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[PATCH] Fix tree forwprop a second time (PR middle-end/38200)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 21 Nov 2008 15:40:59 +0100
- Subject: [PATCH] Fix tree forwprop a second time (PR middle-end/38200)
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
My earlier patch to forward_propagate_addr_expr_1 contained a thinko,
as for x = &a; *x = b; replacement with a = b; we know a's address
has been taken, so a = (a's type) b; is invalid GIMPLE (a = b;
generated previously was also invalid GIMPLE if the type conversion
wasn't useless). The following patch thus never adds a cast,
just checks if the conversion is useless. For
x = &a;
x->j = b;
transforming it to
a.j = b;
doesn't change LHS nor RHS side, so this checking isn't needed.
Ok if bootstrap+regtest succeeds on x86_64-linux?
2008-11-21 Jakub Jelinek <jakub@redhat.com>
PR middle-end/38200
* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Only
propagate x = &a into *x = b if conversion from b to a's type is
useless.
* gcc.dg/pr38200.c: New test.
--- gcc/tree-ssa-forwprop.c.jj 2008-11-18 19:24:09.000000000 +0100
+++ gcc/tree-ssa-forwprop.c 2008-11-21 15:19:55.000000000 +0100
@@ -719,30 +719,18 @@ forward_propagate_addr_expr_1 (tree name
propagate the ADDR_EXPR into the use of NAME and fold the result. */
if (TREE_CODE (lhs) == INDIRECT_REF
&& TREE_OPERAND (lhs, 0) == name
- && may_propagate_address_into_dereference (def_rhs, lhs))
+ && may_propagate_address_into_dereference (def_rhs, lhs)
+ && (lhsp != gimple_assign_lhs_ptr (use_stmt)
+ || useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
+ TREE_TYPE (rhs))))
{
- bool valid = true;
- if (lhsp == gimple_assign_lhs_ptr (use_stmt)
- && !useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
- TREE_TYPE (rhs))
- && !CONVERT_EXPR_CODE_P (rhs_code))
- {
- if (rhs_code == SSA_NAME)
- gimple_assign_set_rhs_code (use_stmt, NOP_EXPR);
- else
- valid = false;
- }
- if (valid)
- {
- *lhsp = unshare_expr (TREE_OPERAND (def_rhs, 0));
- fold_stmt_inplace (use_stmt);
- tidy_after_forward_propagate_addr (use_stmt);
+ *lhsp = unshare_expr (TREE_OPERAND (def_rhs, 0));
+ fold_stmt_inplace (use_stmt);
+ tidy_after_forward_propagate_addr (use_stmt);
- /* Continue propagating into the RHS if this was not the only
- use. */
- if (single_use_p)
- return true;
- }
+ /* Continue propagating into the RHS if this was not the only use. */
+ if (single_use_p)
+ return true;
}
/* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR
--- gcc/testsuite/gcc.dg/pr38200.c.jj 2008-11-21 15:21:52.000000000 +0100
+++ gcc/testsuite/gcc.dg/pr38200.c 2008-11-21 15:07:25.000000000 +0100
@@ -0,0 +1,16 @@
+/* PR middle-end/38200 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-strict-aliasing" } */
+
+typedef int (*callptr) (void);
+int foo (void **x);
+void foo2 (callptr *);
+int (*foo_ptr) (void **x) = foo;
+
+void
+bar (void)
+{
+ void *ptr;
+ foo2 ((callptr *) &ptr);
+ *(void **) &foo_ptr = ptr;
+}
Jakub