08c5a7b8fd
With MSVC, PCH files are created along with an object file that needs to
be linked into the final library or executable. That object file
contains the code generated when building the headers. In particular, it
will include definitions of inline dllexport functions, and because they
are emitted in this object file, other files using the PCH do not need
to emit them. See the bug for an example.
This patch makes clang-cl match MSVC's behaviour in this regard, causing
significant compile-time savings when building dlls using precompiled
headers.
For example, in a 64-bit optimized shared library build of Chromium with
PCH, it reduces the binary size and compile time of
stroke_opacity_custom.obj from 9315564 bytes to 3659629 bytes and 14.6
to 6.63 s. The wall-clock time of building blink_core.dll goes from
38m41s to 22m33s. ("user" time goes from 1979m to 1142m).
Differential Revision: https://reviews.llvm.org/D48426
llvm-svn: 335466
85 lines
3.5 KiB
C++
85 lines
3.5 KiB
C++
// Build PCH without object file, then use it.
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// RUN: %clang_cc1 -triple i686-pc-win32 -fms-extensions -emit-pch -o %t %s
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// RUN: %clang_cc1 -triple i686-pc-win32 -fms-extensions -emit-obj -emit-llvm -include-pch %t -o - %s | FileCheck -check-prefix=PCH %s
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// Build PCH with object file, then use it.
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// RUN: %clang_cc1 -triple i686-pc-win32 -fms-extensions -emit-pch -building-pch-with-obj -o %t %s
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// RUN: %clang_cc1 -triple i686-pc-win32 -fms-extensions -emit-obj -emit-llvm -include-pch %t -building-pch-with-obj -o - %s | FileCheck -check-prefix=OBJ %s
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// RUN: %clang_cc1 -triple i686-pc-win32 -fms-extensions -emit-obj -emit-llvm -include-pch %t -o - %s | FileCheck -check-prefix=PCHWITHOBJ %s
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// Check for vars separately to avoid having to reorder the check statements.
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// RUN: %clang_cc1 -triple i686-pc-win32 -fms-extensions -emit-obj -emit-llvm -include-pch %t -o - %s | FileCheck -check-prefix=PCHWITHOBJVARS %s
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#ifndef IN_HEADER
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#define IN_HEADER
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inline void __declspec(dllexport) foo() {}
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// OBJ: define weak_odr dso_local dllexport void @"?foo@@YAXXZ"
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// PCH: define weak_odr dso_local dllexport void @"?foo@@YAXXZ"
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// PCHWITHOBJ-NOT: define {{.*}}foo
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// This function is referenced, so gets emitted as usual.
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inline void __declspec(dllexport) baz() {}
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// OBJ: define weak_odr dso_local dllexport void @"?baz@@YAXXZ"
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// PCH: define weak_odr dso_local dllexport void @"?baz@@YAXXZ"
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// PCHWITHOBJ: define weak_odr dso_local dllexport void @"?baz@@YAXXZ"
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struct __declspec(dllexport) S {
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void bar() {}
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// OBJ: define weak_odr dso_local dllexport x86_thiscallcc void @"?bar@S@@QAEXXZ"
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// PCH: define weak_odr dso_local dllexport x86_thiscallcc void @"?bar@S@@QAEXXZ"
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// PCHWITHOBJ-NOT: define {{.*}}bar
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};
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// This isn't dllexported, attribute((used)) or referenced, so not emitted.
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inline void quux() {}
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// OBJ-NOT: define {{.*}}quux
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// PCH-NOT: define {{.*}}quux
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// PCHWITHOBJ-NOT: define {{.*}}quux
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// Referenced non-dllexport function.
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inline void referencedNonExported() {}
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// OBJ: define {{.*}}referencedNonExported
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// PCH: define {{.*}}referencedNonExported
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// PCHWITHOBJ: define {{.*}}referencedNonExported
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template <typename T> void __declspec(dllexport) implicitInstantiation(T) {}
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template <typename T> inline void __declspec(dllexport) explicitSpecialization(T) {}
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template <typename T> void __declspec(dllexport) explicitInstantiationDef(T) {}
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template <typename T> void __declspec(dllexport) explicitInstantiationDefAfterDecl(T) {}
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extern template void explicitInstantiationDefAfterDecl<int>(int);
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template <typename T> T __declspec(dllexport) variableTemplate;
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extern template int variableTemplate<int>;
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#else
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void use() {
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baz();
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referencedNonExported();
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}
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// Templates can be tricky. None of the definitions below come from the PCH.
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void useTemplate() { implicitInstantiation(42); }
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// PCHWITHOBJ: define weak_odr dso_local dllexport void @"??$implicitInstantiation@H@@YAXH@Z"
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template<> inline void __declspec(dllexport) explicitSpecialization<int>(int) {}
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// PCHWITHOBJ: define weak_odr dso_local dllexport void @"??$explicitSpecialization@H@@YAXH@Z"
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template void __declspec(dllexport) explicitInstantiationDef<int>(int);
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// PCHWITHOBJ: define weak_odr dso_local dllexport void @"??$explicitInstantiationDef@H@@YAXH@Z"
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template void __declspec(dllexport) explicitInstantiationDefAfterDecl<int>(int);
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// PCHWITHOBJ: define weak_odr dso_local dllexport void @"??$explicitInstantiationDefAfterDecl@H@@YAXH@Z"(i32)
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template int __declspec(dllexport) variableTemplate<int>;
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// PCHWITHOBJVARS: @"??$variableTemplate@H@@3HA" = weak_odr dso_local dllexport global
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#endif
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