new file mode 100644
@@ -0,0 +1,38 @@
+// { dg-do compile }
+// { dg-require-effective-target c++11 }
+// { dg-additional-options "-fdump-tree-optimized" }
+
+#include <cstdint>
+
+const int runs = 92;
+
+union BitfieldStructUnion {
+ struct {
+ uint64_t a : 17;
+ uint64_t padding: 39;
+ uint64_t b : 8;
+ } __attribute__((packed));
+
+ struct {
+ uint32_t value_low;
+ uint32_t value_high;
+ } __attribute__((packed));
+
+ BitfieldStructUnion(uint32_t value_low, uint32_t value_high) : value_low(value_low), value_high(value_high) {}
+};
+
+volatile uint32_t *WRITE = (volatile unsigned*)0x42;
+
+void buggy() {
+ for (int i = 0; i < runs; i++) {
+ BitfieldStructUnion rt{*WRITE, *WRITE};
+
+ rt.a = 99;
+ rt.b = 1;
+
+ *WRITE = rt.value_low;
+ *WRITE = rt.value_high;
+ }
+}
+
+// { dg-final { scan-tree-dump-times "\\\*WRITE\[^\r\n\]* ={v} " 2 "optimized" } }
@@ -3381,7 +3381,9 @@ ifcvt_local_dce (class loop *loop)
gimple_stmt_iterator gsiprev = gsi;
gsi_prev (&gsiprev);
stmt = gsi_stmt (gsi);
- if (gimple_store_p (stmt) && gimple_vdef (stmt))
+ if (!gimple_has_volatile_ops (stmt)
+ && gimple_store_p (stmt)
+ && gimple_vdef (stmt))
{
tree lhs = gimple_get_lhs (stmt);
ao_ref write;