From: Bernd Schmidt <bschmidt@redhat.com>
To: GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Fix PR77880
Date: Fri, 07 Oct 2016 12:18:00 -0000 [thread overview]
Message-ID: <cbc378b0-c2d2-1ed0-70c9-50558e31746a@redhat.com> (raw)
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When encountering a memcmp with something like ULONG_MAX for the size, a
calculation can overflow in by_pieces_ninsns because it uses int rather
than HOST_WIDE_INT.
Bootstrapped & tested on x86_64-linux, committed as obvious.
Bernd
[-- Attachment #2: bypieces.diff --]
[-- Type: text/x-patch, Size: 925 bytes --]
Index: gcc/ChangeLog
===================================================================
--- gcc/ChangeLog (revision 240861)
+++ gcc/ChangeLog (working copy)
@@ -1,3 +1,9 @@
+2016-10-07 Bernd Schmidt <bschmidt@redhat.com>
+
+ PR tree-optimization/77880
+ * expr.c (by_pieces_ninsns): Use unsigned HOST_WIDE_INT where
+ necessary.
+
2016-10-07 Marek Polacek <polacek@redhat.com>
PR c++/77803
Index: gcc/expr.c
===================================================================
--- gcc/expr.c (revision 240861)
+++ gcc/expr.c (working copy)
@@ -785,7 +785,7 @@ by_pieces_ninsns (unsigned HOST_WIDE_INT
case COMPARE_BY_PIECES:
int batch = targetm.compare_by_pieces_branch_ratio (mode);
int batch_ops = 4 * batch - 1;
- int full = n_pieces / batch;
+ unsigned HOST_WIDE_INT full = n_pieces / batch;
n_insns += full * batch_ops;
if (n_pieces % batch != 0)
n_insns++;
reply other threads:[~2016-10-07 12:18 UTC|newest]
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