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63 lines
1.7 KiB
63 lines
1.7 KiB
2 years ago
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From 4e82c85b1c9c9b30253b8624470da6f20a6c0604 Mon Sep 17 00:00:00 2001
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From: Karl Williamson <khw@cpan.org>
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Date: Mon, 15 Mar 2021 21:01:47 -0600
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Subject: [PATCH] Fix broken left shift of IV_MIN under 'use integer'
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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This fixes GH 18639
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When I wrote this code, I conflated casting and complementing.
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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---
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pp.c | 3 ---
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t/op/bop.t | 9 ++++++++-
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2 files changed, 8 insertions(+), 4 deletions(-)
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diff --git a/pp.c b/pp.c
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index d365afea4c..baf0777a47 100644
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--- a/pp.c
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+++ b/pp.c
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@@ -2007,9 +2007,6 @@ static IV S_iv_shift(IV iv, int shift, bool left)
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* 18446744073709551552
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* */
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if (left) {
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- if (iv == IV_MIN) { /* Casting this to a UV is undefined behavior */
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- return 0;
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- }
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return (IV) (((UV) iv) << shift);
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}
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diff --git a/t/op/bop.t b/t/op/bop.t
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index 07f057d0a9..31b6531a03 100644
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--- a/t/op/bop.t
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+++ b/t/op/bop.t
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@@ -18,7 +18,7 @@ BEGIN {
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# If you find tests are failing, please try adding names to tests to track
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# down where the failure is, and supply your new names as a patch.
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# (Just-in-time test naming)
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-plan tests => 502;
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+plan tests => 503;
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# numerics
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ok ((0xdead & 0xbeef) == 0x9ead);
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@@ -33,6 +33,13 @@ ok ((33023 >> 7) == 257);
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# signed vs. unsigned
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ok ((~0 > 0 && do { use integer; ~0 } == -1));
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+{ # GH #18639
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+ my $iv_min = -(~0 >> 1) - 1;
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+ my $shifted;
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+ { use integer; $shifted = $iv_min << 0 };
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+ is($shifted, $iv_min, "IV_MIN << 0 yields IV_MIN under 'use integer'");
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+}
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+
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my $bits = 0;
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for (my $i = ~0; $i; $i >>= 1) { ++$bits; }
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my $cusp = 1 << ($bits - 1);
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--
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2.26.3
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