Add a cmake flag to the benchmarks: SWIFT_BENCHMARK_EXTRA_FLAGS.

We used to have this cmake flag but it seems to have disappeared. Building the
benchmarks with different swiftc flags is central to performance analysis, so
I'm not sure how people were getting this done.

Author: atrick

benchmark/CMakeLists.txt

@@ -225,6 +225,9 @@ if(NOT SWIFT_OPTIMIZATION_LEVELS)
                                 ${SWIFT_EXTRA_BENCH_CONFIGS})
 endif()
 
+set(SWIFT_BENCHMARK_EXTRA_FLAGS "" CACHE STRING
+    "Extra options to pass to swiftc when building the benchmarks")
+
 set(SWIFT_BENCHMARK_NUM_O_ITERATIONS "" CACHE STRING
     "Number of iterations to perform when running -O benchmarks via cmake")
 set(SWIFT_BENCHMARK_NUM_ONONE_ITERATIONS "" CACHE STRING
@@ -289,6 +292,7 @@ message("--")
 message("-- Swift Benchmark Suite:")
 message("--   SWIFT_BENCHMARK_BUILT_STANDALONE = ${SWIFT_BENCHMARK_BUILT_STANDALONE}")
 message("--   SWIFT_EXEC = ${SWIFT_EXEC}")
+message("--   SWIFT_BENCHMARK_EXTRA_FLAGS = ${SWIFT_BENCHMARK_EXTRA_FLAGS}")
 message("--   SWIFT_LIBRARY_PATH = ${SWIFT_LIBRARY_PATH}")
 message("--   CLANG_EXEC = ${CLANG_EXEC}")
 message("--   SWIFT_OPTIMIZATION_LEVELS = ${SWIFT_OPTIMIZATION_LEVELS}")

benchmark/cmake/modules/AddSwiftBenchmarkSuite.cmake

@@ -319,6 +319,7 @@ function (swift_benchmark_compile_archopts)
           ${extra_options}
           "-parse-as-library"
           ${bench_flags}
+          ${SWIFT_BENCHMARK_EXTRA_FLAGS}
           "-module-name" "${module_name}"
           "-emit-module-path" "${swiftmodule}"
           "-I" "${objdir}"
@@ -336,6 +337,7 @@ function (swift_benchmark_compile_archopts)
             ${common_swift4_options}
             "-parse-as-library"
             ${bench_flags}
+            ${SWIFT_BENCHMARK_EXTRA_FLAGS}
             "-module-name" "${module_name}"
             "-I" "${objdir}"
             "-emit-sib"
@@ -363,7 +365,7 @@ function (swift_benchmark_compile_archopts)
         SOURCE_DIR "${srcdir}"
         OBJECT_DIR "${objdir}"
         SOURCES ${${module_name}_sources}
-        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags}
+        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags} ${SWIFT_BENCHMARK_EXTRA_FLAGS}
         DEPENDS ${bench_library_objects} ${stdlib_dependencies})
       precondition(objfile_out)
       list(APPEND SWIFT_BENCH_OBJFILES "${objfile_out}")
@@ -381,7 +383,7 @@ function (swift_benchmark_compile_archopts)
         SOURCE_DIR "${srcdir}"
         OBJECT_DIR "${objdir}"
         SOURCES ${${module_name}_sources}
-        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags}
+        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags} ${SWIFT_BENCHMARK_EXTRA_FLAGS}
         DEPENDS ${bench_library_objects} ${stdlib_dependencies})
       precondition(objfiles_out)
       list(APPEND SWIFT_BENCH_OBJFILES ${objfiles_out})
@@ -399,7 +401,7 @@ function (swift_benchmark_compile_archopts)
         SOURCE_DIR "${srcdir}"
         OBJECT_DIR "${objdir}"
         SOURCES ${${module_name}_sources}
-        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags}
+        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags} ${SWIFT_BENCHMARK_EXTRA_FLAGS}
         DEPENDS ${bench_library_objects} ${stdlib_dependencies})
       precondition(objfile_out)
       list(APPEND SWIFT_BENCH_OBJFILES "${objfile_out}")
@@ -417,7 +419,7 @@ function (swift_benchmark_compile_archopts)
         SOURCE_DIR "${srcdir}"
         OBJECT_DIR "${objdir}"
         SOURCES ${${module_name}_sources}
-        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags}
+        LIBRARY_FLAGS ${common_swift4_options} ${bench_flags} ${SWIFT_BENCHMARK_EXTRA_FLAGS}
         DEPENDS ${bench_library_objects} ${stdlib_dependencies})
       precondition(objfiles_out)
       list(APPEND SWIFT_BENCH_OBJFILES ${objfiles_out})