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Re: patch to fix constant math - first small patch - patch ping for the next stage 1

From: Kenneth Zadeck <zadeck at naturalbridge dot com>
To: Richard Biener <richard dot guenther at gmail dot com>
Cc: "Joseph S. Myers" <joseph at codesourcery dot com>, Mike Stump <mikestump at comcast dot net>, gcc-patches <gcc-patches at gcc dot gnu dot org>, rdsandiford at googlemail dot com, Ian Lance Taylor <iant at google dot com>
Date: Thu, 28 Mar 2013 11:05:49 -0400
Subject: Re: patch to fix constant math - first small patch - patch ping for the next stage 1
References: <506C72C7 dot 7090207 at naturalbridge dot com> <506D9544 dot 7020408 at naturalbridge dot com> <CAFiYyc0No3S6dmRjrzDZbuN=ujbsgUog3R4S2gVn4z2sihBiiw at mail dot gmail dot com> <506DD085 dot 7080608 at naturalbridge dot com> <87txuaox52 dot fsf at talisman dot home> <CAFiYyc1GP46Sf9Tr=YWL1EhWwhcfRFBQoiH8jV-PZv-krsWJmg at mail dot gmail dot com> <87lifli6oj dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com> <CAFiYyc1RYvJ-2_6WaYosA3qm5JhiGhmXnczX3DCNfKt_zg46+g at mail dot gmail dot com> <87ehldi2kr dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com> <CAFiYyc0B27i23X8Sg+=yOd_SqKedB3RunBDs4b-Jm-fSAD-hwA at mail dot gmail dot com> <87a9w1hzq1 dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com> <CAFiYyc0Sj3+yBXRjLUG=0=_NGQiU1VqJk35hjsWqHR9bCnqspg at mail dot gmail dot com> <506F0C1A dot 5010705 at naturalbridge dot com> <87lifkhlo9 dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com> <506F5B50 dot 2040800 at naturalbridge dot com> <Pine dot LNX dot 4 dot 64 dot 1210060013110 dot 3565 at digraph dot polyomino dot org dot uk> <512D51DE dot 6010005 at naturalbridge dot com> <CAFiYyc0FQTmnPqC44ks+EH=Rjri97gdW=CKDZM0A7pX7C8_XSA at mail dot gmail dot com>

richard,

adding the gcc_checking_assert is going to require that i includesystem.h in hwint.h which seems to cause a loop. while in principle, iagree with the assert, this is going to be a mess.


kenny


On 03/27/2013 10:13 AM, Richard Biener wrote:

On Wed, Feb 27, 2013 at 1:22 AM, Kenneth Zadeck
<zadeck@naturalbridge.com> wrote:

Here is the first of my wide int patches with joseph's comments and the
patch rot removed.

I would like to get these pre approved for the next stage 1.

+      int shift = HOST_BITS_PER_WIDE_INT - (prec &
(HOST_BITS_PER_WIDE_INT - 1));

I think this should gcc_checking_assert that prec is not out of range
(any reason why prec is signed int and not unsigned int?) rather than
ignore bits in prec.

+static inline HOST_WIDE_INT
+zext_hwi (HOST_WIDE_INT src, int prec)
+{
+  if (prec == HOST_BITS_PER_WIDE_INT)
+    return src;
+  else
+    return src & (((HOST_WIDE_INT)1
+                  << (prec & (HOST_BITS_PER_WIDE_INT - 1))) - 1);
+}

likewise.  Also I'm not sure I agree about the signedness of the result / src.
zext_hwi (-1, HOST_BITS_PER_WIDE_INT) < 0 is true which is odd.

The patch misses context of uses, so I'm not sure what the above functions
are intended to do.

Richard.

On 10/05/2012 08:14 PM, Joseph S. Myers wrote:

On Fri, 5 Oct 2012, Kenneth Zadeck wrote:

+# define HOST_HALF_WIDE_INT_PRINT "h"

This may cause problems on hosts not supporting %hd (MinGW?), and there's
no real need for using "h" here given the promotion of short to int; you
can just use "" (rather than e.g. needing special handling in xm-mingw32.h
like is done for HOST_LONG_LONG_FORMAT).

References:
- Re: patch to fix constant math - first small patch - patch ping for the next stage 1
  - From: Richard Biener

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