On Fri, Nov 18, 2016 at 04:29:18PM +0100, Dominik Vogt wrote:
> On Fri, Nov 18, 2016 at 08:02:08AM -0600, Segher Boessenkool wrote:
> > On Fri, Nov 18, 2016 at 01:09:24PM +0100, Dominik Vogt wrote:
> > > IN_RANGE(POS...) makes sure that POS is a non-negative number
> > > smaller than UPPER, so (UPPER) - (POS) does not wrap. Or is there
> > > some case that the new macro does not handle?
> >
> > I think it works fine.
> >
> > With a name like UPPER, you may want to have SIZE_POS_IN_RANGE work like
> > IN_RANGE, i.e. UPPER is inclusive then. Dunno.
>
> Yeah, maybe rather call it RANGE to avoid too much similarity.
> Some name that is so vague that one has to read the documentation.
> I'll post an updated patch later.
Third version of the patch attached. The only difference is that
the macro argument name has been changed back to RANGE.
Ciao
Dominik ^_^ ^_^
--
Dominik Vogt
IBM Germany
gcc/ChangeLog
PR target/77822
* system.h (SIZE_POS_IN_RANGE): New.
>From 8e02352c70d478c74155d5d127560da31363dd8a Mon Sep 17 00:00:00 2001
From: Dominik Vogt <v...@linux.vnet.ibm.com>
Date: Thu, 17 Nov 2016 14:49:18 +0100
Subject: [PATCH 1/2] PR target/77822: Add helper macro SIZE_POS_IN_RANGE to
system.h.
The macro can be used to validate the arguments of zero_extract and
sign_extract to fix this problem:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77822
---
gcc/system.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/gcc/system.h b/gcc/system.h
index 8c6127c..6c1228d 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -316,6 +316,15 @@ extern int errno;
((unsigned HOST_WIDE_INT) (VALUE) - (unsigned HOST_WIDE_INT) (LOWER) \
<= (unsigned HOST_WIDE_INT) (UPPER) - (unsigned HOST_WIDE_INT) (LOWER))
+/* A convenience macro to determine whether SIZE lies inclusively
+ within [1, RANGE], POS lies inclusively within between
+ [0, RANGE - 1] and the sum lies inclusively within [1, RANGE].
+ RANGE must be >= 1, but SIZE and POS may be negative. */
+#define SIZE_POS_IN_RANGE(SIZE, POS, RANGE) \
+ (IN_RANGE ((POS), 0, (unsigned HOST_WIDE_INT) (RANGE) - 1) \
+ && IN_RANGE ((SIZE), 1, (unsigned HOST_WIDE_INT) (RANGE) \
+ - (unsigned HOST_WIDE_INT)(POS)))
+
/* Infrastructure for defining missing _MAX and _MIN macros. Note that
macros defined with these cannot be used in #if. */
--
2.3.0
