From 9b7626383822799d60ea3c62e62e700f16337cd6 Mon Sep 17 00:00:00 2001
From: Aldy Hernandez <aldyh@redhat.com>
Date: Mon, 26 Aug 2024 07:33:38 +0200
Subject: [PATCH] Remove recursion in simplify_control_stmt_condition_1
[PR114855].
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.
---
gcc/tree-ssa-threadedge.cc | 118 -------------------------------------
1 file changed, 118 deletions(-)
diff --git a/gcc/tree-ssa-threadedge.cc b/gcc/tree-ssa-threadedge.cc
index 0aa2aa851430..207ec34e3211 100644
--- a/gcc/tree-ssa-threadedge.cc
+++ b/gcc/tree-ssa-threadedge.cc
@@ -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);
--
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