diff --git a/library/init/lean/compiler/default.lean b/library/init/lean/compiler/default.lean
index 960e022875..d3436a9fb5 100644
--- a/library/init/lean/compiler/default.lean
+++ b/library/init/lean/compiler/default.lean
@@ -5,4 +5,6 @@ Authors: Leonardo de Moura
 -/
 prelude
 import init.lean.compiler.constfolding
-import init.lean.compiler.ir init.lean.compiler.pushproj
+import init.lean.compiler.ir
+import init.lean.compiler.pushproj
+import init.lean.compiler.elimdead
diff --git a/library/init/lean/compiler/elimdead.lean b/library/init/lean/compiler/elimdead.lean
new file mode 100644
index 0000000000..cd6e2eb4d1
--- /dev/null
+++ b/library/init/lean/compiler/elimdead.lean
@@ -0,0 +1,48 @@
+/-
+Copyright (c) 2019 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+import init.lean.compiler.ir
+
+namespace Lean
+namespace IR
+
+partial def reshapeWithoutDeadAux : Array FnBody → FnBody → VarIdxSet → FnBody
+| bs b used :=
+  if bs.isEmpty then b
+  else
+    let curr := bs.back in
+    let bs   := bs.pop in
+    let keep (_ : Unit) :=
+      let used := curr.collectFreeVars used in
+      let b    := curr.setBody b in
+      reshapeWithoutDeadAux bs b used in
+    let keepIfUsed (vidx : Index) :=
+      if used.contains vidx then keep ()
+      else reshapeWithoutDeadAux bs b used in
+    match curr with
+    | FnBody.vdecl x _ _  _  := keepIfUsed x.idx
+    | FnBody.jdecl j _ _ _ _ := keepIfUsed j.idx
+    | _                      := keep ()
+
+def reshapeWithoutDead (bs : Array FnBody) (term : FnBody) : FnBody :=
+reshapeWithoutDeadAux bs term term.freeVars
+
+partial def FnBody.elimDead : FnBody → FnBody
+| b :=
+  let (bs, term) := b.flatten in
+  let term       := match term with
+    | FnBody.case tid x alts :=
+      let alts := alts.hmap $ λ alt, alt.modifyBody $ λ b, FnBody.elimDead b in
+      FnBody.case tid x alts
+    | other := other in
+  reshape bs term
+
+@[export lean.ir.decl_elim_dead_core]
+def Decl.elimDead : Decl → Decl
+| (Decl.fdecl f xs t b) := Decl.fdecl f xs t b.elimDead
+| other                 := other
+
+end IR
+end Lean
diff --git a/src/stage0/CMakeLists.txt b/src/stage0/CMakeLists.txt
index 22ff1b68e0..4e2bb3d458 100644
--- a/src/stage0/CMakeLists.txt
+++ b/src/stage0/CMakeLists.txt
@@ -1 +1 @@
-add_library (stage0 OBJECT ./init/coe.cpp ./init/control/alternative.cpp ./init/control/applicative.cpp ./init/control/combinators.cpp ./init/control/default.cpp ./init/control/estate.cpp ./init/control/except.cpp ./init/control/functor.cpp ./init/control/id.cpp ./init/control/lift.cpp ./init/control/monad.cpp ./init/control/monadfail.cpp ./init/control/option.cpp ./init/control/reader.cpp ./init/control/state.cpp ./init/core.cpp ./init/data/array/basic.cpp ./init/data/array/default.cpp ./init/data/assoclist.cpp ./init/data/basic.cpp ./init/data/char/basic.cpp ./init/data/char/default.cpp ./init/data/default.cpp ./init/data/dlist.cpp ./init/data/fin/basic.cpp ./init/data/fin/default.cpp ./init/data/hashable.cpp ./init/data/hashmap/basic.cpp ./init/data/hashmap/default.cpp ./init/data/int/basic.cpp ./init/data/int/default.cpp ./init/data/list/basic.cpp ./init/data/list/default.cpp ./init/data/list/instances.cpp ./init/data/nat/basic.cpp ./init/data/nat/bitwise.cpp ./init/data/nat/default.cpp ./init/data/nat/div.cpp ./init/data/option/basic.cpp ./init/data/option/instances.cpp ./init/data/ordering/basic.cpp ./init/data/ordering/default.cpp ./init/data/rbmap/basic.cpp ./init/data/rbmap/default.cpp ./init/data/rbtree/basic.cpp ./init/data/rbtree/default.cpp ./init/data/repr.cpp ./init/data/string/basic.cpp ./init/data/string/default.cpp ./init/data/tostring.cpp ./init/data/uint.cpp ./init/default.cpp ./init/env_ext.cpp ./init/fix.cpp ./init/io.cpp ./init/lean/compiler/constfolding.cpp ./init/lean/compiler/default.cpp ./init/lean/compiler/ir.cpp ./init/lean/compiler/pushproj.cpp ./init/lean/compiler/util.cpp ./init/lean/config.cpp ./init/lean/declaration.cpp ./init/lean/default.cpp ./init/lean/disjoint_set.cpp ./init/lean/elaborator.cpp ./init/lean/expander.cpp ./init/lean/expr.cpp ./init/lean/extern.cpp ./init/lean/format.cpp ./init/lean/frontend.cpp ./init/lean/kvmap.cpp ./init/lean/level.cpp ./init/lean/message.cpp ./init/lean/name.cpp ./init/lean/name_mangling.cpp ./init/lean/options.cpp ./init/lean/parser/basic.cpp ./init/lean/parser/combinators.cpp ./init/lean/parser/command.cpp ./init/lean/parser/declaration.cpp ./init/lean/parser/identifier.cpp ./init/lean/parser/level.cpp ./init/lean/parser/module.cpp ./init/lean/parser/notation.cpp ./init/lean/parser/parsec.cpp ./init/lean/parser/pratt.cpp ./init/lean/parser/rec.cpp ./init/lean/parser/stringliteral.cpp ./init/lean/parser/syntax.cpp ./init/lean/parser/term.cpp ./init/lean/parser/token.cpp ./init/lean/parser/trie.cpp ./init/lean/position.cpp ./init/lean/trace.cpp ./init/lean/util.cpp ./init/platform.cpp ./init/util.cpp ./init/wf.cpp)
+add_library (stage0 OBJECT ./init/coe.cpp ./init/control/alternative.cpp ./init/control/applicative.cpp ./init/control/combinators.cpp ./init/control/default.cpp ./init/control/estate.cpp ./init/control/except.cpp ./init/control/functor.cpp ./init/control/id.cpp ./init/control/lift.cpp ./init/control/monad.cpp ./init/control/monadfail.cpp ./init/control/option.cpp ./init/control/reader.cpp ./init/control/state.cpp ./init/core.cpp ./init/data/array/basic.cpp ./init/data/array/default.cpp ./init/data/assoclist.cpp ./init/data/basic.cpp ./init/data/char/basic.cpp ./init/data/char/default.cpp ./init/data/default.cpp ./init/data/dlist.cpp ./init/data/fin/basic.cpp ./init/data/fin/default.cpp ./init/data/hashable.cpp ./init/data/hashmap/basic.cpp ./init/data/hashmap/default.cpp ./init/data/int/basic.cpp ./init/data/int/default.cpp ./init/data/list/basic.cpp ./init/data/list/default.cpp ./init/data/list/instances.cpp ./init/data/nat/basic.cpp ./init/data/nat/bitwise.cpp ./init/data/nat/default.cpp ./init/data/nat/div.cpp ./init/data/option/basic.cpp ./init/data/option/instances.cpp ./init/data/ordering/basic.cpp ./init/data/ordering/default.cpp ./init/data/rbmap/basic.cpp ./init/data/rbmap/default.cpp ./init/data/rbtree/basic.cpp ./init/data/rbtree/default.cpp ./init/data/repr.cpp ./init/data/string/basic.cpp ./init/data/string/default.cpp ./init/data/tostring.cpp ./init/data/uint.cpp ./init/default.cpp ./init/env_ext.cpp ./init/fix.cpp ./init/io.cpp ./init/lean/compiler/constfolding.cpp ./init/lean/compiler/default.cpp ./init/lean/compiler/elimdead.cpp ./init/lean/compiler/ir.cpp ./init/lean/compiler/pushproj.cpp ./init/lean/compiler/util.cpp ./init/lean/config.cpp ./init/lean/declaration.cpp ./init/lean/default.cpp ./init/lean/disjoint_set.cpp ./init/lean/elaborator.cpp ./init/lean/expander.cpp ./init/lean/expr.cpp ./init/lean/extern.cpp ./init/lean/format.cpp ./init/lean/frontend.cpp ./init/lean/kvmap.cpp ./init/lean/level.cpp ./init/lean/message.cpp ./init/lean/name.cpp ./init/lean/name_mangling.cpp ./init/lean/options.cpp ./init/lean/parser/basic.cpp ./init/lean/parser/combinators.cpp ./init/lean/parser/command.cpp ./init/lean/parser/declaration.cpp ./init/lean/parser/identifier.cpp ./init/lean/parser/level.cpp ./init/lean/parser/module.cpp ./init/lean/parser/notation.cpp ./init/lean/parser/parsec.cpp ./init/lean/parser/pratt.cpp ./init/lean/parser/rec.cpp ./init/lean/parser/stringliteral.cpp ./init/lean/parser/syntax.cpp ./init/lean/parser/term.cpp ./init/lean/parser/token.cpp ./init/lean/parser/trie.cpp ./init/lean/position.cpp ./init/lean/trace.cpp ./init/lean/util.cpp ./init/platform.cpp ./init/util.cpp ./init/wf.cpp)
diff --git a/src/stage0/init/data/array/basic.cpp b/src/stage0/init/data/array/basic.cpp
index 0f5f85ac23..cda32a081f 100644
--- a/src/stage0/init/data/array/basic.cpp
+++ b/src/stage0/init/data/array/basic.cpp
@@ -18,6 +18,7 @@ obj* l_List_toArrayAux___rarg(obj*, obj*);
 obj* l_Array_extractAux___main___rarg___boxed(obj*, obj*, obj*, obj*, obj*);
 obj* l_Array_append(obj*);
 obj* l_Array_foldlFrom___rarg(obj*, obj*, obj*, obj*);
+obj* l_Array_fswapAt___boxed(obj*);
 obj* l_Array_miterateAux___main___at_Array_append___spec__1___boxed(obj*);
 obj* l_Array_hmmapAux___main___at_Array_hmapIdx___spec__1(obj*);
 obj* l_Array_shrink___main___rarg___boxed(obj*, obj*);
@@ -57,6 +58,7 @@ obj* l_Array_miterateAux___main___at_Array_foldlFrom___spec__1___boxed(obj*, obj
 obj* l___private_init_data_array_basic_1__revIterateAux___main___at_Array_revFoldl___spec__1___rarg(obj*, obj*, obj*, obj*, obj*, obj*);
 obj* l_Array_shrink___rarg(obj*, obj*);
 obj* l_Array_fswap___boxed(obj*, obj*, obj*, obj*);
+obj* l_Array_swapAt___boxed(obj*);
 obj* l_Array_hmmapAux___main___at_Array_hmapIdx___spec__1___rarg(obj*, obj*, obj*, obj*);
 obj* l_Array_any___boxed(obj*);
 obj* l_Array_extractAux(obj*);
@@ -79,6 +81,7 @@ obj* l_Array_size___boxed(obj*, obj*);
 obj* l_Array_isEqvAux___main___boxed(obj*);
 obj* l_List_toArrayAux___main___rarg(obj*, obj*);
 obj* l_Array_isEqv___rarg___boxed(obj*, obj*, obj*);
+obj* l_Array_fswapAt___rarg___boxed(obj*, obj*, obj*);
 obj* l_Array_mfoldlFrom___rarg(obj*, obj*, obj*, obj*, obj*);
 uint8 l_Array_anyAux___main___at_Array_all___spec__1___rarg(obj*, obj*, obj*);
 obj* l_Array_extractAux___rarg(obj*, obj*, obj*, obj*, obj*);
@@ -92,6 +95,7 @@ obj* l_Array_mfind(obj*, obj*, obj*);
 obj* l_Array_mfindAux___main___rarg___lambda__1___boxed(obj*, obj*, obj*, obj*, obj*);
 obj* l_Array_foldl___rarg___boxed(obj*, obj*, obj*);
 obj* l_Array_extractAux___rarg___boxed(obj*, obj*, obj*, obj*, obj*);
+obj* l_Array_swapAt(obj*);
 obj* l_Array_hmmapAux___main___at_Array_hmmap___spec__1___rarg(obj*, obj*, obj*, obj*, obj*);
 obj* l_Array_hmmap(obj*, obj*);
 obj* l_List_redLength___main(obj*);
@@ -149,6 +153,7 @@ obj* l_Array_miterate_u_2082Aux(obj*, obj*, obj*);
 obj* l_Array_revIterate___boxed(obj*, obj*);
 obj* l_Array_revFoldl___rarg___boxed(obj*, obj*, obj*);
 obj* l_Array_miterateAux___main___at_Array_foldlFrom___spec__1___rarg(obj*, obj*, obj*, obj*, obj*);
+obj* l_Array_swapAt___rarg___boxed(obj*, obj*, obj*);
 namespace lean {
 uint8 nat_dec_lt(obj*, obj*);
 }
@@ -232,6 +237,7 @@ obj* l_Array_HasAppend___closed__1;
 obj* l_Array_isEmpty___rarg___boxed(obj*);
 obj* l_Array_isEqv___boxed(obj*);
 obj* l_Array_miterateAux___main___at_Array_mfoldlFrom___spec__1(obj*, obj*, obj*);
+obj* l_Array_fswapAt(obj*);
 obj* l_Array_hmmapAux___main___at_Array_hmmap___spec__1___rarg___lambda__1(obj*, obj*, obj*, obj*, obj*, obj*);
 obj* l_Array_shrink___main___rarg(obj*, obj*);
 obj* l_Array_iterate___rarg(obj*, obj*, obj*);
@@ -303,6 +309,7 @@ obj* l_Array_reverse___rarg(obj*);
 obj* l_Array_mmap___boxed(obj*, obj*);
 obj* l_Array_shrink___main___boxed(obj*);
 obj* l_Array_find(obj*, obj*);
+obj* l_Array_swapAt___rarg(obj*, obj*, obj*);
 obj* l_Array_extractAux___boxed(obj*);
 obj* l_Array_miterateAux___main___at_Array_mmap___spec__1(obj*, obj*);
 obj* l_Array_miterate_u_2082Aux___main___at_Array_mfoldl_u_2082___spec__1___rarg___boxed(obj*, obj*, obj*, obj*, obj*, obj*, obj*);
@@ -340,6 +347,7 @@ obj* l_Array_mkEmpty___boxed(obj*, obj*);
 obj* l_Array_miterateAux___main___at_Array_map___spec__1___boxed(obj*, obj*);
 uint8 l_Array_all___rarg(obj*, obj*);
 obj* l_Array_miterateAux___main___at_Array_iterate___spec__1___boxed(obj*, obj*);
+obj* l_Array_fswapAt___rarg(obj*, obj*, obj*);
 obj* l_Array_miterateAux___main___at_Array_map___spec__1___rarg(obj*, obj*, obj*, obj*, obj*);
 obj* l_Array_miterateAux___main___at_Array_mmap___spec__1___boxed(obj*, obj*);
 obj* l_Array_miterate_u_2082Aux___rarg(obj*, obj*, obj*, obj*, obj*, obj*);
@@ -670,6 +678,97 @@ lean::dec(x_3);
 return x_4;
 }
 }
+obj* l_Array_fswapAt___rarg(obj* x_0, obj* x_1, obj* x_2) {
+_start:
+{
+obj* x_3; obj* x_4; obj* x_5; 
+x_3 = lean::array_index(x_0, x_1);
+x_4 = lean::array_update(x_0, x_1, x_2);
+x_5 = lean::alloc_cnstr(0, 2, 0);
+lean::cnstr_set(x_5, 0, x_3);
+lean::cnstr_set(x_5, 1, x_4);
+return x_5;
+}
+}
+obj* l_Array_fswapAt(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = lean::alloc_closure(reinterpret_cast<void*>(l_Array_fswapAt___rarg___boxed), 3, 0);
+return x_1;
+}
+}
+obj* l_Array_fswapAt___rarg___boxed(obj* x_0, obj* x_1, obj* x_2) {
+_start:
+{
+obj* x_3; 
+x_3 = l_Array_fswapAt___rarg(x_0, x_1, x_2);
+lean::dec(x_1);
+return x_3;
+}
+}
+obj* l_Array_fswapAt___boxed(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = l_Array_fswapAt(x_0);
+lean::dec(x_0);
+return x_1;
+}
+}
+obj* l_Array_swapAt___rarg(obj* x_0, obj* x_1, obj* x_2) {
+_start:
+{
+obj* x_3; uint8 x_4; 
+x_3 = lean::array_get_size(x_0);
+x_4 = lean::nat_dec_lt(x_1, x_3);
+lean::dec(x_3);
+if (x_4 == 0)
+{
+obj* x_6; 
+x_6 = lean::alloc_cnstr(0, 2, 0);
+lean::cnstr_set(x_6, 0, x_2);
+lean::cnstr_set(x_6, 1, x_0);
+return x_6;
+}
+else
+{
+obj* x_7; obj* x_8; obj* x_9; 
+x_7 = lean::array_index(x_0, x_1);
+x_8 = lean::array_update(x_0, x_1, x_2);
+x_9 = lean::alloc_cnstr(0, 2, 0);
+lean::cnstr_set(x_9, 0, x_7);
+lean::cnstr_set(x_9, 1, x_8);
+return x_9;
+}
+}
+}
+obj* l_Array_swapAt(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = lean::alloc_closure(reinterpret_cast<void*>(l_Array_swapAt___rarg___boxed), 3, 0);
+return x_1;
+}
+}
+obj* l_Array_swapAt___rarg___boxed(obj* x_0, obj* x_1, obj* x_2) {
+_start:
+{
+obj* x_3; 
+x_3 = l_Array_swapAt___rarg(x_0, x_1, x_2);
+lean::dec(x_1);
+return x_3;
+}
+}
+obj* l_Array_swapAt___boxed(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = l_Array_swapAt(x_0);
+lean::dec(x_0);
+return x_1;
+}
+}
 obj* l_Array_pop___boxed(obj* x_0, obj* x_1) {
 _start:
 {
diff --git a/src/stage0/init/data/rbtree/basic.cpp b/src/stage0/init/data/rbtree/basic.cpp
index 8df627ea30..478d9c282c 100644
--- a/src/stage0/init/data/rbtree/basic.cpp
+++ b/src/stage0/init/data/rbtree/basic.cpp
@@ -27,6 +27,7 @@ obj* l_rbtreeOf___boxed(obj*);
 obj* l_rbtreeOf(obj*);
 obj* l_List_foldl___main___at_RBTree_fromList___spec__1___rarg(obj*, obj*, obj*);
 obj* l_RBTree_max___boxed(obj*, obj*);
+obj* l_RBTree_HasInsert(obj*);
 obj* l_RBNode_all___main___at_RBTree_subset___spec__1___rarg___boxed(obj*, obj*, obj*);
 obj* l_RBTree_ofList___main(obj*);
 obj* l_RBNode_fold___main___at_RBTree_fold___spec__1(obj*, obj*);
@@ -66,6 +67,7 @@ uint8 l_RBNode_any___main___at_RBTree_any___spec__1___rarg(obj*, obj*);
 namespace lean {
 obj* string_append(obj*, obj*);
 }
+obj* l_RBTree_HasInsert___boxed(obj*);
 obj* l_RBTree_contains___rarg___boxed(obj*, obj*, obj*);
 uint8 l_RBTree_seteq___rarg(obj*, obj*, obj*);
 obj* l_RBTree_fromList(obj*);
@@ -121,6 +123,7 @@ uint8 l_RBTree_isEmpty___rarg(obj*);
 obj* l_RBTree_ofList(obj*);
 obj* l_RBTree_ofList___main___boxed(obj*);
 obj* l_RBTree_depth(obj*, obj*);
+obj* l_RBTree_HasInsert___rarg(obj*, obj*, obj*);
 obj* l_RBTree_fold___boxed(obj*, obj*, obj*);
 obj* l_RBTree_toList___boxed(obj*, obj*);
 obj* l_RBNode_mfold___main___at_RBTree_mfor___spec__1___rarg___lambda__2(obj*, obj*, obj*, obj*, obj*, obj*);
@@ -895,6 +898,45 @@ lean::dec(x_0);
 return x_1;
 }
 }
+obj* l_RBTree_HasInsert___rarg(obj* x_0, obj* x_1, obj* x_2) {
+_start:
+{
+uint8 x_3; 
+x_3 = l_RBNode_isRed___main___rarg(x_2);
+if (x_3 == 0)
+{
+obj* x_4; obj* x_5; 
+x_4 = lean::box(0);
+x_5 = l_RBNode_ins___main___rarg(x_0, x_2, x_1, x_4);
+return x_5;
+}
+else
+{
+obj* x_6; obj* x_7; obj* x_8; 
+x_6 = lean::box(0);
+x_7 = l_RBNode_ins___main___rarg(x_0, x_2, x_1, x_6);
+x_8 = l_RBNode_setBlack___main___rarg(x_7);
+return x_8;
+}
+}
+}
+obj* l_RBTree_HasInsert(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = lean::alloc_closure(reinterpret_cast<void*>(l_RBTree_HasInsert___rarg), 3, 0);
+return x_1;
+}
+}
+obj* l_RBTree_HasInsert___boxed(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = l_RBTree_HasInsert(x_0);
+lean::dec(x_0);
+return x_1;
+}
+}
 obj* l_RBTree_ofList___main___rarg(obj* x_0, obj* x_1) {
 _start:
 {
diff --git a/src/stage0/init/lean/compiler/default.cpp b/src/stage0/init/lean/compiler/default.cpp
index b07752722e..0c319a4d6b 100644
--- a/src/stage0/init/lean/compiler/default.cpp
+++ b/src/stage0/init/lean/compiler/default.cpp
@@ -1,6 +1,6 @@
 // Lean compiler output
 // Module: init.lean.compiler.default
-// Imports: init.lean.compiler.constfolding init.lean.compiler.ir
+// Imports: init.lean.compiler.constfolding init.lean.compiler.ir init.lean.compiler.pushproj init.lean.compiler.elimdead
 #include "runtime/object.h"
 #include "runtime/apply.h"
 typedef lean::object obj;    typedef lean::usize  usize;
@@ -16,6 +16,8 @@ typedef lean::uint32 uint32; typedef lean::uint64 uint64;
 #endif
 obj* initialize_init_lean_compiler_constfolding(obj*);
 obj* initialize_init_lean_compiler_ir(obj*);
+obj* initialize_init_lean_compiler_pushproj(obj*);
+obj* initialize_init_lean_compiler_elimdead(obj*);
 static bool _G_initialized = false;
 obj* initialize_init_lean_compiler_default(obj* w) {
  if (_G_initialized) return w;
@@ -25,5 +27,9 @@ w = initialize_init_lean_compiler_constfolding(w);
 if (io_result_is_error(w)) return w;
 w = initialize_init_lean_compiler_ir(w);
 if (io_result_is_error(w)) return w;
+w = initialize_init_lean_compiler_pushproj(w);
+if (io_result_is_error(w)) return w;
+w = initialize_init_lean_compiler_elimdead(w);
+if (io_result_is_error(w)) return w;
 return w;
 }
diff --git a/src/stage0/init/lean/compiler/elimdead.cpp b/src/stage0/init/lean/compiler/elimdead.cpp
new file mode 100644
index 0000000000..775f3c07b1
--- /dev/null
+++ b/src/stage0/init/lean/compiler/elimdead.cpp
@@ -0,0 +1,391 @@
+// Lean compiler output
+// Module: init.lean.compiler.elimdead
+// Imports: init.default init.lean.compiler.ir
+#include "runtime/object.h"
+#include "runtime/apply.h"
+typedef lean::object obj;    typedef lean::usize  usize;
+typedef lean::uint8  uint8;  typedef lean::uint16 uint16;
+typedef lean::uint32 uint32; typedef lean::uint64 uint64;
+#if defined(__clang__)
+#pragma clang diagnostic ignored "-Wunused-parameter"
+#pragma clang diagnostic ignored "-Wunused-label"
+#elif defined(__GNUC__) && !defined(__CLANG__)
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#pragma GCC diagnostic ignored "-Wunused-label"
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+#endif
+obj* l_Lean_IR_FnBody_collectFreeVars(obj*, obj*);
+namespace lean {
+obj* nat_sub(obj*, obj*);
+}
+obj* l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1(obj*, obj*);
+obj* l_Lean_IR_reshapeWithoutDead(obj*, obj*);
+obj* l_Array_back___at_Lean_IR_reshapeWithoutDeadAux___main___spec__1(obj*);
+obj* l_Lean_IR_reshapeWithoutDeadAux(obj*, obj*, obj*);
+obj* l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1___closed__1;
+obj* l_Array_back___at_Lean_IR_reshapeWithoutDeadAux___main___spec__1___boxed(obj*);
+obj* l_Lean_IR_FnBody_elimDead___main(obj*);
+obj* l_Lean_IR_FnBody_freeVars(obj*);
+obj* l_Lean_IR_reshape(obj*, obj*);
+obj* l_Lean_IR_reshapeWithoutDeadAux___main(obj*, obj*, obj*);
+namespace lean {
+uint8 nat_dec_lt(obj*, obj*);
+}
+namespace lean {
+namespace ir {
+obj* decl_elim_dead_core(obj*);
+}}
+obj* l_RBNode_findCore___main___at___private_init_lean_compiler_ir_2__collectIndex___spec__1(obj*, obj*);
+obj* l_Lean_IR_FnBody_flatten(obj*);
+namespace lean {
+obj* nat_add(obj*, obj*);
+}
+uint8 l_Array_isEmpty___rarg(obj*);
+obj* l_Lean_IR_Decl_elimDead___main(obj*);
+obj* l_Lean_IR_FnBody_setBody___main(obj*, obj*);
+obj* l_Lean_IR_FnBody_elimDead(obj*);
+extern obj* l_Lean_IR_Inhabited;
+obj* l_Array_back___at_Lean_IR_reshapeWithoutDeadAux___main___spec__1(obj* x_0) {
+_start:
+{
+obj* x_1; obj* x_2; obj* x_3; obj* x_5; obj* x_6; 
+x_1 = lean::array_get_size(x_0);
+x_2 = lean::mk_nat_obj(1ul);
+x_3 = lean::nat_sub(x_1, x_2);
+lean::dec(x_1);
+x_5 = l_Lean_IR_Inhabited;
+x_6 = lean::array_get(x_5, x_0, x_3);
+lean::dec(x_3);
+return x_6;
+}
+}
+obj* l_Lean_IR_reshapeWithoutDeadAux___main(obj* x_0, obj* x_1, obj* x_2) {
+_start:
+{
+uint8 x_3; 
+x_3 = l_Array_isEmpty___rarg(x_0);
+if (x_3 == 0)
+{
+obj* x_4; obj* x_5; 
+x_4 = l_Array_back___at_Lean_IR_reshapeWithoutDeadAux___main___spec__1(x_0);
+x_5 = lean::array_pop(x_0);
+switch (lean::obj_tag(x_4)) {
+case 0:
+{
+obj* x_6; obj* x_9; 
+x_6 = lean::cnstr_get(x_4, 0);
+lean::inc(x_6);
+lean::inc(x_2);
+x_9 = l_RBNode_findCore___main___at___private_init_lean_compiler_ir_2__collectIndex___spec__1(x_2, x_6);
+lean::dec(x_6);
+if (lean::obj_tag(x_9) == 0)
+{
+lean::dec(x_4);
+x_0 = x_5;
+goto _start;
+}
+else
+{
+obj* x_15; obj* x_16; 
+lean::dec(x_9);
+lean::inc(x_4);
+x_15 = l_Lean_IR_FnBody_collectFreeVars(x_4, x_2);
+x_16 = l_Lean_IR_FnBody_setBody___main(x_4, x_1);
+x_0 = x_5;
+x_1 = x_16;
+x_2 = x_15;
+goto _start;
+}
+}
+case 1:
+{
+obj* x_18; obj* x_21; 
+x_18 = lean::cnstr_get(x_4, 0);
+lean::inc(x_18);
+lean::inc(x_2);
+x_21 = l_RBNode_findCore___main___at___private_init_lean_compiler_ir_2__collectIndex___spec__1(x_2, x_18);
+lean::dec(x_18);
+if (lean::obj_tag(x_21) == 0)
+{
+lean::dec(x_4);
+x_0 = x_5;
+goto _start;
+}
+else
+{
+obj* x_27; obj* x_28; 
+lean::dec(x_21);
+lean::inc(x_4);
+x_27 = l_Lean_IR_FnBody_collectFreeVars(x_4, x_2);
+x_28 = l_Lean_IR_FnBody_setBody___main(x_4, x_1);
+x_0 = x_5;
+x_1 = x_28;
+x_2 = x_27;
+goto _start;
+}
+}
+case 12:
+{
+obj* x_30; obj* x_31; 
+x_30 = l_Lean_IR_FnBody_collectFreeVars(x_4, x_2);
+x_31 = l_Lean_IR_FnBody_setBody___main(x_4, x_1);
+x_0 = x_5;
+x_1 = x_31;
+x_2 = x_30;
+goto _start;
+}
+default:
+{
+obj* x_34; obj* x_35; 
+lean::inc(x_4);
+x_34 = l_Lean_IR_FnBody_collectFreeVars(x_4, x_2);
+x_35 = l_Lean_IR_FnBody_setBody___main(x_4, x_1);
+x_0 = x_5;
+x_1 = x_35;
+x_2 = x_34;
+goto _start;
+}
+}
+}
+else
+{
+lean::dec(x_0);
+lean::dec(x_2);
+return x_1;
+}
+}
+}
+obj* l_Array_back___at_Lean_IR_reshapeWithoutDeadAux___main___spec__1___boxed(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = l_Array_back___at_Lean_IR_reshapeWithoutDeadAux___main___spec__1(x_0);
+lean::dec(x_0);
+return x_1;
+}
+}
+obj* l_Lean_IR_reshapeWithoutDeadAux(obj* x_0, obj* x_1, obj* x_2) {
+_start:
+{
+obj* x_3; 
+x_3 = l_Lean_IR_reshapeWithoutDeadAux___main(x_0, x_1, x_2);
+return x_3;
+}
+}
+obj* l_Lean_IR_reshapeWithoutDead(obj* x_0, obj* x_1) {
+_start:
+{
+obj* x_3; obj* x_4; 
+lean::inc(x_1);
+x_3 = l_Lean_IR_FnBody_freeVars(x_1);
+x_4 = l_Lean_IR_reshapeWithoutDeadAux___main(x_0, x_1, x_3);
+return x_4;
+}
+}
+obj* _init_l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1___closed__1() {
+_start:
+{
+obj* x_0; obj* x_1; 
+x_0 = lean::box(12);
+x_1 = lean::alloc_cnstr(1, 1, 0);
+lean::cnstr_set(x_1, 0, x_0);
+return x_1;
+}
+}
+obj* l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1(obj* x_0, obj* x_1) {
+_start:
+{
+obj* x_2; uint8 x_3; 
+x_2 = lean::array_get_size(x_1);
+x_3 = lean::nat_dec_lt(x_0, x_2);
+lean::dec(x_2);
+if (x_3 == 0)
+{
+lean::dec(x_0);
+return x_1;
+}
+else
+{
+obj* x_6; obj* x_7; obj* x_8; obj* x_9; obj* x_10; 
+x_6 = lean::array_index(x_1, x_0);
+x_7 = l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1___closed__1;
+x_8 = lean::array_update(x_1, x_0, x_7);
+x_9 = lean::mk_nat_obj(1ul);
+x_10 = lean::nat_add(x_0, x_9);
+if (lean::obj_tag(x_6) == 0)
+{
+obj* x_11; obj* x_13; obj* x_15; obj* x_16; obj* x_17; obj* x_18; 
+x_11 = lean::cnstr_get(x_6, 0);
+x_13 = lean::cnstr_get(x_6, 1);
+if (lean::is_exclusive(x_6)) {
+ x_15 = x_6;
+} else {
+ lean::inc(x_11);
+ lean::inc(x_13);
+ lean::dec(x_6);
+ x_15 = lean::box(0);
+}
+x_16 = l_Lean_IR_FnBody_elimDead___main(x_13);
+if (lean::is_scalar(x_15)) {
+ x_17 = lean::alloc_cnstr(0, 2, 0);
+} else {
+ x_17 = x_15;
+}
+lean::cnstr_set(x_17, 0, x_11);
+lean::cnstr_set(x_17, 1, x_16);
+x_18 = lean::array_update(x_8, x_0, x_17);
+lean::dec(x_0);
+x_0 = x_10;
+x_1 = x_18;
+goto _start;
+}
+else
+{
+obj* x_21; obj* x_23; obj* x_24; obj* x_25; obj* x_26; 
+x_21 = lean::cnstr_get(x_6, 0);
+if (lean::is_exclusive(x_6)) {
+ x_23 = x_6;
+} else {
+ lean::inc(x_21);
+ lean::dec(x_6);
+ x_23 = lean::box(0);
+}
+x_24 = l_Lean_IR_FnBody_elimDead___main(x_21);
+if (lean::is_scalar(x_23)) {
+ x_25 = lean::alloc_cnstr(1, 1, 0);
+} else {
+ x_25 = x_23;
+}
+lean::cnstr_set(x_25, 0, x_24);
+x_26 = lean::array_update(x_8, x_0, x_25);
+lean::dec(x_0);
+x_0 = x_10;
+x_1 = x_26;
+goto _start;
+}
+}
+}
+}
+obj* l_Lean_IR_FnBody_elimDead___main(obj* x_0) {
+_start:
+{
+obj* x_1; obj* x_2; 
+x_1 = l_Lean_IR_FnBody_flatten(x_0);
+x_2 = lean::cnstr_get(x_1, 1);
+lean::inc(x_2);
+switch (lean::obj_tag(x_2)) {
+case 9:
+{
+obj* x_4; obj* x_7; obj* x_9; obj* x_11; obj* x_13; obj* x_14; obj* x_15; obj* x_16; obj* x_17; 
+x_4 = lean::cnstr_get(x_1, 0);
+lean::inc(x_4);
+lean::dec(x_1);
+x_7 = lean::cnstr_get(x_2, 0);
+x_9 = lean::cnstr_get(x_2, 1);
+x_11 = lean::cnstr_get(x_2, 2);
+if (lean::is_exclusive(x_2)) {
+ x_13 = x_2;
+} else {
+ lean::inc(x_7);
+ lean::inc(x_9);
+ lean::inc(x_11);
+ lean::dec(x_2);
+ x_13 = lean::box(0);
+}
+x_14 = lean::mk_nat_obj(0ul);
+x_15 = l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1(x_14, x_11);
+if (lean::is_scalar(x_13)) {
+ x_16 = lean::alloc_cnstr(9, 3, 0);
+} else {
+ x_16 = x_13;
+}
+lean::cnstr_set(x_16, 0, x_7);
+lean::cnstr_set(x_16, 1, x_9);
+lean::cnstr_set(x_16, 2, x_15);
+x_17 = l_Lean_IR_reshape(x_4, x_16);
+return x_17;
+}
+default:
+{
+obj* x_18; obj* x_21; 
+x_18 = lean::cnstr_get(x_1, 0);
+lean::inc(x_18);
+lean::dec(x_1);
+x_21 = l_Lean_IR_reshape(x_18, x_2);
+return x_21;
+}
+}
+}
+}
+obj* l_Lean_IR_FnBody_elimDead(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = l_Lean_IR_FnBody_elimDead___main(x_0);
+return x_1;
+}
+}
+obj* l_Lean_IR_Decl_elimDead___main(obj* x_0) {
+_start:
+{
+if (lean::obj_tag(x_0) == 0)
+{
+obj* x_1; obj* x_3; uint8 x_5; obj* x_6; obj* x_8; obj* x_9; obj* x_10; obj* x_11; 
+x_1 = lean::cnstr_get(x_0, 0);
+x_3 = lean::cnstr_get(x_0, 1);
+x_5 = lean::cnstr_get_scalar<uint8>(x_0, sizeof(void*)*3);
+x_6 = lean::cnstr_get(x_0, 2);
+if (lean::is_exclusive(x_0)) {
+ x_8 = x_0;
+} else {
+ lean::inc(x_1);
+ lean::inc(x_3);
+ lean::inc(x_6);
+ lean::dec(x_0);
+ x_8 = lean::box(0);
+}
+x_9 = l_Lean_IR_FnBody_elimDead___main(x_6);
+if (lean::is_scalar(x_8)) {
+ x_10 = lean::alloc_cnstr(0, 3, 1);
+} else {
+ x_10 = x_8;
+}
+lean::cnstr_set(x_10, 0, x_1);
+lean::cnstr_set(x_10, 1, x_3);
+lean::cnstr_set(x_10, 2, x_9);
+lean::cnstr_set_scalar(x_10, sizeof(void*)*3, x_5);
+x_11 = x_10;
+return x_11;
+}
+else
+{
+return x_0;
+}
+}
+}
+namespace lean {
+namespace ir {
+obj* decl_elim_dead_core(obj* x_0) {
+_start:
+{
+obj* x_1; 
+x_1 = l_Lean_IR_Decl_elimDead___main(x_0);
+return x_1;
+}
+}
+}}
+obj* initialize_init_default(obj*);
+obj* initialize_init_lean_compiler_ir(obj*);
+static bool _G_initialized = false;
+obj* initialize_init_lean_compiler_elimdead(obj* w) {
+ if (_G_initialized) return w;
+ _G_initialized = true;
+if (io_result_is_error(w)) return w;
+w = initialize_init_default(w);
+if (io_result_is_error(w)) return w;
+w = initialize_init_lean_compiler_ir(w);
+if (io_result_is_error(w)) return w;
+ l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1___closed__1 = _init_l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1___closed__1();
+lean::mark_persistent(l_Array_hmmapAux___main___at_Lean_IR_FnBody_elimDead___main___spec__1___closed__1);
+return w;
+}
diff --git a/src/stage0/init/lean/compiler/ir.cpp b/src/stage0/init/lean/compiler/ir.cpp
index 212d4b067f..a123f7fa3d 100644
--- a/src/stage0/init/lean/compiler/ir.cpp
+++ b/src/stage0/init/lean/compiler/ir.cpp
@@ -2001,22 +2001,37 @@ x_3 = lean::mk_nat_obj(0ul);
 x_4 = lean::nat_dec_eq(x_1, x_3);
 if (x_4 == 0)
 {
-obj* x_5; obj* x_6; obj* x_8; obj* x_9; obj* x_10; obj* x_11; obj* x_12; 
+obj* x_5; obj* x_6; obj* x_8; uint8 x_9; 
 x_5 = lean::mk_nat_obj(1ul);
 x_6 = lean::nat_sub(x_1, x_5);
 lean::dec(x_1);
-x_8 = l_Lean_IR_Inhabited;
-x_9 = lean::array_get(x_8, x_0, x_6);
-x_10 = lean::box(12);
-x_11 = lean::array_set(x_0, x_6, x_10);
-x_12 = l_Lean_IR_FnBody_setBody___main(x_9, x_2);
-x_0 = x_11;
+x_8 = lean::array_get_size(x_0);
+x_9 = lean::nat_dec_lt(x_6, x_8);
+lean::dec(x_8);
+if (x_9 == 0)
+{
+obj* x_11; obj* x_12; 
+x_11 = lean::box(12);
+x_12 = l_Lean_IR_FnBody_setBody___main(x_11, x_2);
 x_1 = x_6;
 x_2 = x_12;
 goto _start;
 }
 else
 {
+obj* x_14; obj* x_15; obj* x_16; obj* x_17; 
+x_14 = lean::array_index(x_0, x_6);
+x_15 = lean::box(12);
+x_16 = lean::array_update(x_0, x_6, x_15);
+x_17 = l_Lean_IR_FnBody_setBody___main(x_14, x_2);
+x_0 = x_16;
+x_1 = x_6;
+x_2 = x_17;
+goto _start;
+}
+}
+else
+{
 lean::dec(x_1);
 lean::dec(x_0);
 return x_2;
diff --git a/src/stage0/init/lean/compiler/pushproj.cpp b/src/stage0/init/lean/compiler/pushproj.cpp
index 8bb6152f1e..b12d277ee3 100644
--- a/src/stage0/init/lean/compiler/pushproj.cpp
+++ b/src/stage0/init/lean/compiler/pushproj.cpp
@@ -14,6 +14,7 @@ typedef lean::uint32 uint32; typedef lean::uint64 uint64;
 #pragma GCC diagnostic ignored "-Wunused-label"
 #pragma GCC diagnostic ignored "-Wunused-but-set-variable"
 #endif
+obj* l_RBNode_setBlack___main___rarg(obj*);
 obj* l_Array_hmmapAux___main___at_Lean_IR_pushProjs___main___spec__3(obj*, obj*, obj*, obj*, obj*, obj*);
 obj* l_Lean_IR_FnBody_collectFreeVars(obj*, obj*);
 extern obj* l_Array_empty___closed__1;
@@ -25,6 +26,7 @@ namespace lean {
 namespace ir {
 obj* decl_push_proj_core(obj*);
 }}
+obj* l_RBNode_ins___main___at___private_init_lean_compiler_ir_2__collectIndex___spec__2(obj*, obj*, obj*);
 obj* l_Lean_IR_pushProjs___main___closed__1;
 obj* l_Array_miterateAux___main___at_Lean_IR_FnBody_pushProj___main___spec__1___boxed(obj*, obj*, obj*, obj*);
 obj* l_Array_hmmapAux___main___at_Lean_IR_FnBody_pushProj___main___spec__2(obj*, obj*);
@@ -43,6 +45,7 @@ namespace lean {
 obj* nat_add(obj*, obj*);
 }
 uint8 l_Array_isEmpty___rarg(obj*);
+uint8 l_RBNode_isRed___main___rarg(obj*);
 obj* l_Lean_IR_pushProjs(obj*, obj*, obj*, obj*, obj*);
 obj* l_Lean_IR_FnBody_pushProj___main(obj*);
 obj* l_Nat_decLt___boxed(obj*, obj*);
@@ -611,7 +614,7 @@ lean::inc(x_2);
 switch (lean::obj_tag(x_2)) {
 case 9:
 {
-obj* x_4; obj* x_7; obj* x_9; obj* x_11; obj* x_13; obj* x_14; obj* x_15; obj* x_17; obj* x_18; obj* x_19; obj* x_20; obj* x_21; obj* x_22; obj* x_24; obj* x_27; obj* x_28; obj* x_29; 
+obj* x_4; obj* x_7; obj* x_9; obj* x_11; obj* x_13; obj* x_14; obj* x_15; obj* x_17; obj* x_18; obj* x_19; uint8 x_20; 
 x_4 = lean::cnstr_get(x_1, 0);
 lean::inc(x_4);
 lean::dec(x_1);
@@ -619,6 +622,9 @@ x_7 = lean::cnstr_get(x_2, 0);
 x_9 = lean::cnstr_get(x_2, 1);
 x_11 = lean::cnstr_get(x_2, 2);
 if (lean::is_exclusive(x_2)) {
+ lean::cnstr_set(x_2, 0, lean::box(0));
+ lean::cnstr_set(x_2, 1, lean::box(0));
+ lean::cnstr_set(x_2, 2, lean::box(0));
  x_13 = x_2;
 } else {
  lean::inc(x_7);
@@ -633,33 +639,67 @@ lean::dec(x_14);
 x_17 = lean::mk_nat_obj(0ul);
 x_18 = l_Array_miterateAux___main___at_Lean_IR_FnBody_pushProj___main___spec__1(x_11, x_11, x_17, x_15);
 x_19 = lean::box(0);
-x_20 = l_Array_empty___closed__1;
-x_21 = l_Lean_IR_pushProjs___main(x_4, x_11, x_18, x_20, x_19);
-x_22 = lean::cnstr_get(x_21, 0);
-lean::inc(x_22);
-x_24 = lean::cnstr_get(x_21, 1);
-lean::inc(x_24);
-lean::dec(x_21);
-x_27 = l_Array_hmmapAux___main___at_Lean_IR_FnBody_pushProj___main___spec__2(x_17, x_24);
+x_20 = l_RBNode_isRed___main___rarg(x_19);
+if (x_20 == 0)
+{
+obj* x_21; obj* x_23; obj* x_24; obj* x_25; obj* x_26; obj* x_28; obj* x_31; obj* x_32; obj* x_33; 
+x_21 = lean::box(0);
+lean::inc(x_9);
+x_23 = l_RBNode_ins___main___at___private_init_lean_compiler_ir_2__collectIndex___spec__2(x_19, x_9, x_21);
+x_24 = l_Array_empty___closed__1;
+x_25 = l_Lean_IR_pushProjs___main(x_4, x_11, x_18, x_24, x_23);
+x_26 = lean::cnstr_get(x_25, 0);
+lean::inc(x_26);
+x_28 = lean::cnstr_get(x_25, 1);
+lean::inc(x_28);
+lean::dec(x_25);
+x_31 = l_Array_hmmapAux___main___at_Lean_IR_FnBody_pushProj___main___spec__2(x_17, x_28);
 if (lean::is_scalar(x_13)) {
- x_28 = lean::alloc_cnstr(9, 3, 0);
+ x_32 = lean::alloc_cnstr(9, 3, 0);
 } else {
- x_28 = x_13;
+ x_32 = x_13;
+}
+lean::cnstr_set(x_32, 0, x_7);
+lean::cnstr_set(x_32, 1, x_9);
+lean::cnstr_set(x_32, 2, x_31);
+x_33 = l_Lean_IR_reshape(x_26, x_32);
+return x_33;
+}
+else
+{
+obj* x_34; obj* x_36; obj* x_37; obj* x_38; obj* x_39; obj* x_40; obj* x_42; obj* x_45; obj* x_46; obj* x_47; 
+x_34 = lean::box(0);
+lean::inc(x_9);
+x_36 = l_RBNode_ins___main___at___private_init_lean_compiler_ir_2__collectIndex___spec__2(x_19, x_9, x_34);
+x_37 = l_RBNode_setBlack___main___rarg(x_36);
+x_38 = l_Array_empty___closed__1;
+x_39 = l_Lean_IR_pushProjs___main(x_4, x_11, x_18, x_38, x_37);
+x_40 = lean::cnstr_get(x_39, 0);
+lean::inc(x_40);
+x_42 = lean::cnstr_get(x_39, 1);
+lean::inc(x_42);
+lean::dec(x_39);
+x_45 = l_Array_hmmapAux___main___at_Lean_IR_FnBody_pushProj___main___spec__2(x_17, x_42);
+if (lean::is_scalar(x_13)) {
+ x_46 = lean::alloc_cnstr(9, 3, 0);
+} else {
+ x_46 = x_13;
+}
+lean::cnstr_set(x_46, 0, x_7);
+lean::cnstr_set(x_46, 1, x_9);
+lean::cnstr_set(x_46, 2, x_45);
+x_47 = l_Lean_IR_reshape(x_40, x_46);
+return x_47;
 }
-lean::cnstr_set(x_28, 0, x_7);
-lean::cnstr_set(x_28, 1, x_9);
-lean::cnstr_set(x_28, 2, x_27);
-x_29 = l_Lean_IR_reshape(x_22, x_28);
-return x_29;
 }
 default:
 {
-obj* x_30; obj* x_33; 
-x_30 = lean::cnstr_get(x_1, 0);
-lean::inc(x_30);
+obj* x_48; obj* x_51; 
+x_48 = lean::cnstr_get(x_1, 0);
+lean::inc(x_48);
 lean::dec(x_1);
-x_33 = l_Lean_IR_reshape(x_30, x_2);
-return x_33;
+x_51 = l_Lean_IR_reshape(x_48, x_2);
+return x_51;
 }
 }
 }