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Re: Some wide-int review comments
- 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>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Mike Stump <mikestump at comcast dot net>, Richard Sandiford <rdsandiford at googlemail dot com>
- Date: Tue, 26 Nov 2013 11:33:05 -0500
- Subject: Re: Some wide-int review comments
- Authentication-results: sourceware.org; auth=none
- References: <87mwlfgp8s dot fsf at talisman dot default> <527E456B dot 4050203 at naturalbridge dot com> <CAFiYyc2qJB3onVWWqBu5sYMQE6Otpmys5U3ZpyQtWAfKOFCcCQ at mail dot gmail dot com> <5280E914 dot 2060501 at naturalbridge dot com> <CAFiYyc0tNHO54aS7PaRKLdsWMQ6qN++MdN8=63Eq1AD5GtHrPg at mail dot gmail dot com> <5280F219 dot 6050000 at naturalbridge dot com> <CAFiYyc0LmDSAtMYqAe4kBr=4WcAzNtQm=cjbeX+1OGGyyjS-=g at mail dot gmail dot com> <52825432 dot 5070502 at naturalbridge dot com> <Pine dot LNX dot 4 dot 64 dot 1311121624220 dot 31448 at digraph dot polyomino dot org dot uk> <52825AC9 dot 9050604 at naturalbridge dot com> <CAFiYyc2Zph0ROZcXuapeP-7uXrWV1qXW2Znjseg6Dd0w2e0M2A at mail dot gmail dot com> <528D4649 dot 5020804 at naturalbridge dot com>
Richi,
patch ping
also two more pieces of information. With further testing, this seems
to fix
Tests that now work, but didn't before:
===============
ext/random/hypergeometric_distribution/operators/values.cc (test for
excess errors)
New tests that PASS:
ext/random/hypergeometric_distribution/operators/values.cc execution test
================
also, the corresponding frag for fold-const.c on the wide-int branch
will look like
================
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 205224)
+++ gcc/fold-const.c (working copy)
@@ -1030,51 +1030,51 @@ int_const_binop_1 (enum tree_code code,
case TRUNC_DIV_EXPR:
case EXACT_DIV_EXPR:
- res = wi::div_trunc (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::div_trunc (arg1, arg2, sign, &overflow);
break;
case FLOOR_DIV_EXPR:
- res = wi::div_floor (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::div_floor (arg1, arg2, sign, &overflow);
break;
case CEIL_DIV_EXPR:
- res = wi::div_ceil (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::div_ceil (arg1, arg2, sign, &overflow);
break;
case ROUND_DIV_EXPR:
- res = wi::div_round (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::div_round (arg1, arg2, sign, &overflow);
break;
case TRUNC_MOD_EXPR:
- res = wi::mod_trunc (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::mod_trunc (arg1, arg2, sign, &overflow);
break;
case FLOOR_MOD_EXPR:
- res = wi::mod_floor (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::mod_floor (arg1, arg2, sign, &overflow);
break;
case CEIL_MOD_EXPR:
- res = wi::mod_ceil (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::mod_ceil (arg1, arg2, sign, &overflow);
break;
case ROUND_MOD_EXPR:
- res = wi::mod_round (arg1, arg2, sign, &overflow);
- if (overflow)
+ if (arg2 == 0)
return NULL_TREE;
+ res = wi::mod_round (arg1, arg2, sign, &overflow);
break;
case MIN_EXPR:
================
On 11/20/2013 06:31 PM, Kenneth Zadeck wrote:
On 11/13/2013 04:59 AM, Richard Biener wrote:
On Tue, Nov 12, 2013 at 5:43 PM, Kenneth Zadeck
<zadeck@naturalbridge.com> wrote:
On 11/12/2013 11:27 AM, Joseph S. Myers wrote:
On Tue, 12 Nov 2013, Kenneth Zadeck wrote:
Richi,
i am having a little trouble putting this back the way that you want.
The
issue is rem.
what is supposed to happen for INT_MIN % -1?
I would assume because i am failing the last case of
gcc.dg/c90-const-expr-8.c
that INT_MIN %-1 should not overflow even if INT_MIN / -1 does.
however,
Given the conclusion in C11 that a%b should be considered undefined
if a/b
is not representable, I think it's reasonable to say INT_MIN % -1
*should*
be considered to overflow (for all C standard versions) (and bug
30484 is
only a bug for -fwrapv).
however, my local question is what do we want the api to be
int-const-binop-1? The existing behavior seems to be that at
least for
common modes this function silently returns 0 and it is up to the
front ends
to put their own spin on it.
For wide-int you create 1:1 the behavior of current trunk (if a
change of
behavior in TImode is not tested in the testsuite then you can ignore
that).
Whatever change you do to semantics of functions you do separately
from wide-int (preferably first on trunk, or at your choice after the
wide-int
merge).
For this case in question I'd say a % -1 should return 0, but for
INT_MIN % -1 that 0 should have TREE_OVERFLOW set (and
thus you need to adjust that c90-const-expr-8.c testcase).
Richard.
kenny
richi,
I have done this exactly as you suggested. bootstrapped and
regression tested on x86-64.
2013-11-20 Kenneth Zadeck <zadeck@naturalbridge.com>
* fold-const.c
(int_const_binop_1): Make INT_MIN % -1 return 0 with the overflow
bit set.
2013-11-20 Kenneth Zadeck <zadeck@naturalbridge.com>
* gcc.dg/c90-const-expr-8.c: Look for overflow on INT_MIN % -1.
* gcc.dg/c99-const-expr-8.c: Look for overflow on INT_MIN % -1.
ok to commit?
kenny