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[Frontend][PCH]-Add support for ignoring PCH options (-ignore-pch). (#142409)
Visual Studio has an argument to ignore all PCH related switches. clang-cl has also support option /Y-. Having the same option in clang would be helpful. This commit is to add support for ignoring PCH options (-ignore-pch). The commit includes: 1. Implement -ignore-pch as a Driver option. 2. Add a Driver test and a PCH test. 3. Add a section of -ignore-pch to user manual. 4. Add a release note for the new option '-ignore-pch'. Code reviewed by: Matheus Izvekov <[email protected]>
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‎clang/docs/ReleaseNotes.rst

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@@ -339,6 +339,8 @@ New Compiler Flags
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- New option ``-Wnrvo`` added and disabled by default to warn about missed NRVO opportunities.
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- New option ``-ignore-pch`` added to disable precompiled headers. It overrides ``-emit-pch`` and ``-include-pch``. (#GH142409, `PCHDocs <https://clang.llvm.org/docs/UsersManual.html#ignoring-a-pch-file>`_).
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Deprecated Compiler Flags
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-------------------------
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‎clang/docs/UsersManual.rst

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@@ -1458,6 +1458,19 @@ will be processed from the PCH file. Otherwise, Clang will report an error.
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``test.h`` since ``test.h`` was included directly in the source file and not
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specified on the command line using ``-include-pch``.
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Ignoring a PCH File
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^^^^^^^^^^^^^^^^^^^
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To ignore PCH options, a `-ignore-pch` option is passed to ``clang``:
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.. code-block:: console
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$ clang -x c-header test.h -Xclang -ignore-pch -o test.h.pch
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$ clang -include-pch test.h.pch -Xclang -ignore-pch test.c -o test
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This option disables precompiled headers, overrides -emit-pch and -include-pch.
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test.h.pch is not generated and not used as a prefix header.
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Relocatable PCH Files
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^^^^^^^^^^^^^^^^^^^^^
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‎clang/include/clang/Driver/Options.td

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@@ -3348,6 +3348,9 @@ defm pch_codegen: OptInCC1FFlag<"pch-codegen", "Generate ", "Do not generate ",
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"code for uses of this PCH that assumes an explicit object file will be built for the PCH">;
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defm pch_debuginfo: OptInCC1FFlag<"pch-debuginfo", "Generate ", "Do not generate ",
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"debug info for types in an object file built from this PCH and do not generate them elsewhere">;
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def ignore_pch : Flag<["-"], "ignore-pch">, Group<f_Group>,
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Visibility<[ClangOption]>,
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HelpText<"Disable precompiled headers, overrides -emit-pch and -include-pch">;
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def fimplicit_module_maps : Flag <["-"], "fimplicit-module-maps">, Group<f_Group>,
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Visibility<[ClangOption, CC1Option, CLOption]>,

‎clang/lib/Driver/Driver.cpp

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@@ -4331,6 +4331,15 @@ void Driver::handleArguments(Compilation &C, DerivedArgList &Args,
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YcArg = YuArg = nullptr;
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}
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if (Args.hasArg(options::OPT_include_pch) &&
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(FinalPhase == phases::Preprocess ||
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Args.hasArg(options::OPT_ignore_pch))) {
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// If only preprocessing or -ignore-pch is used, -include-pch is disabled.
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// Since -emit-pch is CC1option, it will not be added to command argments if
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// -ignore-pch is used.
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Args.eraseArg(options::OPT_include_pch);
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}
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bool LinkOnly = phases::Link == FinalPhase && Inputs.size() > 0;
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for (auto &I : Inputs) {
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types::ID InputType = I.first;

‎clang/lib/Driver/ToolChains/Clang.cpp

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@@ -5321,7 +5321,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
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CmdArgs.push_back("-emit-module-interface");
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else if (JA.getType() == types::TY_HeaderUnit)
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CmdArgs.push_back("-emit-header-unit");
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else
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else if (!Args.hasArg(options::OPT_ignore_pch))
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CmdArgs.push_back("-emit-pch");
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} else if (isa<VerifyPCHJobAction>(JA)) {
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CmdArgs.push_back("-verify-pch");
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} else if (JA.getType() == types::TY_PP_Asm) {
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CmdArgs.push_back("-S");
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} else if (JA.getType() == types::TY_AST) {
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CmdArgs.push_back("-emit-pch");
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if (!Args.hasArg(options::OPT_ignore_pch))
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CmdArgs.push_back("-emit-pch");
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} else if (JA.getType() == types::TY_ModuleFile) {
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CmdArgs.push_back("-module-file-info");
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} else if (JA.getType() == types::TY_RewrittenObjC) {

‎clang/test/Driver/ignored-pch.cpp

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// RUN: rm -rf %t
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// RUN: mkdir -p %t
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// Create PCH without -ignore-pch.
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// RUN: %clang -x c++-header %S/../Modules/Inputs/codegen-flags/foo.h -### 2>&1 | FileCheck %s -check-prefix=CHECK-EMIT-PCH
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// RUN: %clang -x c++-header %S/../Modules/Inputs/codegen-flags/foo.h -o %t/foo.h.pch
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// RUN: %clang %s -include-pch %t/foo.h.pch -### 2>&1 | FileCheck %s -check-prefix=CHECK-INCLUDE-PCH
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// RUN: %clang %s -emit-ast -include-pch %t/foo.h.pch -### 2>&1 | FileCheck %s -check-prefixes=CHECK-EMIT-PCH,CHECK-INCLUDE-PCH
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// Create PCH with -ignore-pch.
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// RUN: %clang -x c++-header -ignore-pch %S/../Modules/Inputs/codegen-flags/foo.h -### 2>&1 | FileCheck %s -check-prefix=CHECK-IGNORE-PCH
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// RUN: %clang %s -ignore-pch -include-pch %t/foo.h.pch -### 2>&1 | FileCheck %s -check-prefix=CHECK-IGNORE-PCH
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// RUN: %clang %s -ignore-pch -emit-ast -include-pch %t/foo.h.pch -### 2>&1 | FileCheck %s -check-prefix=CHECK-IGNORE-PCH
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// CHECK-EMIT-PCH: -emit-pch
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// CHECK-INCLUDE-PCH: -include-pch
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// CHECK-IGNORE-PCH-NOT: -emit-pch
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// CHECK-IGNORE-PCH-NOT: -include-pch

‎clang/test/PCH/Inputs/ignored-pch.h

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#ifndef IGNORED_PCH_H
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#define IGNORED_PCH_H
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inline int f() {
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return 42;
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}
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#endif // IGNORED_PCH_H

‎clang/test/PCH/ignored-pch.c

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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -o %t.pch
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// RUN: %clang %s -emit-ast -include-pch %t.pch -o %t.ll
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// RUN: ls %t.pch | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Check that -ignore-pch causes -emit-pch and -include-pch options to be ignored.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH-ERROR %s
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// RUN: ls %t.ll 2>&1 | FileCheck --check-prefix=CHECK-OBJ %s
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -emit-ast %s -include-pch %t.pch -ignore-pch -o %t.ll
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// RUN: not ls %t.ll 2>&1 | FileCheck --check-prefix=CHECK-OBJ-ERROR %s
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// Check that -ignore-pch works for multiple PCH related options.
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// Test with -building-pch-with-obj.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -Xclang -building-pch-with-obj -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -Xclang -building-pch-with-obj -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fallow-pch-with-compiler-errors.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -Xclang -fallow-pch-with-compiler-errors -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -Xclang -fallow-pch-with-compiler-errors -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fallow-pch-with-different-modules-cache-path.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -Xclang -fallow-pch-with-different-modules-cache-path -o %t.pch
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// RUN: %clang -S -emit-llvm %s -ignore-pch -include-pch %t.pch -Xclang -fallow-pch-with-different-modules-cache-path -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fpch-codegen.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -fpch-codegen -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -fpch-codegen -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH-ERROR %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fpch-debuginfo.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -fpch-debuginfo -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -fpch-debuginfo -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fpch-instantiate-templates.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -fpch-instantiate-templates -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -fpch-instantiate-templates -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fno-pch-timestamp.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -Xclang -fno-pch-timestamp -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -Xclang -fno-pch-timestamp -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -fno-validate-pch.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -Xclang -fno-validate-pch -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -Xclang -fno-validate-pch -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -relocatable-pch.
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -relocatable-pch -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -relocatable-pch -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with -pch-through-hdrstop-create/-pch-through-hdrstop-use
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -ignore-pch -Xclang -pch-through-hdrstop-create -o %t.pch
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// RUN: %clang -S -emit-llvm %s -include-pch %t.pch -ignore-pch -Xclang -pch-through-hdrstop-use -o %t.ll
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// RUN: not ls %t.pch 2>&1 | FileCheck --check-prefix=CHECK-PCH %s
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// RUN: ls %t.ll | FileCheck --check-prefix=CHECK-OBJ %s
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// Test with AST dump output:
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// RUN: rm -rf %t.pch %t.ll
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// RUN: %clang -x c-header %S/Inputs/ignored-pch.h -o %t.pch
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// RUN: %clang %s -include-pch %t.pch -Xclang -ast-dump-all -c | FileCheck --check-prefix=CHECK-AST-PCH %s
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// RUN: %clang %s -include-pch %t.pch -ignore-pch -Xclang -ast-dump-all -c | FileCheck --check-prefix=CHECK-AST %s
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// CHECK-PCH: ignored-pch.c.{{.*}}.pch
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// CHECK-OBJ: ignored-pch.c.{{.*}}.ll
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// CHECK-PCH-ERROR: ignored-pch.c.{{.*}}.pch{{'?}}: No such file or directory
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// CHECK-OBJ-ERROR: ignored-pch.c.{{.*}}.ll{{'?}}: No such file or directory
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// CHECK-AST-PCH: <undeserialized declarations>
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// CHECK-AST-NOT: <undeserialized declarations>
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#pragma hdrstop
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#include "Inputs/ignored-pch.h"
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int main() {
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return f();
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}

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