Add an inference remark if constprop is disabled by function heuristic (

JuliaLang#41317)

Would have saved me some debugging, since the function I was trying to
get to constprop happened to be a method of `*`.

base/compiler/abstractinterpretation.jl

@@ -541,7 +541,12 @@ function maybe_get_const_prop_profitable(interp::AbstractInterpreter, result::Me
     const_prop_argument_heuristic(interp, argtypes) || const_prop_rettype_heuristic(interp, result.rt) || return nothing
     allconst = is_allconst(argtypes)
     force = force_const_prop(interp, f, method)
-    force || const_prop_function_heuristic(interp, f, argtypes, nargs, allconst) || return nothing
+    if !force
+        if !const_prop_function_heuristic(interp, f, argtypes, nargs, allconst)
+            add_remark!(interp, sv, "[constprop] Disabled by function heuristic")
+            return nothing
+        end
+    end
     force |= allconst
     mi = specialize_method(match, !force)
     if mi === nothing
@@ -550,14 +555,17 @@ function maybe_get_const_prop_profitable(interp::AbstractInterpreter, result::Me
     end
     mi = mi::MethodInstance
     if !force && !const_prop_methodinstance_heuristic(interp, method, mi)
-        add_remark!(interp, sv, "[constprop] Disabled by heuristic")
+        add_remark!(interp, sv, "[constprop] Disabled by method instance heuristic")
         return nothing
     end
     return mi
 end
 
 function const_prop_entry_heuristic(interp::AbstractInterpreter, result::MethodCallResult, sv::InferenceState)
-    call_result_unused(sv) && result.edgecycle && return false
+    if call_result_unused(sv) && result.edgecycle
+        add_remark!(interp, sv, "[constprop] Edgecycle with unused result")
+        return false
+    end
     return is_improvable(result.rt) && InferenceParams(interp).ipo_constant_propagation
 end