From 6566e853cdc374c66bf9eba5ae09c860cf605312 Mon Sep 17 00:00:00 2001
From: Anthony Donlon <4056887+donlon@users.noreply.github.com>
Date: Fri, 10 Nov 2023 02:05:36 +0000
Subject: [PATCH] Support ccache when compiling Verilator with CMake (#4678)

---
 CMakeLists.txt | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f21ee2782..0041e6d57 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -48,6 +48,27 @@ if (WIN32)
     set(CMAKE_CXX_STANDARD 20)
 endif()
 
+set(OBJCACHE "" CACHE STRING "Path for ccache, auto-detected if empty")
+option(OBJCACHE_ENABLED "Compile Verilator with ccache" ON)
+
+if (OBJCACHE_ENABLED)
+    if (OBJCACHE STREQUAL "")
+        find_program(OBJCACHE_PATH ccache)
+        if (OBJCACHE_PATH STREQUAL "OBJCACHE_PATH-NOTFOUND")
+            set(OBJCACHE_PATH "")
+        endif()
+    else()
+        set(OBJCACHE_PATH "${OBJCACHE}")
+    endif()
+    if (NOT OBJCACHE_PATH STREQUAL "")
+        execute_process(COMMAND "${OBJCACHE_PATH}" --version
+                OUTPUT_VARIABLE objcache_version)
+        string(REGEX MATCH "[^\n\r]+" objcache_version "${objcache_version}")
+        message(STATUS "Found ccache: ${OBJCACHE_PATH} (\"${objcache_version}\")")
+        set(CMAKE_CXX_COMPILER_LAUNCHER "${OBJCACHE_PATH}")
+    endif()
+endif()
+
 find_package(BISON)
 find_package(FLEX)