Revert toolchain expansions and introduce profile changelist defines to linkstamp compile.

In https://github.com/rules_cc/bazel/commit/9cff17dd44cb500a06591355ce39bac66695aecf I added cpp build variables to with the expecation that I would use them in linkstamp compile but it turns out there is a direct approach which avoids this. So in this change, I've reverted the changes to compile_build_variables and introduced the necessary changes to cc_helper_internal.bzl.

PiperOrigin-RevId: 941422065
Change-Id: If1155391ad9fb3f180646cbb0ed18d387402c16a

cc/common/cc_helper_internal.bzl

diff --git a/cc/common/cc_helper_internal.bzl b/cc/common/cc_helper_internal.bzl
index df6b198..6ced37f 100644
--- a/cc/common/cc_helper_internal.bzl
+++ b/cc/common/cc_helper_internal.bzl
@@ -159,6 +159,15 @@
     if fdo_build_stamp:
         stamps["BUILD_FDO_TYPE"] = fdo_build_stamp
 
+    fdo_context = getattr(cc_toolchain, "_fdo_context", None)
+    if fdo_context:
+        fdo_profile_changelist = getattr(fdo_context, "fdo_profile_changelist", None)
+        if fdo_profile_changelist:
+            stamps["BUILD_FDO_PROFILE_CHANGELIST"] = fdo_profile_changelist
+        memprof_profile_changelist = getattr(fdo_context, "memprof_profile_changelist", None)
+        if memprof_profile_changelist:
+            stamps["BUILD_MEMPROF_PROFILE_CHANGELIST"] = memprof_profile_changelist
+
     if feature_configuration.is_enabled("thin_lto"):
         stamps["BUILD_LTO_TYPE"] = "thin"
 

cc/private/compile/compile_build_variables.bzl

diff --git a/cc/private/compile/compile_build_variables.bzl b/cc/private/compile/compile_build_variables.bzl
index f7575da..ed76c6e 100644
--- a/cc/private/compile/compile_build_variables.bzl
+++ b/cc/private/compile/compile_build_variables.bzl
@@ -473,15 +473,6 @@
         variables["memprof_profile_path"] = memprof_profile_artifact.path
 
     branch_fdo_profile = getattr(fdo_context, "branch_fdo_profile", None)
-    if branch_fdo_profile:
-        changelist = getattr(fdo_context, "fdo_profile_changelist", None)
-        if changelist:
-            variables["fdo_profile_changelist"] = changelist
-
-    if memprof_profile_artifact:
-        changelist = getattr(fdo_context, "memprof_profile_changelist", None)
-        if changelist:
-            variables["memprof_profile_changelist"] = changelist
 
     if (branch_fdo_profile and
         auxiliary_fdo_inputs_list and

cc/private/toolchain/unix_cc_toolchain_config.bzl

diff --git a/cc/private/toolchain/unix_cc_toolchain_config.bzl b/cc/private/toolchain/unix_cc_toolchain_config.bzl
index 06d3893..2aba91c 100644
--- a/cc/private/toolchain/unix_cc_toolchain_config.bzl
+++ b/cc/private/toolchain/unix_cc_toolchain_config.bzl
@@ -659,12 +659,6 @@
                         ] + profile_correction_flags,
                         expand_if_available = "fdo_profile_path",
                     ),
-                    flag_group(
-                        expand_if_available = "fdo_profile_changelist",
-                        flags = [
-                            "-DFDO_PROFILE_CHANGELIST=%{fdo_profile_changelist}",
-                        ],
-                    ),
                 ],
             ),
         ],
@@ -827,12 +821,6 @@
                         ] + profile_correction_flags,
                         expand_if_available = "fdo_profile_path",
                     ),
-                    flag_group(
-                        expand_if_available = "fdo_profile_changelist",
-                        flags = [
-                            "-DFDO_PROFILE_CHANGELIST=%{fdo_profile_changelist}",
-                        ],
-                    ),
                 ],
             ),
         ],
@@ -851,12 +839,6 @@
                         ] + profile_correction_flags,
                         expand_if_available = "fdo_profile_path",
                     ),
-                    flag_group(
-                        expand_if_available = "fdo_profile_changelist",
-                        flags = [
-                            "-DFDO_PROFILE_CHANGELIST=%{fdo_profile_changelist}",
-                        ],
-                    ),
                 ],
             ),
         ],