[llvm-bugs] [Bug 25729] New: clang 300x slower to compile recursive constexpr template vs. gcc

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=25729

            Bug ID: 25729
           Summary: clang 300x slower to compile recursive constexpr
                    template vs. gcc
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: Frontend
          Assignee: unassignedclangbugs at nondot.org
          Reporter: paul_robinson at playstation.sony.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 15391
  --> https://llvm.org/bugs/attachment.cgi?id=15391&action=edit
repro with recursive constexpr template

The attached source takes > 10 seconds for me to compile with a
Release build of clang, versus much < .1 seconds for gcc 5.2.1.
The resulting compiled table looks identical.

$ $UP/clang --version
clang version 3.8.0 (trunk 253958)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/probinson/projects/llvm-org/trunk/cobj/bin
$ time $UP/clang -c -std=c++14 h.cpp

real    0m10.348s
user    0m10.311s
sys     0m0.022s
$ gcc-5 --version
gcc-5 (Ubuntu 5.2.1-27ubuntu1~14.04.1) 5.2.1 20141129
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ time gcc-5 -c -std=c++14 h.cpp

real    0m0.027s
user    0m0.015s
sys     0m0.012s

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