The following avoids translating expressions through volatile
copies.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/120944
* tree-ssa-sccvn.cc (vn_reference_lookup_3): Gate optimizations
invalid when volatile is involved.
* gcc.dg/torture/pr120944.c: New testcase.
---
gcc/testsuite/gcc.dg/torture/pr120944.c | 34 +++++++++++++++++++++++++
gcc/tree-ssa-sccvn.cc | 9 +++++--
2 files changed, 41 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr120944.c
diff --git a/gcc/testsuite/gcc.dg/torture/pr120944.c
b/gcc/testsuite/gcc.dg/torture/pr120944.c
new file mode 100644
index 00000000000..92f3c774996
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr120944.c
@@ -0,0 +1,34 @@
+/* { dg-skip-if "" { *-*-* } { "-flto" } { "" } } */
+/* { dg-additional-options "-fdump-tree-optimized" } */
+
+#include <stdlib.h>
+
+typedef union {
+ int u32;
+ struct
+ {
+ int A:1;
+ int B:2;
+ int C:3;
+ };
+} u_t;
+
+typedef union {
+ volatile int u[3];
+ volatile struct {
+ u_t a;
+ int b;
+ int c;
+ };
+} DATA;
+
+void foo (volatile DATA *d)
+{
+ d->a.u32 = ~0;
+ u_t u = d->a;
+ int v = u.A;
+ if (v)
+ abort();
+}
+
+/* { dg-final { scan-tree-dump-times "if \\\(" 1 "optimized" } } */
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 9cdbf3da772..45fb79cd8a1 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -2809,7 +2809,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void
*data_,
we find a VN result with exactly the same value as the
possible clobber. In this case we can ignore the clobber
and return the found value. */
- if (is_gimple_reg_type (TREE_TYPE (lhs))
+ if (!gimple_has_volatile_ops (def_stmt)
+ && is_gimple_reg_type (TREE_TYPE (lhs))
&& types_compatible_p (TREE_TYPE (lhs), vr->type)
&& (ref->ref || data->orig_ref.ref)
&& !data->mask
@@ -3093,7 +3094,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void
*data_,
else if (is_gimple_reg_type (vr->type)
&& gimple_assign_single_p (def_stmt)
&& gimple_assign_rhs_code (def_stmt) == CONSTRUCTOR
- && CONSTRUCTOR_NELTS (gimple_assign_rhs1 (def_stmt)) == 0)
+ && CONSTRUCTOR_NELTS (gimple_assign_rhs1 (def_stmt)) == 0
+ && !TREE_THIS_VOLATILE (gimple_assign_lhs (def_stmt)))
{
tree base2;
poly_int64 offset2, size2, maxsize2;
@@ -3149,6 +3151,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void
*data_,
&& !reverse_storage_order_for_component_p (vr->operands)
&& !contains_storage_order_barrier_p (vr->operands)
&& gimple_assign_single_p (def_stmt)
+ && !TREE_THIS_VOLATILE (gimple_assign_lhs (def_stmt))
&& CHAR_BIT == 8
&& BITS_PER_UNIT == 8
&& BYTES_BIG_ENDIAN == WORDS_BIG_ENDIAN
@@ -3307,6 +3310,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void
*data_,
&& !reverse_storage_order_for_component_p (vr->operands)
&& !contains_storage_order_barrier_p (vr->operands)
&& gimple_assign_single_p (def_stmt)
+ && !TREE_THIS_VOLATILE (gimple_assign_lhs (def_stmt))
&& TREE_CODE (gimple_assign_rhs1 (def_stmt)) == SSA_NAME)
{
tree lhs = gimple_assign_lhs (def_stmt);
@@ -3518,6 +3522,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void
*data_,
the copy kills ref. */
else if (data->vn_walk_kind == VN_WALKREWRITE
&& gimple_assign_single_p (def_stmt)
+ && !gimple_has_volatile_ops (def_stmt)
&& (DECL_P (gimple_assign_rhs1 (def_stmt))
|| TREE_CODE (gimple_assign_rhs1 (def_stmt)) == MEM_REF
|| handled_component_p (gimple_assign_rhs1 (def_stmt))))
--
2.43.0
