diff --git a/.gitignore b/.gitignore
index f81fd54..031a38c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1 @@
-SOURCES/spirv-tools-1fbed83c8aab8517d821fcb4164c08567951938f.tar.gz
+SOURCES/spirv-tools-21e3f681e2004590c7865bc8c0195a4ab8e66c88.tar.gz
diff --git a/.spirv-tools.metadata b/.spirv-tools.metadata
index 34d7abe..2fc929e 100644
--- a/.spirv-tools.metadata
+++ b/.spirv-tools.metadata
@@ -1 +1 @@
-bdb75c83663ab3dc120137ca8858fcdb41f1ed57 SOURCES/spirv-tools-1fbed83c8aab8517d821fcb4164c08567951938f.tar.gz
+0ab8feda8d1e26ad379255c7d51ca38c28abfe6c SOURCES/spirv-tools-21e3f681e2004590c7865bc8c0195a4ab8e66c88.tar.gz
diff --git a/SOURCES/0001-optimizer-restore-previous-ABI.patch b/SOURCES/0001-optimizer-restore-previous-ABI.patch
new file mode 100644
index 0000000..41b9c17
--- /dev/null
+++ b/SOURCES/0001-optimizer-restore-previous-ABI.patch
@@ -0,0 +1,85 @@
+From 76e9ab018c24eaed0bc83c83cf72bc4542e5f1ad Mon Sep 17 00:00:00 2001
+From: Dave Airlie <airlied@redhat.com>
+Date: Mon, 6 Dec 2021 13:49:10 +1000
+Subject: [PATCH] optimizer: restore previous ABI.
+
+The change in
+commit 4ac8e5e541ea992dc6f44a4d4eb065a8fe0888ec
+Author: Greg Fischer <greg@lunarg.com>
+Date:   Wed Sep 15 12:38:34 2021 -0600
+
+    Add preserve_interface mode to aggressive_dead_code_elim (#4520)
+
+Broke the C++ ABI for spirv-tools shared libraries on Linux, for not a great reason.
+
+Restore the previous ABI.
+---
+ include/spirv-tools/optimizer.hpp |  3 ++-
+ source/opt/optimizer.cpp          | 17 +++++++++++------
+ 2 files changed, 13 insertions(+), 7 deletions(-)
+
+diff --git a/include/spirv-tools/optimizer.hpp b/include/spirv-tools/optimizer.hpp
+index 21059cbe..a0314b5f 100644
+--- a/include/spirv-tools/optimizer.hpp
++++ b/include/spirv-tools/optimizer.hpp
+@@ -519,7 +519,8 @@ Optimizer::PassToken CreateDeadInsertElimPass();
+ // interface are considered live and are not eliminated. This mode is needed
+ // by GPU-Assisted validation instrumentation, where a change in the interface
+ // is not allowed.
+-Optimizer::PassToken CreateAggressiveDCEPass(bool preserve_interface = false);
++Optimizer::PassToken CreateAggressiveDCEPass();
++Optimizer::PassToken CreateAggressiveDCEPassPreserveInterface();
+ 
+ // Creates a remove-unused-interface-variables pass.
+ // Removes variables referenced on the |OpEntryPoint| instruction that are not
+diff --git a/source/opt/optimizer.cpp b/source/opt/optimizer.cpp
+index e74db26f..d5534d08 100644
+--- a/source/opt/optimizer.cpp
++++ b/source/opt/optimizer.cpp
+@@ -419,22 +419,22 @@ bool Optimizer::RegisterPassFromFlag(const std::string& flag) {
+     RegisterPass(CreateSimplificationPass());
+     RegisterPass(CreateDeadBranchElimPass());
+     RegisterPass(CreateBlockMergePass());
+-    RegisterPass(CreateAggressiveDCEPass(true));
++    RegisterPass(CreateAggressiveDCEPassPreserveInterface());
+   } else if (pass_name == "inst-desc-idx-check") {
+     RegisterPass(CreateInstBindlessCheckPass(7, 23, true, true));
+     RegisterPass(CreateSimplificationPass());
+     RegisterPass(CreateDeadBranchElimPass());
+     RegisterPass(CreateBlockMergePass());
+-    RegisterPass(CreateAggressiveDCEPass(true));
++    RegisterPass(CreateAggressiveDCEPassPreserveInterface());
+   } else if (pass_name == "inst-buff-oob-check") {
+     RegisterPass(CreateInstBindlessCheckPass(7, 23, false, false, true, true));
+     RegisterPass(CreateSimplificationPass());
+     RegisterPass(CreateDeadBranchElimPass());
+     RegisterPass(CreateBlockMergePass());
+-    RegisterPass(CreateAggressiveDCEPass(true));
++    RegisterPass(CreateAggressiveDCEPassPreserveInterface());
+   } else if (pass_name == "inst-buff-addr-check") {
+     RegisterPass(CreateInstBuffAddrCheckPass(7, 23));
+-    RegisterPass(CreateAggressiveDCEPass(true));
++    RegisterPass(CreateAggressiveDCEPassPreserveInterface());
+   } else if (pass_name == "convert-relaxed-to-half") {
+     RegisterPass(CreateConvertRelaxedToHalfPass());
+   } else if (pass_name == "relax-float-ops") {
+@@ -764,9 +764,14 @@ Optimizer::PassToken CreateLocalMultiStoreElimPass() {
+       MakeUnique<opt::SSARewritePass>());
+ }
+ 
+-Optimizer::PassToken CreateAggressiveDCEPass(bool preserve_interface) {
++Optimizer::PassToken CreateAggressiveDCEPass() {
+   return MakeUnique<Optimizer::PassToken::Impl>(
+-      MakeUnique<opt::AggressiveDCEPass>(preserve_interface));
++      MakeUnique<opt::AggressiveDCEPass>(false));
++}
++
++Optimizer::PassToken CreateAggressiveDCEPassPreserveInterface() {
++  return MakeUnique<Optimizer::PassToken::Impl>(
++      MakeUnique<opt::AggressiveDCEPass>(true));
+ }
+ 
+ Optimizer::PassToken CreateRemoveUnusedInterfaceVariablesPass() {
+-- 
+2.33.1
+
diff --git a/SPECS/spirv-tools.spec b/SPECS/spirv-tools.spec
index 5fd9f0b..39a5e51 100644
--- a/SPECS/spirv-tools.spec
+++ b/SPECS/spirv-tools.spec
@@ -1,17 +1,18 @@
-%global commit 1fbed83c8aab8517d821fcb4164c08567951938f
+%global commit 21e3f681e2004590c7865bc8c0195a4ab8e66c88
 %global shortcommit %(c=%{commit}; echo ${c:0:7})
-%global commit_date 20210825
+%global commit_date 20211110
 %global gitrel .%{commit_date}.git%{shortcommit}
 
 Name:           spirv-tools
-Version:        2021.3
-Release:        1%{?gitrel}%{?dist}
+Version:        2021.4
+Release:        2%{?gitrel}%{?dist}
 Summary:        API and commands for processing SPIR-V modules
 
 License:        ASL 2.0
 URL:            https://github.com/KhronosGroup/SPIRV-Tools
 Source0:        %url/archive/%{commit}.tar.gz#/%{name}-%{commit}.tar.gz
 
+Patch0: 0001-optimizer-restore-previous-ABI.patch
 BuildRequires:  cmake
 BuildRequires:  gcc-c++
 BuildRequires:  ninja-build
@@ -90,6 +91,12 @@ popd
 %{_libdir}/pkgconfig/SPIRV-Tools.pc
 
 %changelog
+* Thu Dec 09 2021 Dave Airlie <airlied@redhat.com> - 2021.4-2.20211110.git21e3f68
+- Restore upstream ABI
+
+* Thu Nov 25 2021 Dave Airlie <airlied@redhat.com> - 2021.4-1.20211110.git21e3f68
+- Update to 1.2.198.0 SDK Version
+
 * Wed Sep 08 2021 Dave Airlie <airlied@redhat.com> - 2021.3-1
 - Update to 1.2.189.0 SDK version