ASP-based solver: split heuristic for duplicate nodes (#39593)

The heuristic for duplicate nodes contains a few typos, and
apparently slows down the solve for specs that have a lot of
sub-optimal choices to be taken.

This is likely because with a lot of sub-optimal choices, the
low priority, flawed heuristic is being used by clingo.

Here I split the heuristic, so complex rules that matter only
if we allow multiple nodes from the same package are used
only in that case.

3 files changed, 27 insertions, 16 deletions

diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index 8ce04cdc5b..c596b81464 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -808,6 +808,8 @@ class PyclingoDriver:
         # Load the file itself
         self.control.load(os.path.join(parent_dir, "concretize.lp"))
         self.control.load(os.path.join(parent_dir, "heuristic.lp"))
+        if spack.config.CONFIG.get("concretizer:duplicates:strategy", "none") != "none":
+            self.control.load(os.path.join(parent_dir, "heuristic_separate.lp"))
         self.control.load(os.path.join(parent_dir, "os_compatibility.lp"))
         self.control.load(os.path.join(parent_dir, "display.lp"))
         if not setup.concretize_everything:
diff --git a/lib/spack/spack/solver/heuristic.lp b/lib/spack/spack/solver/heuristic.lp
index 80c3c529ad..69f925180f 100644
--- a/lib/spack/spack/solver/heuristic.lp
+++ b/lib/spack/spack/solver/heuristic.lp
@@ -4,7 +4,7 @@
 % SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 %=============================================================================
-% Heuristic to speed-up solves
+% Heuristic to speed-up solves (node with ID 0)
 %=============================================================================
 
 
@@ -27,18 +27,3 @@
 % Providers
 #heuristic attr("node", node(0, Package)) : default_provider_preference(Virtual, Package, 0), possible_in_link_run(Package). [30, true]
 
-% node(ID, _)
-#heuristic attr("version", node(ID, Package), Version) : pkg_fact(Package, version_declared(Version, ID)), attr("node", node(ID, Package)). [25-5*ID, true]
-#heuristic version_weight(node(ID, Package), ID) : pkg_fact(Package, version_declared(Version, ID)), attr("node", node(ID, Package)). [25-5*ID, true]
-#heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)). [25-5*ID, true]
-#heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, ID)), attr("node", node(ID, Package)). [25-5*ID, true]
-#heuristic node_target_weight(node(ID, Package), ID) : attr("node", node(ID, Package)). [25-5*ID, true]
-#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(ID, ID), compiler_id(ID), attr("node", node(ID, Package)). [25-5*ID, true]
-
-% node(ID, _), split build dependencies
-#heuristic attr("version", node(ID, Package), Version) : pkg_fact(Package, version_declared(Version, ID)), attr("node", node(ID, Package)), multiple_unification_sets(Package). [25, true]
-#heuristic version_weight(node(ID, Package), ID) : pkg_fact(Package, version_declared(Version, ID)), attr("node", node(ID, Package)), multiple_unification_sets(Package). [25, true]
-#heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)), multiple_unification_sets(Package). [25, true]
-#heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, ID)), attr("node", node(ID, Package)), multiple_unification_sets(Package). [25, true]
-#heuristic node_target_weight(node(ID, Package), ID) : attr("node", node(ID, Package)), multiple_unification_sets(Package). [25, true]
-#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(ID, ID), compiler_id(ID), attr("node", node(ID, Package)), multiple_unification_sets(Package). [25, true]
diff --git a/lib/spack/spack/solver/heuristic_separate.lp b/lib/spack/spack/solver/heuristic_separate.lp
new file mode 100644
index 0000000000..cb4345f3be
--- /dev/null
+++ b/lib/spack/spack/solver/heuristic_separate.lp
@@ -0,0 +1,24 @@
+% Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+% Spack Project Developers. See the top-level COPYRIGHT file for details.
+%
+% SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+%=============================================================================
+% Heuristic to speed-up solves (node with ID > 0)
+%=============================================================================
+
+% node(ID, _)
+#heuristic attr("version", node(ID, Package), Version) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic version_weight(node(ID, Package), 0) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic node_target_weight(node(ID, Package), 0) : attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+
+% node(ID, _), split build dependencies
+#heuristic attr("version", node(ID, Package), Version) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic version_weight(node(ID, Package), 0) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic node_target_weight(node(ID, Package), 0) : attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]