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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/98216] [C++20] template mangling for double template argument is wrong Date: Wed, 06 Oct 2021 14:15:41 +0000 [thread overview] Message-ID: <bug-98216-4-vN2y2tmydH@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-98216-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98216 --- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>: https://gcc.gnu.org/g:1682576e62d41cd761472943372b83aee514254a commit r11-9083-g1682576e62d41cd761472943372b83aee514254a Author: Patrick Palka <ppalka@redhat.com> Date: Fri Sep 24 12:36:26 2021 -0400 real: fix encoding of negative IEEE double/quad values [PR98216] In encode_ieee_double/quad, the assignment unsigned long WORD = r->sign << 31; is intended to set the 31st bit of WORD whenever the sign bit is set. But on LP64 hosts it also unintentionally sets the upper 32 bits of WORD, because r->sign gets promoted from unsigned:1 to int and then the result of the shift (equal to INT_MIN) gets sign extended from int to long. In the C++ frontend, this bug causes incorrect mangling of negative floating point values because the output of real_to_target called from write_real_cst unexpectedly has the upper 32 bits of this word set, which the caller doesn't mask out. This patch fixes this by avoiding the unwanted sign extension. Note that r0-53976 fixed the same bug in encode_ieee_single long ago. PR c++/98216 PR c++/91292 gcc/ChangeLog: * real.c (encode_ieee_double): Avoid unwanted sign extension. (encode_ieee_quad): Likewise. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/nontype-float2.C: New test. (cherry picked from commit 34947d4e97ee72b26491cfe5ff4fa8258fadbe95)
next prev parent reply other threads:[~2021-10-06 14:15 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-09 15:43 [Bug c++/98216] New: [C++20] std::array<double, N> template parameter error with negative values emmanuel.le-trong@cnrs-orleans.fr 2020-12-09 16:04 ` [Bug c++/98216] " redi at gcc dot gnu.org 2020-12-10 7:33 ` rguenth at gcc dot gnu.org 2020-12-10 17:05 ` redi at gcc dot gnu.org 2020-12-10 17:16 ` redi at gcc dot gnu.org 2020-12-10 17:56 ` emmanuel.le-trong@cnrs-orleans.fr 2020-12-14 20:56 ` ppalka at gcc dot gnu.org 2021-07-27 8:08 ` [Bug c++/98216] [C++20] template mangling for double template argument is wrong pinskia at gcc dot gnu.org 2021-09-23 18:57 ` ppalka at gcc dot gnu.org 2021-09-23 19:01 ` ppalka at gcc dot gnu.org 2021-09-24 16:36 ` cvs-commit at gcc dot gnu.org 2021-09-24 19:36 ` emmanuel.le-trong@cnrs-orleans.fr 2021-10-06 14:15 ` cvs-commit at gcc dot gnu.org [this message] 2021-10-14 19:06 ` hq.ks at web dot de 2021-10-14 21:39 ` pinskia at gcc dot gnu.org
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