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C: Fix atomic loads. [PR97981]

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To handle atomic loads correctly, we need to move the code that
drops qualifiers in lvalue conversion after the code that
handles atomics.

2020-12-07  Martin Uecker  <muecker@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.
This commit is contained in:
Martin Uecker 2020-12-07 23:51:25 +01:00
parent b737b70fad
commit a19a242c70
3 changed files with 19 additions and 4 deletions
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6
gcc/c/c-typeck.c
View File

@ -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;
}

2
gcc/testsuite/gcc.dg/pr60195.c
View File

@ -15,7 +15,7 @@ atomic_int
fn2 (void)
{
atomic_int y = 0;
y; /* { dg-warning "statement with no effect" } */
y;
return y;
}

15
gcc/testsuite/gcc.dg/pr97981.c Normal file
View File

@ -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;
}