Revert "[Frontend][PCH]-Add support for ignoring PCH options (-ignore-pch). (#142409)"

This reverts commit 4fb81f1.

Author: MaggieYingYi

clang/docs/ReleaseNotes.rst

@@ -339,8 +339,6 @@ New Compiler Flags
 
 - New option ``-Wnrvo`` added and disabled by default to warn about missed NRVO opportunities.
 
-- 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>`_).
-
 Deprecated Compiler Flags
 -------------------------
 

clang/docs/UsersManual.rst

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

clang/include/clang/Driver/Options.td

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

clang/lib/Driver/Driver.cpp

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

clang/lib/Driver/ToolChains/Clang.cpp

@@ -5184,7 +5184,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back("-emit-module-interface");
     else if (JA.getType() == types::TY_HeaderUnit)
       CmdArgs.push_back("-emit-header-unit");
-    else if (!Args.hasArg(options::OPT_ignore_pch))
+    else
       CmdArgs.push_back("-emit-pch");
   } else if (isa<VerifyPCHJobAction>(JA)) {
     CmdArgs.push_back("-verify-pch");
@@ -5241,8 +5241,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     } else if (JA.getType() == types::TY_PP_Asm) {
       CmdArgs.push_back("-S");
     } else if (JA.getType() == types::TY_AST) {
-      if (!Args.hasArg(options::OPT_ignore_pch))
-        CmdArgs.push_back("-emit-pch");
+      CmdArgs.push_back("-emit-pch");
     } else if (JA.getType() == types::TY_ModuleFile) {
       CmdArgs.push_back("-module-file-info");
     } else if (JA.getType() == types::TY_RewrittenObjC) {