[CMake] allow custom options when building the compiler with debug info

Currently those are hardcoded to `-g`, but in some Apple internal
configurations we would like to change them.

There are other part of the build system that hardcode `-g`
(e.g. in `SwiftCompilerSources` and `AddSwiftStdlib.cmake`),
but we are not interested in those at the moment -- we will address those
in the future if need be.

Supports rdar://127503136

Author: edymtt

CMakeLists.txt

@@ -632,6 +632,9 @@ option(SWIFT_STDLIB_ENABLE_OBJC_INTEROP
        "Should stdlib be built with Obj-C interop."
        "${SWIFT_STDLIB_ENABLE_OBJC_INTEROP_default}")
 
+set(SWIFT_DEBUGINFO_NON_LTO_ARGS "-g" CACHE STRING
+    "Compiler options to use when building the compiler in debug or debuginfo mode. These do not apply when linking with LTO")
+
 #
 # User-configurable experimental options.  Do not use in production builds.
 #

cmake/modules/AddSwift.cmake

@@ -227,7 +227,7 @@ function(_add_host_variant_c_compile_flags target)
       if(_lto_flag_out)
         target_compile_options(${target} PRIVATE $<$<COMPILE_LANGUAGE:C,CXX,OBJC,OBJCXX>:-gline-tables-only>)
       else()
-        target_compile_options(${target} PRIVATE -g)
+        target_compile_options(${target} PRIVATE ${SWIFT_DEBUGINFO_NON_LTO_ARGS})
       endif()
     else()
       target_compile_options(${target} PRIVATE $<$<COMPILE_LANGUAGE:C,CXX,OBJC,OBJCXX>:-g0>)

utils/build_swift/build_swift/driver_arguments.py

@@ -439,6 +439,14 @@ def create_argument_parser():
                 'list "module_regexp;flag". Can be called multiple times to '
                 'add multiple such module_regexp flag pairs. All semicolons '
                 'in flags must be escaped with a "\\"')
+    option('--swift-debuginfo-non-lto-args', append,
+           # We cannot set the default value directly here,
+           # since it will be prepended to any option the user provides.
+           default=None,
+           help='Compilation flags to use when building the swift compiler '
+                ' in debug or debug info mode. Does not apply when building with '
+                ' LTO. Defaults to the default value of the CMake cache variable '
+                ' SWIFT_DEBUGINFO_NON_LTO_ARGS for Swift.')
 
     option('--host-cc', store_path(executable=True),
            help='the absolute path to CC, the "clang" compiler for the host '

utils/build_swift/tests/expected_options.py

@@ -190,6 +190,7 @@
     'export_compile_commands': False,
     'extra_cmake_options': [],
     'extra_swift_args': [],
+    'swift_debuginfo_non_lto_args': None,
     'force_optimized_typechecker': False,
     'foundation_build_variant': 'Debug',
     'host_cc': None,
@@ -826,6 +827,7 @@ class BuildScriptImplOption(_BaseOption):
     SetTrueOption('--infer-cross-compile-hosts-on-darwin'),
     AppendOption('--extra-cmake-options'),
     AppendOption('--extra-swift-args'),
+    AppendOption('--swift-debuginfo-non-lto-args'),
     AppendOption('--test-paths'),
     AppendOption('--llvm-ninja-targets'),
     AppendOption('--llvm-ninja-targets-for-cross-compile-hosts'),

utils/swift_build_support/swift_build_support/products/swift.py

@@ -87,6 +87,8 @@ def __init__(self, args, toolchain, source_dir, build_dir):
         self.cmake_options.extend(
             self._enable_experimental_parser_validation)
 
+        self._handle_swift_debuginfo_non_lto_args()
+
     @classmethod
     def is_build_script_impl_product(cls):
         """is_build_script_impl_product -> bool
@@ -246,6 +248,18 @@ def _enable_experimental_parser_validation(self):
         return [('SWIFT_ENABLE_EXPERIMENTAL_PARSER_VALIDATION:BOOL',
                  self.args.enable_experimental_parser_validation)]
 
+    def _handle_swift_debuginfo_non_lto_args(self):
+        if ('swift_debuginfo_non_lto_args' not in self.args
+                or self.args.swift_debuginfo_non_lto_args is None):
+            # Ensure the final value of the variable is determined
+            # by the build-script invocation, and not by any value present
+            # in CMakeCache.txt (e.g. as a result of previous incremental builds)
+            self.cmake_options.undefine('SWIFT_DEBUGINFO_NON_LTO_ARGS')
+        else:
+            self.cmake_options.extend(
+                [('SWIFT_DEBUGINFO_NON_LTO_ARGS:STRING',
+                 ";".join(self.args.swift_debuginfo_non_lto_args))])
+
     @classmethod
     def get_dependencies(cls):
         return [cmark.CMark,

utils/swift_build_support/tests/products/test_swift.py

@@ -114,6 +114,7 @@ def test_by_default_no_cmake_options(self):
             '-DSWIFT_STDLIB_BUILD_PRIVATE:BOOL=TRUE',
             '-DSWIFT_STDLIB_ENABLE_UNICODE_DATA=TRUE',
             '-DSWIFT_TOOLS_LD64_LTO_CODEGEN_ONLY_FOR_SUPPORTING_TARGETS:BOOL=FALSE',
+            '-USWIFT_DEBUGINFO_NON_LTO_ARGS'
         ]
         self.assertEqual(set(swift.cmake_options), set(expected))
 
@@ -144,6 +145,7 @@ def test_swift_runtime_tsan(self):
             '-DSWIFT_STDLIB_BUILD_PRIVATE:BOOL=TRUE',
             '-DSWIFT_STDLIB_ENABLE_UNICODE_DATA=TRUE',
             '-DSWIFT_TOOLS_LD64_LTO_CODEGEN_ONLY_FOR_SUPPORTING_TARGETS:BOOL=FALSE',
+            '-USWIFT_DEBUGINFO_NON_LTO_ARGS'
         ]
         self.assertEqual(set(swift.cmake_options), set(flags_set))
 
@@ -497,3 +499,49 @@ def test_swift_tools_ld64_lto_codegen_only_for_supporting_targets(self):
              'TRUE'],
             [x for x in swift.cmake_options
                 if 'SWIFT_TOOLS_LD64_LTO_CODEGEN_ONLY_FOR_SUPPORTING_TARGETS' in x])
+
+    def test_swift_debuginfo_non_lto_args(self):
+        self.args.swift_debuginfo_non_lto_args = None
+        swift = Swift(
+            args=self.args,
+            toolchain=self.toolchain,
+            source_dir='/path/to/src',
+            build_dir='/path/to/build')
+        self.assertIn(
+            '-USWIFT_DEBUGINFO_NON_LTO_ARGS',
+            swift.cmake_options)
+
+        self.args.swift_debuginfo_non_lto_args = []
+        swift = Swift(
+            args=self.args,
+            toolchain=self.toolchain,
+            source_dir='/path/to/src',
+            build_dir='/path/to/build')
+        self.assertEqual(
+            ['-DSWIFT_DEBUGINFO_NON_LTO_ARGS:STRING='],
+            [x for x in swift.cmake_options
+                if 'SWIFT_DEBUGINFO_NON_LTO_ARGS' in x])
+
+        self.args.swift_debuginfo_non_lto_args = ['-g']
+        swift = Swift(
+            args=self.args,
+            toolchain=self.toolchain,
+            source_dir='/path/to/src',
+            build_dir='/path/to/build')
+        self.assertEqual(
+            ['-DSWIFT_DEBUGINFO_NON_LTO_ARGS:STRING='
+             '-g'],
+            [x for x in swift.cmake_options
+                if 'SWIFT_DEBUGINFO_NON_LTO_ARGS' in x])
+
+        self.args.swift_debuginfo_non_lto_args = ['-gline-tables-only', '-v']
+        swift = Swift(
+            args=self.args,
+            toolchain=self.toolchain,
+            source_dir='/path/to/src',
+            build_dir='/path/to/build')
+        self.assertEqual(
+            ['-DSWIFT_DEBUGINFO_NON_LTO_ARGS:STRING='
+             '-gline-tables-only;-v'],
+            [x for x in swift.cmake_options
+                if 'SWIFT_DEBUGINFO_NON_LTO_ARGS' in x])