The following avoids queueing duplicate stmts in the set of sinkings
to consider as well as pick candidates in an order that ensures
we don't unnecessarily re-order stores. While we currently only can
trigger the ICE with out-of-bound accesses future enhancements
to how we deal with dependence analysis in this pass could expose
the issue to a wider range of testcases, so this makes it future-proof.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/116747
* tree-ssa-phiopt.cc (cond_if_else_store_replacement): Avoid
duplicate stmts in the set of store pairs to process.
* gcc.dg/tree-ssa/cselim-4.c: New testcase.
---
gcc/testsuite/gcc.dg/tree-ssa/cselim-4.c | 32 ++++++++++++++++++++++++
gcc/tree-ssa-phiopt.cc | 23 ++++++++++++++---
2 files changed, 52 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cselim-4.c
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cselim-4.c
b/gcc/testsuite/gcc.dg/tree-ssa/cselim-4.c
new file mode 100644
index 00000000000..2e1121a834a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/cselim-4.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fno-expensive-optimizations -fno-tree-dse -fgimple" } */
+
+/* We're testing the CSELIM pass but we need VRP to compute the range
+ for b_4 to make the array1[] accesses out-of-bound. */
+
+int array1[1];
+int __GIMPLE (ssa,startwith("vrp"),guessed_local(1073741824))
+f1 (int a, short unsigned int b1, int c)
+{
+ int b;
+
+ __BB(2,guessed_local(1073741824)):
+ b_3 = (int) b1_2(D);
+ b_4 = b_3 + 1;
+ if (a_5(D) != 0)
+ goto __BB3(guessed(67108864));
+ else
+ goto __BB4(guessed(67108864));
+
+ __BB(3,guessed_local(536870912)):
+ array1[b_4] = c_7(D);
+ array1[b_4] = c_7(D);
+ goto __BB5(precise(134217728));
+
+ __BB(4,guessed_local(536870912)):
+ array1[b_4] = c_7(D);
+ goto __BB5(precise(134217728));
+
+ __BB(5,guessed_local(1073741824)):
+ return;
+}
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 167b86b3acc..fcf44136d0a 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -3349,9 +3349,21 @@ cond_if_else_store_replacement (basic_block then_bb,
basic_block else_bb,
return false;
}
- /* Find pairs of stores with equal LHS. */
+ /* Clear visited on else stores, we want to make sure to pick each store
+ at most once to avoid quadratic behavior. */
+ for (auto else_dr : else_datarefs)
+ {
+ if (DR_IS_READ (else_dr))
+ continue;
+ gimple_set_visited (DR_STMT (else_dr), false);
+ }
+
+ /* Find pairs of stores with equal LHS. Work from the end to avoid
+ re-ordering stores unnecessarily. */
auto_vec<std::pair<gimple *, gimple *>, 1> stores_pairs;
- for (auto then_dr : then_datarefs)
+ unsigned i;
+ data_reference_p then_dr;
+ FOR_EACH_VEC_ELT_REVERSE (then_datarefs, i, then_dr)
{
if (DR_IS_READ (then_dr))
continue;
@@ -3362,12 +3374,16 @@ cond_if_else_store_replacement (basic_block then_bb,
basic_block else_bb,
continue;
found = false;
- for (auto else_dr : else_datarefs)
+ unsigned j;
+ data_reference_p else_dr;
+ FOR_EACH_VEC_ELT_REVERSE (else_datarefs, j, else_dr)
{
if (DR_IS_READ (else_dr))
continue;
else_store = DR_STMT (else_dr);
+ if (gimple_visited_p (else_store))
+ continue;
else_lhs = gimple_get_lhs (else_store);
if (else_lhs == NULL_TREE)
continue;
@@ -3382,6 +3398,7 @@ cond_if_else_store_replacement (basic_block then_bb,
basic_block else_bb,
if (!found)
continue;
+ gimple_set_visited (else_store, true);
stores_pairs.safe_push (std::make_pair (then_store, else_store));
}
--
2.51.0
