Add a project version to the build.

Uses `git describe` to get the version according to git,
and sanitizes it for CMake project function for potential
future use with CPack.

Add an option to the c_emulator to report the (git) version.

Author: pmundkur

CMakeLists.txt

@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.20)
 cmake_policy(VERSION 3.20...3.31)
 
-project(sail_riscv)
+include(cmake/project_version.cmake)
+project(sail_riscv VERSION ${sail_riscv_cmake_version})
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED TRUE)

c_emulator/CMakeLists.txt

@@ -1,3 +1,12 @@
+# make version available to emulator
+configure_file(version.h.in version.h @ONLY)
+add_library(version
+  INTERFACE "version.h"
+)
+target_include_directories(version
+  INTERFACE "${CMAKE_CURRENT_BINARY_DIR}"
+)
+
 set(EMULATOR_COMMON_SRCS
     riscv_config.h
     riscv_platform.cpp
@@ -50,7 +59,7 @@ foreach (xlen IN ITEMS 32 64)
             add_dependencies(riscv_sim_${arch} generated_model_${arch})
 
             target_link_libraries(riscv_sim_${arch}
-                PRIVATE softfloat sail_runtime default_config GMP::GMP
+                PRIVATE softfloat sail_runtime default_config version GMP::GMP
             )
 
             target_include_directories(riscv_sim_${arch}

c_emulator/riscv_sim.cpp

@@ -28,12 +28,14 @@
 #include "riscv_sail.h"
 #include "rvfi_dii.h"
 #include "default_config.h"
+#include "version.h"
 
 enum {
   OPT_TRACE_OUTPUT = 1000,
   OPT_PRINT_CONFIG,
   OPT_SAILCOV,
   OPT_ENABLE_EXPERIMENTAL_EXTENSIONS,
+  OPT_VERSION,
 };
 
 static bool do_show_times = false;
@@ -93,6 +95,7 @@ char *sailcov_file = NULL;
 #endif
 
 static struct option options[] = {
+    {"version",                        no_argument,       0, OPT_VERSION     },
     {"device-tree-blob",               required_argument, 0, 'b'             },
     {"terminal-log",                   required_argument, 0, 't'             },
     {"show-times",                     required_argument, 0, 'p'             },
@@ -243,6 +246,9 @@ static int process_args(int argc, char **argv)
       }
       break;
     }
+    case OPT_VERSION:
+      printf("%s\n", SAIL_RISCV_VERSION);
+      exit(0);
     case OPT_PRINT_CONFIG:
       printf("%s", DEFAULT_JSON);
       exit(0);

c_emulator/version.h.in

@@ -0,0 +1,3 @@
+#pragma once
+
+#define SAIL_RISCV_VERSION "@sail_riscv_version@"

cmake/project_version.cmake

@@ -0,0 +1,39 @@
+# Sets GIT_EXECUTABLE
+find_package(Git REQUIRED)
+
+if (NOT ${Git_FOUND})
+  message(FATAL_ERROR "Git not found.")
+endif()
+
+# We could remove --tags if we started annotating the release tags.
+execute_process(
+  COMMAND ${GIT_EXECUTABLE} describe --tags
+  RESULT_VARIABLE git_error
+  OUTPUT_VARIABLE git_describe
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+if (git_error)
+  message(FATAL_ERROR "Failed to run git describe: ${git_error}")
+endif()
+
+# `git describe` cannot directly be used as a CMake VERSION argument
+# for project() due the trailing commit hash failing CMake's semver
+# format check.
+#
+# We could directly set PROJECT_VERSION to ${git_describe}, but that
+# makes it incompatible with CPack in case we decide to use it.
+# https://gitlab.kitware.com/cmake/cmake/-/issues/16716#note_956803
+#
+# Instead, parse the version components for CMake and CPack, and use
+# git_describe for the simulator --version.
+
+if (git_describe MATCHES "^([0-9]+)\\.([0-9]+)(-.*)?$")
+  set(v_major ${CMAKE_MATCH_1})
+  set(v_minor ${CMAKE_MATCH_2})
+else()
+  message(FATAL_ERROR "Cannot parse git describe output: ${git_describe}")
+endif()
+
+set(sail_riscv_version ${git_describe})
+set(sail_riscv_cmake_version "${v_major}.${v_minor}")