Optimize C++ generated code for structures with many conditional fields

compiler/back_end/cpp/BUILD

@@ -389,6 +389,17 @@ emboss_cc_test(
     ],
 )
 
+emboss_cc_test(
+    name = "many_conditionals_benchmark",
+    srcs = [
+        "testcode/many_conditionals_benchmark.cc",
+    ],
+    deps = [
+        "//testdata:many_conditionals_emboss",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
 # New golden test infrastructure
 py_library(
     name = "one_golden_test_lib",
@@ -598,3 +609,9 @@ cpp_golden_test(
     emb_file = "//testdata:imported_genfiles.emb",
     golden_file = "//testdata/golden_cpp:imported_genfiles.emb.h",
 )
+
+cpp_golden_test(
+    name = "many_conditionals_golden_test",
+    emb_file = "//testdata:many_conditionals.emb",
+    golden_file = "//testdata/golden_cpp:many_conditionals.emb.h",
+)

compiler/back_end/cpp/generated_code_templates

@@ -127,6 +127,7 @@ class Generic${name}View final {
   bool Ok() const {
     if (!IsComplete()) return false;
 ${parameter_ok_checks}
+${ok_subexpressions}
 ${field_ok_checks}
 ${requires_check}
     return true;
@@ -391,11 +392,31 @@ ${write_fields}
 // ** ok_method_test ** ////////////////////////////////////////////////////////
     // If we don't have enough information to determine whether ${field} is
     // present in the structure, then structure.Ok() should be false.
-    if (!has_${field}.Known()) return false;
+    if (!has_${field}().Known()) return false;
     // If ${field} is present, but not Ok(), then structure.Ok() should be
     // false.  If ${field} is not present, it does not matter whether it is
     // Ok().
-    if (has_${field}.ValueOrDefault() && !${field}.Ok()) return false;
+    if (has_${field}().ValueOrDefault() && !${field}().Ok()) return false;
+
+
+// ** ok_method_switch_block ** ////////////////////////////////////////////////
+    // Check fields that depend on a common discriminant using a switch.
+    {
+${inner_scope_definitions}
+      const auto emboss_reserved_switch_discrim = ${discriminant};
+      if (!emboss_reserved_switch_discrim.Known()) return false;
+      switch (emboss_reserved_switch_discrim.ValueOrDefault()) {
+${switch_cases}
+      }
+    }
+
+
+// ** ok_method_switch_case ** /////////////////////////////////////////////////
+        case ${case_value}:
+          if (!${field}().Ok()) return false;
+          break;
+
+
 
 
 // ** equals_method_test ** ////////////////////////////////////////////////////