Hi Joseph,
the patch to drop qualifiers during lvalue conversion
was broken, because the code to emit atomic loads did
not trigger anymore. I now added a test that scans for
"atomic_load".
I should have taken the new warning for
_Atomic int y;
y; // warning statement with no effect
as a tell-tale sign that something is wrong,
although I still think the warning would be
correct. Or has a atomic load some special
semantics which imply that it can't be
removed?
(regression tests still running)
--Martin
C: Fix atomic loads. [PR97981]
To handle atomic loads correctly, we need to move the code
top qualifiers in lvalue conversion after
the code that
handles atomics.
2020-12-05 Martin Uecker <muec...@gwdg.de>
gcc/c/
PR c/97981
* c-typeck.c (convert_lvalue_to_rvalue): Move the code
that drops qualifiers to the end of the function.
gcc/testsuite/
PR c/97981
* gcc.dg/pr97981.c: New test.
* gcc.dg/pr60195.c. Adapt test.
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index cdc491a25fd..138af073925 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -2080,9 +2080,6 @@ convert_lvalue_to_rvalue (location_t loc, struct c_expr
exp,
exp = default_function_array_conversion (loc, exp);
if (!VOID_TYPE_P (TREE_TYPE (exp.value)))
exp.value = require_complete_type (loc, exp.value);
- if (convert_p && !error_operand_p (exp.value)
- && (TREE_CODE (TREE_TYPE (exp.value)) != ARRAY_TYPE))
- exp.value = convert (build_qualified_type (TREE_TYPE (exp.value),
TYPE_UNQUALIFIED),
exp.value);
if (really_atomic_lvalue (exp.value))
{
vec<tree, va_gc> *params;
@@ -2119,6 +2116,9 @@ convert_lvalue_to_rvalue (location_t loc, struct c_expr
exp,
exp.value = build4 (TARGET_EXPR, nonatomic_type, tmp, func_call,
NULL_TREE, NULL_TREE);
}
+ if (convert_p && !error_operand_p (exp.value)
+ && (TREE_CODE (TREE_TYPE (exp.value)) != ARRAY_TYPE))
+ exp.value = convert (build_qualified_type (TREE_TYPE (exp.value),
TYPE_UNQUALIFIED),
exp.value);
return exp;
}
diff --git a/gcc/testsuite/gcc.dg/pr60195.c b/gcc/testsuite/gcc.dg/pr60195.c
index 8eccf7f63ad..0a50a30be25 100644
--- a/gcc/testsuite/gcc.dg/pr60195.c
+++ b/gcc/testsuite/gcc.dg/pr60195.c
@@ -15,7 +15,7 @@ atomic_int
fn2 (void)
{
atomic_int y = 0;
- y; /* { dg-warning "statement with no effect" } */
+ y;
return y;
}
diff --git a/gcc/testsuite/gcc.dg/pr97981.c b/gcc/testsuite/gcc.dg/pr97981.c
new file mode 100644
index 00000000000..846b8755c5b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97981.c
@@ -0,0 +1,15 @@
+/* PR c/97981 */
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-original" } */
+/* { dg-final { scan-tree-dump-times "atomic_load" 2 "original" } } */
+
+
+void f(void)
+{
+ volatile _Atomic int x;
+ x;
+ volatile _Atomic double a;
+ double b;
+ b = a;
+}
+
