The first pass of code generation in the D front-end splits up all
compound expressions and discards expressions that have no side effects.
This included calls to the `volatileLoad' intrinsic if its result was
not used, causing such calls to be eliminated from the program.
We already set TREE_THIS_VOLATILE on the expression, however the
tree documentation says if this bit is set in an expression, so is
TREE_SIDE_EFFECTS. So set TREE_SIDE_EFFECTS on the expression too.
This prevents any early discarding from occuring.
PR d/110516
gcc/d/ChangeLog:
* intrinsics.cc (expand_volatile_load): Set TREE_SIDE_EFFECTS on the
expanded expression.
(expand_volatile_store): Likewise.
gcc/testsuite/ChangeLog:
* gdc.dg/torture/pr110516a.d: New test.
* gdc.dg/torture/pr110516b.d: New test.
tree type = build_qualified_type (TREE_TYPE (ptrtype), TYPE_QUAL_VOLATILE);
tree result = indirect_ref (type, ptr);
TREE_THIS_VOLATILE (result) = 1;
+ TREE_SIDE_EFFECTS (result) = 1;
return result;
}
tree type = build_qualified_type (TREE_TYPE (ptrtype), TYPE_QUAL_VOLATILE);
tree result = indirect_ref (type, ptr);
TREE_THIS_VOLATILE (result) = 1;
+ TREE_SIDE_EFFECTS (result) = 1;
/* (*(volatile T *) ptr) = value; */
tree value = CALL_EXPR_ARG (callexp, 1);
--- /dev/null
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110516
+// { dg-do compile }
+// { dg-options "-fno-moduleinfo -fdump-tree-optimized" }
+void fn110516(ubyte* ptr)
+{
+ import core.volatile : volatileLoad;
+ volatileLoad(ptr);
+ volatileLoad(ptr);
+ volatileLoad(ptr);
+ volatileLoad(ptr);
+}
+// { dg-final { scan-tree-dump-times " ={v} " 4 "optimized" } }
--- /dev/null
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110516
+// { dg-do compile }
+// { dg-options "-fno-moduleinfo -fdump-tree-optimized" }
+void fn110516(ubyte* ptr)
+{
+ import core.volatile : volatileStore;
+ volatileStore(ptr, 0);
+ volatileStore(ptr, 0);
+ volatileStore(ptr, 0);
+ volatileStore(ptr, 0);
+}
+// { dg-final { scan-tree-dump-times " ={v} " 4 "optimized" } }