allow profiling without updating of hash values

src/script_opt/ProfileFunc.cc

@@ -546,7 +546,9 @@ void ProfileFunc::CheckRecordConstructor(TypePtr t) {
         }
 }
 
-ProfileFuncs::ProfileFuncs(std::vector<FuncInfo>& funcs, is_compilable_pred pred, bool _full_record_hashes) {
+ProfileFuncs::ProfileFuncs(std::vector<FuncInfo>& funcs, is_compilable_pred pred, bool _compute_func_hashes,
+                           bool _full_record_hashes) {
+    compute_func_hashes = _compute_func_hashes;
     full_record_hashes = _full_record_hashes;
 
     for ( auto& f : funcs ) {
@@ -558,6 +560,11 @@ ProfileFuncs::ProfileFuncs(std::vector<FuncInfo>& funcs, is_compilable_pred pred
         // Track the profile even if we're not compiling the function, since
         // the AST optimizer will still need it to reason about function-call
         // side effects.
+
+        // Propagate previous hash if requested.
+        if ( ! compute_func_hashes && f.Profile() )
+            pf->SetHashVal(f.Profile()->HashVal());
+
         f.SetProfile(std::move(pf));
         func_profs[f.Func()] = f.ProfilePtr();
     }
@@ -805,15 +812,18 @@ void ProfileFuncs::ComputeTypeHashes(const std::vector<const Type*>& types) {
 }
 
 void ProfileFuncs::ComputeBodyHashes(std::vector<FuncInfo>& funcs) {
-    for ( auto& f : funcs )
-        if ( ! f.ShouldSkip() )
-            ComputeProfileHash(f.ProfilePtr());
+    if ( compute_func_hashes )
+        for ( auto& f : funcs )
+            if ( ! f.ShouldSkip() )
+                ComputeProfileHash(f.ProfilePtr());
 
     for ( auto& l : lambdas ) {
         auto pf = ExprProf(l);
         func_profs[l->PrimaryFunc().get()] = pf;
         lambda_primaries[l->Name()] = l->PrimaryFunc().get();
-        ComputeProfileHash(pf);
+
+        if ( compute_func_hashes )
+            ComputeProfileHash(pf);
     }
 }
 

src/script_opt/ProfileFunc.h

@@ -347,13 +347,15 @@ using is_compilable_pred = bool (*)(const ProfileFunc*, const char** reason);
 // Collectively profile an entire collection of functions.
 class ProfileFuncs {
 public:
-    // Updates entries in "funcs" to include profiles.  If pred is
-    // non-nil, then it is called for each profile to see whether it's
-    // compilable, and, if not, the FuncInfo is marked as ShouldSkip().
-    // "full_record_hashes" controls whether the hashes for extended
-    // records covers their final, full form, or should only their
-    // original fields.
-    ProfileFuncs(std::vector<FuncInfo>& funcs, is_compilable_pred pred, bool full_record_hashes);
+    // Updates entries in "funcs" to include profiles.  If pred is non-nil,
+    // then it is called for each profile to see whether it's compilable,
+    // and, if not, the FuncInfo is marked as ShouldSkip().
+    // "compute_func_hashes" governs whether we compute hashes for the
+    // FuncInfo entries, or keep their existing ones.  "full_record_hashes"
+    // controls whether the hashes for extended records covers their final,
+    // full form, or should only their original fields.
+    ProfileFuncs(std::vector<FuncInfo>& funcs, is_compilable_pred pred, bool compute_func_hashes,
+                 bool full_record_hashes);
 
     // The following accessors provide a global profile across all of
     // the (non-skipped) functions in "funcs".  See the comments for
@@ -604,6 +606,9 @@ protected:
     // These can arise for example due to lambdas or record attributes.
     std::vector<const Expr*> pending_exprs;
 
+    // Whether to compute new hashes for the FuncInfo entries.
+    bool compute_func_hashes;
+
     // Whether the hashes for extended records should cover their final,
     // full form, or only their original fields.
     bool full_record_hashes;

src/script_opt/ScriptOpt.cc

@@ -391,7 +391,7 @@ static void use_CPP() {
 
     int num_used = 0;
 
-    auto pfs = std::make_unique<ProfileFuncs>(funcs, is_CPP_compilable, false);
+    auto pfs = std::make_unique<ProfileFuncs>(funcs, is_CPP_compilable, true, false);
 
     for ( auto& f : funcs ) {
         auto hash = f.Profile()->HashVal();
@@ -435,18 +435,16 @@ static void use_CPP() {
         reporter->FatalError("no C++ functions found to use");
 }
 
-static void generate_CPP() {
+static void generate_CPP(std::shared_ptr<ProfileFuncs> pfs) {
     const auto gen_name = CPP_dir + "CPP-gen.cc";
 
     const bool standalone = analysis_options.gen_standalone_CPP;
     const bool report = analysis_options.report_uncompilable;
 
-    auto pfs = std::make_shared<ProfileFuncs>(funcs, is_CPP_compilable, false);
-
     CPPCompile cpp(funcs, pfs, gen_name, standalone, report);
 }
 
-static void analyze_scripts_for_ZAM() {
+static void analyze_scripts_for_ZAM(std::shared_ptr<ProfileFuncs> pfs) {
     if ( analysis_options.usage_issues > 0 && analysis_options.optimize_AST ) {
         fprintf(stderr,
                 "warning: \"-O optimize-AST\" option is incompatible with -u option, "
@@ -454,8 +452,6 @@ static void analyze_scripts_for_ZAM() {
         analysis_options.optimize_AST = false;
     }
 
-    auto pfs = std::make_shared<ProfileFuncs>(funcs, nullptr, true);
-
     if ( analysis_options.profile_ZAM ) {
 #ifdef ENABLE_ZAM_PROFILE
         AST_blocks = std::make_unique<ASTBlockAnalyzer>(funcs);