[flang] Use precompiled headers in Frontend, Lower, Parser, Semantics and Evaluate (llvm#131137)

Precompiling larger headers can save a lot of compile time across
various compilation units.

For the time being, disable precompiled headers for ccache builds on Windows
due to issues with reliably passing the appropriate options to ccache.

Selected compile time & memory improvements are as follows:

flang/lib/Parser/Fortran-parsers.cpp:
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:47.31 -> 0:41.68
Maximum resident set size (kbytes): 2062140 -> 1745584

flang/lib/Lower/Bridge.cpp:
Elapsed (wall clock) time (h:mm:ss or m:ss): 1:19.16 -> 0:45.86
Maximum resident set size (kbytes): 3849144 -> 2443476

flang/lib/Lower/PFTBuilder.cpp
Elapsed (wall clock) time (h:mm:ss or m:ss): 1:29.24 -> 1:00.99
Maximum resident set size (kbytes): 4218368 -> 2923128

flang/lib/Lower/Allocatable.cpp
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:53.03 -> 0:22.50
Maximum resident set size (kbytes): 3092840 -> 2116908

flang/lib/Semantics/Semantics.cpp
Elapsed (wall clock) time (h:mm:ss or m:ss): 1:18.75 -> 1:00.20
Maximum resident set size (kbytes): 3527744 -> 2545308

While the newly added precompiled headers are as follows:

Parser:
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:09.62
Maximum resident set size (kbytes): 1034608

Lower:
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:41.33
Maximum resident set size (kbytes): 3615240

Semantics:
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:26.69
Maximum resident set size (kbytes): 2403776

---------

Signed-off-by: Kajetan Puchalski <[email protected]>

Author: mrkajetanp

flang/lib/Evaluate/CMakeLists.txt

@@ -73,3 +73,17 @@ add_flang_library(FortranEvaluate
   acc_gen
   omp_gen
 )
+
+target_precompile_headers(FortranEvaluate PRIVATE
+  [["flang/Evaluate/common.h"]]
+  [["flang/Evaluate/call.h"]]
+  [["flang/Evaluate/traverse.h"]]
+  [["flang/Evaluate/shape.h"]]
+  [["flang/Evaluate/characteristics.h"]]
+  [["flang/Evaluate/variable.h"]]
+  [["flang/Evaluate/real.h"]]
+  [["flang/Evaluate/type.h"]]
+  [["flang/Evaluate/integer.h"]]
+  [["flang/Evaluate/expression.h"]]
+  [["flang/Evaluate/tools.h"]]
+)

flang/lib/Frontend/CMakeLists.txt

@@ -74,3 +74,11 @@ add_flang_library(flangFrontend
   clangBasic
   clangDriver
 )
+
+target_precompile_headers(flangFrontend PRIVATE
+  [["flang/Parser/parsing.h"]]
+  [["flang/Parser/parse-tree.h"]]
+  [["flang/Parser/dump-parse-tree.h"]]
+  [["flang/Lower/PFTBuilder.h"]]
+  [["flang/Lower/Bridge.h"]]
+)

flang/lib/Lower/CMakeLists.txt

@@ -73,3 +73,14 @@ add_flang_library(FortranLower
   MLIRLLVMDialect
   MLIRSCFToControlFlow
 )
+
+target_precompile_headers(FortranLower PRIVATE
+  [["flang/Lower/ConvertExpr.h"]]
+  [["flang/Lower/SymbolMap.h"]]
+  [["flang/Lower/AbstractConverter.h"]]
+  [["flang/Lower/IterationSpace.h"]]
+  [["flang/Lower/CallInterface.h"]]
+  [["flang/Lower/BoxAnalyzer.h"]]
+  [["flang/Lower/PFTBuilder.h"]]
+  [["flang/Lower/DirectivesCommon.h"]]
+)

flang/lib/Parser/CMakeLists.txt

@@ -36,3 +36,11 @@ add_flang_library(FortranParser
   omp_gen
   acc_gen
 )
+
+target_precompile_headers(FortranParser PRIVATE
+  [["flang/Parser/parsing.h"]]
+  [["flang/Parser/parse-tree.h"]]
+  [["flang/Parser/provenance.h"]]
+  [["flang/Parser/message.h"]]
+  [["flang/Parser/parse-tree-visitor.h"]]
+)

flang/lib/Semantics/CMakeLists.txt

@@ -64,3 +64,12 @@ add_flang_library(FortranSemantics
   FrontendOpenACC
   TargetParser
 )
+
+target_precompile_headers(FortranSemantics PRIVATE
+  [["flang/Semantics/semantics.h"]]
+  [["flang/Semantics/type.h"]]
+  [["flang/Semantics/openmp-modifiers.h"]]
+  [["flang/Semantics/expression.h"]]
+  [["flang/Semantics/tools.h"]]
+  [["flang/Semantics/symbol.h"]]
+)

llvm/CMakeLists.txt

@@ -306,6 +306,13 @@ if(LLVM_CCACHE_BUILD)
       endif()
       set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ${CCACHE_PROGRAM})
     else()
+      # Until a way to reliably configure ccache on Windows is found,
+      # disable precompiled headers for Windows + ccache builds
+      if(NOT CMAKE_DISABLE_PRECOMPILE_HEADERS)
+        message(WARNING "Using ccache with precompiled headers on Windows is currently not supported.
+          CMAKE_DISABLE_PRECOMPILE_HEADERS will be set to ON.")
+        set(CMAKE_DISABLE_PRECOMPILE_HEADERS "ON")
+      endif()
       if(LLVM_CCACHE_MAXSIZE OR LLVM_CCACHE_DIR OR
          NOT LLVM_CCACHE_PARAMS MATCHES "CCACHE_CPP2=yes CCACHE_HASHDIR=yes CCACHE_SLOPPINESS=pch_defines,time_macros")
         message(FATAL_ERROR "Ccache configuration through CMake is not supported on Windows. Please use environment variables.")