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[C++ PATCH] Fix COND_EXPR genericization fixup (PR c++/37819)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Jason Merrill <jason at redhat dot com>, Mark Mitchell <mark at codesourcery dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 14 Oct 2008 10:49:21 +0200
- Subject: [C++ PATCH] Fix COND_EXPR genericization fixup (PR c++/37819)
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
As shown on the testcase below, I was wrong with asserting that
COND_EXPR has always a type compatible with
is_bitfield_expr_with_lowered_type if non-NULL. That's true
during build_conditional_expr, but might not be true afterwards,
because of folding. Say fold_convert (<char>, COND_EXPR<...>)
will fold the COND_EXPR branches to the new type. Usually it will
be just an added NOP_EXPR around the bitfield, which is fine for
cp_genericize_r as well as middle-end (then
is_bitfield_expr_with_lowered_type is false and the types are correct).
But, if the type of the bitfield matches the new type during fold
conversion, no NOP_EXPR is added, but is_bitfield_expr_with_lowered_type
is still non-NULL. The patch below prohibits the fixup if the
type is already correct.
Ok for trunk if bootstrap/regtest passes?
2008-10-14 Jakub Jelinek <jakub@redhat.com>
PR c++/37819
* cp-gimplify.c (cp_genericize_r): Only fold_convert COND_EXPR
arguments if they don't already have COND_EXPR's type.
* g++.dg/expr/bitfield11.C: New test.
--- gcc/cp/cp-gimplify.c.jj 2008-10-14 10:17:49.000000000 +0200
+++ gcc/cp/cp-gimplify.c 2008-10-14 10:31:06.000000000 +0200
@@ -815,14 +815,18 @@ cp_genericize_r (tree *stmt_p, int *walk
= (TREE_OPERAND (stmt, 2)
? is_bitfield_expr_with_lowered_type (TREE_OPERAND (stmt, 2))
: NULL_TREE);
- if (type_left)
+ if (type_left
+ && !useless_type_conversion_p (TREE_TYPE (stmt),
+ TREE_TYPE (TREE_OPERAND (stmt, 1))))
{
TREE_OPERAND (stmt, 1)
= fold_convert (type_left, TREE_OPERAND (stmt, 1));
gcc_assert (useless_type_conversion_p (TREE_TYPE (stmt),
type_left));
}
- if (type_right)
+ if (type_right
+ && !useless_type_conversion_p (TREE_TYPE (stmt),
+ TREE_TYPE (TREE_OPERAND (stmt, 2))))
{
TREE_OPERAND (stmt, 2)
= fold_convert (type_right, TREE_OPERAND (stmt, 2));
--- gcc/testsuite/g++.dg/expr/bitfield11.C.jj 2008-10-14 10:33:30.000000000 +0200
+++ gcc/testsuite/g++.dg/expr/bitfield11.C 2008-10-14 10:32:14.000000000 +0200
@@ -0,0 +1,13 @@
+// PR c++/37819
+// { dg-do compile }
+
+struct A
+{
+ unsigned int a : 1;
+};
+
+bool
+foo (A *x, A *y)
+{
+ x->a = y ? y->a : true;
+}
Jakub