From 32934a4f45a72144cdcd0712cc294fe88c36f13d Mon Sep 17 00:00:00 2001
From: Martin Uecker <muecker@gwdg.de>
Date: Fri, 20 Nov 2020 07:21:40 +0100
Subject: [PATCH] C: Drop qualifiers during lvalue conversion [PR97702]
2020-11-20 Martin Uecker <muecker@gwdg.de>
gcc/
* gimplify.c (gimplify_modify_expr_rhs): Optimizie
NOP_EXPRs that contain compound literals.
gcc/c/
* c-typeck.c (convert_lvalue_to_rvalue): Drop qualifiers.
gcc/testsuite/
* gcc.dg/cond-constqual-1.c: Adapt test.
* gcc.dg/lvalue-11.c: New test.
* gcc.dg/pr60195.c: Add warning.
---
gcc/c/c-typeck.c | 3 ++
gcc/gimplify.c | 13 ++++++++
gcc/testsuite/gcc.dg/cond-constqual-1.c | 2 +-
gcc/testsuite/gcc.dg/lvalue-11.c | 40 +++++++++++++++++++++++++
gcc/testsuite/gcc.dg/pr60195.c | 2 +-
5 files changed, 58 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/lvalue-11.c
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 413109c916c3..286f3d9cd6c6 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -2080,6 +2080,9 @@ 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;
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 2566ec7f0af8..fd0b5202b452 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -5518,6 +5518,19 @@ gimplify_modify_expr_rhs (tree *expr_p, tree *from_p, tree *to_p,
return GS_OK;
}
+ case NOP_EXPR:
+ /* Pull out compound literal expressions from a NOP_EXPR.
+ Those are created in the C FE to drop qualifiers during
+ lvalue conversion. */
+ if ((TREE_CODE (TREE_OPERAND (*from_p, 0)) == COMPOUND_LITERAL_EXPR)
+ && tree_ssa_useless_type_conversion (*from_p))
+ {
+ *from_p = TREE_OPERAND (*from_p, 0);
+ ret = GS_OK;
+ changed = true;
+ }
+ break;
+
case COMPOUND_LITERAL_EXPR:
{
tree complit = TREE_OPERAND (*expr_p, 1);
diff --git a/gcc/testsuite/gcc.dg/cond-constqual-1.c b/gcc/testsuite/gcc.dg/cond-constqual-1.c
index 3354c7214a47..b5a09cb00386 100644
--- a/gcc/testsuite/gcc.dg/cond-constqual-1.c
+++ b/gcc/testsuite/gcc.dg/cond-constqual-1.c
@@ -11,5 +11,5 @@ test (void)
__typeof__ (1 ? foo (0) : 0) texpr;
__typeof__ (1 ? i : 0) texpr2;
texpr = 0; /* { dg-bogus "read-only variable" "conditional expression with call to const function" } */
- texpr2 = 0; /* { dg-error "read-only variable" "conditional expression with const variable" } */
+ texpr2 = 0; /* { dg-bogus "read-only variable" "conditional expression with const variable" } */
}
diff --git a/gcc/testsuite/gcc.dg/lvalue-11.c b/gcc/testsuite/gcc.dg/lvalue-11.c
new file mode 100644
index 000000000000..d8b5a60c9917
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lvalue-11.c
@@ -0,0 +1,40 @@
+/* test that lvalue conversions drops qualifiers, Bug 97702 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+
+const int jc;
+extern int j;
+extern typeof(0,jc) j;
+extern typeof(+jc) j;
+extern typeof(-jc) j;
+extern typeof(1?jc:0) j;
+extern typeof((int)jc) j;
+extern typeof((const int)jc) j;
+
+volatile int kv;
+extern int k;
+extern typeof(0,kv) k;
+extern typeof(+kv) k;
+extern typeof(-kv) k;
+extern typeof(1?kv:0) k;
+extern typeof((int)kv) k;
+extern typeof((volatile int)kv) k;
+
+_Atomic int la;
+extern int l;
+extern typeof(0,la) l;
+extern typeof(+la) l;
+extern typeof(-la) l;
+extern typeof(1?la:0) l;
+extern typeof((int)la) l;
+extern typeof((_Atomic int)la) l;
+
+int * restrict mr;
+extern int *m;
+extern typeof(0,mr) m;
+extern typeof(1?mr:0) m;
+extern typeof((int *)mr) m;
+extern typeof((int * restrict)mr) m;
+
+
diff --git a/gcc/testsuite/gcc.dg/pr60195.c b/gcc/testsuite/gcc.dg/pr60195.c
index 0a50a30be254..8eccf7f63ad7 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;
+ y; /* { dg-warning "statement with no effect" } */
return y;
}
--
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