
if (res2 == NULL_TREE)
;
else if (rhs_code == BIT_AND_EXPR && integer_zerop (res2))
{
/* If B == 0 then (A & B) != 0 is always false. */
if (cond_code == NE_EXPR)
return boolean_false_node;
/* If B == 0 then (A & B) == 0 is always true. */
if (cond_code == EQ_EXPR)
return boolean_true_node;
}
else if (rhs_code == BIT_IOR_EXPR && integer_nonzerop (res2))
{
/* If B != 0 then (A | B) != 0 is always true. */
if (cond_code == NE_EXPR)
return boolean_true_node;
/* If B != 0 then (A | B) == 0 is always false. */
if (cond_code == EQ_EXPR)
return boolean_false_node;
}
if (res1 != NULL_TREE && res2 != NULL_TREE)
{
if (rhs_code == BIT_AND_EXPR
&& TYPE_PRECISION (TREE_TYPE (op0)) == 1
&& integer_nonzerop (res1)
&& integer_nonzerop (res2))
{
/* If A != 0 and B != 0 then (bool)(A & B) != 0 is true. */
if (cond_code == NE_EXPR)
return boolean_true_node;
/* If A != 0 and B != 0 then (bool)(A & B) == 0 is false. */
if (cond_code == EQ_EXPR)
return boolean_false_node;
}
if (rhs_code == BIT_IOR_EXPR
&& integer_zerop (res1)
&& integer_zerop (res2))
{
/* If A == 0 and B == 0 then (A | B) != 0 is false. */
if (cond_code == NE_EXPR)
return boolean_false_node;
/* If A == 0 and B == 0 then (A | B) == 0 is true. */
if (cond_code == EQ_EXPR)
return boolean_true_node;
}
}
}
/* Handle (A CMP B) CMP 0. */
else if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt))
== tcc_comparison)
{
tree rhs1 = gimple_assign_rhs1 (def_stmt);
tree rhs2 = gimple_assign_rhs2 (def_stmt);
tree_code new_cond = gimple_assign_rhs_code (def_stmt);
if (cond_code == EQ_EXPR)
new_cond = invert_tree_comparison (new_cond, false);
tree res
= simplify_control_stmt_condition_1 (e, def_stmt,
rhs1, new_cond, rhs2,
limit - 1);
if (res != NULL_TREE && is_gimple_min_invariant (res))
return res;
}
}
gimple_cond_set_code (dummy_cond, cond_code);
gimple_cond_set_lhs (dummy_cond, op0);
gimple_cond_set_rhs (dummy_cond, op1);