SERVER-76006 make compile half stream for smaller systems

SConstruct

@@ -6405,6 +6405,41 @@ if env.get('UNITTESTS_COMPILE_CONCURRENCY'):
         source_file_regex=r"^.*_test\.cpp$",
     )
 
+first_half_flag = False
+
+
+def half_source_emitter(target, source, env):
+    global first_half_flag
+    if first_half_flag:
+        first_half_flag = False
+        if not 'conftest' in str(target[0]) and not str(source[0]).endswith('_test.cpp'):
+            env.Alias('compile_first_half_non_test_source', target)
+    else:
+        first_half_flag = True
+    return target, source
+
+
+# Cribbed from Tool/cc.py and Tool/c++.py. It would be better if
+# we could obtain this from SCons.
+_CSuffixes = [".c"]
+if not SCons.Util.case_sensitive_suffixes(".c", ".C"):
+    _CSuffixes.append(".C")
+
+_CXXSuffixes = [".cpp", ".cc", ".cxx", ".c++", ".C++"]
+if SCons.Util.case_sensitive_suffixes(".c", ".C"):
+    _CXXSuffixes.append(".C")
+
+for object_builder in SCons.Tool.createObjBuilders(env):
+    emitterdict = object_builder.builder.emitter
+    for suffix in emitterdict.keys():
+        if not suffix in _CSuffixes + _CXXSuffixes:
+            continue
+        base = emitterdict[suffix]
+        emitterdict[suffix] = SCons.Builder.ListEmitter([
+            base,
+            half_source_emitter,
+        ])
+
 # Keep this late in the game so that we can investigate attributes set by all the tools that have run.
 if has_option("cache"):
     if get_option("cache") == "nolinked":

etc/evergreen_yml_components/definitions.yml

@@ -2434,6 +2434,21 @@ tasks:
       task_compile_flags: >-
         PREFIX=dist-test
 
+## compile - build all scons targets except unittests ##
+- name: compile_dist_test_half
+  tags: []
+  depends_on:
+  - name: version_expansions_gen
+    variant: generate-tasks-for-version
+  commands:
+  - func: "scons compile"
+    vars:
+      targets: >-
+        compile_first_half_non_test_source
+        ${additional_compile_targets|}
+      task_compile_flags: >-
+        PREFIX=dist-test
+
 - name: compile_upload_benchmarks
   tags: []
   depends_on:
@@ -8262,6 +8277,29 @@ task_groups:
   - compile_all_but_not_unittests
   - package
 
+# SERVER-76006
+# This is a compile stream meant for non-cached and/or underpowered systems.
+# It joins most of the compile tasks together under a single host spread out
+# across different tasks.
+- <<: *compile_task_group_template
+  name: small_compile_test_and_package_serial_no_unittests_TG
+  tasks:
+  - compile_dist_test_half
+  - compile_dist_test
+  - archive_dist_test
+  - archive_dist_test_debug
+  - compile_integration_test
+  - integration_tests_standalone
+  - integration_tests_standalone_audit
+  - integration_tests_replset
+  - integration_tests_replset_ssl_auth
+  - integration_tests_sharded
+  - compile_dbtest
+  - run_dbtest
+  - archive_dbtest
+  - compile_all_but_not_unittests
+  - package
+
 - <<: *compile_task_group_template
   name: compile_test_benchmark_and_package_serial_TG
   tasks:

etc/evergreen_yml_components/variants/ibm.yml

@@ -118,10 +118,7 @@ buildvariants:
     multiversion_edition: enterprise
     compile_variant: enterprise-rhel-72-s390x
   tasks:
-  - name: compile_test_and_package_serial_no_unittests_TG
-    distros:
-    - rhel72-zseries-build
-  - name: compile_integration_and_test_no_audit_parallel_stream_TG
+  - name: small_compile_test_and_package_serial_no_unittests_TG
     distros:
     - rhel72-zseries-build
   - name: .aggregation .common