[llvm] [CMake] Configure ccache using command line options (PR #134857)

[Kajetan Puchalski via llvm-commits]

================
@@ -271,30 +271,41 @@ set(LLVM_CCACHE_BUILD OFF CACHE BOOL "Set to ON for a ccache enabled build")
 if(LLVM_CCACHE_BUILD)
   find_program(CCACHE_PROGRAM ccache)
   if(CCACHE_PROGRAM)
+    # ccache --version example output: "ccache version 4.9.1\n(..)"
+    execute_process(COMMAND ${CCACHE_PROGRAM} --version OUTPUT_VARIABLE CCACHE_VERSION_STR)
+    string(REGEX MATCH "[0-9]+\.[0-9]+\.?[0-9]*" CCACHE_VERSION "${CCACHE_VERSION_STR}")
+
     set(LLVM_CCACHE_MAXSIZE "" CACHE STRING "Size of ccache")
     set(LLVM_CCACHE_DIR "" CACHE STRING "Directory to keep ccached data")
-    set(LLVM_CCACHE_PARAMS "CCACHE_CPP2=yes CCACHE_HASHDIR=yes"
-        CACHE STRING "Parameters to pass through to ccache")
 
-    if(NOT CMAKE_SYSTEM_NAME MATCHES "Windows")
-      set(CCACHE_PROGRAM "${LLVM_CCACHE_PARAMS} ${CCACHE_PROGRAM}")
+    # ccache only supports passing options on the command line from version 4.8.0
+    # use a workaround with ad-hoc environment variables for older versions
+    if (CCACHE_VERSION VERSION_LESS "4.8.0")
+      set(LLVM_CCACHE_PARAMS CCACHE_CPP2=yes CCACHE_HASHDIR=yes)
+
+      set(launcher_params ${LLVM_CCACHE_PARAMS})
       if (LLVM_CCACHE_MAXSIZE)
-        set(CCACHE_PROGRAM "CCACHE_MAXSIZE=${LLVM_CCACHE_MAXSIZE} ${CCACHE_PROGRAM}")
+        set(launcher_params CCACHE_MAXSIZE=${LLVM_CCACHE_MAXSIZE} ${launcher_params})
       endif()
       if (LLVM_CCACHE_DIR)
-        set(CCACHE_PROGRAM "CCACHE_DIR=${LLVM_CCACHE_DIR} ${CCACHE_PROGRAM}")
+        set(launcher_params CCACHE_DIR=${LLVM_CCACHE_DIR} ${launcher_params})
       endif()
-      set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ${CCACHE_PROGRAM})
+      set(launcher ${launcher_params} ${CCACHE_PROGRAM})
     else()
-      if(LLVM_CCACHE_MAXSIZE OR LLVM_CCACHE_DIR OR
-         NOT LLVM_CCACHE_PARAMS MATCHES "CCACHE_CPP2=yes CCACHE_HASHDIR=yes")
-        message(FATAL_ERROR "Ccache configuration through CMake is not supported on Windows. Please use environment variables.")
+      set(LLVM_CCACHE_PARAMS run_second_cpp=true hash_dir=true)
+
+      set(launcher_params ${LLVM_CCACHE_PARAMS})
+      if (LLVM_CCACHE_MAXSIZE)
+        set(launcher_params max_size=${LLVM_CCACHE_MAXSIZE} ${launcher_params})
       endif()
-      # RULE_LAUNCH_COMPILE should work with Ninja but currently has issues
-      # with cmd.exe and some MSVC tools other than cl.exe
-      set(CMAKE_C_COMPILER_LAUNCHER ${CCACHE_PROGRAM})
-      set(CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE_PROGRAM})
+      if (LLVM_CCACHE_DIR)
+        set(launcher_params cache_dir=${LLVM_CCACHE_DIR} ${launcher_params})
+      endif()
+      set(launcher ${CCACHE_PROGRAM} ${launcher_params})
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mrkajetanp wrote:

thanks!

https://github.com/llvm/llvm-project/pull/134857