diff --git a/lib/spack/spack/ci.py b/lib/spack/spack/ci.py
index 56d1980a3ac..978065489f5 100644
--- a/lib/spack/spack/ci.py
+++ b/lib/spack/spack/ci.py
@@ -33,7 +33,6 @@
 import spack
 import spack.binary_distribution as bindist
 import spack.builder
-import spack.concretize
 import spack.config as cfg
 import spack.error
 import spack.main
@@ -41,6 +40,7 @@
 import spack.mirrors.utils
 import spack.paths
 import spack.repo
+import spack.solver.asp
 import spack.spec
 import spack.util.git
 import spack.util.gpg as gpg_util
@@ -707,7 +707,7 @@ def generate_gitlab_ci_yaml(
             files (spack.yaml, spack.lock), etc should be written.  GitLab
             requires this to be within the project directory.
     """
-    with spack.concretize.disable_compiler_existence_check():
+    with spack.solver.asp.disable_compiler_existence_check():
         with env.write_transaction():
             env.concretize()
             env.write()
diff --git a/lib/spack/spack/cmd/mirror.py b/lib/spack/spack/cmd/mirror.py
index 309a82423c1..fc96ffdb862 100644
--- a/lib/spack/spack/cmd/mirror.py
+++ b/lib/spack/spack/cmd/mirror.py
@@ -17,6 +17,7 @@
 import spack.mirrors.mirror
 import spack.mirrors.utils
 import spack.repo
+import spack.solver.asp
 import spack.spec
 import spack.util.web as web_util
 from spack.cmd.common import arguments
@@ -516,7 +517,7 @@ def extend_with_dependencies(specs):
 
 def concrete_specs_from_cli_or_file(args):
     tty.msg("Concretizing input specs")
-    with spack.concretize.disable_compiler_existence_check():
+    with spack.solver.asp.disable_compiler_existence_check():
         if args.specs:
             specs = spack.cmd.parse_specs(args.specs, concretize=True)
             if not specs:
diff --git a/lib/spack/spack/concretize.py b/lib/spack/spack/concretize.py
index 3a374658e0c..6faf5d7854a 100644
--- a/lib/spack/spack/concretize.py
+++ b/lib/spack/spack/concretize.py
@@ -5,8 +5,7 @@
 """High-level functions to concretize list of specs"""
 import sys
 import time
-from contextlib import contextmanager
-from typing import Iterable, Optional, Sequence, Tuple, Union
+from typing import Iterable, Sequence, Tuple, Union
 
 import llnl.util.tty as tty
 
@@ -15,26 +14,7 @@
 import spack.error
 import spack.repo
 import spack.util.parallel
-from spack.spec import ArchSpec, CompilerSpec, Spec
-
-CHECK_COMPILER_EXISTENCE = True
-
-
-@contextmanager
-def disable_compiler_existence_check():
-    global CHECK_COMPILER_EXISTENCE
-    CHECK_COMPILER_EXISTENCE, saved = False, CHECK_COMPILER_EXISTENCE
-    yield
-    CHECK_COMPILER_EXISTENCE = saved
-
-
-@contextmanager
-def enable_compiler_existence_check():
-    global CHECK_COMPILER_EXISTENCE
-    CHECK_COMPILER_EXISTENCE, saved = True, CHECK_COMPILER_EXISTENCE
-    yield
-    CHECK_COMPILER_EXISTENCE = saved
-
+from spack.spec import Spec
 
 SpecPair = Tuple[Spec, Spec]
 SpecLike = Union[Spec, str]
@@ -51,11 +31,10 @@ def concretize_specs_together(
         tests: list of package names for which to consider tests dependencies. If True, all nodes
             will have test dependencies. If False, test dependencies will be disregarded.
     """
-    import spack.solver.asp
+    from spack.solver.asp import Solver
 
     allow_deprecated = spack.config.get("config:deprecated", False)
-    solver = spack.solver.asp.Solver()
-    result = solver.solve(abstract_specs, tests=tests, allow_deprecated=allow_deprecated)
+    result = Solver().solve(abstract_specs, tests=tests, allow_deprecated=allow_deprecated)
     return [s.copy() for s in result.specs]
 
 
@@ -90,7 +69,7 @@ def concretize_together_when_possible(
         tests: list of package names for which to consider tests dependencies. If True, all nodes
             will have test dependencies. If False, test dependencies will be disregarded.
     """
-    import spack.solver.asp
+    from spack.solver.asp import Solver
 
     to_concretize = [concrete if concrete else abstract for abstract, concrete in spec_list]
     old_concrete_to_abstract = {
@@ -98,9 +77,8 @@ def concretize_together_when_possible(
     }
 
     result_by_user_spec = {}
-    solver = spack.solver.asp.Solver()
     allow_deprecated = spack.config.get("config:deprecated", False)
-    for result in solver.solve_in_rounds(
+    for result in Solver().solve_in_rounds(
         to_concretize, tests=tests, allow_deprecated=allow_deprecated
     ):
         result_by_user_spec.update(result.specs_by_input)
@@ -124,7 +102,7 @@ def concretize_separately(
         tests: list of package names for which to consider tests dependencies. If True, all nodes
             will have test dependencies. If False, test dependencies will be disregarded.
     """
-    import spack.bootstrap
+    from spack.bootstrap import ensure_bootstrap_configuration, ensure_clingo_importable_or_raise
 
     to_concretize = [abstract for abstract, concrete in spec_list if not concrete]
     args = [
@@ -134,8 +112,8 @@ def concretize_separately(
     ]
     ret = [(i, abstract) for i, abstract in enumerate(to_concretize) if abstract.concrete]
     # Ensure we don't try to bootstrap clingo in parallel
-    with spack.bootstrap.ensure_bootstrap_configuration():
-        spack.bootstrap.ensure_clingo_importable_or_raise()
+    with ensure_bootstrap_configuration():
+        ensure_clingo_importable_or_raise()
 
     # Ensure all the indexes have been built or updated, since
     # otherwise the processes in the pool may timeout on waiting
@@ -201,6 +179,8 @@ def concretized(spec: Spec, tests: Union[bool, Iterable[str]] = False) -> Spec:
         tests: if False disregard 'test' dependencies, if a list of names activate them for
             the packages in the list, if True activate 'test' dependencies for all packages.
     """
+    from spack.solver.asp import Solver, SpecBuilder
+
     spec.replace_hash()
 
     for node in spec.traverse():
@@ -213,8 +193,7 @@ def concretized(spec: Spec, tests: Union[bool, Iterable[str]] = False) -> Spec:
         return spec.copy()
 
     allow_deprecated = spack.config.get("config:deprecated", False)
-    solver = spack.solver.asp.Solver()
-    result = solver.solve([spec], tests=tests, allow_deprecated=allow_deprecated)
+    result = Solver().solve([spec], tests=tests, allow_deprecated=allow_deprecated)
 
     # take the best answer
     opt, i, answer = min(result.answers)
@@ -224,27 +203,10 @@ def concretized(spec: Spec, tests: Union[bool, Iterable[str]] = False) -> Spec:
         providers = [s.name for s in answer.values() if s.package.provides(name)]
         name = providers[0]
 
-    node = spack.solver.asp.SpecBuilder.make_node(pkg=name)
+    node = SpecBuilder.make_node(pkg=name)
     assert (
         node in answer
     ), f"cannot find {name} in the list of specs {','.join([n.pkg for n in answer.keys()])}"
 
     concretized = answer[node]
     return concretized
-
-
-class UnavailableCompilerVersionError(spack.error.SpackError):
-    """Raised when there is no available compiler that satisfies a
-    compiler spec."""
-
-    def __init__(self, compiler_spec: CompilerSpec, arch: Optional[ArchSpec] = None) -> None:
-        err_msg = f"No compilers with spec {compiler_spec} found"
-        if arch:
-            err_msg += f" for operating system {arch.os} and target {arch.target}."
-
-        super().__init__(
-            err_msg,
-            "Run 'spack compiler find' to add compilers or "
-            "'spack compilers' to see which compilers are already recognized"
-            " by spack.",
-        )
diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index 436776e2721..61a494e974c 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -29,7 +29,6 @@
 import spack.binary_distribution
 import spack.compiler
 import spack.compilers
-import spack.concretize
 import spack.config
 import spack.deptypes as dt
 import spack.environment as ev
@@ -48,6 +47,7 @@
 import spack.version as vn
 import spack.version.git_ref_lookup
 from spack import traverse
+from spack.spec import ArchSpec, CompilerSpec
 
 from .core import (
     AspFunction,
@@ -66,6 +66,8 @@
 from .requirements import RequirementKind, RequirementParser, RequirementRule
 from .version_order import concretization_version_order
 
+CHECK_COMPILER_EXISTENCE = True
+
 GitOrStandardVersion = Union[spack.version.GitVersion, spack.version.StandardVersion]
 
 TransformFunction = Callable[["spack.spec.Spec", List[AspFunction]], List[AspFunction]]
@@ -3103,7 +3105,6 @@ def with_input_specs(self, input_specs: List["spack.spec.Spec"]) -> "CompilerPar
         Args:
             input_specs: specs to be concretized
         """
-        strict = spack.concretize.CHECK_COMPILER_EXISTENCE
         default_os = str(spack.platforms.host().default_os)
         default_target = str(archspec.cpu.host().family)
         for s in traverse.traverse_nodes(input_specs):
@@ -3117,8 +3118,8 @@ def with_input_specs(self, input_specs: List["spack.spec.Spec"]) -> "CompilerPar
                 continue
 
             # Error when a compiler is not found and strict mode is enabled
-            if strict:
-                raise spack.concretize.UnavailableCompilerVersionError(s.compiler)
+            if CHECK_COMPILER_EXISTENCE:
+                raise UnavailableCompilerVersionError(s.compiler)
 
             # Make up a compiler matching the input spec. This is for bootstrapping.
             compiler_cls = spack.compilers.class_for_compiler_name(s.compiler.name)
@@ -4012,6 +4013,22 @@ def _specs_from_environment_included_concrete(env, included_concrete):
         return []
 
 
+@contextmanager
+def disable_compiler_existence_check():
+    global CHECK_COMPILER_EXISTENCE
+    CHECK_COMPILER_EXISTENCE, saved = False, CHECK_COMPILER_EXISTENCE
+    yield
+    CHECK_COMPILER_EXISTENCE = saved
+
+
+@contextmanager
+def enable_compiler_existence_check():
+    global CHECK_COMPILER_EXISTENCE
+    CHECK_COMPILER_EXISTENCE, saved = True, CHECK_COMPILER_EXISTENCE
+    yield
+    CHECK_COMPILER_EXISTENCE = saved
+
+
 class ReuseStrategy(enum.Enum):
     ROOTS = enum.auto()
     DEPENDENCIES = enum.auto()
@@ -4295,3 +4312,20 @@ def __init__(self, provided, conflicts):
 
 class InvalidSpliceError(spack.error.SpackError):
     """For cases in which the splice configuration is invalid."""
+
+
+class UnavailableCompilerVersionError(spack.error.SpackError):
+    """Raised when there is no available compiler that satisfies a
+    compiler spec."""
+
+    def __init__(self, compiler_spec: CompilerSpec, arch: Optional[ArchSpec] = None) -> None:
+        err_msg = f"No compilers with spec {compiler_spec} found"
+        if arch:
+            err_msg += f" for operating system {arch.os} and target {arch.target}."
+
+        super().__init__(
+            err_msg,
+            "Run 'spack compiler find' to add compilers or "
+            "'spack compilers' to see which compilers are already recognized"
+            " by spack.",
+        )
diff --git a/lib/spack/spack/test/architecture.py b/lib/spack/spack/test/architecture.py
index 7919589fa82..811827ad259 100644
--- a/lib/spack/spack/test/architecture.py
+++ b/lib/spack/spack/test/architecture.py
@@ -11,6 +11,7 @@
 import spack.concretize
 import spack.operating_systems
 import spack.platforms
+import spack.solver.asp
 from spack.spec import ArchSpec, Spec
 
 
@@ -133,6 +134,6 @@ def test_concretize_target_ranges(root_target_range, dep_target_range, result, m
     spec = Spec(
         f"pkg-a %gcc@10 foobar=bar target={root_target_range} ^pkg-b target={dep_target_range}"
     )
-    with spack.concretize.disable_compiler_existence_check():
+    with spack.solver.asp.disable_compiler_existence_check():
         spec = spack.concretize.concretized(spec)
     assert spec.target == spec["pkg-b"].target == result
diff --git a/lib/spack/spack/test/concretization/core.py b/lib/spack/spack/test/concretization/core.py
index 14f33682321..bb740d6d7c9 100644
--- a/lib/spack/spack/test/concretization/core.py
+++ b/lib/spack/spack/test/concretization/core.py
@@ -348,11 +348,11 @@ def test_concretize_with_restricted_virtual(self):
         assert concrete["mpich2"].satisfies("mpich2@1.3.1:1.4")
 
     def test_concretize_enable_disable_compiler_existence_check(self):
-        with spack.concretize.enable_compiler_existence_check():
-            with pytest.raises(spack.concretize.UnavailableCompilerVersionError):
+        with spack.solver.asp.enable_compiler_existence_check():
+            with pytest.raises(spack.solver.asp.UnavailableCompilerVersionError):
                 check_concretize("dttop %gcc@=100.100")
 
-        with spack.concretize.disable_compiler_existence_check():
+        with spack.solver.asp.disable_compiler_existence_check():
             spec = check_concretize("dttop %gcc@=100.100")
             assert spec.satisfies("%gcc@100.100")
             assert spec["dtlink3"].satisfies("%gcc@100.100")
@@ -723,9 +723,9 @@ def test_concretize_propagate_variant_second_level_dep_not_in_source(self):
 
     def test_no_matching_compiler_specs(self, mock_low_high_config):
         # only relevant when not building compilers as needed
-        with spack.concretize.enable_compiler_existence_check():
+        with spack.solver.asp.enable_compiler_existence_check():
             s = Spec("pkg-a %gcc@=0.0.0")
-            with pytest.raises(spack.concretize.UnavailableCompilerVersionError):
+            with pytest.raises(spack.solver.asp.UnavailableCompilerVersionError):
                 s = spack.concretize.concretized(s)
 
     def test_no_compilers_for_arch(self):
@@ -951,7 +951,7 @@ def test_adjusting_default_target_based_on_compiler(
     ):
         best_achievable = archspec.cpu.TARGETS[best_achievable]
         expected = best_achievable if best_achievable < current_host else current_host
-        with spack.concretize.disable_compiler_existence_check():
+        with spack.solver.asp.disable_compiler_existence_check():
             s = spack.concretize.concretized(Spec(spec))
             assert str(s.architecture.target) == str(expected)
 
@@ -966,7 +966,7 @@ def test_compiler_version_matches_any_entry_in_compilers_yaml(self):
         )
 
         # This compiler does not exist
-        with pytest.raises(spack.concretize.UnavailableCompilerVersionError):
+        with pytest.raises(spack.solver.asp.UnavailableCompilerVersionError):
             spack.concretize.concretized(Spec("mpileaks %gcc@=10.2"))
 
     def test_concretize_anonymous(self):
diff --git a/lib/spack/spack/test/solver/intermediate.py b/lib/spack/spack/test/solver/intermediate.py
index f3d624cbd36..6215cac70f0 100644
--- a/lib/spack/spack/test/solver/intermediate.py
+++ b/lib/spack/spack/test/solver/intermediate.py
@@ -7,8 +7,8 @@
 
 import spack.compilers
 import spack.spec
-from spack.concretize import UnavailableCompilerVersionError
 from spack.solver import asp
+from spack.solver.asp import UnavailableCompilerVersionError
 
 
 class TestCompilerParser: