This patch teaches VRP to register along a default switch label
assertions that corresponds to the anti range of each case label.
Does this look OK to commit after bootstrap + regtest on
x86_64-pc-linux-gnu?
---
gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c | 2 +-
gcc/testsuite/gcc.dg/tree-ssa/vrp103.c | 30 ++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/vrp104.c | 32 +++++++++++++++++++
gcc/tree-vrp.c | 39 ++++++++++++++++++++++--
4 files changed, 100 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp103.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp104.c
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
index 5ec4687..551fbac 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c
@@ -1,7 +1,7 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-thread1-details -fdump-tree-thread2-details"
} */
/* { dg-final { scan-tree-dump-times "FSM" 3 "thread1" } } */
-/* { dg-final { scan-tree-dump-times "FSM" 4 "thread2" } } */
+/* { dg-final { scan-tree-dump-times "FSM" 5 "thread2" } } */
int sum0, sum1, sum2, sum3;
int foo (char *s, char **ret)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp103.c
b/gcc/testsuite/gcc.dg/tree-ssa/vrp103.c
new file mode 100644
index 0000000..eea98bb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp103.c
@@ -0,0 +1,30 @@
+/* PR tree-optimization/18046 */
+/* { dg-options "-O2 -fdump-tree-vrp" } */
+/* { dg-final { scan-tree-dump-times "baz \\(0\\);" 4 "vrp1" } } */
+
+void foo ();
+void bar ();
+void baz (int);
+
+void
+test (int i)
+{
+ switch (i)
+ {
+ case 1:
+ case 2:
+ case 3:
+ foo ();
+ break;
+ case 5:
+ bar ();
+ break;
+ default:
+ /* These tests should be folded to 0, resulting in 4 calls to bar (0).
*/
+ baz (i == 1);
+ baz (i == 2);
+ baz (i == 3);
+ baz (i == 5);
+ break;
+ }
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp104.c
b/gcc/testsuite/gcc.dg/tree-ssa/vrp104.c
new file mode 100644
index 0000000..6410847
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp104.c
@@ -0,0 +1,32 @@
+/* PR tree-optimization/18046 */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times "switch" 1 "optimized" } } */
+
+void foo ();
+void bar ();
+
+void
+test (int i)
+{
+ switch (i)
+ {
+ case 1:
+ foo ();
+ break;
+ case 2:
+ bar ();
+ break;
+ default:
+ break;
+ }
+
+ /* This switch should be gone after threading/VRP. */
+ switch (i)
+ {
+ case 1:
+ foo ();
+ break;
+ default:
+ break;
+ }
+}
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 06364b7..32a4de3 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -5917,6 +5917,7 @@ find_switch_asserts (basic_block bb, gswitch *last)
ci[idx].expr = gimple_switch_label (last, idx);
ci[idx].bb = label_to_block (CASE_LABEL (ci[idx].expr));
}
+ edge default_edge = find_edge (bb, ci[0].bb);
qsort (ci, n, sizeof (struct case_info), compare_case_labels);
for (idx = 0; idx < n; ++idx)
@@ -5945,8 +5946,8 @@ find_switch_asserts (basic_block bb, gswitch *last)
max = CASE_LOW (ci[idx].expr);
}
- /* Nothing to do if the range includes the default label until we
- can register anti-ranges. */
+ /* Can't extract a useful assertion out of a range that includes the
+ default label. */
if (min == NULL_TREE)
continue;
@@ -5963,6 +5964,40 @@ find_switch_asserts (basic_block bb, gswitch *last)
fold_convert (TREE_TYPE (op), max));
}
+ /* For each case label, register along the default label an assertion that
+ corresponds to the anti-range of that label. */
+ for (idx = 0; idx < n; ++idx)
+ {
+ tree min, max;
+ tree cl = ci[idx].expr;
+
+ min = CASE_LOW (cl);
+ max = CASE_HIGH (cl);
+
+ if (min == NULL_TREE)
+ continue;
+
+ if (max == NULL_TREE)
+ {
+ /* Register the assertion OP != MIN. */
+ min = fold_convert (TREE_TYPE (op), min);
+ register_edge_assert_for (op, default_edge, bsi, NE_EXPR, op, min);
+ }
+ else
+ {
+ /* Register the assertion (unsigned)OP - MIN > (MAX - MIN),
+ which will give OP the anti-range ~[MIN,MAX]. */
+ tree uop = fold_convert (unsigned_type_for (TREE_TYPE (op)), op);
+ min = fold_convert (TREE_TYPE (uop), min);
+ max = fold_convert (TREE_TYPE (uop), max);
+
+ tree lhs = fold_build2 (MINUS_EXPR, TREE_TYPE (uop), uop, min);
+ tree rhs = int_const_binop (MINUS_EXPR, max, min);
+ register_new_assert_for (op, lhs, GT_EXPR, rhs,
+ NULL, default_edge, bsi);
+ }
+ }
+
XDELETEVEC (ci);
}
--
2.9.2.413.g76d2a70
