On Wed, 30 Oct 2013, Richard Biener wrote:
On Wed, Oct 30, 2013 at 1:09 AM, Marc Glisse <marc.gli...@inria.fr> wrote:
On Tue, 29 Oct 2013, Richard Biener wrote:
For the POINTER_PLUS_EXPR offset argument you should use
int_cst_value () to access it (it will unconditionally sign-extend)
and use host_integerp (..., 0). That leaves the overflow possibility
in place (and you should multiply by BITS_PER_UNIT) which we
ignore in enough other places similar to this to ignore ...
Like this? (passes bootstrap+testsuite on x86_64-linux-gnu)
2013-10-30 Marc Glisse <marc.gli...@inria.fr>
gcc/
* tree-ssa-alias.c (ao_ref_init_from_ptr_and_size): Look for a
POINTER_PLUS_EXPR in the defining statement.
gcc/testsuite/
* gcc.dg/tree-ssa/alias-24.c: New file.
--
Marc Glisse
Index: gcc/testsuite/gcc.dg/tree-ssa/alias-24.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/alias-24.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/alias-24.c (working copy)
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+void f (const char *c, int *i)
+{
+ *i = 42;
+ __builtin_memcpy (i + 1, c, sizeof (int));
+ if (*i != 42) __builtin_abort();
+}
+
+extern void keepit ();
+void g (const char *c, int *i)
+{
+ *i = 33;
+ __builtin_memcpy (i - 1, c, 3 * sizeof (int));
+ if (*i != 33) keepit();
+}
+
+/* { dg-final { scan-tree-dump-not "abort" "optimized" } } */
+/* { dg-final { scan-tree-dump "keepit" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
+
Property changes on: gcc/testsuite/gcc.dg/tree-ssa/alias-24.c
___________________________________________________________________
Added: svn:keywords
## -0,0 +1 ##
+Author Date Id Revision URL
\ No newline at end of property
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property
Index: gcc/tree-ssa-alias.c
===================================================================
--- gcc/tree-ssa-alias.c (revision 204188)
+++ gcc/tree-ssa-alias.c (working copy)
@@ -567,20 +567,29 @@ void
ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
{
HOST_WIDE_INT t1, t2;
ref->ref = NULL_TREE;
if (TREE_CODE (ptr) == SSA_NAME)
{
gimple stmt = SSA_NAME_DEF_STMT (ptr);
if (gimple_assign_single_p (stmt)
&& gimple_assign_rhs_code (stmt) == ADDR_EXPR)
ptr = gimple_assign_rhs1 (stmt);
+ else if (is_gimple_assign (stmt)
+ && gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
+ && host_integerp (gimple_assign_rhs2 (stmt), 0)
+ && (t1 = int_cst_value (gimple_assign_rhs2 (stmt))) >= 0)
No need to restrict this to positive offsets I think.
Actually there is. The function documents that it only handles nonnegative
offsets, and if we ignore that, the "keepit" part of the testcase fails
because ranges_overlap_p works with unsigned offsets. I can try to change
ranges_overlap_p and remove this restriction from
ao_ref_init_from_ptr_and_size, but that's more risky so I'd prefer to do
that as a separate follow-up patch if that's ok.
+ {
+ ao_ref_init_from_ptr_and_size (ref, gimple_assign_rhs1 (stmt),
size);
Please don't recurse - forwprop combines series of POINTER_PLUS_EXPRs
and &MEM[ptr, offset] so it shouldn't be necessary.
Done. (note that if it isn't necessary, then it doesn't hurt either ;-)
+ ref->offset += 8 * t1;
BITS_PER_UNIT instead of 8. I'd say just have a 0-initialized
additional_offset var that you unconditionally add ...
I also changed a few other 8s.
+ return;
+ }
}
if (TREE_CODE (ptr) == ADDR_EXPR)
ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
&ref->offset, &t1, &t2);
else
{
ref->base = build2 (MEM_REF, char_type_node,
ptr, null_pointer_node);
ref->offset = 0;
... here at the end.
Here is a new version, same testing, same ChangeLog.
--
Marc Glisse
Index: gcc/testsuite/gcc.dg/tree-ssa/alias-24.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/alias-24.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/alias-24.c (working copy)
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+void f (const char *c, int *i)
+{
+ *i = 42;
+ __builtin_memcpy (i + 1, c, sizeof (int));
+ if (*i != 42) __builtin_abort();
+}
+
+extern void keepit ();
+void g (const char *c, int *i)
+{
+ *i = 33;
+ __builtin_memcpy (i - 1, c, 3 * sizeof (int));
+ if (*i != 33) keepit();
+}
+
+/* { dg-final { scan-tree-dump-not "abort" "optimized" } } */
+/* { dg-final { scan-tree-dump "keepit" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
+
Property changes on: gcc/testsuite/gcc.dg/tree-ssa/alias-24.c
___________________________________________________________________
Added: svn:keywords
## -0,0 +1 ##
+Author Date Id Revision URL
\ No newline at end of property
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property
Index: gcc/tree-ssa-alias.c
===================================================================
--- gcc/tree-ssa-alias.c (revision 204200)
+++ gcc/tree-ssa-alias.c (working copy)
@@ -559,43 +559,53 @@ ao_ref_alias_set (ao_ref *ref)
}
/* Init an alias-oracle reference representation from a gimple pointer
PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
size is assumed to be unknown. The access is assumed to be only
to or after of the pointer target, not before it. */
void
ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
{
- HOST_WIDE_INT t1, t2;
+ HOST_WIDE_INT t1, t2, extra_offset = 0;
ref->ref = NULL_TREE;
if (TREE_CODE (ptr) == SSA_NAME)
{
gimple stmt = SSA_NAME_DEF_STMT (ptr);
if (gimple_assign_single_p (stmt)
&& gimple_assign_rhs_code (stmt) == ADDR_EXPR)
ptr = gimple_assign_rhs1 (stmt);
+ else if (is_gimple_assign (stmt)
+ && gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
+ && host_integerp (gimple_assign_rhs2 (stmt), 0)
+ && (t1 = int_cst_value (gimple_assign_rhs2 (stmt))) >= 0)
+ {
+ ptr = gimple_assign_rhs1 (stmt);
+ extra_offset = BITS_PER_UNIT * t1;
+ }
}
if (TREE_CODE (ptr) == ADDR_EXPR)
ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
&ref->offset, &t1, &t2);
else
{
ref->base = build2 (MEM_REF, char_type_node,
ptr, null_pointer_node);
ref->offset = 0;
}
+ ref->offset += extra_offset;
if (size
&& host_integerp (size, 0)
- && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
- ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
+ && TREE_INT_CST_LOW (size) * BITS_PER_UNIT / BITS_PER_UNIT
+ == TREE_INT_CST_LOW (size))
+ ref->max_size = ref->size = TREE_INT_CST_LOW (size) * BITS_PER_UNIT;
else
ref->max_size = ref->size = -1;
ref->ref_alias_set = 0;
ref->base_alias_set = 0;
ref->volatile_p = false;
}
/* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
decide. */
