[clang] [flang] [llvm] [mlir] [polly] [CMake][LLVM] Add PCH infrastructure and LLVMSupport PCH (PR #176420)

[Maksim Levental via cfe-commits]

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@@ -13,6 +13,14 @@ add_flang_library(flangFrontend
   TextDiagnosticBuffer.cpp
   TextDiagnostic.cpp
 
+  DISABLE_PCH_REUSE
+  PRECOMPILE_HEADERS
+  [["flang/Parser/parsing.h"]]
+  [["flang/Parser/parse-tree.h"]]
+  [["flang/Parser/dump-parse-tree.h"]]
+  [["flang/Lower/PFTBuilder.h"]]
+  [["flang/Lower/Bridge.h"]]
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makslevental wrote:

just curious (n00b question): why is this the syntax for this argument? Like why the double braces? I realize it was here before this PR but just wondering.

https://github.com/llvm/llvm-project/pull/176420