On Fri, May 18, 2018 at 8:47 PM, tzik via cfe-commits <cfe-commits@lists.llvm.org> wrote: > Ah, sorry. It's still work in progress for now. > I'll resend this soon after adding tests and updating comments there. See Herald rules for exact syntax, but i think adding "[private]" into the subject would have prevented it from going live.
> 2018年5月19日(土) 2:41 Arthur O'Dwyer <arthur.j.odw...@gmail.com>: >> >> https://reviews.llvm.org/D47067 is a "Restricted Differential Revision", >> which I've never seen before! >> Peanut gallery says: This sounds awesome. How does this change interact >> with the diagnostics issued by -Wpessimizing-move and -Wreturn-std-move? >> Should any new test cases be added for those diagnostics? >> >> >> On Fri, May 18, 2018 at 7:12 AM, Taiju Tsuiki via Phabricator via >> cfe-commits <cfe-commits@lists.llvm.org> wrote: >>> >>> tzik created this revision. >>> Herald added a subscriber: cfe-commits. >>> >>> The previous implementation misses an opportunity to apply NRVO (Named >>> Return Value >>> >>> Optimization) below. That discourages user to write early return code. >>> ---------------------------------------------------------------------- >>> >>> struct Foo {}; >>> >>> Foo f(bool b) { >>> >>> if (b) >>> return Foo(); >>> Foo oo; >>> return oo; >>> >>> } >>> - >>> >>> That is, we can/should apply RVO for a return statement if it refers a >>> non-parameter local variable, >>> and the variable is referred by all return statements reachable from the >>> variable declaration. >>> While, the previous implementation disables the RVO in a scope if there >>> are multiple return >>> statements that refers different variables. >>> >>> On the new algorithm, local variables are in NRVO_Candidate state at >>> first, and a return >>> statement changes it to NRVO_Disabled for all visible variables but the >>> return statement refers. >>> Then, at the end of the function AST traversal, NRVO is enabled for >>> variables in NRVO_Candidate >>> state and refers from at least one return statement. >>> >>> >>> Repository: >>> rC Clang >>> >>> https://reviews.llvm.org/D47067 >>> >>> Files: >>> include/clang/AST/Decl.h >>> include/clang/Sema/Scope.h >>> lib/Sema/Scope.cpp >>> lib/Sema/SemaDecl.cpp >>> lib/Sema/SemaStmt.cpp >>> lib/Serialization/ASTReaderDecl.cpp >>> lib/Serialization/ASTWriterDecl.cpp >>> test/CodeGenCXX/nrvo.cpp >>> >>> >>> _______________________________________________ >>> cfe-commits mailing list >>> cfe-commits@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >>> >> > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
