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Re: Speedup int_bit_from_pos
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Richard Biener <rguenther at suse dot de>
- Cc: Jan Hubicka <hubicka at ucw dot cz>, Jeff Law <law at redhat dot com>, gcc-patches at gcc dot gnu dot org
- Date: Mon, 22 Sep 2014 17:51:10 +0200
- Subject: Re: Speedup int_bit_from_pos
- Authentication-results: sourceware.org; auth=none
- References: <20140920040451 dot GC21760 at kam dot mff dot cuni dot cz> <541D948B dot 1030602 at redhat dot com> <20140920160752 dot GA18043 at kam dot mff dot cuni dot cz> <9767d203-5e46-4835-86b2-f983d20fcba8 at email dot android dot com> <20140921141944 dot GA4519 at kam dot mff dot cuni dot cz> <alpine dot LSU dot 2 dot 11 dot 1409220951530 dot 20733 at zhemvz dot fhfr dot qr>
> On Sun, 21 Sep 2014, Jan Hubicka wrote:
>
> > >
> > > Please omit static from inline functions.
> >
> > Yep, I suppose we want to drop static in all inlines? I can make patch for that.
> > >
> > > Also one notable difference with your patches is that the fits hwi is now not tested on the result but on the result input which, multiplied by 8, might not fit a hwi now. So please use wide-ints here (the to_offset flavor).
> >
> > The function must always suceed (so user promise it will fit in HWI) and for
> > performance reasons I would rather not go into wide int by defualt, but I can
> > do that with checking enabled.
>
> wide-int should be fast enough, please use it.
Like this?
Index: tree.h
===================================================================
--- tree.h (revision 215421)
+++ tree.h (working copy)
@@ -3877,10 +3877,20 @@ extern tree size_in_bytes (const_tree);
extern HOST_WIDE_INT int_size_in_bytes (const_tree);
extern HOST_WIDE_INT max_int_size_in_bytes (const_tree);
extern tree bit_position (const_tree);
-extern HOST_WIDE_INT int_bit_position (const_tree);
extern tree byte_position (const_tree);
extern HOST_WIDE_INT int_byte_position (const_tree);
+/* Like bit_position, but return as an integer. It must be representable in
+ that way (since it could be a signed value, we don't have the
+ option of returning -1 like int_size_in_byte can. */
+
+static inline HOST_WIDE_INT int_bit_position (const_tree field)
+{
+ return ((wide_int)DECL_FIELD_OFFSET (field) * BITS_PER_UNIT
+ + (wide_int)DECL_FIELD_BIT_OFFSET (field)).to_shwi ();
+}
+
+
#define sizetype sizetype_tab[(int) stk_sizetype]
#define bitsizetype sizetype_tab[(int) stk_bitsizetype]
#define ssizetype sizetype_tab[(int) stk_ssizetype]