<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Dec 2, 2014 at 9:36 PM, Duncan P. N. Exon Smith <span dir="ltr"><<a href="mailto:dexonsmith@apple.com" target="_blank">dexonsmith@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5"><br>
> On 2014 Dec 2, at 21:00, David Blaikie <<a href="mailto:dblaikie@gmail.com">dblaikie@gmail.com</a>> wrote:<br>
><br>
><br>
><br>
> On Tue, Dec 2, 2014 at 8:45 PM, Duncan P. N. Exon Smith <<a href="mailto:dexonsmith@apple.com">dexonsmith@apple.com</a>> wrote:<br>
> Author: dexonsmith<br>
> Date: Tue Dec 2 22:45:09 2014<br>
> New Revision: 223201<br>
><br>
> URL: <a href="http://llvm.org/viewvc/llvm-project?rev=223201&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=223201&view=rev</a><br>
> Log:<br>
> ADT: Add SmallVector<>::emplace_back()<br>
><br>
> Modified:<br>
> llvm/trunk/include/llvm/ADT/SmallVector.h<br>
> llvm/trunk/unittests/ADT/SmallVectorTest.cpp<br>
><br>
> Modified: llvm/trunk/include/llvm/ADT/SmallVector.h<br>
> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/SmallVector.h?rev=223201&r1=223200&r2=223201&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/SmallVector.h?rev=223201&r1=223200&r2=223201&view=diff</a><br>
> ==============================================================================<br>
> --- llvm/trunk/include/llvm/ADT/SmallVector.h (original)<br>
> +++ llvm/trunk/include/llvm/ADT/SmallVector.h Tue Dec 2 22:45:09 2014<br>
> @@ -236,6 +236,51 @@ public:<br>
> this->setEnd(this->end()-1);<br>
> this->end()->~T();<br>
> }<br>
> +<br>
> +#if LLVM_HAS_VARIADIC_TEMPLATES<br>
> + template <typename... ArgTypes> void emplace_back(ArgTypes &&... Args) {<br>
> + if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))<br>
> + this->grow();<br>
> + ::new ((void *)this->end()) T(std::forward<ArgTypes>(Args)...);<br>
> + this->setEnd(this->end() + 1);<br>
> + }<br>
> +#else<br>
> +private:<br>
> + template <typename Constructor> emplace_back_impl(Constructor emplace) {<br>
><br>
> wow, calling that functor 'emplace' confused me for quite a while (I was wondering why we had an emplace function that took a void* and didn't update the end function) - at some point we might grow SmallVector::emplace to match std::vector::emplace (emplace at a specified location, rather than the back) - so it might be best not to use that name in this context.<br>
<br>
</div></div>Heh, good point. Totally missed that. How do you feel about `construct`?<br></blockquote><div><br>Works for me<br> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<span class=""><br>
><br>
> + if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))<br>
> + this->grow();<br>
><br>
> This can be tricky - I seem to recall seeing some previous changes being careful about allowing, I think it was, insertion of a value referenced within the container being inserted into. That has to carefully split the grow operation - allocating the new buffer, constructing the new element, then moving/copying the old elements over.<br>
><br>
> I don't know if the C++ standard guarantees that, say, v.emplace_back(v[0]), is required to be valid, or if we should bother making that valid, but it's a thing to think about.<br>
<br>
</span>I'm not sure either (and I hadn't thought of it), but I replied to the<br>
other thread that you bumped.<br></blockquote><div><br>*nod* Will continue there.<br> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="HOEnZb"><div class="h5"><br>
><br>
> + emplace((void *)this->end());<br>
> + this->setEnd(this->end() + 1);<br>
> + }<br>
> +<br>
> +public:<br>
> + void emplace_back() {<br>
> + emplace_back_impl([](void *Mem) { ::new (Mem) T(); });<br>
> + }<br>
> + template <typename T1> void emplace_back(T1 &&A1) {<br>
> + emplace_back_impl([&](void *Mem) { ::new (Mem) T(std::forward<T1>(A1)); });<br>
> + }<br>
> + template <typename T1, typename T2> void emplace_back(T1 &&A1, T2 &&A2) {<br>
> + emplace_back_impl([&](void *Mem) {<br>
> + ::new (Mem) T(std::forward<T1>(A1), std::forward<T2>(A2));<br>
> + });<br>
> + }<br>
> + template <typename T1, typename T2, typename T3><br>
> + void emplace_back(T1 &&A1, T2 &&A2, T3 &&A3) {<br>
> + T(std::forward<T1>(A1), std::forward<T2>(A2), std::forward<T3>(A3));<br>
> + emplace_back_impl([&](void *Mem) {<br>
> + ::new (Mem)<br>
> + T(std::forward<T1>(A1), std::forward<T2>(A2), std::forward<T3>(A3));<br>
> + });<br>
> + }<br>
> + template <typename T1, typename T2, typename T3, typename T4><br>
> + void emplace_back(T1 &&A1, T2 &&A2, T3 &&A3, T4 &&A4) {<br>
> + emplace_back_impl([&](void *Mem) {<br>
> + ::new (Mem) T(std::forward<T1>(A1), std::forward<T2>(A2),<br>
> + std::forward<T3>(A3), std::forward<T4>(A4));<br>
> + });<br>
> + }<br>
> +#endif // LLVM_HAS_VARIADIC_TEMPLATES<br>
> };<br>
><br>
> // Define this out-of-line to dissuade the C++ compiler from inlining it.<br>
><br>
> Modified: llvm/trunk/unittests/ADT/SmallVectorTest.cpp<br>
> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/SmallVectorTest.cpp?rev=223201&r1=223200&r2=223201&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/SmallVectorTest.cpp?rev=223201&r1=223200&r2=223201&view=diff</a><br>
> ==============================================================================<br>
> --- llvm/trunk/unittests/ADT/SmallVectorTest.cpp (original)<br>
> +++ llvm/trunk/unittests/ADT/SmallVectorTest.cpp Tue Dec 2 22:45:09 2014<br>
> @@ -699,4 +699,135 @@ TEST(SmallVectorTest, MidInsert) {<br>
> EXPECT_TRUE(m.hasValue);<br>
> }<br>
><br>
> +enum EmplaceableArgState {<br>
> + EAS_Defaulted,<br>
> + EAS_Arg,<br>
> + EAS_LValue,<br>
> + EAS_RValue,<br>
> + EAS_Failure<br>
> +};<br>
> +template <int I> struct EmplaceableArg {<br>
> + EmplaceableArgState State;<br>
> + EmplaceableArg() : State(EAS_Defaulted) {}<br>
> + EmplaceableArg(EmplaceableArg &&X)<br>
> + : State(X.State == EAS_Arg ? EAS_RValue : EAS_Failure) {}<br>
> + EmplaceableArg(EmplaceableArg &X)<br>
> + : State(X.State == EAS_Arg ? EAS_LValue : EAS_Failure) {}<br>
> +<br>
> + explicit EmplaceableArg(bool) : State(EAS_Arg) {}<br>
> +<br>
> +private:<br>
> + EmplaceableArg(const EmplaceableArg &X) LLVM_DELETED_FUNCTION;<br>
> + EmplaceableArg &operator=(EmplaceableArg &&) LLVM_DELETED_FUNCTION;<br>
> + EmplaceableArg &operator=(const EmplaceableArg &) LLVM_DELETED_FUNCTION;<br>
> +};<br>
> +<br>
> +enum EmplaceableState { ES_Emplaced, ES_Moved };<br>
> +struct Emplaceable {<br>
> + EmplaceableArg<0> A0;<br>
> + EmplaceableArg<1> A1;<br>
> + EmplaceableArg<2> A2;<br>
> + EmplaceableArg<3> A3;<br>
> + EmplaceableState State;<br>
> +<br>
> + Emplaceable() : State(ES_Emplaced) {}<br>
> +<br>
> + template <class A0Ty><br>
> + explicit Emplaceable(A0Ty &&A0)<br>
> + : A0(std::forward<A0Ty>(A0)), State(ES_Emplaced) {}<br>
> +<br>
> + template <class A0Ty, class A1Ty><br>
> + Emplaceable(A0Ty &&A0, A1Ty &&A1)<br>
> + : A0(std::forward<A0Ty>(A0)), A1(std::forward<A1Ty>(A1)),<br>
> + State(ES_Emplaced) {}<br>
> +<br>
> + template <class A0Ty, class A1Ty, class A2Ty><br>
> + Emplaceable(A0Ty &&A0, A1Ty &&A1, A2Ty &&A2)<br>
> + : A0(std::forward<A0Ty>(A0)), A1(std::forward<A1Ty>(A1)),<br>
> + A2(std::forward<A2Ty>(A2)), State(ES_Emplaced) {}<br>
> +<br>
> + template <class A0Ty, class A1Ty, class A2Ty, class A3Ty><br>
> + Emplaceable(A0Ty &&A0, A1Ty &&A1, A2Ty &&A2, A3Ty &&A3)<br>
> + : A0(std::forward<A0Ty>(A0)), A1(std::forward<A1Ty>(A1)),<br>
> + A2(std::forward<A2Ty>(A2)), A3(std::forward<A3Ty>(A3)),<br>
> + State(ES_Emplaced) {}<br>
> +<br>
> + Emplaceable(Emplaceable &&) : State(ES_Moved) {}<br>
> + Emplaceable &operator=(Emplaceable &&) {<br>
> + State = ES_Moved;<br>
> + return *this;<br>
> + }<br>
> +<br>
> +private:<br>
> + Emplaceable(const Emplaceable &) LLVM_DELETED_FUNCTION;<br>
> + Emplaceable &operator=(const Emplaceable &) LLVM_DELETED_FUNCTION;<br>
> +};<br>
> +<br>
> +TEST(SmallVectorTest, EmplaceBack) {<br>
> + EmplaceableArg<0> A0(true);<br>
> + EmplaceableArg<1> A1(true);<br>
> + EmplaceableArg<2> A2(true);<br>
> + EmplaceableArg<3> A3(true);<br>
> + {<br>
> + SmallVector<Emplaceable, 3> V;<br>
> + V.emplace_back();<br>
> + EXPECT_TRUE(V.size() == 1);<br>
> + EXPECT_TRUE(V.back().State == ES_Emplaced);<br>
> + EXPECT_TRUE(V.back().A0.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A1.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A2.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A3.State == EAS_Defaulted);<br>
> + }<br>
> + {<br>
> + SmallVector<Emplaceable, 3> V;<br>
> + V.emplace_back(std::move(A0));<br>
> + EXPECT_TRUE(V.size() == 1);<br>
> + EXPECT_TRUE(V.back().State == ES_Emplaced);<br>
> + EXPECT_TRUE(V.back().A0.State == EAS_RValue);<br>
> + EXPECT_TRUE(V.back().A1.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A2.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A3.State == EAS_Defaulted);<br>
> + }<br>
> + {<br>
> + SmallVector<Emplaceable, 3> V;<br>
> + V.emplace_back(A0);<br>
> + EXPECT_TRUE(V.size() == 1);<br>
> + EXPECT_TRUE(V.back().State == ES_Emplaced);<br>
> + EXPECT_TRUE(V.back().A0.State == EAS_LValue);<br>
> + EXPECT_TRUE(V.back().A1.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A2.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A3.State == EAS_Defaulted);<br>
> + }<br>
> + {<br>
> + SmallVector<Emplaceable, 3> V;<br>
> + V.emplace_back(A0, A1);<br>
> + EXPECT_TRUE(V.size() == 1);<br>
> + EXPECT_TRUE(V.back().State == ES_Emplaced);<br>
> + EXPECT_TRUE(V.back().A0.State == EAS_LValue);<br>
> + EXPECT_TRUE(V.back().A1.State == EAS_LValue);<br>
> + EXPECT_TRUE(V.back().A2.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A3.State == EAS_Defaulted);<br>
> + }<br>
> + {<br>
> + SmallVector<Emplaceable, 3> V;<br>
> + V.emplace_back(std::move(A0), std::move(A1));<br>
> + EXPECT_TRUE(V.size() == 1);<br>
> + EXPECT_TRUE(V.back().State == ES_Emplaced);<br>
> + EXPECT_TRUE(V.back().A0.State == EAS_RValue);<br>
> + EXPECT_TRUE(V.back().A1.State == EAS_RValue);<br>
> + EXPECT_TRUE(V.back().A2.State == EAS_Defaulted);<br>
> + EXPECT_TRUE(V.back().A3.State == EAS_Defaulted);<br>
> + }<br>
> + {<br>
> + SmallVector<Emplaceable, 3> V;<br>
> + V.emplace_back(std::move(A0), A1, std::move(A2), A3);<br>
> + EXPECT_TRUE(V.size() == 1);<br>
> + EXPECT_TRUE(V.back().State == ES_Emplaced);<br>
> + EXPECT_TRUE(V.back().A0.State == EAS_RValue);<br>
> + EXPECT_TRUE(V.back().A1.State == EAS_LValue);<br>
> + EXPECT_TRUE(V.back().A2.State == EAS_RValue);<br>
> + EXPECT_TRUE(V.back().A3.State == EAS_LValue);<br>
> + }<br>
> }<br>
> +<br>
> +} // end namespace<br>
><br>
><br>
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</div></div></blockquote></div><br></div></div>