Hi!
For signed a, if we see a >= 0 && a < b and from VR know that b >= 0,
we can optimize those 2 comparisons into one unsigned -
(unsigned) a < (unsigned) b. Similarly for a < 0 || a > b (and also
for a <= b in the first and a >= b in the second).
The patch implements it in the reassoc optimize_range_tests optimization,
so that it can handle even comparisons that aren't adjacent in the && or ||
or & or | conditions, and can handle the conditions across multiple bbs as
well.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2016-10-06 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/77664
* tree-ssa-reassoc.c (update_range_test): Also clear low and high
for the other ranges.
(optimize_range_tests_diff): Fix up formatting.
(optimize_range_tests_var_bound): New function.
(optimize_range_tests): Use it.
* gcc.dg/tree-ssa/pr77664.c: New test.
* gcc.dg/pr77664.c: New test.
--- gcc/tree-ssa-reassoc.c.jj 2016-10-05 17:01:28.724673717 +0200
+++ gcc/tree-ssa-reassoc.c 2016-10-06 13:34:08.872512318 +0200
@@ -2428,6 +2428,8 @@ update_range_test (struct range_entry *r
else
oe->op = error_mark_node;
range->exp = NULL_TREE;
+ range->low = NULL_TREE;
+ range->high = NULL_TREE;
}
return true;
}
@@ -2485,10 +2487,10 @@ optimize_range_tests_xor (enum tree_code
((X - 43U) & ~(75U - 43U)) <= 3U. */
static bool
optimize_range_tests_diff (enum tree_code opcode, tree type,
- tree lowi, tree lowj, tree highi, tree highj,
- vec<operand_entry *> *ops,
- struct range_entry *rangei,
- struct range_entry *rangej)
+ tree lowi, tree lowj, tree highi, tree highj,
+ vec<operand_entry *> *ops,
+ struct range_entry *rangei,
+ struct range_entry *rangej)
{
tree tem1, tem2, mask;
/* Check highi - lowi == highj - lowj. */
@@ -2829,6 +2831,197 @@ optimize_range_tests_to_bit_test (enum t
return any_changes;
}
+/* Attempt to optimize for signed a and b where b is known to be >= 0:
+ a >= 0 && a < b into (unsigned) a < (unsigned) b
+ a >= 0 && a <= b into (unsigned) a <= (unsigned) b */
+
+static bool
+optimize_range_tests_var_bound (enum tree_code opcode, int first, int length,
+ vec<operand_entry *> *ops,
+ struct range_entry *ranges)
+{
+ int i;
+ bool any_changes = false;
+ hash_map<tree, int> *map = NULL;
+
+ for (i = first; i < length; i++)
+ {
+ if (ranges[i].exp == NULL_TREE || !ranges[i].in_p)
+ continue;
+
+ tree type = TREE_TYPE (ranges[i].exp);
+ if (!INTEGRAL_TYPE_P (type)
+ || TYPE_UNSIGNED (type)
+ || ranges[i].low == NULL_TREE
+ || !integer_zerop (ranges[i].low)
+ || ranges[i].high != NULL_TREE)
+ continue;
+ /* EXP >= 0 here. */
+ if (map == NULL)
+ map = new hash_map <tree, int>;
+ map->put (ranges[i].exp, i);
+ }
+
+ if (map == NULL)
+ return false;
+
+ for (i = 0; i < length; i++)
+ {
+ if (ranges[i].low == NULL_TREE
+ || ranges[i].high == NULL_TREE
+ || !integer_zerop (ranges[i].low)
+ || !integer_zerop (ranges[i].high))
+ continue;
+
+ gimple *stmt;
+ tree_code ccode;
+ tree rhs1, rhs2;
+ if (ranges[i].exp)
+ {
+ stmt = SSA_NAME_DEF_STMT (ranges[i].exp);
+ if (!is_gimple_assign (stmt))
+ continue;
+ ccode = gimple_assign_rhs_code (stmt);
+ rhs1 = gimple_assign_rhs1 (stmt);
+ rhs2 = gimple_assign_rhs2 (stmt);
+ }
+ else
+ {
+ operand_entry *oe = (*ops)[ranges[i].idx];
+ stmt = last_stmt (BASIC_BLOCK_FOR_FN (cfun, oe->id));
+ if (gimple_code (stmt) != GIMPLE_COND)
+ continue;
+ ccode = gimple_cond_code (stmt);
+ rhs1 = gimple_cond_lhs (stmt);
+ rhs2 = gimple_cond_rhs (stmt);
+ }
+
+ if (TREE_CODE (rhs1) != SSA_NAME
+ || rhs2 == NULL_TREE
+ || TREE_CODE (rhs2) != SSA_NAME)
+ continue;
+
+ switch (ccode)
+ {
+ case GT_EXPR:
+ case GE_EXPR:
+ if (!ranges[i].in_p)
+ std::swap (rhs1, rhs2);
+ ccode = swap_tree_comparison (ccode);
+ break;
+ case LT_EXPR:
+ case LE_EXPR:
+ if (ranges[i].in_p)
+ std::swap (rhs1, rhs2);
+ break;
+ default:
+ continue;
+ }
+
+ int *idx = map->get (rhs1);
+ if (idx == NULL)
+ continue;
+
+ wide_int nz = get_nonzero_bits (rhs2);
+ if (wi::neg_p (nz))
+ continue;
+
+ /* We have EXP < RHS2 or EXP <= RHS2 where EXP >= 0
+ and RHS2 is known to be RHS2 >= 0. */
+ tree utype = unsigned_type_for (TREE_TYPE (rhs1));
+
+ enum warn_strict_overflow_code wc = WARN_STRICT_OVERFLOW_COMPARISON;
+ if ((ranges[*idx].strict_overflow_p
+ || ranges[i].strict_overflow_p)
+ && issue_strict_overflow_warning (wc))
+ warning_at (gimple_location (stmt), OPT_Wstrict_overflow,
+ "assuming signed overflow does not occur "
+ "when simplifying range test");
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ struct range_entry *r = &ranges[*idx];
+ fprintf (dump_file, "Optimizing range test ");
+ print_generic_expr (dump_file, r->exp, 0);
+ fprintf (dump_file, " +[");
+ print_generic_expr (dump_file, r->low, 0);
+ fprintf (dump_file, ", ");
+ print_generic_expr (dump_file, r->high, 0);
+ fprintf (dump_file, "] and comparison ");
+ print_generic_expr (dump_file, rhs1, 0);
+ fprintf (dump_file, " %s ", op_symbol_code (ccode));
+ print_generic_expr (dump_file, rhs2, 0);
+ fprintf (dump_file, "\n into (");
+ print_generic_expr (dump_file, utype, 0);
+ fprintf (dump_file, ") ");
+ print_generic_expr (dump_file, rhs1, 0);
+ fprintf (dump_file, " %s (", op_symbol_code (ccode));
+ print_generic_expr (dump_file, utype, 0);
+ fprintf (dump_file, ") ");
+ print_generic_expr (dump_file, rhs2, 0);
+ fprintf (dump_file, "\n");
+ }
+
+ if (ranges[i].in_p)
+ std::swap (rhs1, rhs2);
+
+ unsigned int uid = gimple_uid (stmt);
+ gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
+ gimple *g = gimple_build_assign (make_ssa_name (utype), NOP_EXPR, rhs1);
+ gimple_set_uid (g, uid);
+ rhs1 = gimple_assign_lhs (g);
+ gsi_insert_before (&gsi, g, GSI_SAME_STMT);
+ g = gimple_build_assign (make_ssa_name (utype), NOP_EXPR, rhs2);
+ gimple_set_uid (g, uid);
+ rhs2 = gimple_assign_lhs (g);
+ gsi_insert_before (&gsi, g, GSI_SAME_STMT);
+ if (tree_swap_operands_p (rhs1, rhs2, false))
+ {
+ std::swap (rhs1, rhs2);
+ ccode = swap_tree_comparison (ccode);
+ }
+ if (gimple_code (stmt) == GIMPLE_COND)
+ {
+ gcond *c = as_a <gcond *> (stmt);
+ gimple_cond_set_code (c, ccode);
+ gimple_cond_set_lhs (c, rhs1);
+ gimple_cond_set_rhs (c, rhs2);
+ update_stmt (stmt);
+ }
+ else
+ {
+ g = gimple_build_assign (make_ssa_name (TREE_TYPE (ranges[i].exp)),
+ ccode, rhs1, rhs2);
+ gimple_set_uid (g, uid);
+ gsi_insert_before (&gsi, g, GSI_SAME_STMT);
+ ranges[i].exp = gimple_assign_lhs (g);
+ (*ops)[ranges[i].idx]->op = ranges[i].exp;
+ }
+ ranges[i].strict_overflow_p = false;
+ operand_entry *oe = (*ops)[ranges[*idx].idx];
+ /* Now change all the other range test immediate uses, so that
+ those tests will be optimized away. */
+ if (opcode == ERROR_MARK)
+ {
+ if (oe->op)
+ oe->op = build_int_cst (TREE_TYPE (oe->op),
+ oe->rank == BIT_IOR_EXPR ? 0 : 1);
+ else
+ oe->op = (oe->rank == BIT_IOR_EXPR
+ ? boolean_false_node : boolean_true_node);
+ }
+ else
+ oe->op = error_mark_node;
+ ranges[*idx].exp = NULL_TREE;
+ ranges[*idx].low = NULL_TREE;
+ ranges[*idx].high = NULL_TREE;
+ any_changes = true;
+ }
+
+ delete map;
+ return any_changes;
+}
+
/* Optimize range tests, similarly how fold_range_test optimizes
it on trees. The tree code for the binary
operation between all the operands is OPCODE.
@@ -2917,6 +3110,8 @@ optimize_range_tests (enum tree_code opc
if (lshift_cheap_p (optimize_function_for_speed_p (cfun)))
any_changes |= optimize_range_tests_to_bit_test (opcode, first, length,
ops, ranges);
+ any_changes |= optimize_range_tests_var_bound (opcode, first, length, ops,
+ ranges);
if (any_changes && opcode != ERROR_MARK)
{
--- gcc/testsuite/gcc.dg/tree-ssa/pr77664.c.jj 2016-10-06 13:04:18.069234540
+0200
+++ gcc/testsuite/gcc.dg/tree-ssa/pr77664.c 2016-10-06 13:45:48.669579669
+0200
@@ -0,0 +1,49 @@
+/* PR tree-optimization/77664 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-reassoc1-details" } */
+
+extern void foo (void);
+
+/* { dg-final { scan-tree-dump-times "Optimizing range test \[^\n\r]* and
comparison" 6 "reassoc1" } } */
+
+__attribute__((noinline, noclone)) void
+fn1 (long long int a, unsigned short b, int c)
+{
+ if (a >= 0 && c && a < b)
+ foo ();
+}
+
+__attribute__((noinline, noclone)) void
+fn2 (long long int a, unsigned short b, int c)
+{
+ if (a < 0 || c || a >= b)
+ foo ();
+}
+
+__attribute__((noinline, noclone)) void
+fn3 (long long int a, unsigned short b)
+{
+ if (a < 0 || b < a)
+ foo ();
+}
+
+__attribute__((noinline, noclone)) void
+fn4 (long long int a, unsigned short b)
+{
+ if (a <= b && a >= 0)
+ foo ();
+}
+
+__attribute__((noinline, noclone)) void
+fn5 (long long int a, unsigned short b)
+{
+ if (a < 0 | a > b)
+ foo ();
+}
+
+__attribute__((noinline, noclone)) void
+fn6 (long long int a, unsigned short b)
+{
+ if (b >= a & a >= 0)
+ foo ();
+}
--- gcc/testsuite/gcc.dg/pr77664.c.jj 2016-10-06 13:08:58.892676906 +0200
+++ gcc/testsuite/gcc.dg/pr77664.c 2016-10-06 13:45:14.018025091 +0200
@@ -0,0 +1,55 @@
+/* PR tree-optimization/77664 */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include "tree-ssa/pr77664.c"
+
+int cnt;
+
+__attribute__((noinline, noclone)) void
+foo (void)
+{
+ cnt++;
+}
+
+int
+main ()
+{
+ fn1 (65534U, 65535U, 7); if (cnt != 1) __builtin_abort ();
+ fn1 (65534U, 65535U, 0); if (cnt != 1) __builtin_abort ();
+ fn1 (65535U, 65535U, 1); if (cnt != 1) __builtin_abort ();
+ fn1 (0, 65535U, 1); if (cnt != 2) __builtin_abort ();
+ fn1 (-1, 65535U, 1); if (cnt != 2) __builtin_abort ();
+ fn1 (0, 0, 1); if (cnt != 2) __builtin_abort ();
+ fn2 (65534U, 65535U, 7); if (cnt != 3) __builtin_abort ();
+ fn2 (65534U, 65535U, 0); if (cnt != 3) __builtin_abort ();
+ fn2 (65535U, 65535U, 0); if (cnt != 4) __builtin_abort ();
+ fn2 (0, 65535U, 0); if (cnt != 4) __builtin_abort ();
+ fn2 (-1, 65535U, 0); if (cnt != 5) __builtin_abort ();
+ fn2 (0, 0, 0); if (cnt != 6) __builtin_abort ();
+ fn3 (-1, 65534U); if (cnt != 7) __builtin_abort ();
+ fn3 (0, 65534U); if (cnt != 7) __builtin_abort ();
+ fn3 (65534U, 65534U); if (cnt != 7) __builtin_abort ();
+ fn3 (65535U, 65534U); if (cnt != 8) __builtin_abort ();
+ fn3 (0, 0); if (cnt != 8) __builtin_abort ();
+ fn3 (1, 0); if (cnt != 9) __builtin_abort ();
+ fn4 (-1, 65534U); if (cnt != 9) __builtin_abort ();
+ fn4 (0, 65534U); if (cnt != 10) __builtin_abort ();
+ fn4 (65534U, 65534U); if (cnt != 11) __builtin_abort ();
+ fn4 (65535U, 65534U); if (cnt != 11) __builtin_abort ();
+ fn4 (0, 0); if (cnt != 12) __builtin_abort ();
+ fn4 (1, 0); if (cnt != 12) __builtin_abort ();
+ fn5 (-1, 65534U); if (cnt != 13) __builtin_abort ();
+ fn5 (0, 65534U); if (cnt != 13) __builtin_abort ();
+ fn5 (65534U, 65534U); if (cnt != 13) __builtin_abort ();
+ fn5 (65535U, 65534U); if (cnt != 14) __builtin_abort ();
+ fn5 (0, 0); if (cnt != 14) __builtin_abort ();
+ fn5 (1, 0); if (cnt != 15) __builtin_abort ();
+ fn6 (-1, 65534U); if (cnt != 15) __builtin_abort ();
+ fn6 (0, 65534U); if (cnt != 16) __builtin_abort ();
+ fn6 (65534U, 65534U); if (cnt != 17) __builtin_abort ();
+ fn6 (65535U, 65534U); if (cnt != 17) __builtin_abort ();
+ fn6 (0, 0); if (cnt != 18) __builtin_abort ();
+ fn6 (1, 0); if (cnt != 18) __builtin_abort ();
+ return 0;
+}
Jakub
