diff --git a/Project.toml b/Project.toml
index c1d8752..962c0dc 100644
--- a/Project.toml
+++ b/Project.toml
@@ -39,11 +39,13 @@ StaticArraysCore = "1e83bf80-4336-4d27-bf5d-d5a4f845583c"
 Sundials = "c3572dad-4567-51f8-b174-8c6c989267f4"
 SymbolicIndexingInterface = "2efcf032-c050-4f8e-a9bb-153293bab1f5"
 TimerOutputs = "a759f4b9-e2f1-59dc-863e-4aeb61b1ea8f"
-Tracy = "e689c965-62c8-4b79-b2c5-8359227902fd"
 
 [weakdeps]
 ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78"
 
+[extensions]
+DAECompilerCthulhuExt = ["Compiler", "Cthulhu"]
+
 [sources]
 Compiler = {rev = "master", url = "https://github.com/JuliaLang/BaseCompiler.jl.git"}
 Cthulhu = {rev = "master", url = "https://github.com/JuliaDebug/Cthulhu.jl.git"}
diff --git a/ext/DAECompilerCthulhuExt.jl b/ext/DAECompilerCthulhuExt.jl
new file mode 100644
index 0000000..159f440
--- /dev/null
+++ b/ext/DAECompilerCthulhuExt.jl
@@ -0,0 +1,132 @@
+module DAECompilerCthulhuExt
+
+using Core.IR
+using DAECompiler: DAECompiler, DAEIPOResult, UncompilableIPOResult, Settings, ADAnalyzer, structural_analysis!, find_matching_ci, StructureCache, ir_to_src, get_method_instance, MappingInfo, AnalyzedSource
+using Compiler: Compiler, InferenceResult, NativeInterpreter, SOURCE_MODE_GET_SOURCE, get_inference_world, typeinf_ext, Effects, get_ci_mi, NoCallInfo
+using Accessors: setproperties
+using Diffractor: FRuleCallInfo
+
+import Cthulhu as _Cthulhu
+const Cthulhu = Base.get_extension(_Cthulhu, :CthulhuCompilerExt)
+using .Cthulhu: CthulhuState, AbstractProvider, Command, InferenceKey, InferenceDict, PC2Remarks, PC2CallMeta, PC2Effects, PC2Excts, LookupResult, generate_code_instance, value_for_default_command
+
+mutable struct DAEProvider <: AbstractProvider
+    world::UInt
+    settings::Settings
+    remarks::InferenceDict{PC2Remarks}
+    calls::InferenceDict{PC2CallMeta}
+    effects::InferenceDict{PC2Effects}
+    exception_types::InferenceDict{PC2Excts}
+end
+DAEProvider(; world = Base.tls_world_age(), settings = Settings()) = DAEProvider(world, settings, InferenceDict{PC2Remarks}(), InferenceDict{PC2CallMeta}(), InferenceDict{PC2Effects}(), InferenceDict{PC2Excts}())
+
+Cthulhu.get_inference_world(provider::DAEProvider) = provider.world
+
+function Cthulhu.find_method_instance(provider::DAEProvider, @nospecialize(tt::Type{<:Tuple}), world::UInt)
+    return get_method_instance(tt, world)
+end
+
+function check_result(ci::CodeInstance)
+    isa(ci.inferred, UncompilableIPOResult) && throw(ci.inferred.error)
+    return true
+end
+
+function Cthulhu.generate_code_instance(provider::DAEProvider, mi::MethodInstance)
+    world = get_inference_world(provider)
+    ci = find_matching_ci(ci->ci.owner == StructureCache(), mi, world)
+    # XXX: We should not cache the CodeInstance this way, or at least invalidate in the provider in `toggle_setting!`.
+    if ci !== nothing
+        haskey(provider.remarks, ci) && return ci
+    else
+        provider.settings.force_inline_all && @warn "`force_inline_all=true` is not supported yet; this setting will be ignored"
+        analyzer = ADAnalyzer(; world)
+        ci_pre = typeinf_ext(analyzer, mi, SOURCE_MODE_GET_SOURCE)
+        result = structural_analysis!(ci_pre, world, provider.settings)
+        ci = find_matching_ci(ci->ci.owner == StructureCache(), mi, world)::CodeInstance
+    end
+
+    check_result(ci)
+    provider.remarks[ci] = PC2Remarks()
+    provider.calls[ci] = PC2CallMeta()
+    provider.effects[ci] = PC2Effects()
+    provider.exception_types[ci] = PC2Excts()
+
+    @eval Main global result = $(ci.inferred)
+
+    return ci
+end
+
+Cthulhu.get_override(provider::DAEProvider, @nospecialize(info)) = nothing
+
+Cthulhu.get_pc_remarks(provider::DAEProvider, key::CodeInstance) = get(provider.remarks, key, nothing)
+Cthulhu.get_pc_effects(provider::DAEProvider, key::CodeInstance) = get(provider.effects, key, nothing)
+Cthulhu.get_pc_excts(provider::DAEProvider, key::CodeInstance) = get(provider.exception_types, key, nothing)
+
+function Cthulhu.LookupResult(provider::DAEProvider, ci::CodeInstance, optimize::Bool)
+    if isa(ci.inferred, AnalyzedSource)
+        mi = get_ci_mi(ci)
+        new_ci = generate_code_instance(provider, mi)
+        check_result(new_ci)
+        @assert isa(new_ci.inferred, DAEIPOResult) "Inferred type of newly generated `CodeInstance` must be `DAEIPOResult`, got `$(typeof(new_ci.inferred))`"
+        return LookupResult(provider, new_ci, optimize)
+    end
+    result = ci.inferred::DAEIPOResult
+    ir = copy(result.ir)
+    pushfirst!(ir.argtypes, Tuple)
+    src = ir_to_src(ir, provider.settings; widen = false)
+    src.ssavaluetypes = copy(ir.stmts.type)
+    src.min_world = @atomic ci.min_world
+    src.max_world = @atomic ci.max_world
+    optimized = true
+    rt = Cthulhu.cached_return_type(ci)
+    exct = Cthulhu.cached_exception_type(ci)
+    infos = widen_call_infos(ir.stmts.info)
+    return LookupResult(ir, src, rt, exct, infos, src.slottypes, Cthulhu.get_effects(ci), optimized)
+end
+
+function widen_call_infos(infos)
+    infos = copy(infos)
+    for (i, info) in enumerate(infos)
+        while true
+            isa(info, FRuleCallInfo) && (info = info.info; continue)
+            isa(info, MappingInfo) && (info = info.info; continue)
+            break
+        end
+        infos[i] = info
+    end
+    return infos
+end
+
+function toggle_setting(provider::DAEProvider, setting::Symbol, value)
+    return setproperties(provider.settings, NamedTuple((setting => value,)))
+end
+
+function Cthulhu.menu_commands(provider::DAEProvider)
+    commands = Cthulhu.default_menu_commands(provider)
+    filter!(x -> !in(x.name, (:optimize, :dump_params, :llvm, :native)), commands)
+    push!(commands, toggle_setting(provider, 'f', :force_inline_all, "force inline all"))
+    return commands
+end
+
+function toggle_setting(provider::DAEProvider, key::Char, name::Symbol, description::String = string(name))
+  callback = state -> toggle_setting!(state, name)
+  Command(callback, key, name, description, :toggles)
+end
+
+function Cthulhu.value_for_command(provider::DAEProvider, state::CthulhuState, command::Command)
+    hasproperty(provider.settings, command.name) &&
+        return getproperty(provider.settings, command.name)
+    return value_for_default_command(provider, state, command)
+end
+
+function toggle_setting!(state::CthulhuState, name::Symbol)
+  (; provider) = state
+  (; settings) = provider
+  value = !getproperty(settings, name)::Bool
+  provider.settings = setproperties(settings, NamedTuple((name => value,)))
+  state.display_code = true
+end
+
+DAECompiler.dae_provider(args...; kwargs...) = DAEProvider(args...; kwargs...)
+
+end # module
diff --git a/src/DAECompiler.jl b/src/DAECompiler.jl
index a1d7d7f..321e757 100644
--- a/src/DAECompiler.jl
+++ b/src/DAECompiler.jl
@@ -43,4 +43,6 @@ module DAECompiler
     include("analysis/consistency.jl")
     include("interface.jl")
     include("problem_interface.jl")
+
+    export dae_provider # use with Cthulhu, `@descend provider=dae_provider() pingpong()`
 end
diff --git a/src/interface.jl b/src/interface.jl
index 767cf9a..67924d0 100644
--- a/src/interface.jl
+++ b/src/interface.jl
@@ -113,3 +113,6 @@ function refresh()
     return nothing
 end
 refresh()
+
+# methods are to be added via the Cthulhu extension
+function dae_provider end
diff --git a/src/transform/common.jl b/src/transform/common.jl
index 042a29e..a31e142 100644
--- a/src/transform/common.jl
+++ b/src/transform/common.jl
@@ -40,14 +40,10 @@ function widen_extra_info!(ir)
     end
 end
 
-function ir_to_src(ir::IRCode, settings::Settings; slotnames = nothing)
-    isva = false
+function ir_to_src(ir::IRCode, settings::Settings; slotnames = nothing, widen = true, isva = false)
     ir.debuginfo.def === nothing && (ir.debuginfo.def = :var"generated IR for OpaqueClosure")
     maybe_rewrite_debuginfo!(ir, settings)
     nargtypes = length(ir.argtypes)
-    nargs = nargtypes-1
-    sig = Compiler.compute_oc_signature(ir, nargs, isva)
-    rt = Compiler.compute_ir_rettype(ir)
     src = ccall(:jl_new_code_info_uninit, Ref{CodeInfo}, ())
     if slotnames === nothing
         src.slotnames = Symbol[Symbol("arg$i") for i = 1:nargtypes]
@@ -55,11 +51,12 @@ function ir_to_src(ir::IRCode, settings::Settings; slotnames = nothing)
         length(slotnames) == nargtypes || error("mismatched `argtypes` and `slotnames`")
         src.slotnames = slotnames
     end
-    src.nargs = length(ir.argtypes)
-    src.isva = false
+    src.nargs = nargtypes
+    src.isva = isva
     src.slotflags = fill(zero(UInt8), nargtypes)
     src.slottypes = copy(ir.argtypes)
-    src = Compiler.ir_to_codeinf!(src, ir)
+    Compiler.replace_code_newstyle!(src, ir)
+    widen && Compiler.widen_all_consts!(src)
     return src
 end