[XLA:MSA] Adding two debugging functions for memory space assignment …

…to facilitate reproduction of production bugs in small tests through steering decisions at two key points in the MSA pass flow, before and after AllocateSegment() call:

1) debugging_allocation_request_modifier_fn(): allows modification of AllocationRequest before AllocateSegment(AllocationRequest) calls.

2) debugging_allocation_result_modifier_fn(): enables enforcing arbitrary failures on allocation requests, modifying the output of AllocateSegment(AllocationRequest) calls.

PiperOrigin-RevId: 695826893

xla/service/memory_space_assignment/BUILD

@@ -79,6 +79,7 @@ xla_cc_test(
     deps = [
         ":algorithm",
         ":allocation",
+        ":allocation_value",
         ":buffer_interval_comparator",
         ":cost_analysis",
         ":memory_space_assignment",
@@ -107,7 +108,6 @@ xla_cc_test(
         "//xla/service/heap_simulator:allocation_block",
         "//xla/tests:hlo_test_base",
         "//xla/tests:test_utils",
-        "//xla/tests:verified_hlo_module",
         "//xla/tests:xla_internal_test_main",
         "//xla/tsl/lib/core:status_test_util",
         "@com_google_absl//absl/algorithm:container",
@@ -273,6 +273,7 @@ cc_library(
     srcs = [],
     hdrs = ["options.h"],
     deps = [
+        ":allocation_value",
         ":buffer_interval_comparator",
         ":cost_analysis",
         ":memory_space_assignment_proto_cc",
@@ -508,6 +509,7 @@ cc_library(
     hdrs = ["algorithm.h"],
     deps = [
         ":allocation",
+        ":allocation_value",
         ":buffer_interval_comparator",
         ":cost_analysis",
         ":memory_bound_loop_optimizer",
@@ -577,6 +579,18 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "allocation_value",
+    hdrs = ["allocation_value.h"],
+    deps = [
+        ":allocation",
+        "//xla/hlo/ir:hlo",
+        "//xla/service:hlo_value",
+        "@com_google_absl//absl/container:flat_hash_set",
+        "@com_google_absl//absl/types:span",
+    ],
+)
+
 xla_cc_test(
     name = "prefetch_interval_picker_test",
     srcs = ["prefetch_interval_picker_test.cc"],