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From: "jgreenhalgh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/96958] New: Long Double in Hash Table policy forces
 soft-float calculations
Date: Mon, 07 Sep 2020 16:12:07 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 11.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96958

            Bug ID: 96958
           Summary: Long Double in Hash Table policy forces soft-float
                    calculations
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jgreenhalgh at gcc dot gnu.org
  Target Milestone: ---

It was pointed out that some forks of GCC (
https://github.com/FEX-Emu/gcc/commit/8a2b7389f50a50a4e26ec98101d47fb1fc1c1=
bcd
) reduce the hashtable policy implementation from a long double to a double.
Doing this reduces it from a soft-float calculation to hardware floating-po=
int.

Reading the discussion on libstdc++ from when this code was introduced the
intention was to provide massive amounts of forwards compatibility for Very=
 Big
hash tables. We're taking quite an efficiency hit for that future proofing.=