NFC Reword some crosscheck config descriptions

Author: steakhal

clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.def

@@ -189,14 +189,19 @@ ANALYZER_OPTION(
     "crosscheck-with-z3-eqclass-timeout-threshold",
     "Set a timeout for bug report equivalence classes in milliseconds. "
     "If we exhaust this threshold, we will drop the bug report eqclass "
-    "instead of doing more Z3 queries. On fast machines, 700 is a sane value. "
+    "instead of doing more Z3 queries. Setting this to 700 ms in conjunction "
+    "with \"crosscheck-with-z3-timeout-threshold\" of 300 ms, would nicely "
+    "guarantee that no bug report equivalence class can take longer than "
+    "1 second, effectively mitigating Z3 hangs during refutation. "
     "Set 0 for no timeout.", 0)
 
 ANALYZER_OPTION(
     unsigned, Z3CrosscheckTimeoutThreshold,
     "crosscheck-with-z3-timeout-threshold",
-    "Set a timeout for individual Z3 queries in milliseconds. On fast "
-    "machines, 400 is a sane value. "
+    "Set a timeout for individual Z3 queries in milliseconds. "
+    "On fast machines, 300 worked well in some cases. "
+    "The lower it is, the higher the chances of having flaky issues. "
+    "Having no timeout may hang the analyzer indefinitely. "
     "Set 0 for no timeout.", 15'000)
 
 ANALYZER_OPTION(
@@ -205,7 +210,8 @@ ANALYZER_OPTION(
     "Set the Z3 resource limit threshold. This sets a supposedly deterministic "
     "cutoff point for Z3 queries, as longer queries usually consume more "
     "resources. "
-    "Set 0 for unlimited.", 0)
+    "400'000 should on average make Z3 queries run for up to 100ms on modern "
+    "hardware. Set 0 for unlimited.", 0)
 
 ANALYZER_OPTION(bool, ShouldReportIssuesInMainSourceFile,
                 "report-in-main-source-file",