Hi,
int_bit_position is used by ipa-devirt's type walking code. It is currently a
bottleneck
since I introduced speculation into contextes (I plan to solve this by changing
the
way i cache results). But this patch seems to make sense anyway: we do not need
to go
through folding:
tree
bit_from_pos (tree offset, tree bitpos)
{
if (TREE_CODE (offset) == PLUS_EXPR)
offset = size_binop (PLUS_EXPR,
fold_convert (bitsizetype, TREE_OPERAND (offset, 0)),
fold_convert (bitsizetype, TREE_OPERAND (offset, 1)));
else
offset = fold_convert (bitsizetype, offset);
return size_binop (PLUS_EXPR, bitpos,
size_binop (MULT_EXPR, offset, bitsize_unit_node));
}
Because all the code cares only about constant offsets, we do not need to go
through fold_convert,
because all the codes go via int_bit_position that already expects result to be
host wide int,
it seems to make sense to implement quick path for that.
Bootstrap/regtest x86_64 in progress, OK?
Honza
* stor-layout.c (int_bit_from_pos): New function.
* stor-layout.h (int_bit_from_pos): Declare.
* tree.c (int_bit_from_pos): Use it.
Index: stor-layout.c
===================================================================
--- stor-layout.c (revision 215409)
+++ stor-layout.c (working copy)
@@ -858,6 +858,20 @@
size_binop (MULT_EXPR, offset, bitsize_unit_node));
}
+/* Like int_bit_from_pos, but return the result as HOST_WIDE_INT.
+ OFFSET and BITPOS must be constant. */
+
+HOST_WIDE_INT
+int_bit_from_pos (tree offset, tree bitpos)
+{
+ HOST_WIDE_INT off;
+ if (TREE_CODE (offset) == PLUS_EXPR)
+ off = tree_to_shwi (TREE_OPERAND (offset, 0)) + tree_to_shwi (TREE_OPERAND
(offset, 1));
+ else
+ off = tree_to_shwi (offset);
+ return off * BITS_PER_UNIT + tree_to_shwi (bitpos);
+}
+
/* Return the combined truncated byte position for the byte offset OFFSET and
the bit position BITPOS. */
Index: stor-layout.h
===================================================================
--- stor-layout.h (revision 215409)
+++ stor-layout.h (working copy)
@@ -27,6 +27,7 @@
unsigned int);
extern record_layout_info start_record_layout (tree);
extern tree bit_from_pos (tree, tree);
+extern HOST_WIDE_INT int_bit_from_pos (tree, tree);
extern tree byte_from_pos (tree, tree);
extern void pos_from_bit (tree *, tree *, unsigned int, tree);
extern void normalize_offset (tree *, tree *, unsigned int);
Index: tree.c
===================================================================
--- tree.c (revision 215409)
+++ tree.c (working copy)
@@ -2839,7 +2839,8 @@
HOST_WIDE_INT
int_bit_position (const_tree field)
{
- return tree_to_shwi (bit_position (field));
+ return int_bit_from_pos (DECL_FIELD_OFFSET (field),
+ DECL_FIELD_BIT_OFFSET (field));
}
/* Return the byte position of FIELD, in bytes from the start of the record.
