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From: "cfsteefel at arista dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/107163] New: Compile time regression when using templated base classes, virtual method, and Wall Date: Wed, 05 Oct 2022 19:35:24 +0000 [thread overview] Message-ID: <bug-107163-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107163 Bug ID: 107163 Summary: Compile time regression when using templated base classes, virtual method, and Wall Product: gcc Version: 11.3.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: cfsteefel at arista dot com Target Milestone: --- When using templates to create a recursive base class structure, if the base class uses a virtual method and -Wall is enabled, g++-11 shows much worse compile time compared to g++-8. Consider the following code: # 0 "test.cpp" # 0 "<built-in>" # 0 "<command-line>" # 1 "/usr/include/stdc-predef.h" 1 3 4 # 0 "<command-line>" 2 # 1 "test.cpp" class BaseType { virtual int doSomething() { return 1; } }; template< int Seq > class DerivedType : public DerivedType< Seq - 1 > { }; template<> class DerivedType< -1 > : public BaseType { }; int main() { auto * d = new DerivedType< COUNT >(); delete d; return 0; } Compiled as: g++-11 test.cpp -Wall -DCOUNT=200 g++-8 test.cpp -Wall -DCOUNT=200 In g++-11, with COUNT=100, the time to compile is around 2 seconds, while with COUNT=200, the time is around 1 minute, and COUNT=400 took around 28 minutes. For comparison, compiling the same code with g++-8 took around .3 seconds, 1.6 seconds, and 22 seconds, respectively. Removing the virtual will lead to the compile time being near instant again, as will removing the Wall flag (with g++-11). Other details: Compiler versions: g++ (GCC) 11.3.1 20220421 (Red Hat 11.3.1-2) g++ (GCC) 8.4.0 20200304 (Red Hat 8.4.0-4) System: Centos7 based linux Compiler output: test.cpp: In function 'int main()': test.cpp:20:4: warning: deleting object of polymorphic class type 'DerivedType<100>' which has non-virtual destructor might cause undefined behavior [-Wdelete-non-virtual-dtor] 20 | delete d; | ^~~~~~~~ (fixing the warning changes nothing, and seemed to double the compile time). extra g++-11/8 configuration options: %{O*:%{!fomit-frame-pointer:-fno-omit-frame-pointer}} \ %{O*:%{!fno-wrapv:-fwrapv}} \ %{O*:%{!freorder-blocks-and-partition:-fno-reorder-blocks-and-partition}} \ %{mfpmath=sse:-msse2} \ %{!fsemantic-interposition:-fno-semantic-interposition} \ %{g:%{!g0:-gdwarf-4}} \ Using godbolt, I can see similar timing for g++-10 and g++-8, so this seems to be a g++-11 specific regression.
next reply other threads:[~2022-10-05 19:35 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-10-05 19:35 cfsteefel at arista dot com [this message] 2022-10-05 19:49 ` [Bug c++/107163] Compile time regression when using templated base classes, virtual method, and Wall since r10-2823-g6a07489267e55084 marxin at gcc dot gnu.org 2022-10-05 19:53 ` [Bug c++/107163] [10/11/12/13 Regression] huge Compile time " pinskia at gcc dot gnu.org 2022-10-05 20:39 ` [Bug c++/107163] [10/11/12/13 Regression] huge Compile time increase " redi at gcc dot gnu.org 2022-10-18 8:36 ` rguenth at gcc dot gnu.org 2023-03-23 19:59 ` jason at gcc dot gnu.org 2023-03-28 15:27 ` cvs-commit at gcc dot gnu.org 2023-04-18 20:46 ` [Bug c++/107163] [10/11/12 " cvs-commit at gcc dot gnu.org 2023-04-21 20:28 ` [Bug c++/107163] [10/11 " cvs-commit at gcc dot gnu.org 2023-04-22 0:23 ` cvs-commit at gcc dot gnu.org 2023-07-07 10:44 ` [Bug c++/107163] [11 " rguenth at gcc dot gnu.org
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