SERVER-101393 set max link threading for LTO configs (#32818)

GitOrigin-RevId: f7fa80d7df350eb9cd73297b08058b28b5da93b0

.bazelrc

@@ -96,7 +96,7 @@ common --flag_alias=compress_debug_compile=//bazel/config:compress_debug_compile
 common --flag_alias=include_mongot=//bazel/config:include_mongot
 # This flag will only work if you pass it on the command line as it is parsed by bazelisk pre-bazel script
 common --flag_alias=include_autogenerated_targets=//bazel/config:include_autogenerated_targets
-
+common --flag_alias=bolt=//bazel/config:bolt
 common --flag_alias=dwarf_version=//bazel/config:dwarf_version
 common --flag_alias=http_client=//bazel/config:http_client
 common --flag_alias=developer_dir=//bazel/config:developer_dir

WORKSPACE.bazel

@@ -387,3 +387,7 @@ bazel_skylib_workspace()
 load("@buildifier_prebuilt//:defs.bzl", "buildifier_prebuilt_register_toolchains")
 
 buildifier_prebuilt_register_toolchains()
+
+load("//bazel/platforms:local_host_values.bzl", "setup_local_host_values")
+
+setup_local_host_values(name = "local_host_values")

bazel/config/BUILD.bazel

@@ -2274,6 +2274,18 @@ config_setting(
     },
 )
 
+bool_flag(
+    name = "bolt",
+    build_setting_default = False,
+)
+
+config_setting(
+    name = "bolt_enabled",
+    flag_values = {
+        "//bazel/config:bolt": "True",
+    },
+)
+
 bool_flag(
     name = "scons_query",
     build_setting_default = False,

bazel/mongo_src_rules.bzl

@@ -24,6 +24,7 @@ load(
     "extract_debuginfo_binary",
     "extract_debuginfo_test",
 )
+load("@local_host_values//:local_host_values_set.bzl", "NUM_CPUS")
 
 # https://learn.microsoft.com/en-us/cpp/build/reference/md-mt-ld-use-run-time-library?view=msvc-170
 #   /MD defines _MT and _DLL and links in MSVCRT.lib into each .obj file
@@ -2147,7 +2148,11 @@ def _mongo_cc_binary_and_test(
         "copts": MONGO_GLOBAL_COPTS + package_specific_copts + copts + fincludes_copt,
         "data": data + SANITIZER_DATA,
         "tags": tags,
-        "linkopts": MONGO_GLOBAL_LINKFLAGS + package_specific_linkflags + linkopts + rpath_flags,
+        "linkopts": MONGO_GLOBAL_LINKFLAGS + package_specific_linkflags + linkopts + rpath_flags + select({
+            "//bazel/config:thin_lto_enabled": ["-Wl,--threads=" + str(NUM_CPUS)],
+            "//bazel/config:bolt_enabled": ["-Wl,--threads=" + str(NUM_CPUS)],
+            "//conditions:default": [],
+        }),
         "linkstatic": LINKSTATIC_ENABLED,
         "local_defines": MONGO_GLOBAL_DEFINES + local_defines,
         "defines": defines,
@@ -2166,6 +2171,10 @@ def _mongo_cc_binary_and_test(
             # Debug compression significantly reduces .o, .dwo, and .a sizes
             "//bazel/config:compress_debug_compile_enabled": {"cpp_link.coefficient": "6.0"},
             "//conditions:default": {"cpp_link.coefficient": "2.0"},
+        }) | select({
+            "//bazel/config:thin_lto_enabled": {"cpp_link.cpus": str(NUM_CPUS)},
+            "//bazel/config:bolt_enabled": {"cpp_link.cpus": str(NUM_CPUS)},
+            "//conditions:default": {},
         }),
         "env": env | SANITIZER_ENV,
     } | kwargs

bazel/platforms/local_host_values.bzl

@@ -0,0 +1,38 @@
+def _local_host_values(ctx):
+    if "win" in ctx.os.name:
+        result = ctx.execute([
+            ctx.path(ctx.attr.python_interpreter_target_win),
+            "-c",
+            "import os; print(os.cpu_count())",
+        ])
+    else:
+        result = ctx.execute([
+            ctx.path(ctx.attr.python_interpreter_target_default),
+            "-c",
+            "import os; print(os.cpu_count())",
+        ])
+
+    ctx.file(
+        "BUILD.bazel",
+        "",
+    )
+    ctx.file(
+        "local_host_values_set.bzl",
+        """
+NUM_CPUS = %s
+""" % (result.stdout),
+    )
+
+setup_local_host_values = repository_rule(
+    implementation = _local_host_values,
+    attrs = {
+        "python_interpreter_target_default": attr.label(
+            default = "@py_host//:dist/bin/python3",
+            doc = "The target of the Python interpreter used during repository setup, if not windows",
+        ),
+        "python_interpreter_target_win": attr.label(
+            default = "@py_host//:dist/python.exe",
+            doc = "The target of the Python interpreter used during repository setup for windows platforms",
+        ),
+    },
+)